draft-ietf-cellar-ffv1-v4-14.txt		draft-ietf-cellar-ffv1-v4-15.txt
	cellar M. Niedermayer		cellar M. Niedermayer
	Internet-Draft		Internet-Draft
	Intended status: Standards Track D. Rice		Intended status: Standards Track D. Rice
	Expires: 22 February 2021		Expires: 10 April 2021
	J. Martinez		J. Martinez
	21 August 2020		7 October 2020
	FFV1 Video Coding Format Version 4		FFV1 Video Coding Format Version 4
	draft-ietf-cellar-ffv1-v4-14		draft-ietf-cellar-ffv1-v4-15
	Abstract		Abstract
	This document defines FFV1, a lossless intra-frame video encoding		This document defines FFV1, a lossless intra-frame video encoding
	format. FFV1 is designed to efficiently compress video data in a		format. FFV1 is designed to efficiently compress video data in a
	variety of pixel formats. Compared to uncompressed video, FFV1		variety of pixel formats. Compared to uncompressed video, FFV1
	offers storage compression, frame fixity, and self-description, which		offers storage compression, frame fixity, and self-description, which
	makes FFV1 useful as a preservation or intermediate video format.		makes FFV1 useful as a preservation or intermediate video format.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
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	material or to cite them other than as "work in progress."		material or to cite them other than as "work in progress."
	This Internet-Draft will expire on 22 February 2021.		This Internet-Draft will expire on 10 April 2021.
	Copyright Notice		Copyright Notice
	Copyright (c) 2020 IETF Trust and the persons identified as the		Copyright (c) 2020 IETF Trust and the persons identified as the
	document authors. All rights reserved.		document authors. All rights reserved.
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	Provisions Relating to IETF Documents (https://trustee.ietf.org/		Provisions Relating to IETF Documents (https://trustee.ietf.org/
	license-info) in effect on the date of publication of this document.		license-info) in effect on the date of publication of this document.
	Please review these documents carefully, as they describe your rights		Please review these documents carefully, as they describe your rights
	skipping to change at page 2, line 20 ¶		skipping to change at page 2, line 20 ¶
	extracted from this document must include Simplified BSD License text		extracted from this document must include Simplified BSD License text
	as described in Section 4.e of the Trust Legal Provisions and are		as described in Section 4.e of the Trust Legal Provisions and are
	provided without warranty as described in the Simplified BSD License.		provided without warranty as described in the Simplified BSD License.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
	2. Notation and Conventions . . . . . . . . . . . . . . . . . . 4		2. Notation and Conventions . . . . . . . . . . . . . . . . . . 4
	2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4		2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 4
	2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5		2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5
	2.2.1. Pseudo-code . . . . . . . . . . . . . . . . . . . . . 5		2.2.1. Pseudo-code . . . . . . . . . . . . . . . . . . . . . 6
	2.2.2. Arithmetic Operators . . . . . . . . . . . . . . . . 6		2.2.2. Arithmetic Operators . . . . . . . . . . . . . . . . 6
	2.2.3. Assignment Operators . . . . . . . . . . . . . . . . 6		2.2.3. Assignment Operators . . . . . . . . . . . . . . . . 7
	2.2.4. Comparison Operators . . . . . . . . . . . . . . . . 7		2.2.4. Comparison Operators . . . . . . . . . . . . . . . . 7
	2.2.5. Mathematical Functions . . . . . . . . . . . . . . . 7		2.2.5. Mathematical Functions . . . . . . . . . . . . . . . 7
	2.2.6. Order of Operation Precedence . . . . . . . . . . . . 8		2.2.6. Order of Operation Precedence . . . . . . . . . . . . 8
	2.2.7. Range . . . . . . . . . . . . . . . . . . . . . . . . 8		2.2.7. Range . . . . . . . . . . . . . . . . . . . . . . . . 9
	2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 8		2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 9
	2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 9		2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 9
	3. Sample Coding . . . . . . . . . . . . . . . . . . . . . . . . 9		3. Sample Coding . . . . . . . . . . . . . . . . . . . . . . . . 9
	3.1. Border . . . . . . . . . . . . . . . . . . . . . . . . . 9		3.1. Border . . . . . . . . . . . . . . . . . . . . . . . . . 10
	3.2. Samples . . . . . . . . . . . . . . . . . . . . . . . . . 10		3.2. Samples . . . . . . . . . . . . . . . . . . . . . . . . . 10
	3.3. Median Predictor . . . . . . . . . . . . . . . . . . . . 11		3.3. Median Predictor . . . . . . . . . . . . . . . . . . . . 11
	3.4. Quantization Table Sets . . . . . . . . . . . . . . . . . 12		3.4. Quantization Table Sets . . . . . . . . . . . . . . . . . 12
	3.5. Context . . . . . . . . . . . . . . . . . . . . . . . . . 12		3.5. Context . . . . . . . . . . . . . . . . . . . . . . . . . 12
	3.6. Quantization Table Set Indexes . . . . . . . . . . . . . 12		3.6. Quantization Table Set Indexes . . . . . . . . . . . . . 12
	3.7. Color spaces . . . . . . . . . . . . . . . . . . . . . . 13		3.7. Color spaces . . . . . . . . . . . . . . . . . . . . . . 13
	3.7.1. YCbCr . . . . . . . . . . . . . . . . . . . . . . . . 13		3.7.1. YCbCr . . . . . . . . . . . . . . . . . . . . . . . . 13
	3.7.2. RGB . . . . . . . . . . . . . . . . . . . . . . . . . 13		3.7.2. RGB . . . . . . . . . . . . . . . . . . . . . . . . . 14
	3.8. Coding of the Sample Difference . . . . . . . . . . . . . 15		3.8. Coding of the Sample Difference . . . . . . . . . . . . . 15
	3.8.1. Range Coding Mode . . . . . . . . . . . . . . . . . . 15		3.8.1. Range Coding Mode . . . . . . . . . . . . . . . . . . 15
	3.8.2. Golomb Rice Mode . . . . . . . . . . . . . . . . . . 21		3.8.2. Golomb Rice Mode . . . . . . . . . . . . . . . . . . 22
	4. Bitstream . . . . . . . . . . . . . . . . . . . . . . . . . . 26		4. Bitstream . . . . . . . . . . . . . . . . . . . . . . . . . . 28
	4.1. Quantization Table Set . . . . . . . . . . . . . . . . . 27		4.1. Quantization Table Set . . . . . . . . . . . . . . . . . 29
	4.1.1. quant_tables . . . . . . . . . . . . . . . . . . . . 28		4.1.1. quant_tables . . . . . . . . . . . . . . . . . . . . 30
	4.1.2. context_count . . . . . . . . . . . . . . . . . . . . 29		4.1.2. context_count . . . . . . . . . . . . . . . . . . . . 31
	4.2. Parameters . . . . . . . . . . . . . . . . . . . . . . . 29		4.2. Parameters . . . . . . . . . . . . . . . . . . . . . . . 31
	4.2.1. version . . . . . . . . . . . . . . . . . . . . . . . 31		4.2.1. version . . . . . . . . . . . . . . . . . . . . . . . 33
	4.2.2. micro_version . . . . . . . . . . . . . . . . . . . . 31		4.2.2. micro_version . . . . . . . . . . . . . . . . . . . . 33
	4.2.3. coder_type . . . . . . . . . . . . . . . . . . . . . 32		4.2.3. coder_type . . . . . . . . . . . . . . . . . . . . . 34
	4.2.4. state_transition_delta . . . . . . . . . . . . . . . 33		4.2.4. state_transition_delta . . . . . . . . . . . . . . . 35
	4.2.5. colorspace_type . . . . . . . . . . . . . . . . . . . 33		4.2.5. colorspace_type . . . . . . . . . . . . . . . . . . . 35
	4.2.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 34		4.2.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 36
	4.2.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 34		4.2.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 36
	4.2.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 35		4.2.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 37
	4.2.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 35		4.2.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 37
	4.2.10. extra_plane . . . . . . . . . . . . . . . . . . . . . 35		4.2.10. extra_plane . . . . . . . . . . . . . . . . . . . . . 37
	4.2.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 35		4.2.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 37
	4.2.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 36		4.2.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 38
	4.2.13. quant_table_set_count . . . . . . . . . . . . . . . . 36		4.2.13. quant_table_set_count . . . . . . . . . . . . . . . . 38
	4.2.14. states_coded . . . . . . . . . . . . . . . . . . . . 36		4.2.14. states_coded . . . . . . . . . . . . . . . . . . . . 38
	4.2.15. initial_state_delta . . . . . . . . . . . . . . . . . 36		4.2.15. initial_state_delta . . . . . . . . . . . . . . . . . 38
	4.2.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 37		4.2.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 39
	4.2.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 37		4.2.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 39
	4.3. Configuration Record . . . . . . . . . . . . . . . . . . 37		4.3. Configuration Record . . . . . . . . . . . . . . . . . . 39
	4.3.1. reserved_for_future_use . . . . . . . . . . . . . . . 38		4.3.1. reserved_for_future_use . . . . . . . . . . . . . . . 40
	4.3.2. configuration_record_crc_parity . . . . . . . . . . . 38		4.3.2. configuration_record_crc_parity . . . . . . . . . . . 40
	4.3.3. Mapping FFV1 into Containers . . . . . . . . . . . . 38		4.3.3. Mapping FFV1 into Containers . . . . . . . . . . . . 40
	4.4. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 39		4.4. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 41
	4.5. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 41		4.5. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 43
	4.6. Slice Header . . . . . . . . . . . . . . . . . . . . . . 42		4.6. Slice Header . . . . . . . . . . . . . . . . . . . . . . 44
	4.6.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 42		4.6.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 44
	4.6.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 42		4.6.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 44
	4.6.3. slice_width . . . . . . . . . . . . . . . . . . . . . 42		4.6.3. slice_width . . . . . . . . . . . . . . . . . . . . . 44
	4.6.4. slice_height . . . . . . . . . . . . . . . . . . . . 43		4.6.4. slice_height . . . . . . . . . . . . . . . . . . . . 45
	4.6.5. quant_table_set_index_count . . . . . . . . . . . . . 43		4.6.5. quant_table_set_index_count . . . . . . . . . . . . . 45
	4.6.6. quant_table_set_index . . . . . . . . . . . . . . . . 43		4.6.6. quant_table_set_index . . . . . . . . . . . . . . . . 45
	4.6.7. picture_structure . . . . . . . . . . . . . . . . . . 43		4.6.7. picture_structure . . . . . . . . . . . . . . . . . . 45
	4.6.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 44		4.6.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 46
	4.6.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 44		4.6.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 46
	4.6.10. reset_contexts . . . . . . . . . . . . . . . . . . . 44		4.6.10. reset_contexts . . . . . . . . . . . . . . . . . . . 46
	4.6.11. slice_coding_mode . . . . . . . . . . . . . . . . . . 44		4.6.11. slice_coding_mode . . . . . . . . . . . . . . . . . . 46
	4.7. Slice Content . . . . . . . . . . . . . . . . . . . . . . 45		4.7. Slice Content . . . . . . . . . . . . . . . . . . . . . . 47
	4.7.1. primary_color_count . . . . . . . . . . . . . . . . . 45		4.7.1. primary_color_count . . . . . . . . . . . . . . . . . 47
	4.7.2. plane_pixel_height . . . . . . . . . . . . . . . . . 45		4.7.2. plane_pixel_height . . . . . . . . . . . . . . . . . 47
	4.7.3. slice_pixel_height . . . . . . . . . . . . . . . . . 46		4.7.3. slice_pixel_height . . . . . . . . . . . . . . . . . 48
	4.7.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 46		4.7.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 48
	4.8. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 46		4.8. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 48
	4.8.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 46		4.8.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 48
	4.8.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 47		4.8.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 49
	4.8.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 47		4.8.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 49
	4.8.4. sample_difference . . . . . . . . . . . . . . . . . . 47		4.8.4. sample_difference . . . . . . . . . . . . . . . . . . 49
	4.9. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 47		4.9. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 49
	4.9.1. slice_size . . . . . . . . . . . . . . . . . . . . . 48		4.9.1. slice_size . . . . . . . . . . . . . . . . . . . . . 50
	4.9.2. error_status . . . . . . . . . . . . . . . . . . . . 48		4.9.2. error_status . . . . . . . . . . . . . . . . . . . . 50
	4.9.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 48		4.9.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 50
	5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 48		5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 50
	6. Security Considerations . . . . . . . . . . . . . . . . . . . 49		6. Security Considerations . . . . . . . . . . . . . . . . . . . 51
	7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 50		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 52
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 51		7.1. Media Type Definition . . . . . . . . . . . . . . . . . . 52
	9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 51		8. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 53
	10. Normative References . . . . . . . . . . . . . . . . . . . . 51		9. Normative References . . . . . . . . . . . . . . . . . . . . 53
	11. Informative References . . . . . . . . . . . . . . . . . . . 52		10. Informative References . . . . . . . . . . . . . . . . . . . 54
	Appendix A. Multi-theaded decoder implementation suggestions . . 54		Appendix A. Multi-theaded decoder implementation suggestions . . 55
	Appendix B. Future handling of some streams created by non		Appendix B. Future handling of some streams created by non
	conforming encoders . . . . . . . . . . . . . . . . . . . 54		conforming encoders . . . . . . . . . . . . . . . . . . . 56
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 56
	1. Introduction		1. Introduction
	This document describes FFV1, a lossless video encoding format. The		This document describes FFV1, a lossless video encoding format. The
	design of FFV1 considers the storage of image characteristics, data		design of FFV1 considers the storage of image characteristics, data
	fixity, and the optimized use of encoding time and storage		fixity, and the optimized use of encoding time and storage
	requirements. FFV1 is designed to support a wide range of lossless		requirements. FFV1 is designed to support a wide range of lossless
	video applications such as long-term audiovisual preservation,		video applications such as long-term audiovisual preservation,
	scientific imaging, screen recording, and other video encoding		scientific imaging, screen recording, and other video encoding
	scenarios that seek to avoid the generational loss of lossy video		scenarios that seek to avoid the generational loss of lossy video
	skipping to change at page 4, line 46 ¶		skipping to change at page 4, line 46 ¶
	2. Notation and Conventions		2. Notation and Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and		"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
	"OPTIONAL" in this document are to be interpreted as described in BCP		"OPTIONAL" in this document are to be interpreted as described in BCP
	14 [RFC2119] [RFC8174] when, and only when, they appear in all		14 [RFC2119] [RFC8174] when, and only when, they appear in all
	capitals, as shown here.		capitals, as shown here.
	2.1. Definitions		2.1. Definitions
	"Container": Format that encapsulates "Frames" (see Section 4.4) and		"FFV1": choosen name of this video encoding format, short version of
			"FF Video 1", the letters "FF" coming from "FFmpeg", the name of the
			reference decoder, whose the first letters originaly means "Fast
			Forward".
			"Container": Format that encapsulates Frames (see Section 4.4) and
	(when required) a "Configuration Record" into a bitstream.		(when required) a "Configuration Record" into a bitstream.
	"Sample": The smallest addressable representation of a color		"Sample": The smallest addressable representation of a color
	component or a luma component in a "Frame". Examples of "Sample" are		component or a luma component in a Frame. Examples of Sample are
	Luma (Y), Blue-difference Chroma (Cb), Red-difference Chroma (Cr),		Luma (Y), Blue-difference Chroma (Cb), Red-difference Chroma (Cr),
	Transparency, Red, Green, and Blue.		Transparency, Red, Green, and Blue.
	"Plane": A discrete component of a static image comprised of		"Symbol": A value stored in the bitstream, which is defined and
	"Samples" that represent a specific quantification of "Samples" of		decoded through one of the methods described in Table 4.
	that image.
			"Line": A discrete component of a static image composed of Samples
			that represent a specific quantification of Samples of that image.
			"Plane": A discrete component of a static image composed of Lines
			that represent a specific quantification of Lines of that image.
	"Pixel": The smallest addressable representation of a color in a		"Pixel": The smallest addressable representation of a color in a
	"Frame". It is composed of one or more "Samples".		Frame. It is composed of one or more Samples.
	"ESC": An ESCape symbol to indicate that the symbol to be stored is		"ESC": An ESCape Symbol to indicate that the Symbol to be stored is
	too large for normal storage and that an alternate storage method is		too large for normal storage and that an alternate storage method is
	used.		used.
	"MSB": Most Significant Bit, the bit that can cause the largest		"MSB": Most Significant Bit, the bit that can cause the largest
	change in magnitude of the symbol.		change in magnitude of the Symbol.
	"VLC": Variable Length Code, a code that maps source symbols to a		"VLC": Variable Length Code, a code that maps source symbols to a
	variable number of bits.		variable number of bits.
	"RGB": A reference to the method of storing the value of a "Pixel" by		"RGB": A reference to the method of storing the value of a Pixel by
	using three numeric values that represent Red, Green, and Blue.		using three numeric values that represent Red, Green, and Blue.
	"YCbCr": A reference to the method of storing the value of a "Pixel"		"YCbCr": A reference to the method of storing the value of a Pixel by
	by using three numeric values that represent the luma of the "Pixel"		using three numeric values that represent the luma of the Pixel (Y)
	(Y) and the chroma of the "Pixel" (Cb and Cr). YCbCr word is used		and the chroma of the Pixel (Cb and Cr). YCbCr word is used for
	for historical reasons and currently references any color space		historical reasons and currently references any color space relying
	relying on 1 luma "Sample" and 2 chroma "Samples", e.g. YCbCr, YCgCo		on 1 luma Sample and 2 chroma Samples, e.g. YCbCr, YCgCo or ICtCp.
	or ICtCp. The exact meaning of the three numeric values is		The exact meaning of the three numeric values is unspecified.
	unspecified.
	"TBA": To Be Announced. Used in reference to the development of		"TBA": To Be Announced. Used in reference to the development of
	future iterations of the FFV1 specification.		future iterations of the FFV1 specification.
	2.2. Conventions		2.2. Conventions
	2.2.1. Pseudo-code		2.2.1. Pseudo-code
	The FFV1 bitstream is described in this document using pseudo-code.		The FFV1 bitstream is described in this document using pseudo-code.
	Note that the pseudo-code is used for clarity in order to illustrate		Note that the pseudo-code is used for clarity in order to illustrate
	the structure of FFV1 and not intended to specify any particular		the structure of FFV1 and not intended to specify any particular
	implementation. The pseudo-code used is based upon the C programming		implementation. The pseudo-code used is based upon the C programming
	language [ISO.9899.1990] and uses its "if/else", "while" and "for"		language [ISO.9899.2018] and uses its "if/else", "while" and "for"
	keywords as well as functions defined within this document.		keywords as well as functions defined within this document.
	In some instances, pseudo-code is presented in a two-column format		In some instances, pseudo-code is presented in a two-column format
	such as shown in Figure 1. In this form the "type" column provides a		such as shown in Figure 1. In this form the "type" column provides a
	symbol as defined in Table 4 that defines the storage of the data		Symbol as defined in Table 4 that defines the storage of the data
	referenced in that same line of pseudo-code.		referenced in that same line of pseudo-code.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	ExamplePseudoCode( ) { |		ExamplePseudoCode( ) { |
	value | ur		value | ur
	} |		} |
	Figure 1: A depiction of type-labelled pseudo-code used within		Figure 1: A depiction of type-labelled pseudo-code used within
	this document.		this document.
	skipping to change at page 7, line 17 ¶		skipping to change at page 7, line 28 ¶
	"a--" is equivalent to a is assigned a - 1.		"a--" is equivalent to a is assigned a - 1.
	"a += b" is equivalent to a is assigned a + b.		"a += b" is equivalent to a is assigned a + b.
	"a -= b" is equivalent to a is assigned a - b.		"a -= b" is equivalent to a is assigned a - b.
	"a *= b" is equivalent to a is assigned a * b.		"a *= b" is equivalent to a is assigned a * b.
	2.2.4. Comparison Operators		2.2.4. Comparison Operators
	"a > b" means a is greater than b.		"a > b" is true when a is greater than b.
	"a >= b" means a is greater than or equal to b.		"a >= b" is true when a is greater than or equal to b.
	"a < b" means a is less than b.		"a < b" is true when a is less than b.
	"a <= b" means a is less than or equal b.		"a <= b" is true when a is less than or equal b.
	"a == b" means a is equal to b.		"a == b" is true when a is equal to b.
	"a != b" means a is not equal to b.		"a != b" is true when a is not equal to b.
	"a && b" means Boolean logical "and" of a and b.		"a && b" is true when both a is true and b is true.
	"a || b" means Boolean logical "or" of a and b.		"a || b" is true when either a is true or b is true.
	"!a" means Boolean logical "not" of a.		"!a" is true when a is not true.
	"a ? b : c" if a is true, then b, otherwise c.		"a ? b : c" if a is true, then b, otherwise c.
	2.2.5. Mathematical Functions		2.2.5. Mathematical Functions
	"floor(a)" means the largest integer less than or equal to a.		"floor(a)" means the largest integer less than or equal to a.
	"ceil(a)" means the smallest integer greater than or equal to a.		"ceil(a)" means the smallest integer greater than or equal to a.
	"sign(a)" extracts the sign of a number, i.e. if a < 0 then -1, else		"sign(a)" extracts the sign of a number, i.e. if a < 0 then -1, else
	if a > 0 then 1, else 0.		if a > 0 then 1, else 0.
	"abs(a)" means the absolute value of a, i.e. "abs(a)" = "sign(a) *		"abs(a)" means the absolute value of a, i.e. "abs(a)" = "sign(a) *
	a".		a".
	"log2(a)" means the base-two logarithm of a.		"log2(a)" means the base-two logarithm of a.
	"min(a,b)" means the smallest of two values a and b.		"min(a,b)" means the smaller of two values a and b.
	"max(a,b)" means the largest of two values a and b.		"max(a,b)" means the larger of two values a and b.
	"median(a,b,c)" means the numerical middle value in a data set of a,		"median(a,b,c)" means the numerical middle value in a data set of a,
	b, and c, i.e. a+b+c-min(a,b,c)-max(a,b,c).		b, and c, i.e. a+b+c-min(a,b,c)-max(a,b,c).
	"A <== B" means B implies A.		"A <== B" means B implies A.
	"A <==> B" means A <== B , B <== A.		"A <==> B" means A <== B , B <== A.
	a_(b) means the b-th value of a sequence of a		a_(b) means the b-th value of a sequence of a
	skipping to change at page 8, line 29 ¶		skipping to change at page 8, line 39 ¶
	When order of precedence is not indicated explicitly by use of		When order of precedence is not indicated explicitly by use of
	parentheses, operations are evaluated in the following order (from		parentheses, operations are evaluated in the following order (from
	top to bottom, operations of same precedence being evaluated from		top to bottom, operations of same precedence being evaluated from
	left to right). This order of operations is based on the order of		left to right). This order of operations is based on the order of
	operations used in Standard C.		operations used in Standard C.
	a++, a--		a++, a--
	!a, -a		!a, -a
	a ^ b		a ^ b
	a * b, a / b, a % b		a * b, a / b
	a + b, a - b		a + b, a - b
	a << b, a >> b		a << b, a >> b
	a < b, a <= b, a > b, a >= b		a < b, a <= b, a > b, a >= b
	a == b, a != b		a == b, a != b
	a & b		a & b
	a | b		a | b
	a && b		a && b
	a || b		a || b
	a ? b : c		a ? b : c
	a = b, a += b, a -= b, a *= b		a = b, a += b, a -= b, a *= b
	2.2.7. Range		2.2.7. Range
	"a...b" means any value starting from a to b, inclusive.		"a...b" means any value from a to b, inclusive.
	2.2.8. NumBytes		2.2.8. NumBytes
	"NumBytes" is a non-negative integer that expresses the size in 8-bit		"NumBytes" is a non-negative integer that expresses the size in 8-bit
	octets of a particular FFV1 "Configuration Record" or "Frame". FFV1		octets of a particular FFV1 "Configuration Record" or "Frame". FFV1
	relies on its "Container" to store the "NumBytes" values; see		relies on its Container to store the "NumBytes" values; see
	Section 4.3.3.		Section 4.3.3.
	2.2.9. Bitstream Functions		2.2.9. Bitstream Functions
	2.2.9.1. remaining_bits_in_bitstream		2.2.9.1. remaining_bits_in_bitstream
	"remaining_bits_in_bitstream( )" means the count of remaining bits		"remaining_bits_in_bitstream( NumBytes )" means the count of
	after the pointer in that "Configuration Record" or "Frame". It is		remaining bits after the pointer in that "Configuration Record" or
	computed from the "NumBytes" value multiplied by 8 minus the count of		"Frame". It is computed from the "NumBytes" value multiplied by 8
	bits of that "Configuration Record" or "Frame" already read by the		minus the count of bits of that "Configuration Record" or "Frame"
	bitstream parser.		already read by the bitstream parser.
	2.2.9.2. remaining_symbols_in_syntax		2.2.9.2. remaining_symbols_in_syntax
	"remaining_symbols_in_syntax( )" is true as long as the RangeCoder		"remaining_symbols_in_syntax( )" is true as long as the RangeCoder
	has not consumed all the given input bytes.		has not consumed all the given input bytes.
	2.2.9.3. byte_aligned		2.2.9.3. byte_aligned
	"byte_aligned( )" is true if "remaining_bits_in_bitstream( NumBytes		"byte_aligned( )" is true if "remaining_bits_in_bitstream( NumBytes
	)" is a multiple of 8, otherwise false.		)" is a multiple of 8, otherwise false.
	2.2.9.4. get_bits		2.2.9.4. get_bits
	"get_bits( i )" is the action to read the next "i" bits in the		"get_bits( i )" is the action to read the next "i" bits in the
	bitstream, from most significant bit to least significant bit, and to		bitstream, from most significant bit to least significant bit, and to
	return the corresponding value. The pointer is increased by "i".		return the corresponding value. The pointer is increased by "i".
	3. Sample Coding		3. Sample Coding
	For each "Slice" (as described in Section 4.5) of a "Frame", the		For each "Slice" (as described in Section 4.5) of a Frame, the
	"Planes", "Lines", and "Samples" are coded in an order determined by		Planes, Lines, and Samples are coded in an order determined by the
	the "Color Space" (see Section 3.7). Each "Sample" is predicted by		color space (see Section 3.7). Each Sample is predicted by the
	the median predictor as described in Section 3.3 from other "Samples"		median predictor as described in Section 3.3 from other Samples
	within the same "Plane" and the difference is stored using the method		within the same Plane and the difference is stored using the method
	described in Section 3.8.		described in Section 3.8.
	3.1. Border		3.1. Border
	A border is assumed for each coded "Slice" for the purpose of the		A border is assumed for each coded "Slice" for the purpose of the
	median predictor and context according to the following rules:		median predictor and context according to the following rules:
	* one column of "Samples" to the left of the coded slice is assumed		* one column of Samples to the left of the coded slice is assumed as
	as identical to the "Samples" of the leftmost column of the coded		identical to the Samples of the leftmost column of the coded slice
	slice shifted down by one row. The value of the topmost "Sample"		shifted down by one row. The value of the topmost Sample of the
	of the column of "Samples" to the left of the coded slice is		column of Samples to the left of the coded slice is assumed to be
	assumed to be "0"		"0"
	* one column of "Samples" to the right of the coded slice is assumed		* one column of Samples to the right of the coded slice is assumed
	as identical to the "Samples" of the rightmost column of the coded		as identical to the Samples of the rightmost column of the coded
	slice		slice
	* an additional column of "Samples" to the left of the coded slice		* an additional column of Samples to the left of the coded slice and
	and two rows of "Samples" above the coded slice are assumed to be		two rows of Samples above the coded slice are assumed to be "0"
	"0"
	Figure 2 depicts a slice of 9 "Samples" "a,b,c,d,e,f,g,h,i" in a 3x3		Figure 2 depicts a slice of 9 Samples "a,b,c,d,e,f,g,h,i" in a 3x3
	arrangement along with its assumed border.		arrangement along with its assumed border.
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | 0 | 0 | 0 | | 0 |		| 0 | 0 | | 0 | 0 | 0 | | 0 |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | 0 | 0 | 0 | | 0 |		| 0 | 0 | | 0 | 0 | 0 | | 0 |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| | | | | | | | |		| | | | | | | | |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | 0 | | a | b | c | | c |		| 0 | 0 | | a | b | c | | c |
	skipping to change at page 10, line 35 ¶		skipping to change at page 10, line 45 ¶
	| 0 | a | | d | e | f | | f |		| 0 | a | | d | e | f | | f |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	| 0 | d | | g | h | i | | i |		| 0 | d | | g | h | i | | i |
	+---+---+---+---+---+---+---+---+		+---+---+---+---+---+---+---+---+
	Figure 2: A depiction of FFV1's assumed border for a set example		Figure 2: A depiction of FFV1's assumed border for a set example
	Samples.		Samples.
	3.2. Samples		3.2. Samples
	Relative to any "Sample" "X", six other relatively positioned		Relative to any Sample "X", six other relatively positioned Samples
	"Samples" from the coded "Samples" and presumed border are identified		from the coded Samples and presumed border are identified according
	according to the labels used in Figure 3. The labels for these		to the labels used in Figure 3. The labels for these relatively
	relatively positioned "Samples" are used within the median predictor		positioned Samples are used within the median predictor and context.
	and context.
	+---+---+---+---+		+---+---+---+---+
	| | | T | |		| | | T | |
	+---+---+---+---+		+---+---+---+---+
	| |tl | t |tr |		| |tl | t |tr |
	+---+---+---+---+		+---+---+---+---+
	| L | l | X | |		| L | l | X | |
	+---+---+---+---+		+---+---+---+---+
	Figure 3: A depiction of how relatively positions Samples are		Figure 3: A depiction of how relatively positioned Samples are
	references within this document.		referenced within this document.
	The labels for these relative "Samples" are made of the first letters		The labels for these relative Samples are made of the first letters
	of the words Top, Left and Right.		of the words Top, Left and Right.
	3.3. Median Predictor		3.3. Median Predictor
	The prediction for any "Sample" value at position "X" may be computed		The prediction for any Sample value at position "X" may be computed
	based upon the relative neighboring values of "l", "t", and "tl" via		based upon the relative neighboring values of "l", "t", and "tl" via
	this equation:		this equation:
	median(l, t, l + t - tl)		median(l, t, l + t - tl)
	Note, this prediction template is also used in [ISO.14495-1.1999] and		Note, this prediction template is also used in [ISO.14495-1.1999] and
	[HuffYUV].		[HuffYUV].
	Exception for the median predictor: if "colorspace_type == 0 &&		Exception for the median predictor: if "colorspace_type == 0 &&
	bits_per_raw_sample == 16 && ( coder_type == 1 || coder_type == 2 )",		bits_per_raw_sample == 16 && ( coder_type == 1 || coder_type == 2 )"
	the following median predictor MUST be used:		(see Section 4.2.5, Section 4.2.7 and Section 4.2.5), the following
			median predictor MUST be used:
	median(left16s, top16s, left16s + top16s - diag16s)		median(left16s, top16s, left16s + top16s - diag16s)
	where:		where:
	left16s = l >= 32768 ? ( l - 65536 ) : l		left16s = l >= 32768 ? ( l - 65536 ) : l
	top16s = t >= 32768 ? ( t - 65536 ) : t		top16s = t >= 32768 ? ( t - 65536 ) : t
	diag16s = tl >= 32768 ? ( tl - 65536 ) : tl		diag16s = tl >= 32768 ? ( tl - 65536 ) : tl
	Background: a two's complement signed 16-bit signed integer was used		Background: a two's complement 16-bit signed integer was used for
	for storing "Sample" values in all known implementations of FFV1		storing Sample values in all known implementations of FFV1 bitstream.
	bitstream. So in some circumstances, the most significant bit was		So in some circumstances, the most significant bit was wrongly
	wrongly interpreted (used as a sign bit instead of the 16th bit of an		interpreted (used as a sign bit instead of the 16th bit of an
	unsigned integer). Note that when the issue was discovered, the only		unsigned integer). Note that when the issue was discovered, the only
	configuration of all known implementations being impacted is 16-bit		configuration of all known implementations being impacted is 16-bit
	YCbCr with no Pixel transformation with Range Coder coder, as other		YCbCr with no Pixel transformation with Range Coder coder, as other
	potentially impacted configurations (e.g. 15/16-bit JPEG2000-RCT with		potentially impacted configurations (e.g. 15/16-bit JPEG2000-RCT with
	Range Coder coder, or 16-bit content with Golomb Rice coder) were		Range Coder coder, or 16-bit content with Golomb Rice coder) were
	implemented nowhere [ISO.15444-1.2016]. In the meanwhile, 16-bit		implemented nowhere [ISO.15444-1.2016]. In the meanwhile, 16-bit
	JPEG2000-RCT with Range Coder coder was implemented without this		JPEG2000-RCT with Range Coder coder was implemented without this
	issue in one implementation and validated by one conformance checker.		issue in one implementation and validated by one conformance checker.
	It is expected (to be confirmed) to remove this exception for the		It is expected (to be confirmed) to remove this exception for the
	median predictor in the next version of the FFV1 bitstream.		median predictor in the next version of the FFV1 bitstream.
	skipping to change at page 12, line 25 ¶		skipping to change at page 12, line 29 ¶
	Q_(j)[k] = quant_tables[i][j][k&255]		Q_(j)[k] = quant_tables[i][j][k&255]
	Figure 4		Figure 4
	In this formula, "i" is the Quantization Table Set index, "j" is the		In this formula, "i" is the Quantization Table Set index, "j" is the
	Quantized Table index, "k" the Quantized Sample Difference.		Quantized Table index, "k" the Quantized Sample Difference.
	3.5. Context		3.5. Context
	Relative to any "Sample" "X", the Quantized Sample Differences "L-l",		Relative to any Sample "X", the Quantized Sample Differences "L-l",
	"l-tl", "tl-t", "T-t", and "t-tr" are used as context:		"l-tl", "tl-t", "T-t", and "t-tr" are used as context:
	context = Q_(0)[l - tl] +		context = Q_(0)[l - tl] +
	Q_(1)[tl - t] +		Q_(1)[tl - t] +
	Q_(2)[t - tr] +		Q_(2)[t - tr] +
	Q_(3)[L - l] +		Q_(3)[L - l] +
	Q_(4)[T - t]		Q_(4)[T - t]
	Figure 5		Figure 5
	If "context >= 0" then "context" is used and the difference between		If "context >= 0" then "context" is used and the difference between
	the "Sample" and its predicted value is encoded as is, else		the Sample and its predicted value is encoded as is, else "-context"
	"-context" is used and the difference between the "Sample" and its		is used and the difference between the Sample and its predicted value
	predicted value is encoded with a flipped sign.		is encoded with a flipped sign.
	3.6. Quantization Table Set Indexes		3.6. Quantization Table Set Indexes
	For each "Plane" of each slice, a Quantization Table Set is selected		For each Plane of each slice, a Quantization Table Set is selected
	from an index:		from an index:
	* For Y "Plane", "quant_table_set_index[ 0 ]" index is used		* For Y Plane, "quant_table_set_index[ 0 ]" index is used
			* For Cb and Cr Planes, "quant_table_set_index[ 1 ]" index is used
	* For Cb and Cr "Planes", "quant_table_set_index[ 1 ]" index is used
	* For extra "Plane", "quant_table_set_index[ (version <= 3 ||		* For extra Plane, "quant_table_set_index[ (version <= 3 ||
	chroma_planes) ? 2 : 1 ]" index is used		chroma_planes) ? 2 : 1 ]" index is used
	Background: in first implementations of FFV1 bitstream, the index for		Background: in first implementations of FFV1 bitstream, the index for
	Cb and Cr "Planes" was stored even if it is not used (chroma_planes		Cb and Cr Planes was stored even if it is not used (chroma_planes set
	set to 0), this index is kept for "version" <= 3 in order to keep		to 0), this index is kept for "version" <= 3 in order to keep
	compatibility with FFV1 bitstreams in the wild.		compatibility with FFV1 bitstreams in the wild.
	3.7. Color spaces		3.7. Color spaces
	FFV1 supports several color spaces. The count of allowed coded		FFV1 supports several color spaces. The count of allowed coded
	planes and the meaning of the extra "Plane" are determined by the		planes and the meaning of the extra Plane are determined by the
	selected color space.		selected color space.
	The FFV1 bitstream interleaves data in an order determined by the		The FFV1 bitstream interleaves data in an order determined by the
	color space. In YCbCr for each "Plane", each "Line" is coded from		color space. In YCbCr for each Plane, each Line is coded from top to
	top to bottom and for each "Line", each "Sample" is coded from left		bottom and for each Line, each Sample is coded from left to right.
	to right. In JPEG2000-RCT for each "Line" from top to bottom, each		In JPEG2000-RCT for each Line from top to bottom, each Plane is coded
	"Plane" is coded and for each "Plane", each "Sample" is encoded from		and for each Plane, each Sample is encoded from left to right.
	left to right.
	3.7.1. YCbCr		3.7.1. YCbCr
	This color space allows 1 to 4 "Planes".		This color space allows 1 to 4 Planes.
	The Cb and Cr "Planes" are optional, but if used then MUST be used		The Cb and Cr Planes are optional, but if used then MUST be used
	together. Omitting the Cb and Cr "Planes" codes the frames in		together. Omitting the Cb and Cr Planes codes the frames in
	grayscale without color data.		grayscale without color data.
	An optional transparency "Plane" can be used to code transparency		An optional transparency Plane can be used to code transparency data.
	data.
	An FFV1 "Frame" using YCbCr MUST use one of the following		An FFV1 Frame using YCbCr MUST use one of the following arrangements:
	arrangements:
	* Y		* Y
	* Y, Transparency		* Y, Transparency
	* Y, Cb, Cr		* Y, Cb, Cr
	* Y, Cb, Cr, Transparency		* Y, Cb, Cr, Transparency
	The Y "Plane" MUST be coded first. If the Cb and Cr "Planes" are		The Y Plane MUST be coded first. If the Cb and Cr Planes are used
	used then they MUST be coded after the Y "Plane". If a transparency		then they MUST be coded after the Y Plane. If a transparency Plane
	"Plane" is used, then it MUST be coded last.		is used, then it MUST be coded last.
	3.7.2. RGB		3.7.2. RGB
	This color space allows 3 or 4 "Planes".		This color space allows 3 or 4 Planes.
	An optional transparency "Plane" can be used to code transparency		An optional transparency Plane can be used to code transparency data.
	data.
	JPEG2000-RCT is a Reversible Color Transform that codes RGB (red,		JPEG2000-RCT is a Reversible Color Transform that codes RGB (red,
	green, blue) "Planes" losslessly in a modified YCbCr color space		green, blue) Planes losslessly in a modified YCbCr color space
	[ISO.15444-1.2016]. Reversible Pixel transformations between YCbCr		[ISO.15444-1.2016]. Reversible Pixel transformations between YCbCr
	and RGB use the following formulae.		and RGB use the following formulae.
	Cb = b - g		Cb = b - g
	Cr = r - g		Cr = r - g
	Y = g + (Cb + Cr) >> 2		Y = g + (Cb + Cr) >> 2
	g = Y - (Cb + Cr) >> 2		g = Y - (Cb + Cr) >> 2
	r = Cr + g		r = Cr + g
	b = Cb + g		b = Cb + g
	skipping to change at page 14, line 38 ¶		skipping to change at page 14, line 41 ¶
	Cr = r - b		Cr = r - b
	Y = b +(Cb + Cr) >> 2		Y = b +(Cb + Cr) >> 2
	b = Y -(Cb + Cr) >> 2		b = Y -(Cb + Cr) >> 2
	r = Cr + b		r = Cr + b
	g = Cb + b		g = Cb + b
	Figure 7		Figure 7
	Background: At the time of this writing, in all known implementations		Background: At the time of this writing, in all known implementations
	of FFV1 bitstream, when "bits_per_raw_sample" was between 9 and 15		of FFV1 bitstream, when "bits_per_raw_sample" was between 9 and 15
	inclusive and "extra_plane" is 0, GBR "Planes" were used as BGR		inclusive and "extra_plane" is 0, GBR Planes were used as BGR Planes
	"Planes" during both encoding and decoding. In the meanwhile, 16-bit		during both encoding and decoding. In the meanwhile, 16-bit
	JPEG2000-RCT was implemented without this issue in one implementation		JPEG2000-RCT was implemented without this issue in one implementation
	and validated by one conformance checker. Methods to address this		and validated by one conformance checker. Methods to address this
	exception for the transform are under consideration for the next		exception for the transform are under consideration for the next
	version of the FFV1 bitstream.		version of the FFV1 bitstream.
	Cb and Cr are positively offset by "1 << bits_per_raw_sample" after		Cb and Cr are positively offset by "1 << bits_per_raw_sample" after
	the conversion from RGB to the modified YCbCr and are negatively		the conversion from RGB to the modified YCbCr and are negatively
	offseted by the same value before the conversion from the modified		offseted by the same value before the conversion from the modified
	YCbCr to RGB, in order to have only non-negative values after the		YCbCr to RGB, in order to have only non-negative values after the
	conversion.		conversion.
	When FFV1 uses the JPEG2000-RCT, the horizontal "Lines" are		When FFV1 uses the JPEG2000-RCT, the horizontal Lines are interleaved
	interleaved to improve caching efficiency since it is most likely		to improve caching efficiency since it is most likely that the
	that the JPEG2000-RCT will immediately be converted to RGB during		JPEG2000-RCT will immediately be converted to RGB during decoding.
	decoding. The interleaved coding order is also Y, then Cb, then Cr,		The interleaved coding order is also Y, then Cb, then Cr, and then,
	and then if used transparency.		if used, transparency.
	As an example, a "Frame" that is two "Pixels" wide and two "Pixels"		As an example, a Frame that is two Pixels wide and two Pixels high,
	high, could comprise the following structure:		could comprise the following structure:
	+------------------------+------------------------+		+------------------------+------------------------+
	| Pixel(1,1) | Pixel(2,1) |		| Pixel(1,1) | Pixel(2,1) |
	| Y(1,1) Cb(1,1) Cr(1,1) | Y(2,1) Cb(2,1) Cr(2,1) |		| Y(1,1) Cb(1,1) Cr(1,1) | Y(2,1) Cb(2,1) Cr(2,1) |
	+------------------------+------------------------+		+------------------------+------------------------+
	| Pixel(1,2) | Pixel(2,2) |		| Pixel(1,2) | Pixel(2,2) |
	| Y(1,2) Cb(1,2) Cr(1,2) | Y(2,2) Cb(2,2) Cr(2,2) |		| Y(1,2) Cb(1,2) Cr(1,2) | Y(2,2) Cb(2,2) Cr(2,2) |
	+------------------------+------------------------+		+------------------------+------------------------+
	In JPEG2000-RCT, the coding order would be left to right and then top		In JPEG2000-RCT, the coding order would be left to right and then top
	to bottom, with values interleaved by "Lines" and stored in this		to bottom, with values interleaved by Lines and stored in this order:
	order:
	Y(1,1) Y(2,1) Cb(1,1) Cb(2,1) Cr(1,1) Cr(2,1) Y(1,2) Y(2,2) Cb(1,2)		Y(1,1) Y(2,1) Cb(1,1) Cb(2,1) Cr(1,1) Cr(2,1) Y(1,2) Y(2,2) Cb(1,2)
	Cb(2,2) Cr(1,2) Cr(2,2)		Cb(2,2) Cr(1,2) Cr(2,2)
	3.8. Coding of the Sample Difference		3.8. Coding of the Sample Difference
	Instead of coding the n+1 bits of the Sample Difference with Huffman		Instead of coding the n+1 bits of the Sample Difference with Huffman
	or Range coding (or n+2 bits, in the case of JPEG2000-RCT), only the		or Range coding (or n+2 bits, in the case of JPEG2000-RCT), only the
	n (or n+1, in the case of JPEG2000-RCT) least significant bits are		n (or n+1, in the case of JPEG2000-RCT) least significant bits are
	used, since this is sufficient to recover the original "Sample". In		used, since this is sufficient to recover the original Sample. In
	the equation below, the term "bits" represents "bits_per_raw_sample +		the equation below, the term "bits" represents "bits_per_raw_sample +
	1" for JPEG2000-RCT or "bits_per_raw_sample" otherwise:		1" for JPEG2000-RCT or "bits_per_raw_sample" otherwise:
	coder_input = [(sample_difference + 2 ^ (bits - 1)) &		coder_input = [(sample_difference + 2 ^ (bits - 1)) &
	(2 ^ bits - 1)] - 2 ^ (bits - 1)		(2 ^ bits - 1)] - 2 ^ (bits - 1)
	Figure 8: Description of the coding of the Sample Difference in		Figure 8: Description of the coding of the Sample Difference in
	the bitstream.		the bitstream.
	3.8.1. Range Coding Mode		3.8.1. Range Coding Mode
	Early experimental versions of FFV1 used the CABAC Arithmetic coder		Early experimental versions of FFV1 used the CABAC Arithmetic coder
	from H.264 as defined in [ISO.14496-10.2014] but due to the uncertain		from H.264 as defined in [ISO.14496-10.2014] but due to the uncertain
	patent/royalty situation, as well as its slightly worse performance,		patent/royalty situation, as well as its slightly worse performance,
	CABAC was replaced by a Range coder based on an algorithm defined by		CABAC was replaced by a Range coder based on an algorithm defined by
	G. Nigel and N. Martin in 1979 [range-coding].		G. Nigel N. Martin in 1979 [range-coding].
	3.8.1.1. Range Binary Values		3.8.1.1. Range Binary Values
	To encode binary digits efficiently a Range coder is used. C_(i) is		To encode binary digits efficiently a Range coder is used. C_(i) is
	the i-th Context. B_(i) is the i-th byte of the bytestream. b_(i) is		the i-th Context. B_(i) is the i-th byte of the bytestream. b_(i) is
	the i-th Range coded binary value, S_(0, i) is the i-th initial		the i-th Range coded binary value, S_(0, i) is the i-th initial
	state. The length of the bytestream encoding n binary symbols is		state. The length of the bytestream encoding n binary symbols is
	j_(n) bytes.		j_(n) bytes.
	r_(i) = floor( ( R_(i) * S_(i, C_(i)) ) / 2 ^ 8 )		r_(i) = floor( ( R_(i) * S_(i, C_(i)) ) / 2 ^ 8 )
	Figure 9		Figure 9: A formula of the read of a binary value in Range Binary
			mode.
	S_(i + 1, C_(i)) = zero_state_(S_(i, C_(i))) AND		S_(i + 1, C_(i)) = zero_state_(S_(i, C_(i))) AND
	l_(i) = L_(i) AND		l_(i) = L_(i) AND
	t_(i) = R_(i) - r_(i) <==		t_(i) = R_(i) - r_(i) <==
	b_(i) = 0 <==>		b_(i) = 0 <==>
	L_(i) < R_(i) - r_(i)		L_(i) < R_(i) - r_(i)
	S_(i + 1, C_(i)) = one_state_(S_(i, C_(i))) AND		S_(i + 1, C_(i)) = one_state_(S_(i, C_(i))) AND
	l_(i) = L_(i) - R_(i) + r_(i) AND		l_(i) = L_(i) - R_(i) + r_(i) AND
	t_(i) = r_(i) <==		t_(i) = r_(i) <==
	skipping to change at page 17, line 10 ¶		skipping to change at page 17, line 10 ¶
	Figure 13		Figure 13
	L_(0) = 2 ^ 8 * B_(0) + B_(1)		L_(0) = 2 ^ 8 * B_(0) + B_(1)
	Figure 14		Figure 14
	j_(0) = 2		j_(0) = 2
	Figure 15		Figure 15
			range = 0xFF00;
			end = 0;
			low = get_bits(16);
			if (low >= range) {
			low = range;
			end = 1;
			}
			Figure 16: A pseudo-code description of the initial states in
			Range Binary mode.
			refill() {
			if (range < 256) {
			range = range * 256;
			low = low * 256;
			if (!end) {
			c.low += get_bits(8);
			if (remaining_bits_in_bitstream( NumBytes ) == 0) {
			end = 1;
			}
			}
			}
			}
			Figure 17: A pseudo-code description of refilling the Range
			Binary Value coder buffer.
			get_rac(state) {
			rangeoff = (range * state) / 256;
			range -= rangeoff;
			if (low < range) {
			state = zero_state[state];
			refill();
			return 0;
			} else {
			low -= range;
			state = one_state[state];
			range = rangeoff;
			refill();
			return 1;
			}
			}
			Figure 18: A pseudo-code description of the read of a binary
			value in Range Binary mode.
	3.8.1.1.1. Termination		3.8.1.1.1. Termination
	The range coder can be used in three modes.		The range coder can be used in three modes.
	* In "Open mode" when decoding, every symbol the reader attempts to		* In "Open mode" when decoding, every Symbol the reader attempts to
	read is available. In this mode arbitrary data can have been		read is available. In this mode arbitrary data can have been
	appended without affecting the range coder output. This mode is		appended without affecting the range coder output. This mode is
	not used in FFV1.		not used in FFV1.
	* In "Closed mode" the length in bytes of the bytestream is provided		* In "Closed mode" the length in bytes of the bytestream is provided
	to the range decoder. Bytes beyond the length are read as 0 by		to the range decoder. Bytes beyond the length are read as 0 by
	the range decoder. This is generally one byte shorter than the		the range decoder. This is generally one byte shorter than the
	open mode.		open mode.
	* In "Sentinel mode" the exact length in bytes is not known and thus		* In "Sentinel mode" the exact length in bytes is not known and thus
	the range decoder MAY read into the data that follows the range		the range decoder MAY read into the data that follows the range
	coded bytestream by one byte. In "Sentinel mode", the end of the		coded bytestream by one byte. In "Sentinel mode", the end of the
	range coded bytestream is a binary symbol with state 129, which		range coded bytestream is a binary Symbol with state 129, which
	value SHALL be discarded. After reading this symbol, the range		value SHALL be discarded. After reading this Symbol, the range
	decoder will have read one byte beyond the end of the range coded		decoder will have read one byte beyond the end of the range coded
	bytestream. This way the byte position of the end can be		bytestream. This way the byte position of the end can be
	determined. Bytestreams written in "Sentinel mode" can be read in		determined. Bytestreams written in "Sentinel mode" can be read in
	"Closed mode" if the length can be determined, in this case the		"Closed mode" if the length can be determined, in this case the
	last (sentinel) symbol will be read non-corrupted and be of value		last (sentinel) Symbol will be read non-corrupted and be of value
	0.		0.
	Above describes the range decoding. Encoding is defined as any		Above describes the range decoding. Encoding is defined as any
	process which produces a decodable bytestream.		process which produces a decodable bytestream.
	There are three places where range coder termination is needed in		There are three places where range coder termination is needed in
	FFV1. First is in the "Configuration Record", in this case the size		FFV1. First is in the "Configuration Record", in this case the size
	of the range coded bytestream is known and handled as "Closed mode".		of the range coded bytestream is known and handled as "Closed mode".
	Second is the switch from the "Slice Header" which is range coded to		Second is the switch from the "Slice Header" which is range coded to
	Golomb coded slices as "Sentinel mode". Third is the end of range		Golomb coded slices as "Sentinel mode". Third is the end of range
	coded Slices which need to terminate before the CRC at their end.		coded Slices which need to terminate before the CRC at their end.
	This can be handled as "Sentinel mode" or as "Closed mode" if the CRC		This can be handled as "Sentinel mode" or as "Closed mode" if the CRC
	position has been determined.		position has been determined.
	3.8.1.2. Range Non Binary Values		3.8.1.2. Range Non Binary Values
	To encode scalar integers, it would be possible to encode each bit		To encode scalar integers, it would be possible to encode each bit
	separately and use the past bits as context. However that would mean		separately and use the past bits as context. However that would mean
	255 contexts per 8-bit symbol that is not only a waste of memory but		255 contexts per 8-bit Symbol that is not only a waste of memory but
	also requires more past data to reach a reasonably good estimate of		also requires more past data to reach a reasonably good estimate of
	the probabilities. Alternatively assuming a Laplacian distribution		the probabilities. Alternatively assuming a Laplacian distribution
	and only dealing with its variance and mean (as in Huffman coding)		and only dealing with its variance and mean (as in Huffman coding)
	would also be possible, however, for maximum flexibility and		would also be possible, however, for maximum flexibility and
	simplicity, the chosen method uses a single symbol to encode if a		simplicity, the chosen method uses a single Symbol to encode if a
	number is 0, and if not, encodes the number using its exponent,		number is 0, and if not, encodes the number using its exponent,
	mantissa and sign. The exact contexts used are best described by		mantissa and sign. The exact contexts used are best described by
	Figure 16.		Figure 19.
	int get_symbol(RangeCoder *c, uint8_t *state, int is_signed) {		int get_symbol(RangeCoder *c, uint8_t *state, int is_signed) {
	if (get_rac(c, state + 0) {		if (get_rac(c, state + 0) {
	return 0;		return 0;
	}		}
	int e = 0;		int e = 0;
	while (get_rac(c, state + 1 + min(e, 9)) { //1..10		while (get_rac(c, state + 1 + min(e, 9)) { //1..10
	e++;		e++;
	}		}
	skipping to change at page 18, line 45 ¶		skipping to change at page 19, line 45 ¶
	return a;		return a;
	}		}
	if (get_rac(c, state + 11 + min(e, 10))) { //11..21		if (get_rac(c, state + 11 + min(e, 10))) { //11..21
	return -a;		return -a;
	} else {		} else {
	return a;		return a;
	}		}
	}		}
	Figure 16: A pseudo-code description of the contexts of Range Non		Figure 19: A pseudo-code description of the contexts of Range Non
	Binary Values.		Binary Values.
	"get_symbol" is used for the read out of "sample_difference"		"get_symbol" is used for the read out of "sample_difference"
	indicated in Figure 8.		indicated in Figure 8.
	"get_rac" returns a boolean, computed from the bytestream as		"get_rac" returns a boolean, computed from the bytestream as
	described in Section 3.8.1.1.		described in Figure 9 as a formula and in Figure 18 as pseudo-code.
	3.8.1.3. Initial Values for the Context Model		3.8.1.3. Initial Values for the Context Model
	At keyframes all Range coder state variables are set to their initial		When "keyframe" (see Section 4.4) value is 1, all Range coder state
	state.		variables are set to their initial state.
	3.8.1.4. State Transition Table		3.8.1.4. State Transition Table
	one_state_(i) =		one_state_(i) =
	default_state_transition_(i) + state_transition_delta_(i)		default_state_transition_(i) + state_transition_delta_(i)
	Figure 17		Figure 20
	zero_state_(i) = 256 - one_state_(256-i)		zero_state_(i) = 256 - one_state_(256-i)
	Figure 18		Figure 21
	3.8.1.5. default_state_transition		3.8.1.5. default_state_transition
	0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27,		0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27,
	28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42,		28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42,
	43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57,		43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57,
	58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,		58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73,
	skipping to change at page 20, line 43 ¶		skipping to change at page 21, line 43 ¶
	241,242,243,244,245,246,247,248,248, 0, 0, 0, 0, 0, 0, 0,		241,242,243,244,245,246,247,248,248, 0, 0, 0, 0, 0, 0, 0,
	3.8.1.6. Alternative State Transition Table		3.8.1.6. Alternative State Transition Table
	The alternative state transition table has been built using iterative		The alternative state transition table has been built using iterative
	minimization of frame sizes and generally performs better than the		minimization of frame sizes and generally performs better than the
	default. To use it, the "coder_type" (see Section 4.2.3) MUST be set		default. To use it, the "coder_type" (see Section 4.2.3) MUST be set
	to 2 and the difference to the default MUST be stored in the		to 2 and the difference to the default MUST be stored in the
	"Parameters", see Section 4.2. The reference implementation of FFV1		"Parameters", see Section 4.2. The reference implementation of FFV1
	in FFmpeg uses Figure 19 by default at the time of this writing when		in FFmpeg uses Figure 22 by default at the time of this writing when
	Range coding is used.		Range coding is used.
	0, 10, 10, 10, 10, 16, 16, 16, 28, 16, 16, 29, 42, 49, 20, 49,		0, 10, 10, 10, 10, 16, 16, 16, 28, 16, 16, 29, 42, 49, 20, 49,
	59, 25, 26, 26, 27, 31, 33, 33, 33, 34, 34, 37, 67, 38, 39, 39,		59, 25, 26, 26, 27, 31, 33, 33, 33, 34, 34, 37, 67, 38, 39, 39,
	40, 40, 41, 79, 43, 44, 45, 45, 48, 48, 64, 50, 51, 52, 88, 52,		40, 40, 41, 79, 43, 44, 45, 45, 48, 48, 64, 50, 51, 52, 88, 52,
	53, 74, 55, 57, 58, 58, 74, 60,101, 61, 62, 84, 66, 66, 68, 69,		53, 74, 55, 57, 58, 58, 74, 60,101, 61, 62, 84, 66, 66, 68, 69,
	skipping to change at page 21, line 37 ¶		skipping to change at page 22, line 37 ¶
	175,189,179,181,186,183,192,185,200,187,191,188,190,197,193,196,		175,189,179,181,186,183,192,185,200,187,191,188,190,197,193,196,
	197,194,195,196,198,202,199,201,210,203,207,204,205,206,208,214,		197,194,195,196,198,202,199,201,210,203,207,204,205,206,208,214,
	209,211,221,212,213,215,224,216,217,218,219,220,222,228,223,225,		209,211,221,212,213,215,224,216,217,218,219,220,222,228,223,225,
	226,224,227,229,240,230,231,232,233,234,235,236,238,239,237,242,		226,224,227,229,240,230,231,232,233,234,235,236,238,239,237,242,
	241,243,242,244,245,246,247,248,249,250,251,252,252,253,254,255,		241,243,242,244,245,246,247,248,249,250,251,252,252,253,254,255,
	Figure 19: Alternative state transition table for Range coding.		Figure 22: Alternative state transition table for Range coding.
	3.8.2. Golomb Rice Mode		3.8.2. Golomb Rice Mode
	The end of the bitstream of the "Frame" is filled with 0-bits until		The end of the bitstream of the Frame is padded with 0-bits until the
	that the bitstream contains a multiple of 8 bits.		bitstream contains a multiple of 8 bits.
	3.8.2.1. Signed Golomb Rice Codes		3.8.2.1. Signed Golomb Rice Codes
	This coding mode uses Golomb Rice codes. The VLC is split into two		This coding mode uses Golomb Rice codes. The VLC is split into two
	parts. The prefix stores the most significant bits and the suffix		parts. The prefix stores the most significant bits and the suffix
	stores the k least significant bits or stores the whole number in the		stores the k least significant bits or stores the whole number in the
	ESC case.		ESC case.
	int get_ur_golomb(k) {		int get_ur_golomb(k) {
	for (prefix = 0; prefix < 12; prefix++) {		for (prefix = 0; prefix < 12; prefix++) {
	if (get_bits(1)) {		if (get_bits(1)) {
	return get_bits(k) + (prefix << k);		return get_bits(k) + (prefix << k);
	}		}
	}		}
	return get_bits(bits) + 11;		return get_bits(bits) + 11;
	}		}
	Figure 20: A pseudo-code description of the read of an unsigned		Figure 23: A pseudo-code description of the read of an unsigned
	integer in Golomb Rice mode.		integer in Golomb Rice mode.
	int get_sr_golomb(k) {		int get_sr_golomb(k) {
	v = get_ur_golomb(k);		v = get_ur_golomb(k);
	if (v & 1) return - (v >> 1) - 1;		if (v & 1) return - (v >> 1) - 1;
	else return (v >> 1);		else return (v >> 1);
	}		}
	Figure 21: A pseudo-code description of the read of a signed		Figure 24: A pseudo-code description of the read of a signed
	integer in Golomb Rice mode.		integer in Golomb Rice mode.
	3.8.2.1.1. Prefix		3.8.2.1.1. Prefix
	+================+=======+		+================+=======+
	| bits | value |		| bits | value |
	+================+=======+		+================+=======+
	| 1 | 0 |		| 1 | 0 |
	+----------------+-------+		+----------------+-------+
	| 01 | 1 |		| 01 | 1 |
	skipping to change at page 23, line 16 ¶		skipping to change at page 24, line 16 ¶
	+=========+========================================+		+=========+========================================+
	+=========+========================================+		+=========+========================================+
	| non ESC | the k least significant bits MSB first |		| non ESC | the k least significant bits MSB first |
	+---------+----------------------------------------+		+---------+----------------------------------------+
	| ESC | the value - 11, in MSB first order |		| ESC | the value - 11, in MSB first order |
	+---------+----------------------------------------+		+---------+----------------------------------------+
	Table 2		Table 2
	"ESC" MUST NOT be used if the value can be coded as "non ESC".		ESC MUST NOT be used if the value can be coded as non ESC.
	3.8.2.1.3. Examples		3.8.2.1.3. Examples
			Table 3 shows practical examples of how Signed Golomb Rice Codes are
			decoded based on the series of bits extracted from the bitstream as
			described by the method above:
	+=====+=======================+=======+		+=====+=======================+=======+
	| k | bits | value |		| k | bits | value |
	+=====+=======================+=======+		+=====+=======================+=======+
	| 0 | 1 | 0 |		| 0 | 1 | 0 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	| 0 | 001 | 2 |		| 0 | 001 | 2 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	| 2 | 1 00 | 0 |		| 2 | 1 00 | 0 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	| 2 | 1 10 | 2 |		| 2 | 1 10 | 2 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	| 2 | 01 01 | 5 |		| 2 | 01 01 | 5 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	| any | 000000000000 10000000 | 139 |		| any | 000000000000 10000000 | 139 |
	+-----+-----------------------+-------+		+-----+-----------------------+-------+
	Table 3		Table 3: Examples of decoded Signed
			Golomb Rice Codes.
	3.8.2.2. Run Mode		3.8.2.2. Run Mode
	Run mode is entered when the context is 0 and left as soon as a non-0		Run mode is entered when the context is 0 and left as soon as a non-0
	difference is found. The level is identical to the predicted one.		difference is found. The sample difference is identical to the
	The run and the first different level are coded.		predicted one. The run and the first different sample difference are
			coded as defined in Section 3.8.2.4.1.
	3.8.2.2.1. Run Length Coding		3.8.2.2.1. Run Length Coding
	The run value is encoded in two parts. The prefix part stores the		The run value is encoded in two parts. The prefix part stores the
	more significant part of the run as well as adjusting the "run_index"		more significant part of the run as well as adjusting the "run_index"
	that determines the number of bits in the less significant part of		that determines the number of bits in the less significant part of
	the run. The second part of the value stores the less significant		the run. The second part of the value stores the less significant
	part of the run as it is. The "run_index" is reset for each "Plane"		part of the run as it is. The "run_index" is reset for each Plane
	and slice to 0.		and slice to 0.
	log2_run[41] = {		log2_run[41] = {
	0, 0, 0, 0, 1, 1, 1, 1,		0, 0, 0, 0, 1, 1, 1, 1,
	2, 2, 2, 2, 3, 3, 3, 3,		2, 2, 2, 2, 3, 3, 3, 3,
	4, 4, 5, 5, 6, 6, 7, 7,		4, 4, 5, 5, 6, 6, 7, 7,
	8, 9,10,11,12,13,14,15,		8, 9,10,11,12,13,14,15,
	16,17,18,19,20,21,22,23,		16,17,18,19,20,21,22,23,
	24,		24,
	};		};
	skipping to change at page 25, line 49 ¶		skipping to change at page 27, line 44 ¶
	-state->count + 1);		-state->count + 1);
	} else if (state->drift > 0) {		} else if (state->drift > 0) {
	state->bias = min(state->bias + 1, 127);		state->bias = min(state->bias + 1, 127);
	state->drift = min(state->drift - state->count, 0);		state->drift = min(state->drift - state->count, 0);
	}		}
	return ret;		return ret;
	}		}
	3.8.2.4.1. Level Coding		3.8.2.4.1. Golomb Rice Sample Difference Coding
	Level coding is identical to the normal difference coding with the		Level coding is identical to the normal difference coding with the
	exception that the 0 value is removed as it cannot occur:		exception that the 0 value is removed as it cannot occur:
	diff = get_vlc_symbol(context_state);		diff = get_vlc_symbol(context_state);
	if (diff >= 0) {		if (diff >= 0) {
	diff++;		diff++;
	}		}
	Note, this is different from JPEG-LS, which doesn't use prediction in		Note, this is different from JPEG-LS, which doesn't use prediction in
	run mode and uses a different encoding and context model for the last		run mode and uses a different encoding and context model for the last
	difference. On a small set of test "Samples" the use of prediction		difference. On a small set of test Samples the use of prediction
	slightly improved the compression rate.		slightly improved the compression rate.
	3.8.2.5. Initial Values for the VLC context state		3.8.2.5. Initial Values for the VLC context state
	At keyframes all coder state variables are set to their initial		When "keyframe" (see Section 4.4) value is 1, all coder state
	state.		variables are set to their initial state.
	drift = 0;		drift = 0;
	error_sum = 4;		error_sum = 4;
	bias = 0;		bias = 0;
	count = 1;		count = 1;
	4. Bitstream		4. Bitstream
	An FFV1 bitstream is composed of a series of one or more "Frames" and		An FFV1 bitstream is composed of a series of one or more Frames and
	(when required) a "Configuration Record".		(when required) a "Configuration Record".
	Within the following sub-sections, pseudo-code is used to explain the		Within the following sub-sections, pseudo-code is used, as described
	structure of each FFV1 bitstream component, as described in		in Section 2.2.1, to explain the structure of each FFV1 bitstream
	Section 2.2.1. Table 4 lists symbols used to annotate that pseudo-		component. Table 4 lists symbols used to annotate that pseudo-code
	code in order to define the storage of the data referenced in that		in order to define the storage of the data referenced in that line of
	line of pseudo-code.		pseudo-code.
	+========+==============================================+		+========+=================================================+
	| Symbol | Definition |		| Symbol | Definition |
	+========+==============================================+		+========+=================================================+
	| u(n) | unsigned big endian integer using n bits |		| u(n) | unsigned big endian integer Symbol using n bits |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	| sg | Golomb Rice coded signed scalar symbol coded |		| sg | Golomb Rice coded signed scalar Symbol coded |
	| | with the method described in Section 3.8.2 |		| | with the method described in Section 3.8.2 |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	| br | Range coded Boolean (1-bit) symbol with the |		| br | Range coded Boolean (1-bit) Symbol with the |
	| | method described in Section 3.8.1.1 |		| | method described in Section 3.8.1.1 |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	| ur | Range coded unsigned scalar symbol coded |		| ur | Range coded unsigned scalar Symbol coded with |
	| | with the method described in Section 3.8.1.2 |		| | the method described in Section 3.8.1.2 |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	| sr | Range coded signed scalar symbol coded with |		| sr | Range coded signed scalar Symbol coded with the |
	| | the method described in Section 3.8.1.2 |		| | method described in Section 3.8.1.2 |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	| sd | Sample difference coded with the method |		| sd | Sample difference Symbol coded with the method |
	| | described in Section 3.8 |		| | described in Section 3.8 |
	+--------+----------------------------------------------+		+--------+-------------------------------------------------+
	Table 4: Definition of pseudo-code symbols for this		Table 4: Definition of pseudo-code symbols for this
	document.		document.
	The following MUST be provided by external means during		The following MUST be provided by external means during
	initialization of the decoder:		initialization of the decoder:
	"frame_pixel_width" is defined as "Frame" width in "Pixels".		"frame_pixel_width" is defined as Frame width in Pixels.
	"frame_pixel_height" is defined as "Frame" height in "Pixels".		"frame_pixel_height" is defined as Frame height in Pixels.
	Default values at the decoder initialization phase:		Default values at the decoder initialization phase:
	"ConfigurationRecordIsPresent" is set to 0.		"ConfigurationRecordIsPresent" is set to 0.
	4.1. Quantization Table Set		4.1. Quantization Table Set
	The Quantization Table Sets are stored by storing the number of equal		The Quantization Table Sets are stored by storing the number of equal
	entries -1 of the first half of the table (represented as "len - 1"		entries -1 of the first half of the table (represented as "len - 1"
	in the pseudo-code below) using the method described in		in the pseudo-code below) using the method described in
	skipping to change at page 29, line 14 ¶		skipping to change at page 31, line 14 ¶
	4.1.2. context_count		4.1.2. context_count
	"context_count[ i ]" indicates the count of contexts for Quantization		"context_count[ i ]" indicates the count of contexts for Quantization
	Table Set "i". "context_count[ i ]" MUST be less than or equal to		Table Set "i". "context_count[ i ]" MUST be less than or equal to
	32768.		32768.
	4.2. Parameters		4.2. Parameters
	The "Parameters" section contains significant characteristics about		The "Parameters" section contains significant characteristics about
	the decoding configuration used for all instances of "Frame" (in FFV1		the decoding configuration used for all instances of Frame (in FFV1
	version 0 and 1) or the whole FFV1 bitstream (other versions),		version 0 and 1) or the whole FFV1 bitstream (other versions),
	including the stream version, color configuration, and quantization		including the stream version, color configuration, and quantization
	tables. Figure 22 describes the contents of the bitstream.		tables. Figure 25 describes the contents of the bitstream.
	"Parameters" has its own initial states, all set to 128.		"Parameters" has its own initial states, all set to 128.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Parameters( ) { |		Parameters( ) { |
	version | ur		version | ur
	if (version >= 3) { |		if (version >= 3) { |
	micro_version | ur		micro_version | ur
	} |		} |
	skipping to change at page 30, line 50 ¶		skipping to change at page 32, line 50 ¶
	initial_state_delta[ i ][ j ][ k ] | sr		initial_state_delta[ i ][ j ][ k ] | sr
	} |		} |
	} |		} |
	} |		} |
	} |		} |
	ec | ur		ec | ur
	intra | ur		intra | ur
	} |		} |
	} |		} |
	Figure 22: A pseudo-code description of the bitstream contents.		Figure 25: A pseudo-code description of the bitstream contents.
	CONTEXT_SIZE is 32.		CONTEXT_SIZE is 32.
	4.2.1. version		4.2.1. version
	"version" specifies the version of the FFV1 bitstream.		"version" specifies the version of the FFV1 bitstream.
	Each version is incompatible with other versions: decoders SHOULD		Each version is incompatible with other versions: decoders SHOULD
	reject FFV1 bitstreams due to an unknown version.		reject FFV1 bitstreams due to an unknown version.
	skipping to change at page 34, line 5 ¶		skipping to change at page 36, line 5 ¶
	If "state_transition_delta" is not present in the FFV1 bitstream, all		If "state_transition_delta" is not present in the FFV1 bitstream, all
	Range coder custom state transition table elements are assumed to be		Range coder custom state transition table elements are assumed to be
	0.		0.
	4.2.5. colorspace_type		4.2.5. colorspace_type
	"colorspace_type" specifies the color space encoded, the pixel		"colorspace_type" specifies the color space encoded, the pixel
	transformation used by the encoder, the extra plane content, as well		transformation used by the encoder, the extra plane content, as well
	as interleave method.		as interleave method.
	+=======+=============+================+==============+=============+		+=======+==============+================+==============+============+
	| value | color space | pixel | extra plane | interleave |		| value | color space | pixel | extra plane | interleave |
	| | encoded | transformation | content | method |		| | encoded | transformation | content | method |
	+=======+=============+================+==============+=============+		+=======+==============+================+==============+============+
	| 0 | YCbCr | None | Transparency | "Plane" |		| 0 | YCbCr | None | Transparency | Plane then |
	| | | | | then |		| | | | | Line |
	| | | | | "Line" |		+-------+--------------+----------------+--------------+------------+
	+-------+-------------+----------------+--------------+-------------+		| 1 | RGB | JPEG2000-RCT | Transparency | Line then |
	| 1 | RGB | JPEG2000-RCT | Transparency | "Line" |		| | | | | Plane |
	| | | | | then |		+-------+--------------+----------------+--------------+------------+
	| | | | | "Plane" |		| Other | reserved | reserved for | reserved for | reserved |
	+-------+-------------+----------------+--------------+-------------+		| | for future | future use | future use | for future |
	| Other | reserved | reserved for | reserved for | reserved |		| | use | | | use |
	| | for future | future use | future use | for future |		+-------+--------------+----------------+--------------+------------+
	| | use | | | use |
	+-------+-------------+----------------+--------------+-------------+
	Table 9		Table 9
	FFV1 bitstreams with "colorspace_type" == 1 && ("chroma_planes" !=		FFV1 bitstreams with "colorspace_type" == 1 && ("chroma_planes" !=
	1 || "log2_h_chroma_subsample" != 0 || "log2_v_chroma_subsample" !=		1 || "log2_h_chroma_subsample" != 0 || "log2_v_chroma_subsample" !=
	0) are not part of this specification.		0) are not part of this specification.
	4.2.6. chroma_planes		4.2.6. chroma_planes
	"chroma_planes" indicates if chroma (color) "Planes" are present.		"chroma_planes" indicates if chroma (color) Planes are present.
	+=======+=================================+		+=======+===============================+
	| value | presence |		| value | presence |
	+=======+=================================+		+=======+===============================+
	| 0 | chroma "Planes" are not present |		| 0 | chroma Planes are not present |
	+-------+---------------------------------+		+-------+-------------------------------+
	| 1 | chroma "Planes" are present |		| 1 | chroma Planes are present |
	+-------+---------------------------------+		+-------+-------------------------------+
	Table 10		Table 10
	4.2.7. bits_per_raw_sample		4.2.7. bits_per_raw_sample
	"bits_per_raw_sample" indicates the number of bits for each "Sample".		"bits_per_raw_sample" indicates the number of bits for each Sample.
	Inferred to be 8 if not present.		Inferred to be 8 if not present.
	+=======+===================================+		+=======+=================================+
	| value | bits for each sample |		| value | bits for each sample |
	+=======+===================================+		+=======+=================================+
	| 0 | reserved* |		| 0 | reserved* |
	+-------+-----------------------------------+		+-------+---------------------------------+
	| Other | the actual bits for each "Sample" |		| Other | the actual bits for each Sample |
	+-------+-----------------------------------+		+-------+---------------------------------+
	Table 11		Table 11
	* Encoders MUST NOT store "bits_per_raw_sample" = 0. Decoders SHOULD		* Encoders MUST NOT store "bits_per_raw_sample" = 0. Decoders SHOULD
	accept and interpret "bits_per_raw_sample" = 0 as 8.		accept and interpret "bits_per_raw_sample" = 0 as 8.
	4.2.8. log2_h_chroma_subsample		4.2.8. log2_h_chroma_subsample
	"log2_h_chroma_subsample" indicates the subsample factor, stored in		"log2_h_chroma_subsample" indicates the subsample factor, stored in
	powers to which the number 2 must be raised, between luma and chroma		powers to which the number 2 is raised, between luma and chroma width
	width ("chroma_width = 2 ^ -log2_h_chroma_subsample * luma_width").		("chroma_width = 2 ^ -log2_h_chroma_subsample * luma_width").
	4.2.9. log2_v_chroma_subsample		4.2.9. log2_v_chroma_subsample
	"log2_v_chroma_subsample" indicates the subsample factor, stored in		"log2_v_chroma_subsample" indicates the subsample factor, stored in
	powers to which the number 2 must be raised, between luma and chroma		powers to which the number 2 is raised, between luma and chroma
	height ("chroma_height = 2 ^ -log2_v_chroma_subsample *		height ("chroma_height = 2 ^ -log2_v_chroma_subsample *
	luma_height").		luma_height").
	4.2.10. extra_plane		4.2.10. extra_plane
	"extra_plane" indicates if an extra "Plane" is present.		"extra_plane" indicates if an extra Plane is present.
	+=======+==============================+		+=======+============================+
	| value | presence |		| value | presence |
	+=======+==============================+		+=======+============================+
	| 0 | extra "Plane" is not present |		| 0 | extra Plane is not present |
	+-------+------------------------------+		+-------+----------------------------+
	| 1 | extra "Plane" is present |		| 1 | extra Plane is present |
	+-------+------------------------------+		+-------+----------------------------+
	Table 12		Table 12
	4.2.11. num_h_slices		4.2.11. num_h_slices
	"num_h_slices" indicates the number of horizontal elements of the		"num_h_slices" indicates the number of horizontal elements of the
	slice raster.		slice raster.
	Inferred to be 1 if not present.		Inferred to be 1 if not present.
	skipping to change at page 36, line 46 ¶		skipping to change at page 38, line 46 ¶
	Table 13		Table 13
	4.2.15. initial_state_delta		4.2.15. initial_state_delta
	"initial_state_delta[ i ][ j ][ k ]" indicates the initial Range		"initial_state_delta[ i ][ j ][ k ]" indicates the initial Range
	coder state, it is encoded using "k" as context index and		coder state, it is encoded using "k" as context index and
	pred = j ? initial_states[ i ][j - 1][ k ] : 128		pred = j ? initial_states[ i ][j - 1][ k ] : 128
	Figure 23		Figure 26
	initial_state[ i ][ j ][ k ] =		initial_state[ i ][ j ][ k ] =
	( pred + initial_state_delta[ i ][ j ][ k ] ) & 255		( pred + initial_state_delta[ i ][ j ][ k ] ) & 255
	Figure 24		Figure 27
	4.2.16. ec		4.2.16. ec
	"ec" indicates the error detection/correction type.		"ec" indicates the error detection/correction type.
	+=======+=================================================+		+=======+=================================================+
	| value | error detection/correction type |		| value | error detection/correction type |
	+=======+=================================================+		+=======+=================================================+
	| 0 | 32-bit CRC in "ConfigurationRecord" |		| 0 | 32-bit CRC in "ConfigurationRecord" |
	+-------+-------------------------------------------------+		+-------+-------------------------------------------------+
	| 1 | 32-bit CRC in "Slice" and "ConfigurationRecord" |		| 1 | 32-bit CRC in "Slice" and "ConfigurationRecord" |
	+-------+-------------------------------------------------+		+-------+-------------------------------------------------+
	| Other | reserved for future use |		| Other | reserved for future use |
	+-------+-------------------------------------------------+		+-------+-------------------------------------------------+
	Table 14		Table 14
	4.2.17. intra		4.2.17. intra
	"intra" indicates the constraint on "keyframe" in each instance of		"intra" indicates the constraint on "keyframe" in each instance of
	"Frame".		Frame.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	+=======+=======================================================+		+=======+=======================================================+
	| value | relationship |		| value | relationship |
	+=======+=======================================================+		+=======+=======================================================+
	| 0 | "keyframe" can be 0 or 1 (non keyframes or keyframes) |		| 0 | "keyframe" can be 0 or 1 (non keyframes or keyframes) |
	+-------+-------------------------------------------------------+		+-------+-------------------------------------------------------+
	| 1 | "keyframe" MUST be 1 (keyframes only) |		| 1 | "keyframe" MUST be 1 (keyframes only) |
	+-------+-------------------------------------------------------+		+-------+-------------------------------------------------------+
	| Other | reserved for future use |		| Other | reserved for future use |
	+-------+-------------------------------------------------------+		+-------+-------------------------------------------------------+
	Table 15		Table 15
	4.3. Configuration Record		4.3. Configuration Record
	In the case of a FFV1 bitstream with "version >= 3", a "Configuration		In the case of a FFV1 bitstream with "version >= 3", a "Configuration
	Record" is stored in the underlying "Container" as described in		Record" is stored in the underlying Container as described in
	Section 4.3.3. It contains the "Parameters" used for all instances		Section 4.3.3. It contains the "Parameters" used for all instances
	of "Frame". The size of the "Configuration Record", "NumBytes", is		of Frame. The size of the "Configuration Record", "NumBytes", is
	supplied by the underlying "Container".		supplied by the underlying Container.
	pseudo-code | type		pseudo-code | type
	-----------------------------------------------------------|-----		-----------------------------------------------------------|-----
	ConfigurationRecord( NumBytes ) { |		ConfigurationRecord( NumBytes ) { |
	ConfigurationRecordIsPresent = 1 |		ConfigurationRecordIsPresent = 1 |
	Parameters( ) |		Parameters( ) |
	while (remaining_symbols_in_syntax(NumBytes - 4)) { |		while (remaining_symbols_in_syntax(NumBytes - 4)) { |
	reserved_for_future_use | br/ur/sr		reserved_for_future_use | br/ur/sr
	} |		} |
	configuration_record_crc_parity | u(32)		configuration_record_crc_parity | u(32)
	} |		} |
	4.3.1. reserved_for_future_use		4.3.1. reserved_for_future_use
	"reserved_for_future_use" has semantics that are reserved for future		"reserved_for_future_use" is a placeholder for future updates of this
	use.		specification.
	Encoders conforming to this version of this specification SHALL NOT		Encoders conforming to this version of this specification SHALL NOT
	write this value.		write "reserved_for_future_use".
	Decoders conforming to this version of this specification SHALL		Decoders conforming to this version of this specification SHALL
	ignore its value.		ignore "reserved_for_future_use".
	4.3.2. configuration_record_crc_parity		4.3.2. configuration_record_crc_parity
	"configuration_record_crc_parity" 32 bits that are chosen so that the		"configuration_record_crc_parity" 32 bits that are chosen so that the
	"Configuration Record" as a whole has a CRC remainder of 0.		"Configuration Record" as a whole has a CRC remainder of 0.
	This is equivalent to storing the CRC remainder in the 32-bit parity.		This is equivalent to storing the CRC remainder in the 32-bit parity.
	The CRC generator polynomial used is described in Section 4.9.3.		The CRC generator polynomial used is described in Section 4.9.3.
	skipping to change at page 39, line 42 ¶		skipping to change at page 41, line 42 ¶
	versions 2 or less, the Matroska "CodecPrivate" Element SHOULD NOT be		versions 2 or less, the Matroska "CodecPrivate" Element SHOULD NOT be
	used. For FFV1 versions 3 or greater, the Matroska "CodecPrivate"		used. For FFV1 versions 3 or greater, the Matroska "CodecPrivate"
	Element MUST contain the FFV1 "Configuration Record" structure and no		Element MUST contain the FFV1 "Configuration Record" structure and no
	other data. See [Matroska] for more information about elements.		other data. See [Matroska] for more information about elements.
	"NumBytes" is defined as the "Element Data Size" of the		"NumBytes" is defined as the "Element Data Size" of the
	"CodecPrivate" Element.		"CodecPrivate" Element.
	4.4. Frame		4.4. Frame
	A "Frame" is an encoded representation of a complete static image.		A Frame is an encoded representation of a complete static image. The
	The whole "Frame" is provided by the underlaying container.		whole Frame is provided by the underlaying container.
	A "Frame" consists of the "keyframe" field, "Parameters" (if		A Frame consists of the "keyframe" field, "Parameters" (if "version"
	"version" <= 1), and a sequence of independent slices. The pseudo-		<= 1), and a sequence of independent slices. The pseudo-code below
	code below describes the contents of a "Frame".		describes the contents of a Frame.
	"keyframe" field has its own initial state, set to 128.		"keyframe" field has its own initial state, set to 128.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Frame( NumBytes ) { |		Frame( NumBytes ) { |
	keyframe | br		keyframe | br
	if (keyframe && !ConfigurationRecordIsPresent { |		if (keyframe && !ConfigurationRecordIsPresent { |
	Parameters( ) |		Parameters( ) |
	} |		} |
	while (remaining_bits_in_bitstream( NumBytes )) { |		while (remaining_bits_in_bitstream( NumBytes )) { |
	Slice( ) |		Slice( ) |
	} |		} |
	} |		} |
	Architecture overview of slices in a "Frame":		Architecture overview of slices in a Frame:
	+=================================================================+		+=================================================================+
	+=================================================================+		+=================================================================+
	| first slice header |		| first slice header |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	| first slice content |		| first slice content |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	| first slice footer |		| first slice footer |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	| --------------------------------------------------------------- |		| --------------------------------------------------------------- |
	skipping to change at page 41, line 7 ¶		skipping to change at page 43, line 7 ¶
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	| last slice content |		| last slice content |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	| last slice footer |		| last slice footer |
	+-----------------------------------------------------------------+		+-----------------------------------------------------------------+
	Table 16		Table 16
	4.5. Slice		4.5. Slice
	A "Slice" is an independent spatial sub-section of a "Frame" that is		A "Slice" is an independent spatial sub-section of a Frame that is
	encoded separately from another region of the same "Frame". The use		encoded separately from another region of the same Frame. The use of
	of more than one "Slice" per "Frame" can be useful for taking		more than one "Slice" per Frame can be useful for taking advantage of
	advantage of the opportunities of multithreaded encoding and		the opportunities of multithreaded encoding and decoding.
	decoding.
	A "Slice" consists of a "Slice Header" (when relevant), a "Slice		A "Slice" consists of a "Slice Header" (when relevant), a "Slice
	Content", and a "Slice Footer" (when relevant). The pseudo-code		Content", and a "Slice Footer" (when relevant). The pseudo-code
	below describes the contents of a "Slice".		below describes the contents of a "Slice".
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Slice( ) { |		Slice( ) { |
	if (version >= 3) { |		if (version >= 3) { |
	SliceHeader( ) |		SliceHeader( ) |
	skipping to change at page 41, line 46 ¶		skipping to change at page 43, line 45 ¶
	} |		} |
	} |		} |
	"padding" specifies a bit without any significance and used only for		"padding" specifies a bit without any significance and used only for
	byte alignment. MUST be 0.		byte alignment. MUST be 0.
	"reserved" specifies a bit without any significance in this revision		"reserved" specifies a bit without any significance in this revision
	of the specification and may have a significance in a later revision		of the specification and may have a significance in a later revision
	of this specification.		of this specification.
	Encoders SHOULD NOT fill these bits.		Encoders SHOULD NOT fill "reserved".
	Decoders SHOULD ignore these bits.		Decoders SHOULD ignore "reserved".
	4.6. Slice Header		4.6. Slice Header
	A "Slice Header" provides information about the decoding		A "Slice Header" provides information about the decoding
	configuration of the "Slice", such as its spatial position, size, and		configuration of the "Slice", such as its spatial position, size, and
	aspect ratio. The pseudo-code below describes the contents of the		aspect ratio. The pseudo-code below describes the contents of the
	"Slice Header".		"Slice Header".
	"Slice Header" has its own initial states, all set to 128.		"Slice Header" has its own initial states, all set to 128.
	skipping to change at page 43, line 30 ¶		skipping to change at page 45, line 30 ¶
	"quant_table_set_index" indicates the Quantization Table Set index to		"quant_table_set_index" indicates the Quantization Table Set index to
	select the Quantization Table Set and the initial states for the		select the Quantization Table Set and the initial states for the
	"Slice Content".		"Slice Content".
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	4.6.7. picture_structure		4.6.7. picture_structure
	"picture_structure" specifies the temporal and spatial relationship		"picture_structure" specifies the temporal and spatial relationship
	of each "Line" of the "Frame".		of each Line of the Frame.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	+=======+=========================+		+=======+=========================+
	| value | picture structure used |		| value | picture structure used |
	+=======+=========================+		+=======+=========================+
	| 0 | unknown |		| 0 | unknown |
	+-------+-------------------------+		+-------+-------------------------+
	| 1 | top field first |		| 1 | top field first |
	+-------+-------------------------+		+-------+-------------------------+
	skipping to change at page 44, line 7 ¶		skipping to change at page 46, line 7 ¶
	+-------+-------------------------+		+-------+-------------------------+
	| 3 | progressive |		| 3 | progressive |
	+-------+-------------------------+		+-------+-------------------------+
	| Other | reserved for future use |		| Other | reserved for future use |
	+-------+-------------------------+		+-------+-------------------------+
	Table 17		Table 17
	4.6.8. sar_num		4.6.8. sar_num
	"sar_num" specifies the "Sample" aspect ratio numerator.		"sar_num" specifies the Sample aspect ratio numerator.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	A value of 0 means that aspect ratio is unknown.		A value of 0 means that aspect ratio is unknown.
	Encoders MUST write 0 if "Sample" aspect ratio is unknown.		Encoders MUST write 0 if Sample aspect ratio is unknown.
	If "sar_den" is 0, decoders SHOULD ignore the encoded value and		If "sar_den" is 0, decoders SHOULD ignore the encoded value and
	consider that "sar_num" is 0.		consider that "sar_num" is 0.
	4.6.9. sar_den		4.6.9. sar_den
	"sar_den" specifies the "Sample" aspect ratio denominator.		"sar_den" specifies the Sample aspect ratio denominator.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	A value of 0 means that aspect ratio is unknown.		A value of 0 means that aspect ratio is unknown.
	Encoders MUST write 0 if "Sample" aspect ratio is unknown.		Encoders MUST write 0 if Sample aspect ratio is unknown.
	If "sar_num" is 0, decoders SHOULD ignore the encoded value and		If "sar_num" is 0, decoders SHOULD ignore the encoded value and
	consider that "sar_den" is 0.		consider that "sar_den" is 0.
	4.6.10. reset_contexts		4.6.10. reset_contexts
	"reset_contexts" indicates if slice contexts must be reset.		"reset_contexts" indicates if slice contexts MUST be reset.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	4.6.11. slice_coding_mode		4.6.11. slice_coding_mode
	"slice_coding_mode" indicates the slice coding mode.		"slice_coding_mode" indicates the slice coding mode.
	Inferred to be 0 if not present.		Inferred to be 0 if not present.
	+=======+=============================+		+=======+=============================+
	skipping to change at page 45, line 19 ¶		skipping to change at page 47, line 19 ¶
	+-------+-----------------------------+		+-------+-----------------------------+
	| 1 | raw PCM |		| 1 | raw PCM |
	+-------+-----------------------------+		+-------+-----------------------------+
	| Other | reserved for future use |		| Other | reserved for future use |
	+-------+-----------------------------+		+-------+-----------------------------+
	Table 18		Table 18
	4.7. Slice Content		4.7. Slice Content
	A "Slice Content" contains all "Line" elements part of the "Slice".		A "Slice Content" contains all Line elements part of the "Slice".
	Depending on the configuration, "Line" elements are ordered by		Depending on the configuration, Line elements are ordered by Plane
	"Plane" then by row (YCbCr) or by row then by "Plane" (RGB).		then by row (YCbCr) or by row then by Plane (RGB).
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	SliceContent( ) { |		SliceContent( ) { |
	if (colorspace_type == 0) { |		if (colorspace_type == 0) { |
	for (p = 0; p < primary_color_count; p++) { |		for (p = 0; p < primary_color_count; p++) { |
	for (y = 0; y < plane_pixel_height[ p ]; y++) { |		for (y = 0; y < plane_pixel_height[ p ]; y++) { |
	Line( p, y ) |		Line( p, y ) |
	} |		} |
	} |		} |
	skipping to change at page 45, line 50 ¶		skipping to change at page 47, line 50 ¶
	} |		} |
	4.7.1. primary_color_count		4.7.1. primary_color_count
	"primary_color_count" is defined as:		"primary_color_count" is defined as:
	1 + ( chroma_planes ? 2 : 0 ) + ( extra_plane ? 1 : 0 )		1 + ( chroma_planes ? 2 : 0 ) + ( extra_plane ? 1 : 0 )
	4.7.2. plane_pixel_height		4.7.2. plane_pixel_height
	"plane_pixel_height[ p ]" is the height in "Pixels" of "Plane" p of		"plane_pixel_height[ p ]" is the height in Pixels of Plane p of the
	the "Slice". It is defined as:		"Slice". It is defined as:
	chroma_planes == 1 && (p == 1 || p == 2)		chroma_planes == 1 && (p == 1 || p == 2)
	? ceil(slice_pixel_height / (1 << log2_v_chroma_subsample))		? ceil(slice_pixel_height / (1 << log2_v_chroma_subsample))
	: slice_pixel_height		: slice_pixel_height
	4.7.3. slice_pixel_height		4.7.3. slice_pixel_height
	"slice_pixel_height" is the height in pixels of the slice. It is		"slice_pixel_height" is the height in pixels of the slice. It is
	defined as:		defined as:
	skipping to change at page 46, line 29 ¶		skipping to change at page 48, line 29 ¶
	4.7.4. slice_pixel_y		4.7.4. slice_pixel_y
	"slice_pixel_y" is the slice vertical position in pixels. It is		"slice_pixel_y" is the slice vertical position in pixels. It is
	defined as:		defined as:
	floor( slice_y * frame_pixel_height / num_v_slices )		floor( slice_y * frame_pixel_height / num_v_slices )
	4.8. Line		4.8. Line
	A "Line" is a list of the sample differences (relative to the		A Line is a list of the sample differences (relative to the
	predictor) of primary color components. The pseudo-code below		predictor) of primary color components. The pseudo-code below
	describes the contents of the "Line".		describes the contents of the Line.
	pseudo-code | type		pseudo-code | type
	--------------------------------------------------------------|-----		--------------------------------------------------------------|-----
	Line( p, y ) { |		Line( p, y ) { |
	if (colorspace_type == 0) { |		if (colorspace_type == 0) { |
	for (x = 0; x < plane_pixel_width[ p ]; x++) { |		for (x = 0; x < plane_pixel_width[ p ]; x++) { |
	sample_difference[ p ][ y ][ x ] | sd		sample_difference[ p ][ y ][ x ] | sd
	} |		} |
	} else if (colorspace_type == 1) { |		} else if (colorspace_type == 1) { |
	for (x = 0; x < slice_pixel_width; x++) { |		for (x = 0; x < slice_pixel_width; x++) { |
	sample_difference[ p ][ y ][ x ] | sd		sample_difference[ p ][ y ][ x ] | sd
	} |		} |
	} |		} |
	} |		} |
	4.8.1. plane_pixel_width		4.8.1. plane_pixel_width
	"plane_pixel_width[ p ]" is the width in "Pixels" of "Plane" p of the		"plane_pixel_width[ p ]" is the width in Pixels of Plane p of the
	"Slice". It is defined as:		"Slice". It is defined as:
	chroma\_planes == 1 && (p == 1 || p == 2)		chroma\_planes == 1 && (p == 1 || p == 2)
	? ceil( slice_pixel_width / (1 << log2_h_chroma_subsample) )		? ceil( slice_pixel_width / (1 << log2_h_chroma_subsample) )
	: slice_pixel_width.		: slice_pixel_width.
	4.8.2. slice_pixel_width		4.8.2. slice_pixel_width
	"slice_pixel_width" is the width in "Pixels" of the slice. It is		"slice_pixel_width" is the width in Pixels of the slice. It is
	defined as:		defined as:
	floor(		floor(
	( slice_x + slice_width )		( slice_x + slice_width )
	* slice_pixel_width		* slice_pixel_width
	/ num_h_slices		/ num_h_slices
	) - slice_pixel_x		) - slice_pixel_x
	4.8.3. slice_pixel_x		4.8.3. slice_pixel_x
	"slice_pixel_x" is the slice horizontal position in "Pixels". It is		"slice_pixel_x" is the slice horizontal position in Pixels. It is
	defined as:		defined as:
	floor( slice_x * frame_pixel_width / num_h_slices )		floor( slice_x * frame_pixel_width / num_h_slices )
	4.8.4. sample_difference		4.8.4. sample_difference
	"sample_difference[ p ][ y ][ x ]" is the sample difference for		"sample_difference[ p ][ y ][ x ]" is the sample difference for
	"Sample" at "Plane" "p", y position "y", and x position "x". The		Sample at Plane "p", y position "y", and x position "x". The Sample
	"Sample" value is computed based on median predictor and context		value is computed based on median predictor and context described in
	described in Section 3.2.		Section 3.2.
	4.9. Slice Footer		4.9. Slice Footer
	A "Slice Footer" provides information about slice size and		A "Slice Footer" provides information about slice size and
	(optionally) parity. The pseudo-code below describes the contents of		(optionally) parity. The pseudo-code below describes the contents of
	the "Slice Footer".		the "Slice Footer".
	Note: "Slice Footer" is always byte aligned.		Note: "Slice Footer" is always byte aligned.
	pseudo-code | type		pseudo-code | type
	skipping to change at page 48, line 48 ¶		skipping to change at page 50, line 48 ¶
	The CRC generator polynomial used is the standard IEEE CRC polynomial		The CRC generator polynomial used is the standard IEEE CRC polynomial
	(0x104C11DB7), with initial value 0, without pre-inversion and		(0x104C11DB7), with initial value 0, without pre-inversion and
	without post-inversion.		without post-inversion.
	5. Restrictions		5. Restrictions
	To ensure that fast multithreaded decoding is possible, starting with		To ensure that fast multithreaded decoding is possible, starting with
	version 3 and if "frame_pixel_width * frame_pixel_height" is more		version 3 and if "frame_pixel_width * frame_pixel_height" is more
	than 101376, "slice_width * slice_height" MUST be less or equal to		than 101376, "slice_width * slice_height" MUST be less or equal to
	"num_h_slices * num_v_slices / 4". Note: 101376 is the frame size in		"num_h_slices * num_v_slices / 4". Note: 101376 is the frame size in
	"Pixels" of a 352x288 frame also known as CIF ("Common Intermediate		Pixels of a 352x288 frame also known as CIF ("Common Intermediate
	Format") frame size format.		Format") frame size format.
	For each "Frame", each position in the slice raster MUST be filled by		For each Frame, each position in the slice raster MUST be filled by
	one and only one slice of the "Frame" (no missing slice position, no		one and only one slice of the Frame (no missing slice position, no
	slice overlapping).		slice overlapping).
	For each "Frame" with "keyframe" value of 0, each slice MUST have the		For each Frame with "keyframe" value of 0, each slice MUST have the
	same value of "slice_x", "slice_y", "slice_width", "slice_height" as		same value of "slice_x", "slice_y", "slice_width", "slice_height" as
	a slice in the previous "Frame", except if "reset_contexts" is 1.		a slice in the previous Frame, except if "reset_contexts" is 1.
	6. Security Considerations		6. Security Considerations
	Like any other codec, (such as [RFC6716]), FFV1 should not be used		Like any other codec, (such as [RFC6716]), FFV1 should not be used
	with insecure ciphers or cipher-modes that are vulnerable to known		with insecure ciphers or cipher-modes that are vulnerable to known
	plaintext attacks. Some of the header bits as well as the padding		plaintext attacks. Some of the header bits as well as the padding
	are easily predictable.		are easily predictable.
	Implementations of the FFV1 codec need to take appropriate security		Implementations of the FFV1 codec need to take appropriate security
	considerations into account, as outlined in [RFC4732]. It is		considerations into account, as outlined in [RFC4732]. It is
	extremely important for the decoder to be robust against malicious		extremely important for the decoder to be robust against malicious
	payloads. Malicious payloads must not cause the decoder to overrun		payloads. Malicious payloads MUST NOT cause the decoder to overrun
	its allocated memory or to take an excessive amount of resources to		its allocated memory or to take an excessive amount of resources to
	decode. The same applies to the encoder, even though problems in		decode. The same applies to the encoder, even though problems in
	encoders are typically rarer. Malicious video streams must not cause		encoders are typically rarer. Malicious video streams MUST NOT cause
	the encoder to misbehave because this would allow an attacker to		the encoder to misbehave because this would allow an attacker to
	attack transcoding gateways. A frequent security problem in image		attack transcoding gateways. A frequent security problem in image
	and video codecs is also to not check for integer overflows, for		and video codecs is failure to check for integer overflows. An
	example to allocate "frame_pixel_width * frame_pixel_height" in		example is allocating "frame_pixel_width * frame_pixel_height" in
	"Pixel" count computations without considering that the		Pixel count computations without considering that the multiplication
	multiplication result may have overflowed the arithmetic types range.		result may have overflowed the arithmetic types range. The range
	The range coder could, if implemented naively, read one byte over the		coder could, if implemented naively, read one byte over the end. The
	end. The implementation must ensure that no read outside allocated		implementation MUST ensure that no read outside allocated and
	and initialized memory occurs.		initialized memory occurs.
	None of the content carried in FFV1 is intended to be executable.		None of the content carried in FFV1 is intended to be executable.
	The reference implementation [REFIMPL] contains no known buffer		The reference implementation [REFIMPL] contains no known buffer
	overflow or cases where a specially crafted packet or video segment		overflow or cases where a specially crafted packet or video segment
	could cause a significant increase in CPU load.		could cause a significant increase in CPU load.
	The reference implementation [REFIMPL] was validated in the following		The reference implementation [REFIMPL] was validated in the following
	conditions:		conditions:
	skipping to change at page 50, line 13 ¶		skipping to change at page 52, line 13 ¶
	then subjected to random corruption.		then subjected to random corruption.
	* Sending the decoder random packets that are not FFV1.		* Sending the decoder random packets that are not FFV1.
	In all of the conditions above, the decoder and encoder was run		In all of the conditions above, the decoder and encoder was run
	inside the [VALGRIND] memory debugger as well as clangs address		inside the [VALGRIND] memory debugger as well as clangs address
	sanitizer [Address-Sanitizer], which track reads and writes to		sanitizer [Address-Sanitizer], which track reads and writes to
	invalid memory regions as well as the use of uninitialized memory.		invalid memory regions as well as the use of uninitialized memory.
	There were no errors reported on any of the tested conditions.		There were no errors reported on any of the tested conditions.
	7. Media Type Definition		7. IANA Considerations
			The IANA is requested to register the following values:
			7.1. Media Type Definition
	This registration is done using the template defined in [RFC6838] and		This registration is done using the template defined in [RFC6838] and
	following [RFC4855].		following [RFC4855].
	Type name: video		Type name: video
	Subtype name: FFV1		Subtype name: FFV1
	Required parameters: None.		Required parameters: None.
	skipping to change at page 51, line 32 ¶		skipping to change at page 53, line 39 ¶
	Niedermayer michael@niedermayer.cc (mailto:michael@niedermayer.cc)		Niedermayer michael@niedermayer.cc (mailto:michael@niedermayer.cc)
	Intended usage: COMMON		Intended usage: COMMON
	Restrictions on usage: None.		Restrictions on usage: None.
	Author: Dave Rice dave@dericed.com (mailto:dave@dericed.com)		Author: Dave Rice dave@dericed.com (mailto:dave@dericed.com)
	Change controller: IETF cellar working group delegated from the IESG.		Change controller: IETF cellar working group delegated from the IESG.
	8. IANA Considerations		8. Changelog
	The IANA is requested to register the following values:
	* Media type registration as described in Section 7.
	9. Changelog
	See https://github.com/FFmpeg/FFV1/commits/master		See https://github.com/FFmpeg/FFV1/commits/master
	(https://github.com/FFmpeg/FFV1/commits/master)		(https://github.com/FFmpeg/FFV1/commits/master)
	[RFC Editor: Please remove this Changelog section prior to		[RFC Editor: Please remove this Changelog section prior to
	publication.]		publication.]
	10. Normative References		9. Normative References
			[ISO.15444-1.2016]
			International Organization for Standardization,
			"Information technology -- JPEG 2000 image coding system:
			Core coding system", October 2016.
			[ISO.9899.2018]
			International Organization for Standardization,
			"Programming languages - C", ISO Standard 9899, 2018.
			[Matroska] IETF, "Matroska", 2019, <https://datatracker.ietf.org/doc/
			draft-ietf-cellar-matroska/>.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet		[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
	Denial-of-Service Considerations", RFC 4732,		Denial-of-Service Considerations", RFC 4732,
	DOI 10.17487/RFC4732, December 2006,		DOI 10.17487/RFC4732, December 2006,
	<https://www.rfc-editor.org/info/rfc4732>.		<https://www.rfc-editor.org/info/rfc4732>.
	[ISO.9899.2018]		[RFC4855] Casner, S., "Media Type Registration of RTP Payload
	International Organization for Standardization,		Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
	"Programming languages - C", ISO Standard 9899, 2018.		<https://www.rfc-editor.org/info/rfc4855>.
			[RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the
			Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716,
			September 2012, <https://www.rfc-editor.org/info/rfc6716>.
	[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type		[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
	Specifications and Registration Procedures", BCP 13,		Specifications and Registration Procedures", BCP 13,
	RFC 6838, DOI 10.17487/RFC6838, January 2013,		RFC 6838, DOI 10.17487/RFC6838, January 2013,
	<https://www.rfc-editor.org/info/rfc6838>.		<https://www.rfc-editor.org/info/rfc6838>.
	[ISO.9899.1990]		[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
	International Organization for Standardization,		2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
	"Programming languages - C", ISO Standard 9899, 1990.		May 2017, <https://www.rfc-editor.org/info/rfc8174>.
	[ISO.15444-1.2016]
	International Organization for Standardization,
	"Information technology -- JPEG 2000 image coding system:
	Core coding system", October 2016.
	[RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the		10. Informative References
	Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716,
	September 2012, <https://www.rfc-editor.org/info/rfc6716>.
	[RFC4855] Casner, S., "Media Type Registration of RTP Payload		[Address-Sanitizer]
	Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,		The Clang Team, "ASAN AddressSanitizer website", undated,
	<https://www.rfc-editor.org/info/rfc4855>.		<https://clang.llvm.org/docs/AddressSanitizer.html>.
	[Matroska] IETF, "Matroska", 2019, <https://datatracker.ietf.org/doc/		[AVI] Microsoft, "AVI RIFF File Reference", undated,
	draft-ietf-cellar-matroska/>.		<https://msdn.microsoft.com/en-us/library/windows/desktop/
			dd318189%28v=vs.85%29.aspx>.
	11. Informative References		[HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003,
			<https://web.archive.org/web/20040402121343/
			http://cultact-server.novi.dk/kpo/huffyuv/huffyuv.html>.
	[I-D.ietf-cellar-ffv1]		[I-D.ietf-cellar-ffv1]
	Niedermayer, M., Rice, D., and J. Martinez, "FFV1 Video		Niedermayer, M., Rice, D., and J. Martinez, "FFV1 Video
	Coding Format Version 0, 1, and 3", Work in Progress,		Coding Format Version 0, 1, and 3", Work in Progress,
	Internet-Draft, draft-ietf-cellar-ffv1-16, 2 July 2020,		Internet-Draft, draft-ietf-cellar-ffv1-17, 21 August 2020,
	<https://tools.ietf.org/html/draft-ietf-cellar-ffv1-16>.		<https://tools.ietf.org/html/draft-ietf-cellar-ffv1-17>.
	[ISO.14495-1.1999]		[ISO.14495-1.1999]
	International Organization for Standardization,		International Organization for Standardization,
	"Information technology -- Lossless and near-lossless		"Information technology -- Lossless and near-lossless
	compression of continuous-tone still images: Baseline",		compression of continuous-tone still images: Baseline",
	December 1999.		December 1999.
	[NUT] Niedermayer, M., "NUT Open Container Format", December
	2013, <https://ffmpeg.org/~michael/nut.txt>.
	[YCbCr] Wikipedia, "YCbCr", undated,
	<https://en.wikipedia.org/w/index.php?title=YCbCr>.
	[ISO.14496-10.2014]		[ISO.14496-10.2014]
	International Organization for Standardization,		International Organization for Standardization,
	"Information technology -- Coding of audio-visual objects		"Information technology -- Coding of audio-visual objects
	-- Part 10: Advanced Video Coding", September 2014.		-- Part 10: Advanced Video Coding", September 2014.
	[VALGRIND] Valgrind Developers, "Valgrind website", undated,
	<https://valgrind.org/>.
	[REFIMPL] Niedermayer, M., "The reference FFV1 implementation / the
	FFV1 codec in FFmpeg", undated, <https://ffmpeg.org>.
	[HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003,
	<https://web.archive.org/web/20040402121343/
	http://cultact-server.novi.dk/kpo/huffyuv/huffyuv.html>.
	[ISO.14496-12.2015]		[ISO.14496-12.2015]
	International Organization for Standardization,		International Organization for Standardization,
	"Information technology -- Coding of audio-visual objects		"Information technology -- Coding of audio-visual objects
	-- Part 12: ISO base media file format", December 2015.		-- Part 12: ISO base media file format", December 2015.
			[NUT] Niedermayer, M., "NUT Open Container Format", December
			2013, <https://ffmpeg.org/~michael/nut.txt>.
	[range-coding]		[range-coding]
	Nigel, G. and N. Martin, "Range encoding: an algorithm for		Martin, G. N. N., "Range encoding: an algorithm for
	removing redundancy from a digitised message.",		removing redundancy from a digitised message", Proceedings
	Proceedings of the Conference on Video and Data		of the Conference on Video and Data Recording. Institution
	Recording. Institution of Electronic and Radio Engineers,		of Electronic and Radio Engineers, Hampshire, England,
	Hampshire, England, July 1979.		July 1979.
	[AVI] Microsoft, "AVI RIFF File Reference", undated,		[REFIMPL] Niedermayer, M., "The reference FFV1 implementation / the
	<https://msdn.microsoft.com/en-us/library/windows/desktop/		FFV1 codec in FFmpeg", undated, <https://ffmpeg.org>.
	dd318189%28v=vs.85%29.aspx>.
	[Address-Sanitizer]		[VALGRIND] Valgrind Developers, "Valgrind website", undated,
	The Clang Team, "ASAN AddressSanitizer website", undated,		<https://valgrind.org/>.
	<https://clang.llvm.org/docs/AddressSanitizer.html>.
			[YCbCr] Wikipedia, "YCbCr", undated,
			<https://en.wikipedia.org/w/index.php?title=YCbCr>.
	Appendix A. Multi-theaded decoder implementation suggestions		Appendix A. Multi-theaded decoder implementation suggestions
	This appendix is informative.		This appendix is informative.
	The FFV1 bitstream is parsable in two ways: in sequential order as		The FFV1 bitstream is parsable in two ways: in sequential order as
	described in this document or with the pre-analysis of the footer of		described in this document or with the pre-analysis of the footer of
	each slice. Each slice footer contains a "slice_size" field so the		each slice. Each slice footer contains a "slice_size" field so the
	boundary of each slice is computable without having to parse the		boundary of each slice is computable without having to parse the
	slice content. That allows multi-threading as well as independence		slice content. That allows multi-threading as well as independence
End of changes. 167 change blocks.
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