draft-ietf-cellar-ffv1-13.txt   draft-ietf-cellar-ffv1-14.txt 
cellar M. Niedermayer cellar M. Niedermayer
Internet-Draft Internet-Draft
Intended status: Informational D. Rice Intended status: Informational D. Rice
Expires: 30 October 2020 Expires: 27 November 2020
J. Martinez J. Martinez
28 April 2020 26 May 2020
FFV1 Video Coding Format Version 0, 1, and 3 FFV1 Video Coding Format Version 0, 1, and 3
draft-ietf-cellar-ffv1-13 draft-ietf-cellar-ffv1-14
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
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
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 30 October 2020. This Internet-Draft will expire on 27 November 2020.
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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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
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Notation and Conventions . . . . . . . . . . . . . . . . . . 4 2. Notation and Conventions . . . . . . . . . . . . . . . . . . 5
2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 5
2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 6 2.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 5
2.2.1. Pseudo-code . . . . . . . . . . . . . . . . . . . . . 6 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 . . . . . . . . . . . . . . . . 6
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 . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 8 2.2.8. NumBytes . . . . . . . . . . . . . . . . . . . . . . 8
2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 8 2.2.9. Bitstream Functions . . . . . . . . . . . . . . . . . 8
3. Sample Coding . . . . . . . . . . . . . . . . . . . . . . . . 9 3. Sample Coding . . . . . . . . . . . . . . . . . . . . . . . . 9
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4.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . 26 4.1. Parameters . . . . . . . . . . . . . . . . . . . . . . . 26
4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 28 4.1.1. version . . . . . . . . . . . . . . . . . . . . . . . 28
4.1.2. micro_version . . . . . . . . . . . . . . . . . . . . 28 4.1.2. micro_version . . . . . . . . . . . . . . . . . . . . 28
4.1.3. coder_type . . . . . . . . . . . . . . . . . . . . . 29 4.1.3. coder_type . . . . . . . . . . . . . . . . . . . . . 29
4.1.4. state_transition_delta . . . . . . . . . . . . . . . 29 4.1.4. state_transition_delta . . . . . . . . . . . . . . . 29
4.1.5. colorspace_type . . . . . . . . . . . . . . . . . . . 30 4.1.5. colorspace_type . . . . . . . . . . . . . . . . . . . 30
4.1.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 30 4.1.6. chroma_planes . . . . . . . . . . . . . . . . . . . . 30
4.1.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 31 4.1.7. bits_per_raw_sample . . . . . . . . . . . . . . . . . 31
4.1.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 31 4.1.8. log2_h_chroma_subsample . . . . . . . . . . . . . . . 31
4.1.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 31 4.1.9. log2_v_chroma_subsample . . . . . . . . . . . . . . . 31
4.1.10. "extra\_plane" . . . . . . . . . . . . . . . . . . . 31 4.1.10. extra_plane . . . . . . . . . . . . . . . . . . . . . 31
4.1.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 31 4.1.11. num_h_slices . . . . . . . . . . . . . . . . . . . . 32
4.1.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 32 4.1.12. num_v_slices . . . . . . . . . . . . . . . . . . . . 32
4.1.13. quant_table_set_count . . . . . . . . . . . . . . . . 32 4.1.13. quant_table_set_count . . . . . . . . . . . . . . . . 32
4.1.14. states_coded . . . . . . . . . . . . . . . . . . . . 32 4.1.14. states_coded . . . . . . . . . . . . . . . . . . . . 32
4.1.15. initial_state_delta . . . . . . . . . . . . . . . . . 32 4.1.15. initial_state_delta . . . . . . . . . . . . . . . . . 32
4.1.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.1.16. ec . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.1.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 33 4.1.17. intra . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2. Configuration Record . . . . . . . . . . . . . . . . . . 33 4.2. Configuration Record . . . . . . . . . . . . . . . . . . 34
4.2.1. reserved_for_future_use . . . . . . . . . . . . . . . 34 4.2.1. reserved_for_future_use . . . . . . . . . . . . . . . 34
4.2.2. configuration_record_crc_parity . . . . . . . . . . . 34 4.2.2. configuration_record_crc_parity . . . . . . . . . . . 34
4.2.3. Mapping FFV1 into Containers . . . . . . . . . . . . 34 4.2.3. Mapping FFV1 into Containers . . . . . . . . . . . . 34
4.3. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.3. Frame . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.4. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 37 4.4. Slice . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.5. Slice Header . . . . . . . . . . . . . . . . . . . . . . 38 4.5. Slice Header . . . . . . . . . . . . . . . . . . . . . . 38
4.5.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 38 4.5.1. slice_x . . . . . . . . . . . . . . . . . . . . . . . 38
4.5.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 38 4.5.2. slice_y . . . . . . . . . . . . . . . . . . . . . . . 38
4.5.3. slice_width . . . . . . . . . . . . . . . . . . . . . 38 4.5.3. slice_width . . . . . . . . . . . . . . . . . . . . . 38
4.5.4. slice_height . . . . . . . . . . . . . . . . . . . . 39 4.5.4. slice_height . . . . . . . . . . . . . . . . . . . . 38
4.5.5. quant_table_set_index_count . . . . . . . . . . . . . 39 4.5.5. quant_table_set_index_count . . . . . . . . . . . . . 39
4.5.6. quant_table_set_index . . . . . . . . . . . . . . . . 39 4.5.6. quant_table_set_index . . . . . . . . . . . . . . . . 39
4.5.7. picture_structure . . . . . . . . . . . . . . . . . . 39 4.5.7. picture_structure . . . . . . . . . . . . . . . . . . 39
4.5.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 39 4.5.8. sar_num . . . . . . . . . . . . . . . . . . . . . . . 39
4.5.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 40 4.5.9. sar_den . . . . . . . . . . . . . . . . . . . . . . . 40
4.6. Slice Content . . . . . . . . . . . . . . . . . . . . . . 40 4.6. Slice Content . . . . . . . . . . . . . . . . . . . . . . 40
4.6.1. primary_color_count . . . . . . . . . . . . . . . . . 41 4.6.1. primary_color_count . . . . . . . . . . . . . . . . . 40
4.6.2. plane_pixel_height . . . . . . . . . . . . . . . . . 41 4.6.2. plane_pixel_height . . . . . . . . . . . . . . . . . 41
4.6.3. slice_pixel_height . . . . . . . . . . . . . . . . . 41 4.6.3. slice_pixel_height . . . . . . . . . . . . . . . . . 41
4.6.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 41 4.6.4. slice_pixel_y . . . . . . . . . . . . . . . . . . . . 41
4.7. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4.7. Line . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.7.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 42 4.7.1. plane_pixel_width . . . . . . . . . . . . . . . . . . 41
4.7.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 42 4.7.2. slice_pixel_width . . . . . . . . . . . . . . . . . . 42
4.7.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 42 4.7.3. slice_pixel_x . . . . . . . . . . . . . . . . . . . . 42
4.7.4. sample_difference . . . . . . . . . . . . . . . . . . 42 4.7.4. sample_difference . . . . . . . . . . . . . . . . . . 42
4.8. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 43 4.8. Slice Footer . . . . . . . . . . . . . . . . . . . . . . 42
4.8.1. slice_size . . . . . . . . . . . . . . . . . . . . . 43 4.8.1. slice_size . . . . . . . . . . . . . . . . . . . . . 42
4.8.2. error_status . . . . . . . . . . . . . . . . . . . . 43 4.8.2. error_status . . . . . . . . . . . . . . . . . . . . 43
4.8.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 43 4.8.3. slice_crc_parity . . . . . . . . . . . . . . . . . . 43
4.9. Quantization Table Set . . . . . . . . . . . . . . . . . 44 4.9. Quantization Table Set . . . . . . . . . . . . . . . . . 43
4.9.1. quant_tables . . . . . . . . . . . . . . . . . . . . 45 4.9.1. quant_tables . . . . . . . . . . . . . . . . . . . . 44
4.9.2. context_count . . . . . . . . . . . . . . . . . . . . 45 4.9.2. context_count . . . . . . . . . . . . . . . . . . . . 44
5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 45 5. Restrictions . . . . . . . . . . . . . . . . . . . . . . . . 45
6. Security Considerations . . . . . . . . . . . . . . . . . . . 46 6. Security Considerations . . . . . . . . . . . . . . . . . . . 45
7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 47 7. Media Type Definition . . . . . . . . . . . . . . . . . . . . 46
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 47
9. Appendix A: Multi-theaded decoder implementation 9. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 48
suggestions . . . . . . . . . . . . . . . . . . . . . . . 48 10. Normative References . . . . . . . . . . . . . . . . . . . . 48
10. Changelog . . . . . . . . . . . . . . . . . . . . . . . . . . 49 11. Informative References . . . . . . . . . . . . . . . . . . . 49
11. Normative References . . . . . . . . . . . . . . . . . . . . 49 Appendix A. Multi-theaded decoder implementation suggestions . . 50
12. Informative References . . . . . . . . . . . . . . . . . . . 50 Appendix B. Future handling of some streams created by non
conforming encoders . . . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51
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
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* Version 3 of FFV1 adds several features such as increased * Version 3 of FFV1 adds several features such as increased
description of the characteristics of the encoding images and description of the characteristics of the encoding images and
embedded CRC data to support fixity verification of the encoding. embedded CRC data to support fixity verification of the encoding.
Version 3 has been in non-experimental use since August 17, 2013 Version 3 has been in non-experimental use since August 17, 2013
[FFV1_V3]. [FFV1_V3].
This document assumes familiarity with mathematical and coding This document assumes familiarity with mathematical and coding
concepts such as Range coding [range-coding] and YCbCr color spaces concepts such as Range coding [range-coding] and YCbCr color spaces
[YCbCr]. [YCbCr].
This specification describes the valid bitstream and how to decode
such valid bitstream. Bitstreams not conforming to this
specification or how they are handled is outside this specification.
A decoder could reject every invalid bitstream or attempt to perform
error concealment or re-download or use a redundant copy of the
invalid part or any other action it deems appropriate.
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
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"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, Blue Chrominance, Red Chrominance, Transparency, Red, Green, Luma, Blue Chrominance, Red Chrominance, Transparency, Red, Green,
and Blue. and Blue.
"Plane": A discrete component of a static image comprised of "Plane": A discrete component of a static image comprised of
"Samples" that represent a specific quantification of "Samples" of "Samples" that represent a specific quantification of "Samples" of
that image. 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 1 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.
"RCT": Reversible Color Transform, a near linear, exactly reversible
integer transform that converts between RGB and YCbCr representations
of a "Pixel".
"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 using three numeric values that represent the luma of the "Pixel" by using three numeric values that represent the luma of the "Pixel"
(Y) and the chrominance of the "Pixel" (Cb and Cr). YCbCr word is (Y) and the chrominance of the "Pixel" (Cb and Cr). YCbCr word is
used for historical reasons and currently references any color space used for historical reasons and currently references any color space
relying on 1 luma "Sample" and 2 chrominance "Samples", e.g. YCbCr, relying on 1 luma "Sample" and 2 chrominance "Samples", e.g. YCbCr,
YCgCo or ICtCp. The exact meaning of the three numeric values is YCgCo or ICtCp. The exact meaning of the three numeric values is
unspecified. unspecified.
"TBA": To Be Announced. Used in reference to the development of
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.9899.1990] 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.
2.2.2. Arithmetic Operators 2.2.2. Arithmetic Operators
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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.9899.1990] 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.
2.2.2. Arithmetic Operators 2.2.2. Arithmetic Operators
Note: the operators and the order of precedence are the same as used Note: the operators and the order of precedence are the same as used
in the C programming language [ISO.9899.2018]. With the exception of in the C programming language [ISO.9899.2018], with the exception of
">>" (removal of implementation defined behavior) and "^" (power ">>" (removal of implementation defined behavior) and "^" (power
instead of XOR) operators which are re-defined within this section. instead of XOR) operators which are re-defined within this section.
"a + b" means a plus b. "a + b" means a plus b.
"a - b" means a minus b. "a - b" means a minus b.
"-a" means negation of a. "-a" means negation of a.
"a * b" means a multiplied by b. "a * b" means a multiplied by b.
"a / b" means a divided by b. "a / b" means a divided by b.
"a ^ b" means a raised to the b-th power. "a ^ b" means a raised to the b-th power.
"a & b" means bit-wise "and" of a and b. "a & b" means bit-wise "and" of a and b.
"a | b" means bit-wise "or" of a and b. "a | b" means bit-wise "or" of a and b.
"a >> b" means arithmetic right shift of two's complement integer "a >> b" means arithmetic right shift of two's complement integer
representation of a by b binary digits. This is equivalent to, b representation of a by b binary digits. This is equivalent to
times dividing a by 2 with rounding toward negative infinity. dividing a by 2, b times, with rounding toward negative infinity.
"a << b" means arithmetic left shift of two's complement integer "a << b" means arithmetic left shift of two's complement integer
representation of a by b binary digits. representation of a by b binary digits.
2.2.3. Assignment Operators 2.2.3. Assignment Operators
"a = b" means a is assigned b. "a = b" means a is assigned b.
"a++" is equivalent to a is assigned a + 1. "a++" is equivalent to a is assigned a + 1.
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"a && b" means Boolean logical "and" of a and b. "a && b" means Boolean logical "and" of a and b.
"a || b" means Boolean logical "or" of a and b. "a || b" means Boolean logical "or" of a and b.
"!a" means Boolean logical "not" of a. "!a" means Boolean logical "not" of a.
"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) the largest integer less than or equal to a "floor(a)" means the largest integer less than or equal to a.
ceil(a) 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 if "sign(a)" extracts the sign of a number, i.e. if a < 0 then -1, else
a > 0 then 1, else 0 if a > 0 then 1, else 0.
abs(a) the absolute value of a, i.e. abs(a) = sign(a)*a "abs(a)" means the absolute value of a, i.e. "abs(a)" = "sign(a) *
a".
log2(a) the base-two logarithm of a "log2(a)" means the base-two logarithm of a.
min(a,b) the smallest of two values a and b "min(a,b)" means the smallest of two values a and b.
max(a,b) the largest of two values a and b "max(a,b)" means the largest of two values a and b.
median(a,b,c) the numerical middle value in a data set of a, b, and "median(a,b,c)" means the numerical middle value in a data set of a,
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 B implies A
A <==> B A <== B , B <== A "A <== B" means B implies A.
"A <==> B" means A <== B , B <== A.
2.2.6. Order of Operation Precedence 2.2.6. Order of Operation Precedence
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--
skipping to change at page 10, line 50 skipping to change at page 10, line 50
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: 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 -
top16s = t >= 32768 ? ( t - 65536 ) : 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 signed 16-bit signed integer was used
for storing "Sample" values in all known implementations of FFV1 for storing "Sample" values in all known implementations of FFV1
bitstream. So in some circumstances, the most significant bit was bitstream. So in some circumstances, the most significant bit was
wrongly interpreted (used as a sign bit instead of the 16th bit of an wrongly interpreted (used as a sign bit instead of the 16th bit of an
unsigned integer). Note that when the issue is 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 7 skipping to change at page 12, line 7
Figure 3 Figure 3
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" is used and the difference between the "Sample" and its "-context" is used and the difference between the "Sample" and its
predicted value is encoded with a flipped sign. predicted value is encoded with a flipped sign.
3.5. Quantization Table Sets 3.5. Quantization Table Sets
The FFV1 bitstream contains 1 or more Quantization Table Sets. Each The FFV1 bitstream contains one or more Quantization Table Sets.
Quantization Table Set contains exactly 5 Quantization Tables with Each Quantization Table Set contains exactly 5 Quantization Tables
each Quantization Table corresponding to 1 of the 5 Quantized Sample with each Quantization Table corresponding to one of the five
Differences. For each Quantization Table, both the number of Quantized Sample Differences. For each Quantization Table, both the
quantization steps and their distribution are stored in the FFV1 number of quantization steps and their distribution are stored in the
bitstream; each Quantization Table has exactly 256 entries, and the 8 FFV1 bitstream; each Quantization Table has exactly 256 entries, and
least significant bits of the Quantized Sample Difference are used as the 8 least significant bits of the Quantized Sample Difference are
index: used as index:
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.
3.6. Quantization Table Set Indexes 3.6. Quantization Table Set Indexes
skipping to change at page 12, line 37 skipping to change at page 12, line 37
* 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 to 0), this index is kept for version <= 3 in order to keep set 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
skipping to change at page 13, line 43 skipping to change at page 13, line 43
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
Figure 5 Figure 5
Exception for the JPEG2000-RCT conversion: if "bits_per_raw_sample" Exception for the JPEG2000-RCT conversion: if "bits_per_raw_sample"
is between 9 and 15 inclusive and "extra_plane" is 0, the following is between 9 and 15 inclusive and "extra_plane" is 0, the following
formulae for reversible conversions between YCbCr and RGB MUST be formulae for reversible conversions between YCbCr and RGB MUST be
used instead of the ones above: used instead of the ones above:
Cb=g-b Cb = g - b
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 6 Figure 6
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" during both encoding and decoding. In the meanwhile, 16-bit "Planes" 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 offseted 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 to improve caching efficiency since it is most likely interleaved to improve caching efficiency since it is most likely
that the JPEG2000-RCT will immediately be converted to RGB during that the JPEG2000-RCT will immediately be converted to RGB during
decoding. The interleaved coding order is also Y, then Cb, then Cr, decoding. The interleaved coding order is also Y, then Cb, then Cr,
and then if used transparency. and then if used transparency.
skipping to change at page 15, line 21 skipping to change at page 15, line 21
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 = coder_input =
[(sample_difference + 2^(bits-1)) & (2^bits - 1)] - 2^(bits-1) [(sample_difference + 2 ^ (bits-1)) & (2 ^ bits - 1)] - 2 ^ (bits - 1)
Figure 7 Figure 7
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 and 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)" 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 is 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 8 Figure 8
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
skipping to change at page 16, line 23 skipping to change at page 16, line 23
t_i = r_i <== t_i = r_i <==
b_i = 1 <==> b_i = 1 <==>
L_i >= R_i - r_i L_i >= R_i - r_i
Figure 9 Figure 9
S_{i+1,k} = S_{i,k} <== C_i != k S_{i+1,k} = S_{i,k} <== C_i != k
Figure 10 Figure 10
R_{i+1} = 2^8 * t_{i} AND R_{i+1} = 2 ^ 8 * t_{i} AND
L_{i+1} = 2^8 * l_{i} + B_{j_{i}} AND L_{i+1} = 2 ^ 8 * l_{i} + B_{j_{i}} AND
j_{i+1} = j_{i} + 1 <== j_{i+1} = j_{i} + 1 <==
t_{i} < 2^8 t_{i} < 2 ^ 8
R_{i+1} = t_{i} AND R_{i+1} = t_{i} AND
L_{i+1} = l_{i} AND L_{i+1} = l_{i} AND
j_{i+1} = j_{i} <== j_{i+1} = j_{i} <==
t_{i} >= 2^8 t_{i} >= 2 ^ 8
Figure 11 Figure 11
R_{0} = 65280 R_{0} = 65280
Figure 12 Figure 12
L_{0} = 2^8 * B_{0} + B_{1} L_{0} = 2 ^ 8 * B_{0} + B_{1}
Figure 13 Figure 13
j_{0} = 2 j_{0} = 2
Figure 14 Figure 14
3.8.1.1.1. Termination 3.8.1.1.1. Termination
The range coder can be used in 3 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 1 byte shorter than the open the range decoder. This is generally one byte shorter than the
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 3 places where range coder termination is needed in FFV1. There are three places where range coder termination is needed in
First is in the "Configuration Record", in this case the size of the FFV1. First is in the "Configuration Record", in this case the size
range coded bytestream is known and handled as "Closed mode". Second of the range coded bytestream is known and handled as "Closed mode".
is the switch from the "Slice Header" which is range coded to Golomb Second is the switch from the "Slice Header" which is range coded to
coded slices as "Sentinel mode". Third is the end of range coded Golomb coded slices as "Sentinel mode". Third is the end of range
Slices which need to terminate before the CRC at their end. This can coded Slices which need to terminate before the CRC at their end.
be handled as "Sentinel mode" or as "Closed mode" if the CRC position This can be handled as "Sentinel mode" or as "Closed mode" if the CRC
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
skipping to change at page 20, line 46 skipping to change at page 20, line 46
Figure 18: Alternative state transition table for Range coding. Figure 18: 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 filled with 0-bits until
that the bitstream contains a multiple of 8 bits. that the 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 2 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.
pseudo-code | type pseudo-code | type
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
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) |
} | } |
skipping to change at page 21, line 46 skipping to change at page 22, line 7
+----------------+-------+ +----------------+-------+
| 0000 0000 0001 | 11 | | 0000 0000 0001 | 11 |
+----------------+-------+ +----------------+-------+
| 0000 0000 0000 | ESC | | 0000 0000 0000 | ESC |
+----------------+-------+ +----------------+-------+
Table 1 Table 1
3.8.2.1.2. Suffix 3.8.2.1.2. Suffix
+---------+--------------------------------------------------+ +---------+----------------------------------------+
+=========+==================================================+ +=========+========================================+
| 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 may only | | ESC | the value - 11, in MSB first order |
| | be used if the value cannot be coded as non ESC | +---------+----------------------------------------+
+---------+--------------------------------------------------+
Table 2 Table 2
"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
+-----+-------------------------+-------+ +-----+-------------------------+-------+
| 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 |
skipping to change at page 22, line 34 skipping to change at page 22, line 46
Table 3 Table 3
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 level is identical to the predicted one.
The run and the first different level are coded. The run and the first different level are coded.
3.8.2.2.1. Run Length Coding 3.8.2.2.1. Run Length Coding
The run value is encoded in 2 parts, the prefix part stores the more The run value is encoded in two parts. The prefix part stores the
significant part of the run as well as adjusting the "run_index" that more significant part of the run as well as adjusting the "run_index"
determines the number of bits in the less significant part of the that determines the number of bits in the less significant part of
run. The 2nd part of the value stores the less significant part of the run. The second part of the value stores the less significant
the run as it is. The run_index is reset for each "Plane" and slice part of the run as it is. The run_index is reset for each "Plane"
to 0. and slice to 0.
pseudo-code | type pseudo-code | type
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
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 23, line 35 skipping to change at page 23, line 35
} else { | } else { |
run_count = 0; | run_count = 0; |
} | } |
if (run_index) { | if (run_index) { |
run_index--; | run_index--; |
} | } |
run_mode = 2; | run_mode = 2; |
} | } |
} | } |
The "log2_run" function is also used within [ISO.14495-1.1999]. The "log2_run" array is also used within [ISO.14495-1.1999].
3.8.2.2.2. Level Coding
Level coding is identical to the normal difference coding with the
exception that the 0 value is removed as it cannot occur:
diff = get_vlc_symbol(context_state);
if (diff >= 0) {
diff++;
}
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
difference On a small set of test "Samples" the use of prediction
slightly improved the compression rate.
3.8.2.3. Scalar Mode 3.8.2.3. Scalar Mode
Each difference is coded with the per context mean prediction removed Each difference is coded with the per context mean prediction removed
and a per context value for k. and a per context value for k.
get_vlc_symbol(state) { get_vlc_symbol(state) {
i = state->count; i = state->count;
k = 0; k = 0;
while (i < state->error_sum) { while (i < state->error_sum) {
skipping to change at page 24, line 49 skipping to change at page 24, 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;
} }
3.8.2.3.1. Level Coding
Level coding is identical to the normal difference coding with the
exception that the 0 value is removed as it cannot occur:
diff = get_vlc_symbol(context_state);
if (diff >= 0) {
diff++;
}
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
difference. On a small set of test "Samples" the use of prediction
slightly improved the compression rate.
3.8.2.4. Initial Values for the VLC context state 3.8.2.4. Initial Values for the VLC context state
At keyframes all coder state variables are set to their initial At keyframes all coder state variables are set to their initial
state. 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 1 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 to explain the
structure of each FFV1 bitstream component, as described in structure of each FFV1 bitstream component, as described in
Section 2.2.1. Table 4 lists symbols used to annotate that pseudo- Section 2.2.1. Table 4 lists symbols used to annotate that pseudo-
code in order to define the storage of the data referenced in that code in order to define the storage of the data referenced in that
line of pseudo-code. line of pseudo-code.
+--------+----------------------------------------------+ +--------+----------------------------------------------+
| Symbol | Definition | | Symbol | Definition |
skipping to change at page 25, line 38 skipping to change at page 26, line 22
+--------+----------------------------------------------+ +--------+----------------------------------------------+
| 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 the method described in Section 3.8.1.2 | | | with 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 method described in Section 3.8.1.2 | | | the method described in Section 3.8.1.2 |
+--------+----------------------------------------------+ +--------+----------------------------------------------+
| sd | Sample difference coded with the method |
| | 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 same context that is initialized to 128 is used for all fields in The same context that is initialized to 128 is used for all fields in
the header. the header.
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:
skipping to change at page 28, line 10 skipping to change at page 28, line 10
Figure 19: A pseudo-code description of the bitstream contents. Figure 19: A pseudo-code description of the bitstream contents.
CONTEXT_SIZE is 32. CONTEXT_SIZE is 32.
4.1.1. version 4.1.1. 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 a file due to an unknown version. reject FFV1 bitstreams due to an unknown version.
Decoders SHOULD reject a file with version <= 1 && Decoders SHOULD reject FFV1 bitstreams with version <= 1 &&
ConfigurationRecordIsPresent == 1. ConfigurationRecordIsPresent == 1.
Decoders SHOULD reject a file with version >= 3 && Decoders SHOULD reject FFV1 bitstreams with version >= 3 &&
ConfigurationRecordIsPresent == 0. ConfigurationRecordIsPresent == 0.
+-------+-------------------------+ +-------+-------------------------+
| value | version | | value | version |
+=======+=========================+ +=======+=========================+
| 0 | FFV1 version 0 | | 0 | FFV1 version 0 |
+-------+-------------------------+ +-------+-------------------------+
| 1 | FFV1 version 1 | | 1 | FFV1 version 1 |
+-------+-------------------------+ +-------+-------------------------+
| 2 | reserved* | | 2 | reserved* |
+-------+-------------------------+ +-------+-------------------------+
| 3 | FFV1 version 3 | | 3 | FFV1 version 3 |
+-------+-------------------------+ +-------+-------------------------+
| Other | reserved for future use | | Other | reserved for future use |
+-------+-------------------------+ +-------+-------------------------+
Table 5 Table 5
* Version 2 was never enabled in the encoder thus version 2 files * Version 2 was experimental and this document does not describe it.
SHOULD NOT exist, and this document does not describe them to keep
the text simpler.
4.1.2. micro_version 4.1.2. micro_version
"micro_version" specifies the micro-version of the FFV1 bitstream. "micro_version" specifies the micro-version of the FFV1 bitstream.
After a version is considered stable (a micro-version value is After a version is considered stable (a micro-version value is
assigned to be the first stable variant of a specific version), each assigned to be the first stable variant of a specific version), each
new micro-version after this first stable variant is compatible with new micro-version after this first stable variant is compatible with
the previous micro-version: decoders SHOULD NOT reject a file due to the previous micro-version: decoders SHOULD NOT reject FFV1
an unknown micro-version equal or above the micro-version considered bitstreams due to an unknown micro-version equal or above the micro-
as stable. version considered as stable.
Meaning of "micro_version" for version 3: Meaning of "micro_version" for "version" 3:
+-------+-------------------------+ +-------+-------------------------+
| value | micro_version | | value | micro_version |
+=======+=========================+ +=======+=========================+
| 0...3 | reserved* | | 0...3 | reserved* |
+-------+-------------------------+ +-------+-------------------------+
| 4 | first stable variant | | 4 | first stable variant |
+-------+-------------------------+ +-------+-------------------------+
| Other | reserved for future use | | Other | reserved for future use |
+-------+-------------------------+ +-------+-------------------------+
Table 6: The definitions for Table 6: The definitions for
"micro_version" values. "micro_version" values for FFV1
version 3.
* development versions may be incompatible with the stable variants. * development versions may be incompatible with the stable variants.
4.1.3. coder_type 4.1.3. coder_type
"coder_type" specifies the coder used. "coder_type" specifies the coder used.
+-------+-------------------------------------------------+ +-------+-------------------------------------------------+
| value | coder used | | value | coder used |
+=======+=================================================+ +=======+=================================================+
skipping to change at page 29, line 43 skipping to change at page 29, line 44
| Other | reserved for future use | | Other | reserved for future use |
+-------+-------------------------------------------------+ +-------+-------------------------------------------------+
Table 7 Table 7
Restrictions: Restrictions:
If "coder_type" is 0, then "bits_per_raw_sample" SHOULD NOT be > 8. If "coder_type" is 0, then "bits_per_raw_sample" SHOULD NOT be > 8.
Background: At the time of this writing, there is no known Background: At the time of this writing, there is no known
implementations of FFV1 bitstream supporting Golomb Rice algorithm implementation of FFV1 bitstream supporting Golomb Rice algorithm
with "bits_per_raw_sample" greater than 8, and Range Coder is with "bits_per_raw_sample" greater than 8, and Range Coder is
prefered. prefered.
4.1.4. state_transition_delta 4.1.4. state_transition_delta
"state_transition_delta" specifies the Range coder custom state "state_transition_delta" specifies the Range coder custom state
transition table. transition table.
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
skipping to change at page 30, line 34 skipping to change at page 30, line 34
| | | | | then | | | | | | then |
| | | | | "Plane" | | | | | | "Plane" |
+-------+-------------+----------------+--------------+-------------+ +-------+-------------+----------------+--------------+-------------+
| Other | reserved | reserved for | reserved for | reserved | | Other | reserved | reserved for | reserved for | reserved |
| | for future | future use | future use | for future | | | for future | future use | future use | for future |
| | use | | | use | | | use | | | use |
+-------+-------------+----------------+--------------+-------------+ +-------+-------------+----------------+--------------+-------------+
Table 8 Table 8
Restrictions: FFV1 bitstreams with "colorspace_type" == 1 && ("chroma_planes" !=
1 || "log2_h_chroma_subsample" != 0 || "log2_v_chroma_subsample" !=
If "colorspace_type" is 1, then "chroma_planes" MUST be 1, 0) are not part of this specification.
"log2_h_chroma_subsample" MUST be 0, and "log2_v_chroma_subsample"
MUST be 0.
4.1.6. chroma_planes 4.1.6. 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 |
+-------+---------------------------------+ +-------+---------------------------------+
skipping to change at page 31, line 20 skipping to change at page 31, line 20
+-------+-----------------------------------+ +-------+-----------------------------------+
| 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 10 Table 10
* 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.
4.1.8. log2_h_chroma_subsample 4.1.8. 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 must be raised, between luma and chroma
width ("chroma_width = 2^-log2_h_chroma_subsample^ * luma_width"). width ("chroma_width = 2 ^ -log2_h_chroma_subsample * luma_width").
4.1.9. log2_v_chroma_subsample 4.1.9. 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 must be raised, between luma and chroma
height ("chroma_height=2^-log2_v_chroma_subsample^ * luma_height"). height ("chroma_height = 2 ^ -log2_v_chroma_subsample *
luma_height").
4.1.10. "extra\_plane" 4.1.10. 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 |
+-------+------------------------------+ +-------+------------------------------+
skipping to change at page 32, line 46 skipping to change at page 32, line 51
| 1 | initial states are present | | 1 | initial states are present |
+-------+--------------------------------+ +-------+--------------------------------+
Table 12 Table 12
4.1.15. initial_state_delta 4.1.15. 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 ] pred = j ? initial_states[ i ][j - 1][ k ] : 128
Figure 20 Figure 20
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 21 Figure 21
4.1.16. ec 4.1.16. 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 on the global header | | 0 | 32-bit CRC on the global header |
skipping to change at page 34, line 30 skipping to change at page 34, line 38
Encoders conforming to this version of this specification SHALL NOT Encoders conforming to this version of this specification SHALL NOT
write this value. write this value.
Decoders conforming to this version of this specification SHALL Decoders conforming to this version of this specification SHALL
ignore its value. ignore its value.
4.2.2. configuration_record_crc_parity 4.2.2. 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 the standard IEEE CRC polynomial The CRC generator polynomial used is described in Section 4.8.3.
(0x104C11DB7) with initial value 0.
4.2.3. Mapping FFV1 into Containers 4.2.3. Mapping FFV1 into Containers
This "Configuration Record" can be placed in any file format This "Configuration Record" can be placed in any file format
supporting "Configuration Records", fitting as much as possible with supporting "Configuration Records", fitting as much as possible with
how the file format uses to store "Configuration Records". The how the file format uses to store "Configuration Records". The
"Configuration Record" storage place and "NumBytes" are currently "Configuration Record" storage place and "NumBytes" are currently
defined and supported by this version of this specification for the defined and supported by this version of this specification for the
following formats: following formats:
skipping to change at page 35, line 46 skipping to change at page 36, line 6
"NumBytes" is defined as the "Element Data Size" of the "NumBytes" is defined as the "Element Data Size" of the
"CodecPrivate" Element. "CodecPrivate" Element.
4.3. Frame 4.3. Frame
A "Frame" is an encoded representation of a complete static image. A "Frame" is an encoded representation of a complete static image.
The whole "Frame" is provided by the underlaying container. The 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" <=1), and a sequence of independent slices. The pseudo- "version" <= 1), and a sequence of independent slices. The pseudo-
code below describes the contents of a "Frame". code below describes the contents of a "Frame".
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 )) { |
skipping to change at page 37, line 8 skipping to change at page 37, line 8
| last slice content | | last slice content |
+-----------------------------------------------------------------+ +-----------------------------------------------------------------+
| last slice footer | | last slice footer |
+-----------------------------------------------------------------+ +-----------------------------------------------------------------+
Table 15 Table 15
4.4. Slice 4.4. 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 an other region of the same "Frame". The use encoded separately from another region of the same "Frame". The use
of more than one "Slice" per "Frame" can be useful for taking of more than one "Slice" per "Frame" can be useful for taking
advantage of the opportunities of multithreaded encoding and advantage of 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
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
skipping to change at page 37, line 50 skipping to change at page 38, line 5
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 these bits.
Decoders SHOULD ignore these bits. Decoders SHOULD ignore these bits.
Note in case these bits are used in a later revision of this
specification: any revision of this specification SHOULD care about
avoiding to add 40 bits of content after "SliceContent" for "version"
0 and 1 of the bitstream. Background: Due to some non-conforming
encoders, some bitstreams were found with 40 extra bits corresponding
to "error_status" and "slice_crc_parity". As a result, a decoder
conforming to the revised specification could not distinguish between
a revised bitstream and a buggy bitstream.
4.5. Slice Header 4.5. 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".
pseudo-code | type pseudo-code | type
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
SliceHeader( ) { | SliceHeader( ) { |
skipping to change at page 39, line 14 skipping to change at page 39, line 9
4.5.4. slice_height 4.5.4. slice_height
"slice_height" indicates the height on the slice raster formed by "slice_height" indicates the height on the slice raster formed by
num_v_slices. num_v_slices.
Inferred to be 1 if not present. Inferred to be 1 if not present.
4.5.5. quant_table_set_index_count 4.5.5. quant_table_set_index_count
"quant_table_set_index_count" is defined as "1 + ( ( chroma_planes || "quant_table_set_index_count" is defined as:
version <= 3 ) ? 1 : 0 ) + ("extra_plane"? 1 : 0 )".
1 + ( ( chroma_planes || version <= 3 ) ? 1 : 0 ) + ( extra_plane ? 1
: 0 )
4.5.6. quant_table_set_index 4.5.6. quant_table_set_index
"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. slice.
Inferred to be 0 if not present. Inferred to be 0 if not present.
4.5.7. picture_structure 4.5.7. picture_structure
skipping to change at page 41, line 7 skipping to change at page 40, line 50
for (y = 0; y < slice_pixel_height; y++) { | for (y = 0; y < slice_pixel_height; y++) { |
for (p = 0; p < primary_color_count; p++) { | for (p = 0; p < primary_color_count; p++) { |
Line( p, y ) | Line( p, y ) |
} | } |
} | } |
} | } |
} | } |
4.6.1. primary_color_count 4.6.1. primary_color_count
"primary_color_count" is defined as "1 + ( chroma_planes ? 2 : 0 ) + "primary_color_count" is defined as:
("extra_plane"? 1 : 0 )".
4.6.2. plane_pixel_height 1 + ( chroma_planes ? 2 : 0 ) + ( extra_plane ? 1 : 0 )
"plane_pixel_height[ p ]" is the height in pixels of plane p of the 4.6.2. plane_pixel_height
slice.
"plane_pixel_height[ 0 ]" and "plane_pixel_height[ 1 + ( "plane_pixel_height[ p ]" is the height in "Pixels" of "Plane" p of
chroma_planes ? 2 : 0 ) ]" value is "slice_pixel_height". the "Slice". It is defined as:
If "chroma_planes" is set to 1, "plane_pixel_height[ 1 ]" and (chroma_planes == 1 && (p == 1 || p == 2)) ? ceil(slice_pixel_height
"plane_pixel_height[ 2 ]" value is "ceil( slice_pixel_height / (1 << / (1 << log2_v_chroma_subsample)) : slice_pixel_height
log2_v_chroma_subsample) )".
4.6.3. slice_pixel_height 4.6.3. slice_pixel_height
"slice_pixel_height" is the height in pixels of the slice. "slice_pixel_height" is the height in pixels of the slice. It is
defined as:
Its value is "floor( ( slice_y + slice_height ) * slice_pixel_height floor( ( slice_y + slice_height ) * slice_pixel_height / num_v_slices
/ num_v_slices ) - slice_pixel_y". ) - slice_pixel_y.
4.6.4. slice_pixel_y 4.6.4. slice_pixel_y
"slice_pixel_y" is the slice vertical position in pixels. "slice_pixel_y" is the slice vertical position in pixels. It is
defined as:
Its value is "floor( slice_y * frame_pixel_height / num_v_slices )". floor( slice_y * frame_pixel_height / num_v_slices )
4.7. Line 4.7. 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 ] | 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 ] | sample_difference[ p ][ y ][ x ] | sd
} | } |
} | } |
} | } |
4.7.1. plane_pixel_width 4.7.1. 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. "Slice". It is defined as:
"plane_pixel_width[ 0 ]" and "plane_pixel_width[ 1 + ( chroma_planes
? 2 : 0 ) ]" value is "slice_pixel_width".
If "chroma_planes" is set to 1, "plane_pixel_width[ 1 ]" and (chroma_planes == 1 && (p == 1 || p == 2)) ? ceil( slice_pixel_width
"plane_pixel_width[ 2 ]" value is "ceil( slice_pixel_width / (1 << / (1 << log2_h_chroma_subsample) ) : slice_pixel_width.
log2_h_chroma_subsample) )".
4.7.2. slice_pixel_width 4.7.2. slice_pixel_width
"slice_pixel_width" is the width in "Pixels" of the slice. "slice_pixel_width" is the width in "Pixels" of the slice. It is
defined as:
Its value is "floor( ( slice_x + slice_width ) * slice_pixel_width / floor( ( slice_x + slice_width ) * slice_pixel_width / num_h_slices )
num_h_slices ) - slice_pixel_x". - slice_pixel_x
4.7.3. slice_pixel_x 4.7.3. slice_pixel_x
"slice_pixel_x" is the slice horizontal position in "Pixels". "slice_pixel_x" is the slice horizontal position in "Pixels". It is
defined as:
Its value is "floor( slice_x * frame_pixel_width / num_h_slices )". floor( slice_x * frame_pixel_width / num_h_slices )
4.7.4. sample_difference 4.7.4. 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" value is computed based on median predictor and context "Sample" value is computed based on median predictor and context
described in Section 3.2. described in Section 3.2.
4.8. Slice Footer 4.8. Slice Footer
skipping to change at page 44, line 39 skipping to change at page 44, line 17
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
QuantizationTableSet( i ) { | QuantizationTableSet( i ) { |
scale = 1 | scale = 1 |
for (j = 0; j < MAX_CONTEXT_INPUTS; j++) { | for (j = 0; j < MAX_CONTEXT_INPUTS; j++) { |
QuantizationTable( i, j, scale ) | QuantizationTable( i, j, scale ) |
scale *= 2 * len_count[ i ][ j ] - 1 | scale *= 2 * len_count[ i ][ j ] - 1 |
} | } |
context_count[ i ] = ceil( scale / 2 ) | context_count[ i ] = ceil( scale / 2 ) |
} | } |
MAX_CONTEXT_INPUTS is 5. "MAX_CONTEXT_INPUTS" is 5.
pseudo-code | type pseudo-code | type
--------------------------------------------------------------|----- --------------------------------------------------------------|-----
QuantizationTable(i, j, scale) { | QuantizationTable(i, j, scale) { |
v = 0 | v = 0 |
for (k = 0; k < 128;) { | for (k = 0; k < 128;) { |
len - 1 | ur len - 1 | ur
for (a = 0; a < len; a++) { | for (a = 0; a < len; a++) { |
quant_tables[ i ][ j ][ k ] = scale * v | quant_tables[ i ][ j ][ k ] = scale * v |
k++ | k++ |
skipping to change at page 45, line 41 skipping to change at page 45, line 8
4.9.2. context_count 4.9.2. 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.
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
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Subtype name: FFV1 Subtype name: FFV1
Required parameters: None. Required parameters: None.
Optional parameters: Optional parameters:
This parameter is used to signal the capabilities of a receiver This parameter is used to signal the capabilities of a receiver
implementation. This parameter MUST NOT be used for any other implementation. This parameter MUST NOT be used for any other
purpose. purpose.
"version": The version of the FFV1 encoding as defined by "version": The "version" of the FFV1 encoding as defined by
Section 4.1.1. Section 4.1.1.
"micro_version": The "micro_version" of the FFV1 encoding as defined "micro_version": The "micro_version" of the FFV1 encoding as defined
by Section 4.1.2. by Section 4.1.2.
"coder_type": The "coder_type" of the FFV1 encoding as defined by "coder_type": The "coder_type" of the FFV1 encoding as defined by
Section 4.1.3. Section 4.1.3.
"colorspace_type": The "colorspace_type" of the FFV1 encoding as "colorspace_type": The "colorspace_type" of the FFV1 encoding as
defined by Section 4.1.5. defined by Section 4.1.5.
skipping to change at page 48, line 43 skipping to change at page 48, line 5
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. IANA Considerations
The IANA is requested to register the following values: The IANA is requested to register the following values:
* Media type registration as described in Section 7. * Media type registration as described in Section 7.
9. Appendix A: Multi-theaded decoder implementation suggestions 9. Changelog
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
each slice. Each slice footer contains a "slice_size" field so the
boundary of each slice is computable without having to parse the
slice content. That allows multi-threading as well as independence
of slice content (a bitstream error in a slice header or slice
content has no impact on the decoding of the other slices).
After having checked "keyframe" field, a decoder SHOULD parse
"slice_size" fields, from "slice_size" of the last slice at the end
of the "Frame" up to "slice_size" of the first slice at the beginning
of the "Frame", before parsing slices, in order to have slices
boundaries. A decoder MAY fallback on sequential order e.g. in case
of a corrupted "Frame" (frame size unknown, "slice_size" of slices
not coherent...) or if there is no possibility of seeking into the
stream.
10. 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.]
11. Normative References 10. Normative References
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[ISO.9899.1990] [ISO.15444-1.2016]
International Organization for Standardization, International Organization for Standardization,
"Programming languages - C", 1990. "Information technology -- JPEG 2000 image coding system:
Core coding system", October 2016.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload [Matroska] IETF, "Matroska", 2019, <https://datatracker.ietf.org/doc/
Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007, draft-ietf-cellar-matroska/>.
<https://www.rfc-editor.org/info/rfc4855>.
[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.15444-1.2016] [RFC4855] Casner, S., "Media Type Registration of RTP Payload
International Organization for Standardization, Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
"Information technology -- JPEG 2000 image coding system: <https://www.rfc-editor.org/info/rfc4855>.
Core coding system", October 2016.
[ISO.9899.2018] [ISO.9899.2018]
International Organization for Standardization, International Organization for Standardization,
"Programming languages - C", 2018. "Programming languages - C", 2018.
[RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the [RFC6716] Valin, JM., Vos, K., and T. Terriberry, "Definition of the
Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716, Opus Audio Codec", RFC 6716, DOI 10.17487/RFC6716,
September 2012, <https://www.rfc-editor.org/info/rfc6716>. September 2012, <https://www.rfc-editor.org/info/rfc6716>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[Matroska] IETF, "Matroska", 2019, <https://datatracker.ietf.org/doc/
draft-ietf-cellar-matroska/>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
12. Informative References [ISO.9899.1990]
International Organization for Standardization,
"Programming languages - C", 1990.
[AVI] Microsoft, "AVI RIFF File Reference", undated, [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
<https://msdn.microsoft.com/en-us/library/windows/desktop/ Specifications and Registration Procedures", BCP 13,
dd318189%28v=vs.85%29.aspx>. RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[range-coding] [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Nigel, G. and N. Martin, "Range encoding: an algorithm for Requirement Levels", BCP 14, RFC 2119,
removing redundancy from a digitised message.", July 1979. DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[FFV1_V1] Niedermayer, M., "Commit to release FFV1 version 1", April 11. Informative References
2009, <https://git.videolan.org/?p=ffmpeg.git;a=commit;h=6
8f8d33becbd73b4d0aa277f472a6e8e72ea6849>. [YCbCr] Wikipedia, "YCbCr", undated,
<https://en.wikipedia.org/w/index.php?title=YCbCr>.
[REFIMPL] Niedermayer, M., "The reference FFV1 implementation / the
FFV1 codec in FFmpeg", undated, <https://ffmpeg.org>.
[Address-Sanitizer] [Address-Sanitizer]
The Clang Team, "ASAN AddressSanitizer website", undated, The Clang Team, "ASAN AddressSanitizer website", undated,
<https://clang.llvm.org/docs/AddressSanitizer.html>. <https://clang.llvm.org/docs/AddressSanitizer.html>.
[YCbCr] Wikipedia, "YCbCr", undated, [VALGRIND] Valgrind Developers, "Valgrind website", undated,
<https://en.wikipedia.org/w/index.php?title=YCbCr>. <https://valgrind.org/>.
[ISO.14495-1.1999]
International Organization for Standardization,
"Information technology -- Lossless and near-lossless
compression of continuous-tone still images: Baseline",
December 1999.
[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.
[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.
[HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003,
<https://web.archive.org/web/20040402121343/
http://cultact-server.novi.dk/kpo/huffyuv/huffyuv.html>.
[AVI] Microsoft, "AVI RIFF File Reference", undated,
<https://msdn.microsoft.com/en-us/library/windows/desktop/
dd318189%28v=vs.85%29.aspx>.
[NUT] Niedermayer, M., "NUT Open Container Format", December [NUT] Niedermayer, M., "NUT Open Container Format", December
2013, <https://ffmpeg.org/~michael/nut.txt>. 2013, <https://ffmpeg.org/~michael/nut.txt>.
[FFV1_V3] Niedermayer, M., "Commit to mark FFV1 version 3 as non-
experimental", August 2013, <https://git.videolan.org/?p=f
fmpeg.git;a=commit;h=abe76b851c05eea8743f6c899cbe5f7409b0f
301>.
[range-coding]
Nigel, G. and N. Martin, "Range encoding: an algorithm for
removing redundancy from a digitised message.", July 1979.
[FFV1_V0] Niedermayer, M., "Commit to mark FFV1 version 0 as non- [FFV1_V0] Niedermayer, M., "Commit to mark FFV1 version 0 as non-
experimental", April 2006, <https://git.videolan.org/?p=ff experimental", April 2006, <https://git.videolan.org/?p=ff
mpeg.git;a=commit;h=b548f2b91b701e1235608ac882ea6df915167c mpeg.git;a=commit;h=b548f2b91b701e1235608ac882ea6df915167c
7e>. 7e>.
[FFV1_V3] Niedermayer, M., "Commit to mark FFV1 version 3 as non- [FFV1_V1] Niedermayer, M., "Commit to release FFV1 version 1", April
experimental", August 2013, <https://git.videolan.org/?p=f 2009, <https://git.videolan.org/?p=ffmpeg.git;a=commit;h=6
fmpeg.git;a=commit;h=abe76b851c05eea8743f6c899cbe5f7409b0f 8f8d33becbd73b4d0aa277f472a6e8e72ea6849>.
301>.
[REFIMPL] Niedermayer, M., "The reference FFV1 implementation / the Appendix A. Multi-theaded decoder implementation suggestions
FFV1 codec in FFmpeg", undated, <https://ffmpeg.org>.
[VALGRIND] Valgrind Developers, "Valgrind website", undated, This appendix is informative.
<https://valgrind.org/>.
[ISO.14495-1.1999] The FFV1 bitstream is parsable in two ways: in sequential order as
International Organization for Standardization, described in this document or with the pre-analysis of the footer of
"Information technology -- Lossless and near-lossless each slice. Each slice footer contains a "slice_size" field so the
compression of continuous-tone still images: Baseline", boundary of each slice is computable without having to parse the
December 1999. slice content. That allows multi-threading as well as independence
of slice content (a bitstream error in a slice header or slice
content has no impact on the decoding of the other slices).
[HuffYUV] Rudiak-Gould, B., "HuffYUV", December 2003, After having checked "keyframe" field, a decoder SHOULD parse
<https://web.archive.org/web/20040402121343/ "slice_size" fields, from "slice_size" of the last slice at the end
http://cultact-server.novi.dk/kpo/huffyuv/huffyuv.html>. of the "Frame" up to "slice_size" of the first slice at the beginning
of the "Frame", before parsing slices, in order to have slices
boundaries. A decoder MAY fallback on sequential order e.g. in case
of a corrupted "Frame" (frame size unknown, "slice_size" of slices
not coherent...) or if there is no possibility of seeking into the
stream.
Appendix B. Future handling of some streams created by non conforming
encoders
This appendix is informative.
Some bitstreams were found with 40 extra bits corresponding to
"error_status" and "slice_crc_parity" in the "reserved" bits of
"Slice()". Any revision of this specification SHOULD care about
avoiding to add 40 bits of content after "SliceContent" if "version"
== 0 or "version" == 1. Else a decoder conforming to the revised
specification could not distinguish between a revised bitstream and
such buggy bitstream in the wild.
Authors' Addresses Authors' Addresses
Michael Niedermayer Michael Niedermayer
Email: michael@niedermayer.cc Email: michael@niedermayer.cc
Dave Rice Dave Rice
Email: dave@dericed.com Email: dave@dericed.com
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