draft-ietf-fecframe-raptor-02.txt   draft-ietf-fecframe-raptor-03.txt 
FEC Framework M. Watson FEC Framework M. Watson
Internet-Draft Qualcomm, Inc. Internet-Draft Netflix
Intended status: Standards Track March 5, 2010 Intended status: Standards Track T. Stockhammer
Expires: September 6, 2010 Expires: May 27, 2011 Nomor Research
November 23, 2010
Raptor FEC Schemes for FECFRAME Raptor FEC Schemes for FECFRAME
draft-ietf-fecframe-raptor-02 draft-ietf-fecframe-raptor-03
Abstract Abstract
This document describes Fully-Specified Forward Error Correction This document describes Fully-Specified Forward Error Correction
(FEC) Schemes for the Raptor and RaptorQ codes and their application (FEC) Schemes for the Raptor and RaptorQ codes and their application
to reliable delivery of media streams in the context of FEC to reliable delivery of media streams in the context of FEC
Framework. The Raptor and RaptorQ codes are systematic codes, where Framework. The Raptor and RaptorQ codes are systematic codes, where
a number of repair symbols are generated from a set of source symbols a number of repair symbols are generated from a set of source symbols
and sent in one or more repair flows in addition to the source and sent in one or more repair flows in addition to the source
symbols that are sent to the receiver(s) within a source flow. The symbols that are sent to the receiver(s) within a source flow. The
Raptor and RaptorQ codes offer close to optimal protection against Raptor and RaptorQ codes offer close to optimal protection against
arbitrary packet losses at a low computational complexity. Six FEC arbitrary packet losses at a low computational complexity. Six FEC
Schemes are defined, two for protection of arbitrary packet flows, Schemes are defined, two for protection of arbitrary packet flows,
two that are optimised for small source blocks and another two for two that are optimised for small source blocks and another two for
protection of a single flow that already contains a sequence number. protection of a single flow that already contains a sequence number.
Repair data may be sent over arbitrary datagram transport (e.g. UDP) Repair data may be sent over arbitrary datagram transport (e.g. UDP)
or using RTP. or using RTP.
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Document Outline . . . . . . . . . . . . . . . . . . . . . . . 5 2. Document Outline . . . . . . . . . . . . . . . . . . . . . . . 5
3. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5 3. Requirements Notation . . . . . . . . . . . . . . . . . . . . 5
4. Definitions and Abbreviations . . . . . . . . . . . . . . . . 5 4. Definitions and Abbreviations . . . . . . . . . . . . . . . . 5
4.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Definitions . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 6 4.2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . 6
5. General procedures for Raptor FEC Schemes . . . . . . . . . . 7 5. General procedures for Raptor FEC Schemes . . . . . . . . . . 7
6. Raptor FEC Schemes for arbitrary packet flows . . . . . . . . 8 6. Raptor FEC Schemes for arbitrary packet flows . . . . . . . . 8
6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 8 6.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 8
6.2. Formats and Codes . . . . . . . . . . . . . . . . . . . . 8 6.2. Formats and Codes . . . . . . . . . . . . . . . . . . . . 8
6.2.1. FEC Framework Configuration Information . . . . . . . 8 6.2.1. FEC Framework Configuration Information . . . . . . . 8
6.2.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 9 6.2.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 9
6.2.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 10 6.2.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 10
6.3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 11 6.3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 12
6.3.1. Source symbol construction . . . . . . . . . . . . . . 11 6.3.1. Source symbol construction . . . . . . . . . . . . . . 12
6.3.2. Repair packet construction . . . . . . . . . . . . . . 11 6.3.2. Repair packet construction . . . . . . . . . . . . . . 12
6.4. FEC Code Specification . . . . . . . . . . . . . . . . . . 12 6.4. FEC Code Specification . . . . . . . . . . . . . . . . . . 12
7. Optimised Raptor FEC Scheme for arbitrary packet flows . . . . 12 7. Optimised Raptor FEC Scheme for arbitrary packet flows . . . . 13
7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 12 7.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 13
7.2. Formats and Codes . . . . . . . . . . . . . . . . . . . . 13 7.2. Formats and Codes . . . . . . . . . . . . . . . . . . . . 13
7.2.1. FEC Framework Configuration Information . . . . . . . 13 7.2.1. FEC Framework Configuration Information . . . . . . . 13
7.2.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 13 7.2.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 14
7.2.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 13 7.2.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 14
7.3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 13 7.3. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 14
7.3.1. Source symbol construction . . . . . . . . . . . . . . 13 7.3.1. Source symbol construction . . . . . . . . . . . . . . 14
7.3.2. Repair packet construction . . . . . . . . . . . . . . 13 7.3.2. Repair packet construction . . . . . . . . . . . . . . 14
7.4. FEC Code Specification . . . . . . . . . . . . . . . . . . 14 7.4. FEC Code Specification . . . . . . . . . . . . . . . . . . 14
8. Raptor FEC Scheme for a single sequenced flow . . . . . . . . 14 8. Raptor FEC Scheme for a single sequenced flow . . . . . . . . 15
8.1. Formats and codes . . . . . . . . . . . . . . . . . . . . 14 8.1. Formats and codes . . . . . . . . . . . . . . . . . . . . 15
8.1.1. FEC Framework Configuration Information . . . . . . . 14 8.1.1. FEC Framework Configuration Information . . . . . . . 15
8.1.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 15 8.1.2. Source FEC Payload ID . . . . . . . . . . . . . . . . 15
8.1.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 15 8.1.3. Repair FEC Payload ID . . . . . . . . . . . . . . . . 15
8.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 16 8.2. Procedures . . . . . . . . . . . . . . . . . . . . . . . . 17
8.2.1. Source symbol construction . . . . . . . . . . . . . . 16 8.2.1. Source symbol construction . . . . . . . . . . . . . . 17
8.2.2. Derivation of Source FEC Packet Identification 8.2.2. Derivation of Source FEC Packet Identification
Information . . . . . . . . . . . . . . . . . . . . . 16 Information . . . . . . . . . . . . . . . . . . . . . 17
8.2.3. Repair packet construction . . . . . . . . . . . . . . 17 8.2.3. Repair packet construction . . . . . . . . . . . . . . 18
8.2.4. Procedures for RTP source flows . . . . . . . . . . . 18 8.2.4. Procedures for RTP source flows . . . . . . . . . . . 18
8.3. FEC Code Specification . . . . . . . . . . . . . . . . . . 18 8.3. FEC Code Specification . . . . . . . . . . . . . . . . . . 18
9. Security Considerations . . . . . . . . . . . . . . . . . . . 18 9. Security Considerations . . . . . . . . . . . . . . . . . . . 19
10. Session Description Protocol (SDP) Signaling . . . . . . . . . 18 10. Session Description Protocol (SDP) Signaling . . . . . . . . . 19
11. Congestion Control Considerations . . . . . . . . . . . . . . 19 11. Congestion Control Considerations . . . . . . . . . . . . . . 19
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
12.1. Registration of FEC Scheme IDs . . . . . . . . . . . . . . 19 12.1. Registration of FEC Scheme IDs . . . . . . . . . . . . . . 19
13. Normative References . . . . . . . . . . . . . . . . . . . . . 20 13. Normative References . . . . . . . . . . . . . . . . . . . . . 20
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
The FEC Framework [I-D.ietf-fecframe-framework] describes a framework The FEC Framework [I-D.ietf-fecframe-framework] describes a framework
for the application of Forward Error Correction to arbitrary packet for the application of Forward Error Correction to arbitrary packet
flows. Modelled after the FEC Building Block developed by the IETF flows. Modelled after the FEC Building Block developed by the IETF
Reliable Multicast Transport working group [RFC5052], the FEC Reliable Multicast Transport working group [RFC5052], the FEC
Framework defines the concept of FEC Schemes which provide specific Framework defines the concept of FEC Schemes which provide specific
Forward Error Correction schemes. This document describes six FEC Forward Error Correction schemes. This document describes six FEC
Schemes which make use of the Raptor and RaptorQ FEC codes as defined Schemes which make use of the Raptor and RaptorQ FEC codes as defined
skipping to change at page 4, line 28 skipping to change at page 4, line 28
example audio or video data. In general, the operation of the example audio or video data. In general, the operation of the
protection mechanism is as follows: protection mechanism is as follows:
o The sender determines a set of source packets (a source block) to o The sender determines a set of source packets (a source block) to
be protected together based on the FEC Framework Configuration be protected together based on the FEC Framework Configuration
Information. Information.
o The sender arranges the source packets into a set of source o The sender arranges the source packets into a set of source
symbols, each of which is the same size. symbols, each of which is the same size.
o The sender applies the Raptor protection operation on the source o The sender applies the Raptor/RaptorQ protection operation on the
symbols to generate the required number of repair symbols. source symbols to generate the required number of repair symbols.
o The sender packetizes the repair symbols and sends the repair o The sender packetizes the repair symbols and sends the repair
packet(s) along with the source packets to the receiver(s). packet(s) along with the source packets to the receiver(s).
Per the FEC Framework requirements, the sender MUST transmit the Per the FEC Framework requirements, the sender MUST transmit the
source and repair packets in different source and repair flows, or in source and repair packets in different source and repair flows, or in
the case RTP transport is used for Repair packets, in different RTP the case RTP transport is used for Repair packets, in different RTP
streams. At the receiver side, if all of the source packets are streams. At the receiver side, if all of the source packets are
successfully received, there is no need for FEC recovery and the successfully received, there is no need for FEC recovery and the
repair packets are discarded. However, if there are missing source repair packets are discarded. However, if there are missing source
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Otherwise, it is necessary to add data to the source packets for FEC Otherwise, it is necessary to add data to the source packets for FEC
purposes in the form of a non-empty FEC Source Payload ID. This case purposes in the form of a non-empty FEC Source Payload ID. This case
if referred to as the "arbitrary packet flow" case. Accordingly, if referred to as the "arbitrary packet flow" case. Accordingly,
this document defines two FEC Schemes, one for the case of a single this document defines two FEC Schemes, one for the case of a single
sequenced flow and another for the case of arbitrary packet flows. sequenced flow and another for the case of arbitrary packet flows.
2. Document Outline 2. Document Outline
This document is organised as follows: This document is organised as follows:
Section 5 defines general procedures applicable to the use of the o Section 5 defines general procedures applicable to the use of the
Raptor and RaptorQ codes in the context of the FEC Framework. Raptor and RaptorQ codes in the context of the FEC Framework.
Section 6defines an FEC Scheme for the case of arbitrary source o Section 6defines an FEC Scheme for the case of arbitrary source
flows and follows the format defined for FEC Schemes in flows and follows the format defined for FEC Schemes in
[I-D.ietf-fecframe-framework]. When used with Raptor codes, this [I-D.ietf-fecframe-framework]. When used with Raptor codes, this
scheme is equivalent to that defined in [MBMSTS]. scheme is equivalent to that defined in [MBMSTS].
Section 7 defines an FEC Scheme similar to that defined in o Section 7 defines an FEC Scheme similar to that defined in
Section 6but with optimisations for the case where only limited Section 6but with optimisations for the case where only limited
source block sizes are required. When used with Raptor codes, source block sizes are required. When used with Raptor codes,
this scheme is equivalent to that defined in [dvbts] for arbitrary this scheme is equivalent to that defined in [dvbts] for arbitrary
packet flows. packet flows.
Section 8 defines an FEC Scheme for the case of a single flow o Section 8 defines an FEC Scheme for the case of a single flow
which is already provided with a source packet sequence number. which is already provided with a source packet sequence number.
When used with Raptor codes, this scheme is equivalent to that When used with Raptor codes, this scheme is equivalent to that
defined in [dvbts] for the case of a single sequenced flow. defined in [dvbts] for the case of a single sequenced flow.
3. Requirements Notation 3. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
skipping to change at page 6, line 12 skipping to change at page 6, line 12
The definitions, notations and abbreviations commonly used in this The definitions, notations and abbreviations commonly used in this
document are summarized in this section. document are summarized in this section.
4.1. Definitions 4.1. Definitions
This document uses the following definitions. For further This document uses the following definitions. For further
definitions that apply to FEC Framework in general, see definitions that apply to FEC Framework in general, see
[I-D.ietf-fecframe-framework]. [I-D.ietf-fecframe-framework].
Source Flow: The packet flow(s) or stream(s) carrying the source Source Flow: The packet flow(s) or stream(s) carrying the source
data and to which FEC protection is to be applied. data and to which FEC protection is to be applied.
Repair Flow: The packet flow(s) or stream(s) carrying the repair Repair Flow: The packet flow(s) or stream(s) carrying the repair
data. data.
Symbol: A unit of data. Its size, in bytes, is referred to as the Symbol: A unit of data. Its size, in bytes, is referred to as the
symbol size. symbol size.
Source Symbol: The smallest unit of data used during the encoding Source Symbol: The smallest unit of data used during the encoding
process. process.
Repair Symbol: Repair symbols are generated from the source symbols. Repair Symbol: Repair symbols are generated from the source symbols.
Source Packet: Data packets that contain only source symbols. Source Packet: Data packets that contain only source symbols.
Repair Packet: Data packets that contain only repair symbols. Repair Packet: Data packets that contain only repair symbols.
Source Block: A block of source symbols that are considered together Source Block: A block of source symbols that are considered together
in the encoding process. in the encoding process.
FEC Framework Configuration Information: Information that controls FEC Framework Configuration Information: Information that controls
the operation of the FEC Framework. Each FEC Framework instance has the operation of the FEC Framework. Each FEC Framework instance
its own configuration information. has its own configuration information.
FEC Payload ID: Information that identifies the contents of a packet FEC Payload ID: Information that identifies the contents of a packet
with respect to the FEC scheme. with respect to the FEC scheme.
Source FEC Payload ID: An FEC Payload ID specifically used with Source FEC Payload ID: An FEC Payload ID specifically used with
source packets. source packets.
Repair FEC Payload ID: An FEC Payload ID specifically used with Repair FEC Payload ID: An FEC Payload ID specifically used with
repair packets. repair packets.
4.2. Abbreviations 4.2. Abbreviations
o FSSI: FEC-Scheme-Specific Information. FSSI: FEC-Scheme-Specific Information.
o SS-FSSI: Sender-Side FEC-Scheme-Specific Information. SS-FSSI: Sender-Side FEC-Scheme-Specific Information.
o RS-FSSI: Receiver-Side FEC-Scheme-Specific Information. RS-FSSI: Receiver-Side FEC-Scheme-Specific Information.
ADU Application Data Unit
ADUI Application Data Unit Information
5. General procedures for Raptor FEC Schemes 5. General procedures for Raptor FEC Schemes
This section specifies general procedures which apply to all Raptor This section specifies general procedures which apply to all Raptor
and RaptorQ FEC Schemes, specifically the construction of source and RaptorQ FEC Schemes, specifically the construction of source
symbols from a set of source transport payloads. As described in symbols from a set of source transport payloads. As described in
[I-D.ietf-fecframe-framework] for each Application Data Unit in a [I-D.ietf-fecframe-framework] for each Application Data Unit (ADU) in
source block, the FEC Scheme is provided with: a source block, the FEC Scheme is provided with:
o A description of the source data flow with which the Application o A description of the source data flow with which the ADU is
Data Unit is associated and an integer identifier associated with associated and an integer identifier associated with that flow.
that flow.
o The Application Data Unit itself. o The ADU itself.
o The length of the Application Data Unit. o The length of the ADU.
For each Application Data Unit, we define the Application Data Unit For each ADU, we define the Application Data Unit Information (ADUI)
Information (ADUI) as follows: as follows:
Let Let
n be the number of Application Data Units in the source block. o n be the number of ADUs in the source block.
T be the source symbol size in bytes. Note: this information is o T be the source symbol size in bytes. Note: this information is
provided by the FEC Scheme as defined below. provided by the FEC Scheme as defined below.
i the index to the (i+1)-th Application Data Unit to be added to o i the index to the (i+1)-th ADU to be added to the source block, 0
the source block, 0 <= i < n. <= i < n.
R[i] denote the number of octets in the (i+1)-th Application Data o R[i] denote the number of octets in the (i+1)-th ADU.
Unit.
l[i] be a length indication associated with the i-th Application o l[i] be a length indication associated with the i-th ADU - the
Data Unit - the nature of the length indication is defined by the nature of the length indication is defined by the FEC Scheme.
FEC Scheme.
L[i] denote two octets representing the value of l[i] in network o L[i] denote two octets representing the value of l[i] in network
byte order (high order octet first) of the i-th Application Data byte order (high order octet first) of the i-th ADU.
Unit.
f[i] denote the integer identifier associated with the source data o f[i] denote the integer identifier associated with the source data
flow from which the i-th Application Data Unit was taken. flow from which the i-th ADU was taken.
F[i] denote a single octet representing the value of f[i]. o F[i] denote a single octet representing the value of f[i].
s[i] be the smallest integer such that s[i]*T >= (l[i]+3). Note o s[i] be the smallest integer such that s[i]*T >= (l[i]+3). Note
s[i] is the length of SPI[i] in units of symbols of size T bytes. s[i] is the length of SPI[i] in units of symbols of size T bytes.
P[i] denote s[i]*T-(l[i]+3) zero octets. Note: P[i] are padding o P[i] denote s[i]*T-(l[i]+3) zero octets. Note: P[i] are padding
octets to align the start of each UDP packet with the start of a octets to align the start of each UDP packet with the start of a
symbol. symbol.
ADUI[i] be the concatenation of F[i] ,L[i], R[i] and P[i]. o ADUI[i] be the concatenation of F[i] ,L[i], R[i] and P[i].
Then, a source data block is constructed by concatenating ADUI[i] for Then, a source data block is constructed by concatenating ADUI[i] for
i = 0, 1, 2, ... n-1. The source data block size, S, is then given i = 0, 1, 2, ... n-1. The source data block size, S, is then given
by sum {s[i]*T, i=0, ..., n-1}. Symbols are allocated integer by sum {s[i]*T, i=0, ..., n-1}. Symbols are allocated integer
Encoding Symbol IDs consecutively starting from zero within the Encoding Symbol IDs consecutively starting from zero within the
source block. Each Application Data Unit is associated with the source block. Each ADU is associated with the Encoding Symbol ID of
Encoding Symbol ID of the first symbol containing SPI for that the first symbol containing SPI for that packet. Thus, the Encoding
packet. Thus, the Encoding Symbol ID value associated with the j-th Symbol ID value associated with the j-th source packet, ESI[j], is
source packet, ESI[j], is given by ESI[j] = 0, for j=0 and ESI[j] = given by ESI[j] = 0, for j=0 and ESI[j] = sum{s[i], i=0,...,(j-1)},
sum{s[i], i=0,...,(j-1)}, for 0 < j < n. for 0 < j < n.
Source blocks are identified by integer Source Block Numbers. This Source blocks are identified by integer Source Block Numbers. This
specification does not specify how Source Block Numbers are allocated specification does not specify how Source Block Numbers are allocated
to source blocks. The Source FEC Packet Identification Information to source blocks. The Source FEC Packet Identification Information
consists of the identity of the source block and the Encoding Symbol consists of the identity of the source block and the Encoding Symbol
ID associated with the packet. ID associated with the packet.
6. Raptor FEC Schemes for arbitrary packet flows 6. Raptor FEC Schemes for arbitrary packet flows
6.1. Introduction 6.1. Introduction
skipping to change at page 9, line 6 skipping to change at page 9, line 11
The value of the FEC Scheme ID for the fully-specified FEC scheme The value of the FEC Scheme ID for the fully-specified FEC scheme
defined in this section is XXX when [RFC5053] is used and YYY when defined in this section is XXX when [RFC5053] is used and YYY when
[I-D.ietf-rmt-bb-fec-raptorq] is used, as assigned by IANA. [I-D.ietf-rmt-bb-fec-raptorq] is used, as assigned by IANA.
6.2.1.2. Scheme-Specific Elements 6.2.1.2. Scheme-Specific Elements
The scheme-specific elements of the FEC Framework Configuration The scheme-specific elements of the FEC Framework Configuration
information for this scheme are as follows: information for this scheme are as follows:
Maximum Source Block Length Name: "Kmax", Value range: A decimal Maximum Source Block Length Name: "Kmax", Value range: A decimal
non-negative integer less than 8192 (for Raptor) or 56405 (for non-negative integer less than 8192 (for Raptor) or 56403 (for
RaptorQ), in units of symbols RaptorQ), in units of symbols
Encoding Symbol Size Name: "T", Value range: A decimal non- Encoding Symbol Size Name: "T", Value range: A decimal non-
negative integer less than 65536, in units of bytes negative integer less than 65536, in units of bytes
Payload ID Format Name: "P", Value range: "A" or "B" Payload ID Format Name: "P", Value range: "A" or "B"
An encoding format for The Maximum Source Block Length and Encoding An encoding format for The Maximum Source Block Length and Encoding
Symbol Size is defined below. Symbol Size is defined below.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Symbol Size (T) |Max. Source Block Length (Kmax)| | Symbol Size (T) |Max. Source Block Length (Kmax)|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|P| Reserved | |P| Reserved |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 1: FEC Scheme Specific Information Figure 1: FEC Scheme Specific Information
The P bit shall be set to zero to indicate Format A or to 1 to The P bit shall be set to zero to indicate Format A or to one to
indicate Format B. The last octet of the above encoding may be indicate Format B. The last octet of the above encoding may be
omitted, in which case Format A shall be assumed. omitted, in which case Format A shall be assumed.
The Payload ID Format identifier defines which of the Source FEC The Payload ID Format identifier defines which of the Source FEC
Payload ID and Repair FEC Payload ID formats defined below shall be Payload ID and Repair FEC Payload ID formats defined below shall be
used. Payload ID Format B SHALL NOT be used when[RFC5053] is used. used. Payload ID Format B SHALL NOT be used when[RFC5053] is used.
6.2.2. Source FEC Payload ID 6.2.2. Source FEC Payload ID
This scheme makes use of an Explicit Source FEC Payload ID, which is This scheme makes use of an Explicit Source FEC Payload ID, which is
appended to the end of the source packets. Two formats are defined appended to the end of the source packets. Two formats are defined
for the Source FEC Payload ID, format A and format B. The format that for the Source FEC Payload ID, format A and format B. The format that
is used is signalled as part of the FEC Framework Configuration is used is signalled as part of the FEC Framework Configuration
Information Information.
The Source FEC Payload ID for format A is provided in Figure 2.
.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Block Number (SBN) | Encoding Symbol ID (ESI) | | Source Block Number (SBN) | Encoding Symbol ID (ESI) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Source FEC Payload ID - Format A Figure 2: Source FEC Payload ID - Format A
Source Block Number (SBN), (16 bits): An integer identifier for the Source Block Number (SBN), (16 bits): An integer identifier for the
source block that the source data within the packet relates to. source block that the source data within the packet relates to.
Encoding Symbol ID (ESI), (16 bits): The starting symbol index of Encoding Symbol ID (ESI), (16 bits): The starting symbol index of
the source packet in the source block. the source packet in the source block.
The Source FEC Payload ID for format B is provided in Figure 3.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SBN | Encoding Symbol ID (ESI) | | SBN | Encoding Symbol ID (ESI) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: Source FEC Payload ID - Format B Figure 3: Source FEC Payload ID - Format B
Source Block Number (SBN), (8 bits): An integer identifier for the Source Block Number (SBN), (8 bits): An integer identifier for the
source block that the source data within the packet relates to. source block that the source data within the packet relates to.
Encoding Symbol ID (ESI), (24 bits): The starting symbol index of Encoding Symbol ID (ESI), (24 bits): The starting symbol index of
the source packet in the source block the source packet in the source block.
6.2.3. Repair FEC Payload ID 6.2.3. Repair FEC Payload ID
Two formats for the Repair FEC Payload ID, Format A and Format B are Two formats for the Repair FEC Payload ID, Format A and Format B are
defined below: defined below.
The Repair FEC Payload ID for format A is provided in Figure 4.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Block Number (SBN) | Encoding Symbol ID (ESI) | | Source Block Number (SBN) | Encoding Symbol ID (ESI) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Block Length (SBL) | | Source Block Length (SBL) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Repair FEC Payload ID - Format A Figure 4: Repair FEC Payload ID - Format A
Source Block Number (SBN), (16 bits) An integer identifier for the
source block that the repair symbols within the packet relate to.
For format A, it is of size 16 bits.
Encoding Symbol ID (ESI), (16 bits) Integer identifier for the
encoding symbols within the packet.
Source Block Length (SBL), (16 bits) The number of source symbols in
the source block.
The Repair FEC Payload ID for format B is provided in Figure 5.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SBN | Encoding Symbol ID (ESI) | | SBN | Encoding Symbol ID (ESI) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Block Length (SBL) | | Source Block Length (SBL) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Repair FEC Payload ID - Format B Figure 5: Repair FEC Payload ID - Format B
Source Block Number (SBN), (16 bits) An integer identifier for the Source Block Number (SBN), (8 bits) An integer identifier for the
source block that the repair symbols within the packet relate to. source block that the repair symbols within the packet relate to.
For format A, it is of size 16 bits.
Encoding Symbol ID (ESI), (16 bits) Integer identifier for the Encoding Symbol ID (ESI), (24 bits) Integer identifier for the
encoding symbols within the packet. encoding symbols within the packet.
Source Block Length (SBL), (16 bits) The number of source symbols in Source Block Length (SBL), (16 bits) The number of source symbols in
the source block. the source block.
The interpretation of the Source Block Number, Encoding Symbol The interpretation of the Source Block Number, Encoding Symbol
Identifier and Source Block Length is defined by the FEC Code Identifier and Source Block Length is defined by the FEC Code
Specification. Specification.
6.3. Procedures 6.3. Procedures
skipping to change at page 12, line 40 skipping to change at page 13, line 17
7.1. Introduction 7.1. Introduction
This section specifies a slightly modified version of the FEC Scheme This section specifies a slightly modified version of the FEC Scheme
specified in Section 6 which is applicable to scenarios in which only specified in Section 6 which is applicable to scenarios in which only
relatively small block sizes will be used. These modifications admit relatively small block sizes will be used. These modifications admit
substantial optimisations to both sender and receiver substantial optimisations to both sender and receiver
implementations. implementations.
In outline, the modifications are: In outline, the modifications are:
All source blocks within a stream are encoded using the same o All source blocks within a stream are encoded using the same
source block size. Code shortening is used to encode blocks of source block size. Code shortening is used to encode blocks of
different sizes. This is achieved by padding every block to the different sizes. This is achieved by padding every block to the
required size using zero symbols before encoding. The zero required size using zero symbols before encoding. The zero
symbols are then discarded after decoding. The source block size symbols are then discarded after decoding. The source block size
to be used for a stream is signalled in the Maximum Source Block to be used for a stream is signalled in the Maximum Source Block
Size field of the scheme-specific information. This allows for Size field of the scheme-specific information. This allows for
efficient parallel encoding of multiple streams. efficient parallel encoding of multiple streams. Note that th
epadding operation is equivalent to the padding operation in
[I-D.ietf-rmt-bb-fec-raptorq] with K' the specified single source
block size and K the actual source block size K.
A restricted set of possible source block sizes is specified. o A restricted set of possible source block sizes is specified.
This allows explicit operation sequences for encoding the This allows explicit operation sequences for encoding the
restricted set of block sizes to be pre-calculated and embedded in restricted set of block sizes to be pre-calculated and embedded in
software or handware. software or handware.
This scheme is equivalent to that specified in [dvbts] for arbitrary When the Raptor FEC encoder as defined in [RFC5053] is used, this
scheme is equivalent to that specified in [dvbts] for arbitrary
packet flows. packet flows.
7.2. Formats and Codes 7.2. Formats and Codes
7.2.1. FEC Framework Configuration Information 7.2.1. FEC Framework Configuration Information
7.2.1.1. FEC Scheme ID 7.2.1.1. FEC Scheme ID
The value of the FEC Scheme ID for the fully-specified FEC scheme The value of the FEC Scheme ID for the fully-specified FEC scheme
defined in this section is XXX when [RFC5053] is used and YYY when defined in this section is XXX when [RFC5053] is used and YYY when
skipping to change at page 14, line 32 skipping to change at page 15, line 13
number of source symbols in any source block is at most 8192. The number of source symbols in any source block is at most 8192. The
Maximum Source Block Length parameter - and hence the number of Maximum Source Block Length parameter - and hence the number of
symbols used in the FEC Encoding and Decoding operations - SHALL be symbols used in the FEC Encoding and Decoding operations - SHALL be
set to one of the following values: set to one of the following values:
101, 120, 148, 164, 212, 237, 297, 371, 450, 560, 680, 842, 1031, 101, 120, 148, 164, 212, 237, 297, 371, 450, 560, 680, 842, 1031,
1139, 1281 1139, 1281
When [I-D.ietf-rmt-bb-fec-raptorq] is used, the parameter T SHALL be When [I-D.ietf-rmt-bb-fec-raptorq] is used, the parameter T SHALL be
set such that the number of source symbols in any source block is set such that the number of source symbols in any source block is
less than 56404. The Maximum Source Block Length parameter SHALL be less than 56403. The Maximum Source Block Length parameter SHALL be
set to one of the supported vaoues for K' defined in Section 5.6 of set to one of the supported values for K' defined in Section 5.6 of
[I-D.ietf-rmt-bb-fec-raptorq]. [I-D.ietf-rmt-bb-fec-raptorq].
8. Raptor FEC Scheme for a single sequenced flow 8. Raptor FEC Scheme for a single sequenced flow
8.1. Formats and codes 8.1. Formats and codes
8.1.1. FEC Framework Configuration Information 8.1.1. FEC Framework Configuration Information
8.1.1.1. FEC Scheme ID 8.1.1.1. FEC Scheme ID
skipping to change at page 15, line 23 skipping to change at page 16, line 13
Format B. Format B.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Initial Sequence Number | Encoding Symbol ID | | Initial Sequence Number | Encoding Symbol ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Source Block Length | | Source Block Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: Repair FEC Payload ID - Format A Figure 6: Repair FEC Payload ID - Format A
Initial Sequence Number (Flow i ISN) - 16 bits This field specifies Initial Sequence Number (Flow i ISN) - 16 bits This field specifies
the lowest 16 bits of the sequence number of the first packet to the lowest 16 bits of the sequence number of the first packet to
be included in this sub-block. If the sequence numbers are be included in this sub-block. If the sequence numbers are
shorter than 16 bits then the received Sequence Number SHALL be shorter than 16 bits then the received Sequence Number SHALL be
logically padded with zero bits to become 16 bits in length logically padded with zero bits to become 16 bits in length
respectively. respectively.
Encoding Symbol ID (ESI) - 16 bits This field indicates which repair Encoding Symbol ID (ESI) - 16 bits This field indicates which repair
symbols are contained within this repair packet. The ESI provided symbols are contained within this repair packet. The ESI provided
skipping to change at page 15, line 47 skipping to change at page 16, line 37
of the source block in symbols. of the source block in symbols.
1 2 3 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Initial Sequence Number | Source Block Length | | Initial Sequence Number | Source Block Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Encoding Symbol ID | | Encoding Symbol ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: Repair FEC Payload ID - Format B Figure 7: Repair FEC Payload ID - Format B
Initial Sequence Number (Flow i ISN) - 16 bits This field specifies Initial Sequence Number (Flow i ISN) - 16 bits This field specifies
the lowest 16 bits of the sequence number of the first packet to the lowest 16 bits of the sequence number of the first packet to
be included in this sub-block. If the sequence numbers are be included in this sub-block. If the sequence numbers are
shorter than 16 bits then the received Sequence Number SHALL be shorter than 16 bits then the received Sequence Number SHALL be
logically padded with zero bits to become 16 bits in length logically padded with zero bits to become 16 bits in length
respectively. respectively.
Encoding Symbol ID (ESI) - 16 bits This field indicates which repair Encoding Symbol ID (ESI) - 16 bits This field indicates which repair
symbols are contained within this repair packet. The ESI provided symbols are contained within this repair packet. The ESI provided
skipping to change at page 17, line 14 skipping to change at page 18, line 4
containing encoding symbols of the repair packets (i.e. not including containing encoding symbols of the repair packets (i.e. not including
the Repair FEC Payload ID) for that block, which MUST be the same for the Repair FEC Payload ID) for that block, which MUST be the same for
all repair packets. The Application Data Unit Information Length all repair packets. The Application Data Unit Information Length
(ADUIL) in symbols is equal to this length divided by the Encoding (ADUIL) in symbols is equal to this length divided by the Encoding
Symbol Size (which is signaled in the FEC Framework Configuration Symbol Size (which is signaled in the FEC Framework Configuration
Information). The set of source packets which are included in the Information). The set of source packets which are included in the
source block is determined from the Initial Sequence Number (ISN) and source block is determined from the Initial Sequence Number (ISN) and
Source Block Length (SBL) as follows: Source Block Length (SBL) as follows:
Let, Let,
o I be the Initial Sequence Number of the source block
I be the Initial Sequence Number of the source block o LP be the Source Packet Information Length in symbols
LP be the Source Packet Information Length in symbols
LB be the Source Block Length in symbols o LB be the Source Block Length in symbols
Then, source packets with sequence numbers from I to I +LB/LP-1 Then, source packets with sequence numbers from I to I +LB/LP-1
inclusive are included in the source block. inclusive are included in the source block.
Note that if no FEC Repair packets are received then no FEC decoding Note that if no FEC Repair packets are received then no FEC decoding
is possible and it is unnecessary for the receiver to identify the is possible and it is unnecessary for the receiver to identify the
Source FEC Packet Identification Information for the source packets. Source FEC Packet Identification Information for the source packets.
The Encoding Symbol ID for a packet is derived from the following The Encoding Symbol ID for a packet is derived from the following
information: information:
The sequence number, Ns, of the packet o The sequence number, Ns, of the packet
The Source Packet Information Length for the source block, LP o The Source Packet Information Length for the source block, LP
The Initial Sequence Number of the source block, I o The Initial Sequence Number of the source block, I
Then the Encoding Symbol ID for packet with sequence number Ns is Then the Encoding Symbol ID for packet with sequence number Ns is
determined by the following formula: determined by the following formula:
ESI = ( Ns - I ) * LP ESI = ( Ns - I ) * LP
Note that all repair packet associated to a given Source Block MUST Note that all repair packet associated to a given Source Block MUST
contain the same Source Block Length and Initial Sequence Number. contain the same Source Block Length and Initial Sequence Number.
8.2.3. Repair packet construction 8.2.3. Repair packet construction
skipping to change at page 20, line 12 skipping to change at page 20, line 31
o XXX for the Raptor FEC Scheme for a single sequence flow o XXX for the Raptor FEC Scheme for a single sequence flow
(Section 8) using Raptor [RFC5053]. (Section 8) using Raptor [RFC5053].
o XXX for the Raptor FEC Scheme for a single sequence flow o XXX for the Raptor FEC Scheme for a single sequence flow
(Section 8) using RaptorQ [I-D.ietf-rmt-bb-fec-raptorq]. (Section 8) using RaptorQ [I-D.ietf-rmt-bb-fec-raptorq].
13. Normative References 13. Normative References
[I-D.ietf-fecframe-framework] [I-D.ietf-fecframe-framework]
Watson, M., "Forward Error Correction (FEC) Framework", Watson, M., "Forward Error Correction (FEC) Framework",
draft-ietf-fecframe-framework-06 (work in progress), draft-ietf-fecframe-framework-10 (work in progress),
March 2010. September 2010.
[I-D.ietf-fecframe-sdp-elements] [I-D.ietf-fecframe-sdp-elements]
Begen, A., "SDP Elements for FEC Framework", Begen, A., "Session Description Protocol Elements for FEC
draft-ietf-fecframe-sdp-elements-04 (work in progress), Framework", draft-ietf-fecframe-sdp-elements-11 (work in
August 2009. progress), October 2010.
[RFC5052] Watson, M., Luby, M., and L. Vicisano, "Forward Error [RFC5052] Watson, M., Luby, M., and L. Vicisano, "Forward Error
Correction (FEC) Building Block", RFC 5052, August 2007. Correction (FEC) Building Block", RFC 5052, August 2007.
[RFC5053] Luby, M., Shokrollahi, A., Watson, M., and T. Stockhammer, [RFC5053] Luby, M., Shokrollahi, A., Watson, M., and T. Stockhammer,
"Raptor Forward Error Correction Scheme for Object "Raptor Forward Error Correction Scheme for Object
Delivery", RFC 5053, October 2007. Delivery", RFC 5053, October 2007.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, July 2006. Description Protocol", RFC 4566, July 2006.
[I-D.ietf-mmusic-rfc4756bis] [I-D.ietf-mmusic-rfc4756bis]
Begen, A., "Forward Error Correction Grouping Semantics in Begen, A., "Forward Error Correction Grouping Semantics in
Session Description Protocol", Session Description Protocol",
draft-ietf-mmusic-rfc4756bis-06 (work in progress), draft-ietf-mmusic-rfc4756bis-10 (work in progress),
February 2010. June 2010.
[I-D.ietf-rmt-bb-fec-raptorq] [I-D.ietf-rmt-bb-fec-raptorq]
Luby, M., Shokrollahi, A., Watson, M., and T. Stockhammer, Luby, M., Shokrollahi, A., Watson, M., Stockhammer, T.,
"RaptorQ Forward Error Correction Scheme for Object and L. Minder, "RaptorQ Forward Error Correction Scheme
Delivery", draft-ietf-rmt-bb-fec-raptorq-01 (work in for Object Delivery", draft-ietf-rmt-bb-fec-raptorq-04
progress), February 2010. (work in progress), August 2010.
[dvbts] "ETSI TS 102 034 - Digital Video Broadcasting (DVB); [dvbts] "ETSI TS 102 034 - Digital Video Broadcasting (DVB);
Transport of MPEG-2 Based DVB Services over IP Based Transport of MPEG-2 Based DVB Services over IP Based
Networks", March 2005. Networks", March 2005.
[MBMSTS] 3GPP, "Multimedia Broadcast/Multicast Service (MBMS); [MBMSTS] 3GPP, "Multimedia Broadcast/Multicast Service (MBMS);
Protocols and codecs", 3GPP TS 26.346, April 2005. Protocols and codecs", 3GPP TS 26.346, April 2005.
Author's Address Authors' Addresses
Mark Watson Mark Watson
Qualcomm, Inc. Netflix
3165 Kifer Road 100 Winchester Circle
Santa Clara, CA 95051 Los Gatos, CA 95032
U.S.A. U.S.A.
Email: watson@qualcomm.com Email: watsonm@netflix.com
Thomas Stockhammer
Nomor Research
Brecherspitzstrasse 8
Munich 81541
Germany
Email: stockhammer@nomor.de
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