draft-ietf-payload-vp9-10.txt   draft-ietf-payload-vp9-11.txt 
AVTCore Working Group J. Uberti AVTCore Working Group J. Uberti
Internet-Draft S. Holmer Internet-Draft S. Holmer
Intended status: Standards Track M. Flodman Intended status: Standards Track M. Flodman
Expires: January 8, 2021 D. Hong Expires: 6 August 2021 D. Hong
Google Google
J. Lennox J. Lennox
8x8 / Jitsi 8x8 / Jitsi
July 7, 2020 2 February 2021
RTP Payload Format for VP9 Video RTP Payload Format for VP9 Video
draft-ietf-payload-vp9-10 draft-ietf-payload-vp9-11
Abstract Abstract
This memo describes an RTP payload format for the VP9 video codec. This memo describes an RTP payload format for the VP9 video codec.
The payload format has wide applicability, as it supports The payload format has wide applicability, as it supports
applications from low bit-rate peer-to-peer usage, to high bit-rate applications from low bit-rate peer-to-peer usage, to high bit-rate
video conferences. It includes provisions for temporal and spatial video conferences. It includes provisions for temporal and spatial
scalability. scalability.
Status of This Memo Status of This Memo
skipping to change at page 1, line 38 skipping to change at page 1, line 38
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 January 8, 2021. This Internet-Draft will expire on 6 August 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions, Definitions and Acronyms . . . . . . . . . . . . 3 2. Conventions, Definitions and Acronyms . . . . . . . . . . . . 3
3. Media Format Description . . . . . . . . . . . . . . . . . . 3 3. Media Format Description . . . . . . . . . . . . . . . . . . 3
4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . 5 4. Payload Format . . . . . . . . . . . . . . . . . . . . . . . 5
4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 5 4.1. RTP Header Usage . . . . . . . . . . . . . . . . . . . . 5
4.2. VP9 Payload Descriptor . . . . . . . . . . . . . . . . . 6 4.2. VP9 Payload Descriptor . . . . . . . . . . . . . . . . . 6
4.2.1. Scalability Structure (SS): . . . . . . . . . . . . . 11 4.2.1. Scalability Structure (SS): . . . . . . . . . . . . . 11
4.3. Frame Fragmentation . . . . . . . . . . . . . . . . . . . 13 4.3. Frame Fragmentation . . . . . . . . . . . . . . . . . . . 12
4.4. Scalable encoding considerations . . . . . . . . . . . . 13 4.4. Scalable encoding considerations . . . . . . . . . . . . 13
4.5. Examples of VP9 RTP Stream . . . . . . . . . . . . . . . 14 4.5. Examples of VP9 RTP Stream . . . . . . . . . . . . . . . 13
4.5.1. Reference picture use for scalable structure . . . . 14 4.5.1. Reference picture use for scalable structure . . . . 13
5. Feedback Messages and Header Extensions . . . . . . . . . . . 14 5. Feedback Messages and Header Extensions . . . . . . . . . . . 14
5.1. Reference Picture Selection Indication (RPSI) . . . . . . 15 5.1. Reference Picture Selection Indication (RPSI) . . . . . . 14
5.2. Full Intra Request (FIR) . . . . . . . . . . . . . . . . 15 5.2. Full Intra Request (FIR) . . . . . . . . . . . . . . . . 15
5.3. Layer Refresh Request (LRR) . . . . . . . . . . . . . . . 15 5.3. Layer Refresh Request (LRR) . . . . . . . . . . . . . . . 15
5.4. Frame Marking . . . . . . . . . . . . . . . . . . . . . . 16 6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 16
6. Payload Format Parameters . . . . . . . . . . . . . . . . . . 17 6.1. Media Type Definition . . . . . . . . . . . . . . . . . . 16
6.1. Media Type Definition . . . . . . . . . . . . . . . . . . 17 6.2. SDP Parameters . . . . . . . . . . . . . . . . . . . . . 18
6.2. SDP Parameters . . . . . . . . . . . . . . . . . . . . . 19
6.2.1. Mapping of Media Subtype Parameters to SDP . . . . . 19 6.2.1. Mapping of Media Subtype Parameters to SDP . . . . . 19
6.2.2. Offer/Answer Considerations . . . . . . . . . . . . . 20 6.2.2. Offer/Answer Considerations . . . . . . . . . . . . . 19
7. Security Considerations . . . . . . . . . . . . . . . . . . . 20 7. Security Considerations . . . . . . . . . . . . . . . . . . . 20
8. Congestion Control . . . . . . . . . . . . . . . . . . . . . 21 8. Congestion Control . . . . . . . . . . . . . . . . . . . . . 20
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 21
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 21
11.1. Normative References . . . . . . . . . . . . . . . . . . 21 11.1. Normative References . . . . . . . . . . . . . . . . . . 21
11.2. Informative References . . . . . . . . . . . . . . . . . 23 11.2. Informative References . . . . . . . . . . . . . . . . . 22
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 23
1. Introduction 1. Introduction
This memo describes an RTP payload specification applicable to the This memo describes an RTP payload specification applicable to the
transmission of video streams encoded using the VP9 video codec transmission of video streams encoded using the VP9 video codec
[VP9-BITSTREAM]. The format described in this document can be used [VP9-BITSTREAM]. The format described in this document can be used
both in peer-to-peer and video conferencing applications. both in peer-to-peer and video conferencing applications.
The VP9 video codec was developed by Google, and is the successor to The VP9 video codec was developed by Google, and is the successor to
skipping to change at page 5, line 43 skipping to change at page 6, line 4
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : VP9 pyld hdr | | | : VP9 pyld hdr | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| | | |
+ | + |
: Bytes 2..N of VP9 payload : : Bytes 2..N of VP9 payload :
| | | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| : OPTIONAL RTP padding | | : OPTIONAL RTP padding |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1
The VP9 payload descriptor will be described in Section 4.2; the VP9 The VP9 payload descriptor will be described in Section 4.2; the VP9
payload header is described in [VP9-BITSTREAM]. OPTIONAL RTP padding payload header is described in [VP9-BITSTREAM]. OPTIONAL RTP padding
MUST NOT be included unless the P bit is set. The figure MUST NOT be included unless the P bit is set. The figure
specifically shows the format for the first packet in a frame. specifically shows the format for the first packet in a frame.
Subsequent packets will not contain the VP9 payload header, and will Subsequent packets will not contain the VP9 payload header, and will
have later octets in the frame payload. have later octets in the frame payload.
Figure 1
Marker bit (M): MUST be set to 1 for the final packet of the highest Marker bit (M): MUST be set to 1 for the final packet of the highest
spatial layer frame (the final packet of the picture), and 0 spatial layer frame (the final packet of the picture), and 0
otherwise. Unless spatial scalability is in use for this picture, otherwise. Unless spatial scalability is in use for this picture,
this will have the same value as the E bit described below. Note this will have the same value as the E bit described below. Note
this bit MUST be set to 1 for the target spatial layer frame if a this bit MUST be set to 1 for the target spatial layer frame if a
stream is being rewritten to remove higher spatial layers. stream is being rewritten to remove higher spatial layers.
Payload Type (PT): In line with the policy in Section 3 of Payload Type (PT): In line with the policy in Section 3 of
[RFC3551], applications using the VP9 RTP payload profile MUST [RFC3551], applications using the VP9 RTP payload profile MUST
assign a dynamic payload type number to be used in each RTP assign a dynamic payload type number to be used in each RTP
session and provide a mechanism to indicate the mapping. See session and provide a mechanism to indicate the mapping. See
Section 6.2 for the mechanism to be used with the Session Section 6.2 for the mechanism to be used with the Session
Description Protocol (SDP) [RFC4566]. Description Protocol (SDP) [RFC8866].
Timestamp: The RTP timestamp indicates the time when the input frame Timestamp: The RTP timestamp indicates the time when the input frame
was sampled, at a clock rate of 90 kHz. If the input picture is was sampled, at a clock rate of 90 kHz. If the input picture is
encoded with multiple layer frames, all of the frames of the encoded with multiple layer frames, all of the frames of the
picture MUST have the same timestamp. picture MUST have the same timestamp.
If a frame has the VP9 show_frame field set to 0 (i.e., it is If a frame has the VP9 show_frame field set to 0 (i.e., it is
meant only to populate a reference buffer, without being output) meant only to populate a reference buffer, without being output)
its timestamp MAY alternately be set to be the same as the its timestamp MAY alternately be set to be the same as the
subsequent frame with show_frame equal to 1. (This will be subsequent frame with show_frame equal to 1. (This will be
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M: | EXTENDED PID | (RECOMMENDED) M: | EXTENDED PID | (RECOMMENDED)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED) L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED)
+-+-+-+-+-+-+-+-+ -\ +-+-+-+-+-+-+-+-+ -\
P,F: | P_DIFF |N| (CONDITIONALLY REQUIRED) - up to 3 times P,F: | P_DIFF |N| (CONDITIONALLY REQUIRED) - up to 3 times
+-+-+-+-+-+-+-+-+ -/ +-+-+-+-+-+-+-+-+ -/
V: | SS | V: | SS |
| .. | | .. |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 2 Figure 2
In non-flexible mode (with the F bit below set to 0), The first In non-flexible mode (with the F bit below set to 0), The first
octets after the RTP header are the VP9 payload descriptor, with the octets after the RTP header are the VP9 payload descriptor, with the
following structure. following structure.
0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|I|P|L|F|B|E|V|Z| (REQUIRED) |I|P|L|F|B|E|V|Z| (REQUIRED)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
I: |M| PICTURE ID | (RECOMMENDED) I: |M| PICTURE ID | (RECOMMENDED)
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M: | EXTENDED PID | (RECOMMENDED) M: | EXTENDED PID | (RECOMMENDED)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED) L: | TID |U| SID |D| (CONDITIONALLY RECOMMENDED)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
| TL0PICIDX | (CONDITIONALLY REQUIRED) | TL0PICIDX | (CONDITIONALLY REQUIRED)
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
V: | SS | V: | SS |
| .. | | .. |
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Figure 3 Figure 3
I: Picture ID (PID) present. When set to one, the OPTIONAL PID MUST I: Picture ID (PID) present. When set to one, the OPTIONAL PID MUST
be present after the mandatory first octet and specified as below. be present after the mandatory first octet and specified as below.
Otherwise, PID MUST NOT be present. If the SS field was present Otherwise, PID MUST NOT be present. If the SS field was present
in the stream's most recent start of a keyframe (i.e., non- in the stream's most recent start of a keyframe (i.e., non-
flexible scalability mode is in use), then the PID MUST also be flexible scalability mode is in use), then the PID MUST also be
present in every packet. present in every packet.
P: Inter-picture predicted frame. When set to zero, the frame does P: Inter-picture predicted frame. When set to zero, the frame does
not utilize inter-picture prediction. In this case, up-switching not utilize inter-picture prediction. In this case, up-switching
to a current spatial layer's frame is possible from directly lower to a current spatial layer's frame is possible from directly lower
spatial layer frame. P SHOULD also be set to zero when encoding a spatial layer frame. P SHOULD also be set to zero when encoding a
layer synchronization frame in response to an LRR layer synchronization frame in response to an LRR
[I-D.ietf-avtext-lrr] message (see Section 5.3). When P is set to [I-D.ietf-avtext-lrr] message (see Section 5.3). When P is set to
zero, the TID field (described below) MUST also be set to 0 (if zero, the TID field (described below) MUST also be set to 0 (if
present). Note that the P bit does not forbid intra-picture, present). Note that the P bit does not forbid intra-picture,
inter-layer prediction from earlier frames of the same picture, if inter-layer prediction from earlier frames of the same picture, if
any. any.
L: Layer indices present. When set to one, the one or two octets L: Layer indices present. When set to one, the one or two octets
following the mandatory first octet and the PID (if present) is as following the mandatory first octet and the PID (if present) is as
described by "Layer indices" below. If the F bit (described described by "Layer indices" below. If the F bit (described
below) is set to 1 (indicating flexible mode), then only one octet below) is set to 1 (indicating flexible mode), then only one octet
is present for the layer indices. Otherwise if the F bit is set is present for the layer indices. Otherwise if the F bit is set
to 0 (indicating non-flexible mode), then two octets are present to 0 (indicating non-flexible mode), then two octets are present
for the layer indices. for the layer indices.
F: Flexible mode. F set to one indicates flexible mode and if the P F: Flexible mode. F set to one indicates flexible mode and if the P
bit is also set to one, then the octets following the mandatory bit is also set to one, then the octets following the mandatory
first octet, the PID, and layer indices (if present) are as first octet, the PID, and layer indices (if present) are as
described by "Reference indices" below. This MUST only be set to described by "Reference indices" below. This MUST only be set to
1 if the I bit is also set to one; if the I bit is set to zero, 1 if the I bit is also set to one; if the I bit is set to zero,
then this MUST also be set to zero and ignored by receivers. The then this MUST also be set to zero and ignored by receivers. The
value of this F bit MUST only change on the first packet of a key value of this F bit MUST only change on the first packet of a key
picture. A key picture is a picture whose base spatial layer picture. A key picture is a picture whose base spatial layer
frame is a key frame, and which thus completely resets the encoder frame is a key frame, and which thus completely resets the encoder
state. This packet will have its P bit equal to zero, SID or D state. This packet will have its P bit equal to zero, SID or D
bit (described below) equal to zero, and B bit (described below) bit (described below) equal to zero, and B bit (described below)
equal to 1. equal to 1.
B: Start of a frame. MUST be set to 1 if the first payload octet of B: Start of a frame. MUST be set to 1 if the first payload octet of
the RTP packet is the beginning of a new VP9 frame, and MUST NOT the RTP packet is the beginning of a new VP9 frame, and MUST NOT
be 1 otherwise. Note that this frame might not be the first frame be 1 otherwise. Note that this frame might not be the first frame
of a picture. of a picture.
E: End of a frame. MUST be set to 1 for the final RTP packet of a E: End of a frame. MUST be set to 1 for the final RTP packet of a
VP9 frame, and 0 otherwise. This enables a decoder to finish VP9 frame, and 0 otherwise. This enables a decoder to finish
decoding the frame, where it otherwise may need to wait for the decoding the frame, where it otherwise may need to wait for the
next packet to explicitly know that the frame is complete. Note next packet to explicitly know that the frame is complete. Note
that, if spatial scalability is in use, more frames from the same that, if spatial scalability is in use, more frames from the same
picture may follow; see the description of the M bit above. picture may follow; see the description of the M bit above.
V: Scalability structure (SS) data present. When set to one, the V: Scalability structure (SS) data present. When set to one, the
OPTIONAL SS data MUST be present in the payload descriptor. OPTIONAL SS data MUST be present in the payload descriptor.
Otherwise, the SS data MUST NOT be present. Otherwise, the SS data MUST NOT be present.
Z: Not a reference frame for upper spatial layers. If set to 1, Z: Not a reference frame for upper spatial layers. If set to 1,
indicates that frames with higher spatial layers SID+1 of the indicates that frames with higher spatial layers SID+1 of the
current and following pictures do not depend on the current current and following pictures do not depend on the current
spatial layer SID frame. This enables a decoder which is spatial layer SID frame. This enables a decoder which is
targeting a higher spatial layer to know that it can safely targeting a higher spatial layer to know that it can safely
discard this packet's frame without processing it, without having discard this packet's frame without processing it, without having
to wait for the "D" bit in the higher-layer frame (see below). to wait for the "D" bit in the higher-layer frame (see below).
The mandatory first octet is followed by the extension data fields The mandatory first octet is followed by the extension data fields
that are enabled: that are enabled:
M: The most significant bit of the first octet is an extension flag. M: The most significant bit of the first octet is an extension flag.
The field MUST be present if the I bit is equal to one. If set, The field MUST be present if the I bit is equal to one. If set,
the PID field MUST contain 15 bits; otherwise, it MUST contain 7 the PID field MUST contain 15 bits; otherwise, it MUST contain 7
bits. See PID below. bits. See PID below.
Picture ID (PID): Picture ID represented in 7 or 15 bits, depending Picture ID (PID): Picture ID represented in 7 or 15 bits, depending
on the M bit. This is a running index of the pictures. The field on the M bit. This is a running index of the pictures. The field
MUST be present if the I bit is equal to one. If M is set to MUST be present if the I bit is equal to one. If M is set to
zero, 7 bits carry the PID; else if M is set to one, 15 bits carry zero, 7 bits carry the PID; else if M is set to one, 15 bits carry
the PID in network byte order. The sender may choose between a 7- the PID in network byte order. The sender may choose between a 7-
or 15-bit index. The PID SHOULD start on a random number, and or 15-bit index. The PID SHOULD start on a random number, and
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The TID and SID fields indicate the temporal and spatial layers The TID and SID fields indicate the temporal and spatial layers
and can help middleboxes and and endpoints quickly identify which and can help middleboxes and and endpoints quickly identify which
layer a packet belongs to. layer a packet belongs to.
TID: The temporal layer ID of current frame. In the case of non- TID: The temporal layer ID of current frame. In the case of non-
flexible mode, if PID is mapped to a picture in a specified PG, flexible mode, if PID is mapped to a picture in a specified PG,
then the value of TID MUST match the corresponding TID value of then the value of TID MUST match the corresponding TID value of
the mapped picture in the PG. the mapped picture in the PG.
U: Switching up point. If this bit is set to 1 for the current U: Switching up point. If this bit is set to 1 for the current
picture with temporal layer ID equal to TID, then "switch up" picture with temporal layer ID equal to TID, then "switch up"
to a higher frame rate is possible as subsequent higher to a higher frame rate is possible as subsequent higher
temporal layer pictures will not depend on any picture before temporal layer pictures will not depend on any picture before
the current picture (in coding order) with temporal layer ID the current picture (in coding order) with temporal layer ID
greater than TID. greater than TID.
SID: The spatial layer ID of current frame. Note that frames SID: The spatial layer ID of current frame. Note that frames
with spatial layer SDI > 0 may be dependent on decoded spatial with spatial layer SDI > 0 may be dependent on decoded spatial
layer SID-1 frame within the same picture. Different frames of layer SID-1 frame within the same picture. Different frames of
the same picture MUST have distinct spatial layer IDs, and the same picture MUST have distinct spatial layer IDs, and
frames' spatial layers MUST appear in increasing order within frames' spatial layers MUST appear in increasing order within
the frame. the frame.
D: Inter-layer dependency used. MUST be set to one if current D: Inter-layer dependency used. MUST be set to one if current
spatial layer SID frame depends on spatial layer SID-1 frame of spatial layer SID frame depends on spatial layer SID-1 frame of
the same picture. MUST only be set to zero if current spatial the same picture. MUST only be set to zero if current spatial
layer SID frame does not depend on spatial layer SID-1 frame of layer SID frame does not depend on spatial layer SID-1 frame of
the same picture. For the base layer frame (with SID equal to the same picture. For the base layer frame (with SID equal to
0), this D bit MUST be set to zero. 0), this D bit MUST be set to zero.
TL0PICIDX: 8 bits temporal layer zero index. TL0PICIDX is only TL0PICIDX: 8 bits temporal layer zero index. TL0PICIDX is only
present in the non-flexible mode (F = 0). This is a running present in the non-flexible mode (F = 0). This is a running
index for the temporal base layer pictures, i.e., the pictures index for the temporal base layer pictures, i.e., the pictures
with TID set to 0. If TID is larger than 0, TL0PICIDX with TID set to 0. If TID is larger than 0, TL0PICIDX
skipping to change at page 11, line 24 skipping to change at page 11, line 19
the N bit below. When either P or F is set to zero, then no the N bit below. When either P or F is set to zero, then no
reference index is specified. reference index is specified.
P_DIFF: The reference index (in 7 bits) specified as the relative P_DIFF: The reference index (in 7 bits) specified as the relative
PID from the current picture. For example, when P_DIFF=3 on a PID from the current picture. For example, when P_DIFF=3 on a
packet containing the picture with PID 112 means that the packet containing the picture with PID 112 means that the
picture refers back to the picture with PID 109. This picture refers back to the picture with PID 109. This
calculation is done modulo the size of the PID field, i.e., calculation is done modulo the size of the PID field, i.e.,
either 7 or 15 bits. either 7 or 15 bits.
N: 1 if there is additional P_DIFF following the current P_DIFF. N: 1 if there is additional P_DIFF following the current P_DIFF.
4.2.1. Scalability Structure (SS): 4.2.1. Scalability Structure (SS):
The scalability structure (SS) data describes the resolution of each The scalability structure (SS) data describes the resolution of each
frame within a picture as well as the inter-picture dependencies for frame within a picture as well as the inter-picture dependencies for
a picture group (PG). If the VP9 payload descriptor's "V" bit is a picture group (PG). If the VP9 payload descriptor's "V" bit is
set, the SS data is present in the position indicated in Figure 2 and set, the SS data is present in the position indicated in Figure 2 and
Figure 3. Figure 3.
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
skipping to change at page 12, line 23 skipping to change at page 11, line 47
+ + . + + .
| | (OPTIONAL) . | | (OPTIONAL) .
+-+-+-+-+-+-+-+-+ -/ +-+-+-+-+-+-+-+-+ -/
G: | N_G | (OPTIONAL) G: | N_G | (OPTIONAL)
+-+-+-+-+-+-+-+-+ -\ +-+-+-+-+-+-+-+-+ -\
N_G: | TID |U| R |-|-| (OPTIONAL) . N_G: | TID |U| R |-|-| (OPTIONAL) .
+-+-+-+-+-+-+-+-+ -\ . - N_G times +-+-+-+-+-+-+-+-+ -\ . - N_G times
| P_DIFF | (OPTIONAL) . - R times . | P_DIFF | (OPTIONAL) . - R times .
+-+-+-+-+-+-+-+-+ -/ -/ +-+-+-+-+-+-+-+-+ -/ -/
Figure 4 Figure 4
N_S: N_S + 1 indicates the number of spatial layers present in the N_S: N_S + 1 indicates the number of spatial layers present in the
VP9 stream. VP9 stream.
Y: Each spatial layer's frame resolution present. When set to one, Y: Each spatial layer's frame resolution present. When set to one,
the OPTIONAL WIDTH (2 octets) and HEIGHT (2 octets) MUST be the OPTIONAL WIDTH (2 octets) and HEIGHT (2 octets) MUST be
present for each layer frame. Otherwise, the resolution MUST NOT present for each layer frame. Otherwise, the resolution MUST NOT
be present. be present.
G: PG description present flag. G: PG description present flag.
-: Bit reserved for future use. MUST be set to zero and MUST be -: Bit reserved for future use. MUST be set to zero and MUST be
ignored by the receiver. ignored by the receiver.
N_G: N_G indicates the number of pictures in a Picture Group (PG). N_G: N_G indicates the number of pictures in a Picture Group (PG).
If N_G is greater than 0, then the SS data allows the inter- If N_G is greater than 0, then the SS data allows the inter-
picture dependency structure of the VP9 stream to be pre-declared, picture dependency structure of the VP9 stream to be pre-declared,
rather than indicating it on the fly with every packet. If N_G is rather than indicating it on the fly with every packet. If N_G is
greater than 0, then for N_G pictures in the PG, each picture's greater than 0, then for N_G pictures in the PG, each picture's
temporal layer ID (TID), switch up point (U), and the R reference temporal layer ID (TID), switch up point (U), and the R reference
indices (P_DIFFs) are specified. indices (P_DIFFs) are specified.
skipping to change at page 14, line 15 skipping to change at page 14, line 5
4.5. Examples of VP9 RTP Stream 4.5. Examples of VP9 RTP Stream
4.5.1. Reference picture use for scalable structure 4.5.1. Reference picture use for scalable structure
As discussed in Section 3, the VP9 codec can maintain up to eight As discussed in Section 3, the VP9 codec can maintain up to eight
reference frames, of which up to three can be referenced or updated reference frames, of which up to three can be referenced or updated
by any new frame. This section illustrates one way that a scalable by any new frame. This section illustrates one way that a scalable
structure (with three spatial layers and three temporal layers) can structure (with three spatial layers and three temporal layers) can
be constructed using these reference frames. be constructed using these reference frames.
+----------+---------+------------+---------+ +==========+=========+============+=========+
| Temporal | Spatial | References | Updates | | Temporal | Spatial | References | Updates |
+----------+---------+------------+---------+ +==========+=========+============+=========+
| 0 | 0 | 0 | 0 | | 0 | 0 | 0 | 0 |
| | | | | +----------+---------+------------+---------+
| 0 | 1 | 0,1 | 1 | | 0 | 1 | 0,1 | 1 |
| | | | | +----------+---------+------------+---------+
| 0 | 2 | 1,2 | 2 | | 0 | 2 | 1,2 | 2 |
| | | | | +----------+---------+------------+---------+
| 2 | 0 | 0 | 6 | | 2 | 0 | 0 | 6 |
| | | | | +----------+---------+------------+---------+
| 2 | 1 | 1,6 | 7 | | 2 | 1 | 1,6 | 7 |
| | | | | +----------+---------+------------+---------+
| 2 | 2 | 2,7 | - | | 2 | 2 | 2,7 | - |
| | | | | +----------+---------+------------+---------+
| 1 | 0 | 0 | 3 | | 1 | 0 | 0 | 3 |
| | | | | +----------+---------+------------+---------+
| 1 | 1 | 1,3 | 4 | | 1 | 1 | 1,3 | 4 |
| | | | | +----------+---------+------------+---------+
| 1 | 2 | 2,4 | 5 | | 1 | 2 | 2,4 | 5 |
| | | | | +----------+---------+------------+---------+
| 2 | 0 | 3 | 6 | | 2 | 0 | 3 | 6 |
| | | | | +----------+---------+------------+---------+
| 2 | 1 | 4,6 | 7 | | 2 | 1 | 4,6 | 7 |
| | | | | +----------+---------+------------+---------+
| 2 | 2 | 5,7 | - | | 2 | 2 | 5,7 | - |
+----------+---------+------------+---------+ +----------+---------+------------+---------+
Example scalability structure Table 1: Example scalability structure
This structure is constructed such that the "U" bit can always be This structure is constructed such that the "U" bit can always be
set. set.
5. Feedback Messages and Header Extensions 5. Feedback Messages and Header Extensions
5.1. Reference Picture Selection Indication (RPSI) 5.1. Reference Picture Selection Indication (RPSI)
The reference picture selection index is a payload-specific feedback The reference picture selection index is a payload-specific feedback
message defined within the RTCP-based feedback format. The RPSI message defined within the RTCP-based feedback format. The RPSI
message is generated by a receiver and can be used in two ways. message is generated by a receiver and can be used in two ways.
Either it can signal a preferred reference picture when a loss has Either it can signal a preferred reference picture when a loss has
been detected by the decoder -- preferably then a reference that the been detected by the decoder -- preferably then a reference that the
decoder knows is perfect -- or, it can be used as positive feedback decoder knows is perfect -- or, it can be used as positive feedback
information to acknowledge correct decoding of certain reference information to acknowledge correct decoding of certain reference
pictures. The positive feedback method is useful for VP9 used for pictures. The positive feedback method is useful for VP9 used for
skipping to change at page 15, line 50 skipping to change at page 15, line 37
request a single layer of a spatially or temporally encoded stream to request a single layer of a spatially or temporally encoded stream to
be refreshed, without necessarily affecting the stream's other be refreshed, without necessarily affecting the stream's other
layers. layers.
+---------------+---------------+ +---------------+---------------+
|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7| |0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+---------------+---------+-----+ +---------------+---------+-----+
| RES | TID | RES | SID | | RES | TID | RES | SID |
+---------------+---------+-----+ +---------------+---------+-----+
Figure 5 Figure 5
Figure 5 shows the format of LRR's layer index fields for VP9 Figure 5 shows the format of LRR's layer index fields for VP9
streams. The two "RES" fields MUST be set to 0 on transmission and streams. The two "RES" fields MUST be set to 0 on transmission and
ingnored on reception. See Section 4.2 for details on the TID and ingnored on reception. See Section 4.2 for details on the TID and
SID fields. SID fields.
Identification of a layer refresh frame can be derived from the Identification of a layer refresh frame can be derived from the
reference IDs of each frame by backtracking the dependency chain reference IDs of each frame by backtracking the dependency chain
until reaching a point where only decodable frames are being until reaching a point where only decodable frames are being
referenced. Therefore it's recommended for both the flexible and the referenced. Therefore it's recommended for both the flexible and the
skipping to change at page 16, line 30 skipping to change at page 16, line 16
LRR {1,0}, {2,1} is sent by an MCU when it is currently relaying LRR {1,0}, {2,1} is sent by an MCU when it is currently relaying
{1,0} to a receiver and which wants to upgrade to {2,1}. In response {1,0} to a receiver and which wants to upgrade to {2,1}. In response
the encoder should encode the next frames in layers {1,1} and {2,1} the encoder should encode the next frames in layers {1,1} and {2,1}
by only referring to frames in {1,0}, or {0,0}. by only referring to frames in {1,0}, or {0,0}.
In the non-flexible mode, periodic upgrade frames can be defined by In the non-flexible mode, periodic upgrade frames can be defined by
the layer structure of the SS, thus periodic upgrade frames can be the layer structure of the SS, thus periodic upgrade frames can be
automatically identified by the picture ID. automatically identified by the picture ID.
5.4. Frame Marking
The Frame Marking RTP header extension [I-D.ietf-avtext-framemarking]
is a mechanism to provide information about frames of video streams
in a largely codec-independent manner. However, for its extension
for scalable codecs, the specific manner in which codec layers are
identified needs to be specified specifically for each codec. This
section defines how frame marking is used with VP9.
0 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID=2 | L=2 |S|E|I|D|B| TID |0|0|0|0|0| SID | TL0PICIDX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6
When this header extension is used with VP9, the TID and SID fields
MUST match the values in the packet which the header extension is
attached to; see Section 4.2 for details on these fields.
See [I-D.ietf-avtext-framemarking] for explanations of the other
fields, which are generic.
6. Payload Format Parameters 6. Payload Format Parameters
This payload format has two optional parameters. This payload format has two optional parameters.
6.1. Media Type Definition 6.1. Media Type Definition
This registration is done using the template defined in [RFC6838] and This registration is done using the template defined in [RFC6838] and
following [RFC4855]. following [RFC4855].
Type name: video Type name:
video
Subtype name: VP9 Subtype name:
VP9
Required parameters: None. Required parameters:
None.
Optional parameters: Optional parameters:
These parameters are used to signal the capabilities of a receiver These parameters are used to signal the capabilities of a receiver
implementation. If the implementation is willing to receive implementation. If the implementation is willing to receive
media, both parameters MUST be provided. These parameters MUST media, both parameters MUST be provided. These parameters MUST
NOT be used for any other purpose. NOT be used for any other purpose.
max-fr: The value of max-fr is an integer indicating the maximum max-fr: The value of max-fr is an integer indicating the maximum
frame rate in units of frames per second that the decoder is frame rate in units of frames per second that the decoder is
capable of decoding. capable of decoding.
skipping to change at page 17, line 43 skipping to change at page 17, line 8
The decoder is capable of decoding this frame size as long as The decoder is capable of decoding this frame size as long as
the width and height of the frame in macroblocks are less than the width and height of the frame in macroblocks are less than
int(sqrt(max-fs * 8)) - for instance, a max-fs of 1200 (capable int(sqrt(max-fs * 8)) - for instance, a max-fs of 1200 (capable
of supporting 640x480 resolution) will support widths and of supporting 640x480 resolution) will support widths and
heights up to 1552 pixels (97 macroblocks). heights up to 1552 pixels (97 macroblocks).
profile-id: The value of profile-id is an integer indicating the profile-id: The value of profile-id is an integer indicating the
default coding profile, the subset of coding tools that may default coding profile, the subset of coding tools that may
have been used to generate the stream or that the receiver have been used to generate the stream or that the receiver
supports). Table 1 lists all of the profiles defined in supports). Table 2 lists all of the profiles defined in
section 7.2 of [VP9-BITSTREAM] and the corresponding integer section 7.2 of [VP9-BITSTREAM] and the corresponding integer
values to be used. values to be used.
If no profile-id is present, Profile 0 MUST be inferred. If no profile-id is present, Profile 0 MUST be inferred.
Informative note: See Table 2 for capabilities of coding Informative note: See Table 3 for capabilities of coding
profiles defined in section 7.2 of [VP9-BITSTREAM]. profiles defined in section 7.2 of [VP9-BITSTREAM].
Encoding considerations: Encoding considerations:
This media type is framed in RTP and contains binary data; see This media type is framed in RTP and contains binary data; see
Section 4.8 of [RFC6838]. Section 4.8 of [RFC6838].
Security considerations: See Section 7 of RFC xxxx. Security considerations:
See Section 7 of RFC xxxx.
[RFC Editor: Upon publication as an RFC, please replace "XXXX" [RFC Editor: Upon publication as an RFC, please replace "XXXX"
with the number assigned to this document and remove this note.] with the number assigned to this document and remove this note.]
Interoperability considerations: None. Interoperability considerations:
None.
Published specification:
VP9 bitstream format [VP9-BITSTREAM] and RFC XXXX.
Published specification: VP9 bitstream format [VP9-BITSTREAM] and
RFC XXXX.
[RFC Editor: Upon publication as an RFC, please replace "XXXX" [RFC Editor: Upon publication as an RFC, please replace "XXXX"
with the number assigned to this document and remove this note.] with the number assigned to this document and remove this note.]
Applications which use this media type: Applications which use this media type:
For example: Video over IP, video conferencing. For example: Video over IP, video conferencing.
Fragment identifier considerations: N/A. Fragment identifier considerations:
N/A.
Additional information: None. Additional information:
None.
Person & email address to contact for further information: Person & email address to contact for further information:
Jonathan Lennox <jonathan.lennox@8x8.com> Jonathan Lennox <jonathan.lennox@8x8.com>
Intended usage: COMMON Intended usage:
COMMON
Restrictions on usage: Restrictions on usage:
This media type depends on RTP framing, and hence is only defined This media type depends on RTP framing, and hence is only defined
for transfer via RTP [RFC3550]. for transfer via RTP [RFC3550].
Author: Jonathan Lennox <jonathan.lennox@8x8.com> Author:
Jonathan Lennox <jonathan.lennox@8x8.com>
Change controller: Change controller:
IETF AVTCore Working Group delegated from the IESG. IETF AVTCore Working Group delegated from the IESG.
+---------+------------+ +=========+============+
| Profile | profile-id | | Profile | profile-id |
+---------+------------+ +=========+============+
| 0 | 0 | | 0 | 0 |
| | | +---------+------------+
| 1 | 1 | | 1 | 1 |
| | | +---------+------------+
| 2 | 2 | | 2 | 2 |
| | | +---------+------------+
| 3 | 3 | | 3 | 3 |
+---------+------------+ +---------+------------+
Table 1: Table 1. Table of profile-id integer values representing Table 2: Table 1.
the VP9 profile corresponding to the set of coding tools supported. Table of profile-id
integer values
representing the VP9
profile corresponding
to the set of coding
tools supported.
+---------+-----------+-----------------+--------------------------+ +=========+===========+=================+==========================+
| Profile | Bit Depth | SRGB Colorspace | Chroma Subsampling | | Profile | Bit Depth | SRGB Colorspace | Chroma Subsampling |
+---------+-----------+-----------------+--------------------------+ +=========+===========+=================+==========================+
| 0 | 8 | No | YUV 4:2:0 | | 0 | 8 | No | YUV 4:2:0 |
| | | | | +---------+-----------+-----------------+--------------------------+
| 1 | 8 | Yes | YUV 4:2:0,4:4:0 or 4:4:4 | | 1 | 8 | Yes | YUV 4:2:0,4:4:0 or 4:4:4 |
| | | | | +---------+-----------+-----------------+--------------------------+
| 2 | 10 or 12 | No | YUV 4:2:0 | | 2 | 10 or 12 | No | YUV 4:2:0 |
| | | | | +---------+-----------+-----------------+--------------------------+
| 3 | 10 or 12 | Yes | YUV 4:2:0,4:4:0 or 4:4:4 | | 3 | 10 or 12 | Yes | YUV 4:2:0,4:4:0 or 4:4:4 |
+---------+-----------+-----------------+--------------------------+ +---------+-----------+-----------------+--------------------------+
Table 2: Table 2. Table of profile capabilities. Table 3: Table 2. Table of profile capabilities.
6.2. SDP Parameters 6.2. SDP Parameters
The receiver MUST ignore any fmtp parameter unspecified in this memo. The receiver MUST ignore any fmtp parameter unspecified in this memo.
6.2.1. Mapping of Media Subtype Parameters to SDP 6.2.1. Mapping of Media Subtype Parameters to SDP
The media type video/VP9 string is mapped to fields in the Session The media type video/VP9 string is mapped to fields in the Session
Description Protocol (SDP) [RFC4566] as follows: Description Protocol (SDP) [RFC8866] as follows:
o The media name in the "m=" line of SDP MUST be video. * The media name in the "m=" line of SDP MUST be video.
o The encoding name in the "a=rtpmap" line of SDP MUST be VP9 (the * The encoding name in the "a=rtpmap" line of SDP MUST be VP9 (the
media subtype). media subtype).
o The clock rate in the "a=rtpmap" line MUST be 90000. * The clock rate in the "a=rtpmap" line MUST be 90000.
o The parameters "max-fs", and "max-fr", MUST be included in the * The parameters "max-fs", and "max-fr", MUST be included in the
"a=fmtp" line of SDP if SDP is used to declare receiver "a=fmtp" line of SDP if SDP is used to declare receiver
capabilities. These parameters are expressed as a media subtype capabilities. These parameters are expressed as a media subtype
string, in the form of a semicolon separated list of string, in the form of a semicolon separated list of
parameter=value pairs. parameter=value pairs.
o The OPTIONAL parameter profile-id, when present, SHOULD be * The OPTIONAL parameter profile-id, when present, SHOULD be
included in the "a=fmtp" line of SDP. This parameter is expressed included in the "a=fmtp" line of SDP. This parameter is expressed
as a media subtype string, in the form of a parameter=value pair. as a media subtype string, in the form of a parameter=value pair.
When the parameter is not present, a value of 0 MUST be used for When the parameter is not present, a value of 0 MUST be used for
profile-id. profile-id.
6.2.1.1. Example 6.2.1.1. Example
An example of media representation in SDP is as follows: An example of media representation in SDP is as follows:
m=video 49170 RTP/AVPF 98 m=video 49170 RTP/AVPF 98 a=rtpmap:98 VP9/90000 a=fmtp:98 max-fr=30;
a=rtpmap:98 VP9/90000 max-fs=3600; profile-id=0;
a=fmtp:98 max-fr=30; max-fs=3600; profile-id=0;
6.2.2. Offer/Answer Considerations 6.2.2. Offer/Answer Considerations
When VP9 is offered over RTP using SDP in an Offer/Answer model When VP9 is offered over RTP using SDP in an Offer/Answer model
[RFC3264] for negotiation for unicast usage, the following [RFC3264] for negotiation for unicast usage, the following
limitations and rules apply: limitations and rules apply:
o The parameter identifying a media format configuration for VP9 is * The parameter identifying a media format configuration for VP9 is
profile-id. This media format configuration parameter MUST be profile-id. This media format configuration parameter MUST be
used symmetrically; that is, the answerer MUST either maintain all used symmetrically; that is, the answerer MUST either maintain all
configuration parameters or remove the media format (payload type) configuration parameters or remove the media format (payload type)
completely if one or more of the parameter values are not completely if one or more of the parameter values are not
supported. supported.
o To simplify the handling and matching of these configurations, the * To simplify the handling and matching of these configurations, the
same RTP payload type number used in the offer SHOULD also be used same RTP payload type number used in the offer SHOULD also be used
in the answer, as specified in [RFC3264]. An answer MUST NOT in the answer, as specified in [RFC3264]. An answer MUST NOT
contain the payload type number used in the offer unless the contain the payload type number used in the offer unless the
configuration is exactly the same as in the offer. configuration is exactly the same as in the offer.
7. Security Considerations 7. Security Considerations
RTP packets using the payload format defined in this specification RTP packets using the payload format defined in this specification
are subject to the security considerations discussed in the RTP are subject to the security considerations discussed in the RTP
specification [RFC3550], and in any applicable RTP profile such as specification [RFC3550], and in any applicable RTP profile such as
skipping to change at page 21, line 48 skipping to change at page 21, line 23
Alex Eleftheriadis, Yuki Ito, Won Kap Jang, Sergio Garcia Murillo, Alex Eleftheriadis, Yuki Ito, Won Kap Jang, Sergio Garcia Murillo,
Roi Sasson, Timothy Terriberry, Emircan Uysaler, and Thomas Volkert Roi Sasson, Timothy Terriberry, Emircan Uysaler, and Thomas Volkert
commented on the development of this document and provided helpful commented on the development of this document and provided helpful
comments and feedback. comments and feedback.
11. References 11. References
11.1. Normative References 11.1. Normative References
[I-D.ietf-avtext-framemarking]
Zanaty, M., Berger, E., and S. Nandakumar, "Frame Marking
RTP Header Extension", draft-ietf-avtext-framemarking-10
(work in progress), November 2019.
[I-D.ietf-avtext-lrr] [I-D.ietf-avtext-lrr]
Lennox, J., Hong, D., Uberti, J., Holmer, S., and M. Lennox, J., Hong, D., Uberti, J., Holmer, S., and M.
Flodman, "The Layer Refresh Request (LRR) RTCP Feedback Flodman, "The Layer Refresh Request (LRR) RTCP Feedback
Message", draft-ietf-avtext-lrr-07 (work in progress), Message", Work in Progress, Internet-Draft, draft-ietf-
July 2017. avtext-lrr-07, 2 July 2017, <http://www.ietf.org/internet-
drafts/draft-ietf-avtext-lrr-07.txt>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model
with Session Description Protocol (SDP)", RFC 3264, with Session Description Protocol (SDP)", RFC 3264,
DOI 10.17487/RFC3264, June 2002, DOI 10.17487/RFC3264, June 2002,
<https://www.rfc-editor.org/info/rfc3264>. <https://www.rfc-editor.org/info/rfc3264>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550, Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/info/rfc3550>. July 2003, <https://www.rfc-editor.org/info/rfc3550>.
[RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", RFC 4566, DOI 10.17487/RFC4566,
July 2006, <https://www.rfc-editor.org/info/rfc4566>.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey, [RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control "Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585, Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006, DOI 10.17487/RFC4585, July 2006,
<https://www.rfc-editor.org/info/rfc4585>. <https://www.rfc-editor.org/info/rfc4585>.
[RFC4855] Casner, S., "Media Type Registration of RTP Payload [RFC4855] Casner, S., "Media Type Registration of RTP Payload
Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007, Formats", RFC 4855, DOI 10.17487/RFC4855, February 2007,
<https://www.rfc-editor.org/info/rfc4855>. <https://www.rfc-editor.org/info/rfc4855>.
[RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman, [RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
"Codec Control Messages in the RTP Audio-Visual Profile "Codec Control Messages in the RTP Audio-Visual Profile
with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104, with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
February 2008, <https://www.rfc-editor.org/info/rfc5104>. February 2008, <https://www.rfc-editor.org/info/rfc5104>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type [RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13, Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013, RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>. <https://www.rfc-editor.org/info/rfc6838>.
[RFC8866] Begen, A., Kyzivat, P., Perkins, C., and M. Handley, "SDP:
Session Description Protocol", RFC 8866,
DOI 10.17487/RFC8866, January 2021,
<https://www.rfc-editor.org/info/rfc8866>.
[VP9-BITSTREAM] [VP9-BITSTREAM]
Grange, A., de Rivaz, P., and J. Hunt, "VP9 Bitstream & Grange, A., de Rivaz, P., and J. Hunt, "VP9 Bitstream &
Decoding Process Specification", Version 0.6, March 2016, Decoding Process Specification", Version 0.6, 31 March
2016,
<https://storage.googleapis.com/downloads.webmproject.org/ <https://storage.googleapis.com/downloads.webmproject.org/
docs/vp9/ docs/vp9/vp9-bitstream-specification-
vp9-bitstream-specification-v0.6-20160331-draft.pdf>. v0.6-20160331-draft.pdf>.
11.2. Informative References 11.2. Informative References
[RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and [RFC3551] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and
Video Conferences with Minimal Control", STD 65, RFC 3551, Video Conferences with Minimal Control", STD 65, RFC 3551,
DOI 10.17487/RFC3551, July 2003, DOI 10.17487/RFC3551, July 2003,
<https://www.rfc-editor.org/info/rfc3551>. <https://www.rfc-editor.org/info/rfc3551>.
[RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K. [RFC3711] Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
Norrman, "The Secure Real-time Transport Protocol (SRTP)", Norrman, "The Secure Real-time Transport Protocol (SRTP)",
skipping to change at page 23, line 48 skipping to change at page 23, line 19
[RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP [RFC7202] Perkins, C. and M. Westerlund, "Securing the RTP
Framework: Why RTP Does Not Mandate a Single Media Framework: Why RTP Does Not Mandate a Single Media
Security Solution", RFC 7202, DOI 10.17487/RFC7202, April Security Solution", RFC 7202, DOI 10.17487/RFC7202, April
2014, <https://www.rfc-editor.org/info/rfc7202>. 2014, <https://www.rfc-editor.org/info/rfc7202>.
Authors' Addresses Authors' Addresses
Justin Uberti Justin Uberti
Google, Inc. Google, Inc.
747 6th Street South 747 6th Street South
Kirkland, WA 98033 Kirkland, WA 98033
USA United States of America
Email: justin@uberti.name Email: justin@uberti.name
Stefan Holmer Stefan Holmer
Google, Inc. Google, Inc.
Kungsbron 2 Kungsbron 2
Stockholm 111 22 SE-111 22 Stockholm
Sweden Sweden
Email: holmer@google.com Email: holmer@google.com
Magnus Flodman Magnus Flodman
Google, Inc. Google, Inc.
Kungsbron 2 Kungsbron 2
Stockholm 111 22 SE-111 22 Stockholm
Sweden Sweden
Email: mflodman@google.com Email: mflodman@google.com
Danny Hong Danny Hong
Google, Inc. Google, Inc.
1585 Charleston Road 1585 Charleston Road
Mountain View, CA 94043 Mountain View, CA 94043
US United States of America
Email: dannyhong@google.com Email: dannyhong@google.com
Jonathan Lennox Jonathan Lennox
8x8, Inc. / Jitsi 8x8, Inc. / Jitsi
1350 Broadway 1350 Broadway
New York, NY 10018 New York, NY 10018
US United States of America
Email: jonathan.lennox@8x8.com Email: jonathan.lennox@8x8.com
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