Payload Working Group
Internet Engineering Task Force (IETF) J. Lennox
Internet-Draft
Request for Comments: 9627 D. Hong
Intended status:
Category: Standards Track Vidyo
Expires: January 11, 2018
ISSN: 2070-1721 J. Uberti
S. Holmer
M. Flodman
Google
July 10, 2017
August 2024
The Layer Refresh Request (LRR) RTCP Feedback Message
draft-ietf-avtext-lrr-07
Abstract
This memo describes the RTCP Payload-Specific Feedback Message "Layer Layer
Refresh Request" Request (LRR), which can be used to request a state refresh
of one or more substreams of a layered media stream. It also defines
its use with several RTP payloads for scalable media formats.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid the IETF community. It has
received public review and has been approved for a maximum publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of six months RFC 7841.
Information about the current status of this document, any errata,
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 11, 2018.
https://www.rfc-editor.org/info/rfc9627.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions, Definitions Conventions and Acronyms . . . . . . . . . . . . 2 Terminology
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Layer Refresh Request . . . . . . . . . . . . . . . . . . . . 5
3.1. Message Format . . . . . . . . . . . . . . . . . . . . . 6
3.2. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Usage with specific codecs . . . . . . . . . . . . . . . . . 8 Specific Codecs
4.1. H264 SVC . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. VP8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3. H265 . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Usage with different scalability transmission mechanisms . . 11 Different Scalability Transmission Mechanisms
6. SDP Definitions . . . . . . . . . . . . . . . . . . . . . . . 11
7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
This memo describes an RTCP [RFC3550] Payload-Specific Feedback
Message [RFC4585] "Layer Layer Refresh Request" Request (LRR). It is designed to
allow a receiver of a layered media stream to request that one or
more of its substreams be refreshed, refreshed such that it can then be decoded
by an endpoint which that previously was not receiving those layers,
without requiring that the entire stream be refreshed (as it would be
if the receiver sent a Full Intra Request (FIR); [RFC5104] (FIR) [RFC5104]; see also
[RFC8082]).
The feedback message is applicable both to both temporally and spatially
scaled streams, streams and to both single-stream and multi-stream scalability
modes.
2. Conventions, Definitions Conventions and Acronyms Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in [RFC2119]. BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2.1. Terminology
A "Layer Refresh Point" "layer refresh point" is a point in a scalable stream after which a
decoder, which previously had been able to decode only some (possibly
none) of the available layers of stream, is able to decode a greater
number of the layers.
For spatial (or quality) layers, in normal encoding, a subpicture can
depend both on earlier pictures of that spatial layer and also on
lower-layer pictures of the current picture. A However, a layer refresh,
however,
refresh typically requires that a spatial layer picture be encoded in
a way that references only the lower-layer subpictures of the current
picture, not any earlier pictures of that spatial layer.
Additionally, the encoder must promise that no earlier pictures of
that spatial layer will be used as reference in the future.
However, even in a layer refresh, layers other than the ones being
refreshed may still maintain dependency on earlier content of the
stream. This is the difference between a layer refresh and a Full
Intra Request FIR
[RFC5104]. This minimizes the coding overhead of refresh to only
those parts of the stream that actually need to be refreshed at any
given time.
An illustration of
The spatial layer refresh of an enhancement layer is shown below. <--
The "<--" indicates a coding dependency.
... <-- S1 <-- S1 S1 <-- S1 <-- ...
| | | |
\/ \/ \/ \/
... <-- S0 <-- S0 <-- S0 <-- S0 <-- ...
1 2 3 4
Figure 1
In Figure 1, frame 3 is a layer refresh point for spatial layer S1; a
decoder which that had previously only been decoding spatial layer S0 would
be able to decode layer S1 starting at frame 3.
An illustration of
The spatial layer refresh of a base layer is shown below. <-- The "<--"
indicates a coding dependency.
... <-- S1 <-- S1 <-- S1 <-- S1 <-- ...
| | | |
\/ \/ \/ \/
... <-- S0 <-- S0 S0 <-- S0 <-- ...
1 2 3 4
Figure 2
In Figure 2, frame 3 is a layer refresh point for spatial layer S0; a
decoder which that had previously not been decoding the stream at all could
decode layer S0 starting at frame 3.
For temporal layers, while normal encoding allows frames to depend on
earlier frames of the same temporal layer, layer refresh requires
that the layer be "temporally nested", i.e. i.e., use as reference only
earlier frames of a lower temporal layer, not any earlier frames of
this temporal layer, layer and also promise that no future frames of this
temporal layer will reference frames of this temporal layer before
the refresh point. In many cases, the temporal structure of the
stream will mean that all frames are temporally nested, nested; in which case this case,
decoders will have no need to send LRR messages for the stream.
An illustration of
The temporal layer refresh is shown below. <-- The "<--" indicates a
coding dependency.
... <----- T1 <------ T1 T1 <------ ...
/ / /
|_ |_ |_
... <-- T0 <------ T0 <------ T0 <------ T0 <--- ...
1 2 3 4 5 6 7
Figure 3
In Figure 3, frame 6 is a layer refresh point for temporal layer T1;
a decoder which that had previously only been decoding temporal layer T0
would be able to decode layer T1 starting at frame 6.
An illustration of an inherently temporally nested stream is shown below. <-- The "<--"
indicates a coding dependency.
T1 T1 T1
/ / /
|_ |_ |_
... <-- T0 <------ T0 <------ T0 <------ T0 <--- ...
1 2 3 4 5 6 7
Figure 4
In Figure 4, the stream is temporally nested in its ordinary
structure; a decoder receiving layer T0 can begin decoding layer T1
at any point.
A "Layer Index" "layer index" is a numeric label for a specific spatial and
temporal layer of a scalable stream. It consists of the pair of both a "temporal
ID" identifying the temporal layer, layer and a "layer ID" identifying the
spatial or quality layer. The details of how layers of a scalable
stream are labeled are codec-specific. codec specific. Details for several codecs
are defined in Section 4.
3. Layer Refresh Request
A layer refresh frame can be requested by sending a Layer Refresh
Request (LRR), which is an RTP Control Protocol (RTCP) RTCP [RFC3550] payload-specific feedback
message [RFC4585] asking the encoder to encode a frame which that makes it
possible to upgrade to a higher layer. The LRR contains one or two
tuples, indicating the temporal and spatial layer the decoder wants
to upgrade to, to and (optionally) the currently highest temporal and
spatial layer the decoder can decode.
The specific format of the tuples, and the mechanism by which a
receiver recognizes a refresh frame, is codec-dependent. codec dependent. Usage for
several codecs is discussed in Section 4.
An LRR follows the FIR model of the Full Intra Request (FIR) [RFC5104] (Section 3.5.1) 3.5.1 of [RFC5104]) for its
retransmission, reliability, and use in multipoint conferences.
The LRR message is identified by RTCP packet type value PT=PSFB and
FMT=TBD.
FMT=10. The FCI Feedback Control Information (FCI) field MUST contain
one or more LRR entries. Each entry applies to a different media
sender, identified by its SSRC.
[NOTE TO RFC Editor: Please replace "TBD" with the IANA-assigned
payload-specific feedback number.] Synchronization Source (SSRC).
3.1. Message Format
The Feedback Control Information (FCI) FCI for the Layer Refresh Request consists of one or more FCI
entries, the content of which is depicted in Figure 5. The length of
the LRR feedback message MUST be set to 2+3*N 32-bit words, where N
is the number of FCI entries.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SSRC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seq nr. |C| Payload Type| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RES | TTID| TLID | RES | CTID| CLID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5
SSRC
Synchronization Source (SSRC) (32 bits) bits):
The SSRC value of the media sender that is requested to send a
layer refresh point.
Seq nr. (8 bits) Command bits):
The command sequence number. The sequence number space is unique
for each pairing of the SSRC of command source and the SSRC of the
command target. The sequence number SHALL be increased by 1 for
each new command (modulo 256, so the value after 255 is 0). A
repetition SHALL NOT increase the sequence number. The initial
value is arbitrary.
C (1 bit) bit):
A flag bit indicating whether the "Current Current Temporal Layer ID (CTID)" (CTID)
and "Current Current Layer ID (CLID)" (CLID) fields are present in the FCI. If
this bit is 0, the sender of the LRR message is requesting refresh
of all layers up to and including the target layer.
Payload Type (7 bits) bits):
The RTP payload type for which the LRR is being requested. This
gives the context in which the target layer index is to be
interpreted.
Reserved (RES) (three separate fields, fields of 16 bits / 5 bits / 5 bits)
bits):
All bits SHALL be set to 0 by the sender and SHALL be ignored on
reception.
Target Temporal Layer ID (TTID) (3 bits) bits):
The temporal ID of the target layer for which the receiver wishes
a refresh point.
Target Layer ID (TLID) (8 bits) bits):
The layer ID of the target spatial or quality layer for which the
receiver wishes a refresh point. Its format is dependent on the
payload type field.
Current Temporal Layer ID (CTID) (3 bits) bits):
If C is 1, the ID of the current temporal layer being decoded by
the receiver. This message is not requesting refresh of layers at
or below this layer. If C is 0, this field SHALL be set to 0 by
the sender and SHALL be ignored on reception.
Current Layer ID (CLID) (8 bits) bits):
If C is 1, the layer ID of the current spatial or quality layer
being decoded by the receiver. This message is not requesting
refresh of layers at or below this layer. If C is 0, this field
SHALL be set to 0 by the sender and SHALL be ignored on reception.
When C is 1, TTID MUST NOT be less than CTID, and TLID MUST NOT be
less than CLID; at least one of either TTID or TLID MUST be greater
than CTID or CLID CLID, respectively. That is to say, the target layer
index <TTID, TLID> MUST be a layer upgrade from the current layer
index <CTID, CLID>. A sender MAY request an upgrade in both temporal
and spatial/quality layers simultaneously.
A receiver receiving an LRR feedback packet which that does not satisfy the
requirements of the previous paragraph, i.e. i.e., one where the C bit is
present but the TTID is less than the CTID or the TLID is less than
the CLID, MUST discard the request.
Note: the syntax of the TTID, TLID, CTID, and CLID fields match, by
design, the TID and LID fields in [I-D.ietf-avtext-framemarking]. [RFC9626].
3.2. Semantics
Within the common packet header for feedback messages (as defined in
section
Section 6.1 of [RFC4585]), the "SSRC of packet sender" field
indicates the source of the request, and the "SSRC of media source"
is not used and SHALL be set to 0. The SSRCs of the media senders to
which the LRR command applies are in the corresponding FCI entries.
A
An LRR message MAY contain requests to multiple media senders, using
one FCI entry per target media sender.
Upon reception of an LRR, the encoder MUST send a decoder refresh
point (see Section 2.1) as soon as possible.
The sender MUST respect bandwidth limits provided by the application
of congestion control, as described in Section 5 of [RFC5104]. As
layer refresh points will often be larger than non-refreshing frames,
this may restrict a sender's ability to send a layer refresh point
quickly.
An LRR MUST NOT be sent as a reaction to picture losses due to packet
loss or corruption -- corruption; it is RECOMMENDED to use a PLI (Picture Loss
Indication) [RFC4585] instead. An LRR SHOULD be used only in
situations where there is an explicit change in a decoders' behavior, behavior:
for example example, when a receiver will start decoding a layer which that it
previously had been discarding.
4. Usage with specific codecs Specific Codecs
In order for an LRR to be used with a scalable codec, the format of
the temporal and layer ID fields (for both the target and current
layer indices) needs to be specified for that codec's RTP
packetization. New RTP packetization specifications for scalable
codecs SHOULD define how this is done. (The VP9 payload [I-D.ietf-payload-vp9], [RFC9628],
for instance, has done so.) If the payload also specifies how it is
used with the Frame Marking RTP Header Extension
[I-D.ietf-avtext-framemarking], [RFC9626], the
syntax MUST be defined in the same manner as the TID and LID fields
in that header.
4.1. H264 SVC
H.264 SVC [RFC6190] defines temporal, dependency (spatial), and
quality scalability modes.
+---------------+---------------+
|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RES | TID |R| DID | QID |
+---------------+---------------+
Figure 6
Figure 6 shows the format of the layer index fields for H.264 SVC
streams. The "R" and "RES" fields MUST be set to 0 on transmission
and ignored on reception. See [RFC6190] Section 1.1.3 of [RFC6190] for details
on the DID, QID, dependency_id (DID), quality_id (QID), and TID temporal_id (TID)
fields.
A dependency or quality layer refresh of a given layer in H.264 SVC
can be identified by the "I" bit (idr_flag) in the extended NAL Network
Abstraction Layer (NAL) unit header, present in NAL unit types 14
(prefix NAL unit) and 20 (coded scalable slice). Layer refresh of
the base layer can also be identified by its NAL unit type of its
coded slices, which is "5" rather than "1". A dependency or quality
layer refresh is complete once this bit has been seen on all the
appropriate layers (in decoding order) above the current layer index
(if any, or beginning from the base layer if not) through the target
layer index.
Note that as the "I" bit in a PACSI Payload Content Scalability Information
(PACSI) header is set if the corresponding bit is set in any of the
aggregated NAL units it describes; thus, it is not sufficient to
identify layer refresh when NAL units of multiple dependency or
quality layers are aggregated.
In H.264 SVC, temporal layer refresh information can be determined
from various Supplemental Encoding Information (SEI) messages in the
bitstream.
Whether an H.264 SVC stream is scalably nested can be determined from
the Scalability Information SEI message's temporal_id_nesting flag.
If this flag is set in a stream's currently applicable Scalability
Information SEI, receivers SHOULD NOT send temporal LRR messages for
that stream, as every frame is implicitly a temporal layer refresh
point. (The Scalability Information SEI message may also be
available in the signaling negotiation of H.264 SVC, SVC as the sprop-
scalability-info parameter.)
If a stream's temporal_id_nesting flag is not set, the Temporal Level
Switching Point SEI message identifies temporal layer switching
points. A temporal layer refresh is satisfied when this SEI message
is present in a frame with the target layer index, if the message's
delta_frame_num refers to a frame with the requested current layer
index. (Alternately, temporal layer refresh can also be satisfied by
a complete state refresh, such as an IDR.) Instantaneous Decoding Refresh
(IDR).) Senders which that support receiving an LRR for non-temporally-nested streams that are
not temporally nested MUST insert Temporal Level Switching Point SEI
messages as appropriate.
4.2. VP8
The VP8 RTP payload format [RFC7741] defines temporal scalability
modes. It does not support spatial scalability.
+---------------+---------------+
|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RES | TID | RES |
+---------------+---------------+
Figure 7
Figure 7 shows the format of the layer index field for VP8 streams.
The "RES" fields MUST be set to 0 on transmission and be ignored on
reception. See [RFC7741] Section 4.2 of [RFC7741] for details on the TID
field.
A VP8 layer refresh point can be identified by the presence of the
"Y" bit in the VP8 payload header. When this bit is set, this and
all subsequent frames depend only on the current base temporal layer.
On receipt of an LRR for a VP8 stream, A a sender which that supports LRR LRRs
MUST encode the stream so it can set the Y bit in a packet whose
temporal layer is at or below the target layer index.
Note that in VP8, not every layer switch point can be identified by
the Y bit, bit since the Y bit implies layer switch of all layers, not
just the layer in which it is sent. Thus Thus, the use of an LRR with VP8
can result in some inefficiency in transmision. transmission. However, this is
not expected to be a major issue for temporal structures in normal
use.
4.3. H265
The initial version of the H.265 payload format [RFC7798] defines
temporal scalability, with protocol elements reserved for spatial or
other scalability modes (which are expected to be defined in a future
version of the specification).
+---------------+---------------+
|0|1|2|3|4|5|6|7|0|1|2|3|4|5|6|7|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RES | TID |RES| LayerId |
+---------------+---------------+
Figure 8
Figure 8 shows the format of the layer index field for H.265 streams.
The "RES" fields MUST be set to 0 on transmission and ignored on
reception. See [RFC7798] Section 1.1.4 of [RFC7798] for details on the LayerId
and TID fields.
H.265 streams signal whether they are temporally nested, nested by using the
vps_temporal_id_nesting_flag in the Video Parameter Set (VPS), (VPS) and the
sps_temporal_id_nesting_flag in the Sequence Parameter Set (SPS). If
this flag is set in a stream's currently applicable VPS or SPS,
receivers SHOULD NOT send temporal LRR messages for that stream, as
every frame is implicitly a temporal layer refresh point.
If a stream's sps_temporal_id_nesting_flag is not set, the NAL unit
types 2 to 5 inclusively identify temporal layer switching points. A
layer refresh to any higher target temporal layer is satisfied when a
NAL unit type of 4 or 5 with TID equal to 1 more than current TID is
seen. Alternatively, layer refresh to a target temporal layer can be
incrementally satisfied with a NAL unit type of 2 or 3. In this
case, given current TID = TO and target TID = TN, layer refresh to TN
is satisfied when a NAL unit type of 2 or 3 is seen for TID = T1,
then TID = T2, all the way up to TID = TN. During this incremental
process, layer refresh to TN can be completely satisfied as soon as a
NAL unit type of 2 or 3 is seen.
Of course, temporal layer refresh can also be satisfied whenever any
Intra Random
Intra-Random Access Point (IRAP) NAL unit type (with values 16-23,
inclusively) is seen. An IRAP picture is similar to an IDR picture
in H.264 (NAL unit type of 5 in H.264) where decoding of the picture
can start without any older pictures.
In the (future) H.265 payloads that support spatial scalability, a
spatial layer refresh of a specific layer can be identified by NAL
units with the requested layer ID and NAL unit types between 16 and
21
21, inclusive. A dependency or quality layer refresh is complete
once NAL units of this type have been seen on all the appropriate
layers (in decoding order) above the current layer index (if any, or
beginning from the base layer if not) through the target layer index.
5. Usage with different scalability transmission mechanisms Different Scalability Transmission Mechanisms
Several different mechanisms are defined for how scalable streams can
be transmitted in RTP. The RTP Taxonomy [RFC7656] Section (Section 3.7 of [RFC7656])
defines three mechanisms: Single RTP Stream stream on a Single Media media
Transport (SRST), Multiple RTP Streams streams on a Single Media media Transport
(MRST), and Multiple RTP Streams streams on Multiple Media media Transports (MRMT).
The LRR message is applicable to all these mechanisms. For MRST and
MRMT mechanisms, the "media source" field of the LRR FCI is set to
the SSRC of the RTP stream containing the layer indicated by the
Current Layer Index (if "C" is 1), 1) or the stream containing the base
encoded stream (if "C" is 0). For MRMT, it is sent on the RTP
session on which this stream is sent. On receipt, the sender MUST
refresh all the layers requested in the stream, simultaneously in
decode order.
6. SDP Definitions
Section 7 of [RFC5104] defines SDP Session Description Protocol (SDP)
procedures for indicating and negotiating support for codec control messages Codec Control
Messages (CCM) in SDP. This document extends this with a new codec
control command, "lrr", which indicates support of the Layer Refresh Request (LRR). LRR.
Figure 9 gives a formal Augmented Backus-Naur Form (ABNF) [RFC5234]
showing this grammar extension, extending the grammar defined in
[RFC5104].
rtcp-fb-ccm-param =/ SP "lrr" ; Layer Refresh Request
Figure 9: Syntax of the "lrr" ccm CCM
The Offer-Answer considerations defined in [RFC5104] Section 7.2 of [RFC5104]
apply.
7. Security Considerations
All the security considerations of FIR feedback packets [RFC5104]
apply to LRR feedback packets as well. Additionally, media senders
receiving LRR feedback packets MUST validate that the payload types
and layer indices they are receiving are valid for the stream they
are currently sending, and discard the requests if not.
8. IANA Considerations
This document defines a new entry to the "Codec Control Messages"
subregistry of the "Session Description Protocol (SDP) Parameters"
registry, according to the following data:
Value name: Name: lrr
Long name: Name: Layer Refresh Request Command
Usable with: ccm
Mux: IDENTICAL-PER-PT
Reference: RFC XXXX 9627
This document also defines a new entry to the "FMT Values for PSFB
Payload Types" subregistry of the "Real-Time Transport Protocol (RTP)
Parameters" registry, according to the following data:
Name: LRR
Long Name: Layer Refresh Request Command
Value: TBD 10
Reference: RFC XXXX 9627
9. References
9.1. Normative References
[I-D.ietf-avtext-framemarking]
Berger, E., Nandakumar, S., and M. Zanaty, "Frame Marking
RTP Header Extension", draft-ietf-avtext-framemarking-05
(work in progress), July 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <http://www.rfc-editor.org/info/rfc3550>. <https://www.rfc-editor.org/info/rfc3550>.
[RFC4585] Ott, J., Wenger, S., Sato, N., Burmeister, C., and J. Rey,
"Extended RTP Profile for Real-time Transport Control
Protocol (RTCP)-Based Feedback (RTP/AVPF)", RFC 4585,
DOI 10.17487/RFC4585, July 2006,
<http://www.rfc-editor.org/info/rfc4585>.
<https://www.rfc-editor.org/info/rfc4585>.
[RFC5104] Wenger, S., Chandra, U., Westerlund, M., and B. Burman,
"Codec Control Messages in the RTP Audio-Visual Profile
with Feedback (AVPF)", RFC 5104, DOI 10.17487/RFC5104,
February 2008, <http://www.rfc-editor.org/info/rfc5104>. <https://www.rfc-editor.org/info/rfc5104>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<http://www.rfc-editor.org/info/rfc5234>.
<https://www.rfc-editor.org/info/rfc5234>.
[RFC6190] Wenger, S., Wang, Y., Y.-K., Schierl, T., and A.
Eleftheriadis, "RTP Payload Format for Scalable Video
Coding", RFC 6190, DOI 10.17487/RFC6190, May 2011,
<http://www.rfc-editor.org/info/rfc6190>.
<https://www.rfc-editor.org/info/rfc6190>.
[RFC7741] Westin, P., Lundin, H., Glover, M., Uberti, J., and F.
Galligan, "RTP Payload Format for VP8 Video", RFC 7741,
DOI 10.17487/RFC7741, March 2016,
<http://www.rfc-editor.org/info/rfc7741>.
<https://www.rfc-editor.org/info/rfc7741>.
[RFC7798] Wang, Y., Y.-K., Sanchez, Y., Schierl, T., Wenger, S., and M.
M. Hannuksela, "RTP Payload Format for High Efficiency
Video Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798,
March 2016, <http://www.rfc-editor.org/info/rfc7798>. <https://www.rfc-editor.org/info/rfc7798>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC9626] Zanaty, M., Berger, E., and S. Nandakumar, "Video Frame
Marking RTP Header Extension", RFC 9621,
DOI 10.17487/RFC9621, August 2024,
<https://www.rfc-editor.org/info/rfc9626>.
9.2. Informative References
[I-D.ietf-payload-vp9]
Uberti, J., Holmer, S., Flodman, M., Lennox, J., and D.
Hong, "RTP Payload Format for VP9 Video", draft-ietf-
payload-vp9-04 (work in progress), July 2017.
[RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
DOI 10.17487/RFC7656, November 2015,
<http://www.rfc-editor.org/info/rfc7656>.
<https://www.rfc-editor.org/info/rfc7656>.
[RFC8082] Wenger, S., Lennox, J., Burman, B., and M. Westerlund,
"Using Codec Control Messages in the RTP Audio-Visual
Profile with Feedback with Layered Codecs", RFC 8082,
DOI 10.17487/RFC8082, March 2017,
<http://www.rfc-editor.org/info/rfc8082>.
<https://www.rfc-editor.org/info/rfc8082>.
[RFC9628] Lennox, J., Hong, D., Uberti, J., Holmer, S., and M.
Flodman, "The Layer Refresh Request (LRR) RTCP Feedback
Message", RFC 9628, DOI 10.17487/RFC9628, August 2024,
<https://www.rfc-editor.org/info/rfc9628>.
Authors' Addresses
Jonathan Lennox
Vidyo, Inc.
433 Hackensack Avenue
Seventh Floor
Hackensack, NJ 07601
US
United States of America
Email: jonathan@vidyo.com
Danny Hong
Vidyo, Inc.
433 Hackensack Avenue
Seventh Floor
Hackensack, NJ 07601
US
United States of America
Email: danny@vidyo.com
Justin Uberti
Google, Inc.
747 6th Street South
Kirkland, WA 98033
USA
United States of America
Email: justin@uberti.name
Stefan Holmer
Google, Inc.
Kungsbron 2
Stockholm 111
SE-111 22 Stockholm
Sweden
Email: holmer@google.com
Magnus Flodman
Google, Inc.
Kungsbron 2
Stockholm 111
SE-111 22 Stockholm
Sweden
Email: mflodman@google.com