draft-ietf-avtext-lrr-06.txt   draft-ietf-avtext-lrr-07.txt 
Payload Working Group J. Lennox Payload Working Group J. Lennox
Internet-Draft D. Hong Internet-Draft D. Hong
Intended status: Standards Track Vidyo Intended status: Standards Track Vidyo
Expires: December 17, 2017 J. Uberti Expires: December 31, 2017 J. Uberti
S. Holmer S. Holmer
M. Flodman M. Flodman
Google Google
June 15, 2017 June 29, 2017
The Layer Refresh Request (LRR) RTCP Feedback Message The Layer Refresh Request (LRR) RTCP Feedback Message
draft-ietf-avtext-lrr-06 draft-ietf-avtext-lrr-07
Abstract Abstract
This memo describes the RTCP Payload-Specific Feedback Message "Layer This memo describes the RTCP Payload-Specific Feedback Message "Layer
Refresh Request" (LRR), which can be used to request a state refresh Refresh Request" (LRR), which can be used to request a state refresh
of one or more substreams of a layered media stream. It also defines of one or more substreams of a layered media stream. It also defines
its use with several RTP payloads for scalable media formats. its use with several RTP payloads for scalable media formats.
Status of This Memo Status of This Memo
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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 http://datatracker.ietf.org/drafts/current/. Drafts is at http://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 December 17, 2017. This Internet-Draft will expire on December 31, 2017.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions, Definitions and Acronyms . . . . . . . . . . . . 2 2. Conventions, Definitions and Acronyms . . . . . . . . . . . . 2
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
3. Layer Refresh Request . . . . . . . . . . . . . . . . . . . . 5 3. Layer Refresh Request . . . . . . . . . . . . . . . . . . . . 5
3.1. Message Format . . . . . . . . . . . . . . . . . . . . . 5 3.1. Message Format . . . . . . . . . . . . . . . . . . . . . 6
3.2. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2. Semantics . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Usage with specific codecs . . . . . . . . . . . . . . . . . 7 4. Usage with specific codecs . . . . . . . . . . . . . . . . . 8
4.1. H264 SVC . . . . . . . . . . . . . . . . . . . . . . . . 7 4.1. H264 SVC . . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. VP8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. VP8 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
4.3. H265 . . . . . . . . . . . . . . . . . . . . . . . . . . 9 4.3. H265 . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Usage with different scalability transmission mechanisms . . 10 5. Usage with different scalability transmission mechanisms . . 11
6. Security Considerations . . . . . . . . . . . . . . . . . . . 11 6. SDP Definitions . . . . . . . . . . . . . . . . . . . . . . . 11
7. SDP Definitions . . . . . . . . . . . . . . . . . . . . . . . 11 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
9.1. Normative References . . . . . . . . . . . . . . . . . . 12 9.1. Normative References . . . . . . . . . . . . . . . . . . 12
9.2. Informative References . . . . . . . . . . . . . . . . . 13 9.2. Informative References . . . . . . . . . . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction 1. Introduction
This memo describes an RTCP [RFC3550] Payload-Specific Feedback This memo describes an RTCP [RFC3550] Payload-Specific Feedback
Message [RFC4585] "Layer Refresh Request" (LRR). It is designed to Message [RFC4585] "Layer Refresh Request" (LRR). It is designed to
allow a receiver of a layered media stream to request that one or allow a receiver of a layered media stream to request that one or
more of its substreams be refreshed, such that it can then be decoded more of its substreams be refreshed, such that it can then be decoded
by an endpoint which previously was not receiving those layers, by an endpoint which previously was not receiving those layers,
without requiring that the entire stream be refreshed (as it would be without requiring that the entire stream be refreshed (as it would be
if the receiver sent a Full Intra Request (FIR); [RFC5104] see also if the receiver sent a Full Intra Request (FIR); [RFC5104] see also
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"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].
2.1. Terminology 2.1. Terminology
A "Layer Refresh Point" is a point in a scalable stream after which a A "Layer Refresh Point" is a point in a scalable stream after which a
decoder, which previously had been able to decode only some (possibly decoder, which previously had been able to decode only some (possibly
none) of the available layers of stream, is able to decode a greater none) of the available layers of stream, is able to decode a greater
number of the layers. number of the layers.
For spatial (or quality) layers, layer refresh typically requires For spatial (or quality) layers, in normal encoding, a subpicture can
that a spatial layer be encoded in a way that references only lower- depend both on earlier pictures of that spatial layer and also on
layer subpictures of the current picture, not any earlier pictures of lower-layer pictures of the current picture. A layer refresh,
that spatial layer. Additionally, the encoder must promise that no however, typically requires that a spatial layer picture be encoded
earlier pictures of that spatial layer will be used as reference in in a way that references only the lower-layer subpictures of the
the future. 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.
In a layer refresh, however, other layers than the ones requested for However, even in a layer refresh, layers other than the ones being
refresh may still maintain dependency on earlier content of the refreshed may still maintain dependency on earlier content of the
stream. This is the difference between a layer refresh and a Full stream. This is the difference between a layer refresh and a Full
Intra Request [RFC5104]. This minimizes the coding overhead of Intra Request [RFC5104]. This minimizes the coding overhead of
refresh to only those parts of the stream that actually need to be refresh to only those parts of the stream that actually need to be
refreshed at any given time. refreshed at any given time.
An illustration of spatial layer refresh of an enhancement layer is An illustration of spatial layer refresh of an enhancement layer is
shown below. shown below. <-- indicates a coding dependency.
... <-- S1 <-- S1 S1 <-- S1 <-- ... ... <-- S1 <-- S1 S1 <-- S1 <-- ...
| | | | | | | |
\/ \/ \/ \/ \/ \/ \/ \/
... <-- S0 <-- S0 <-- S0 <-- S0 <-- ... ... <-- S0 <-- S0 <-- S0 <-- S0 <-- ...
1 2 3 4 1 2 3 4
Figure 1 Figure 1
In Figure 1, frame 3 is a layer refresh point for spatial layer S1; a In Figure 1, frame 3 is a layer refresh point for spatial layer S1; a
decoder which had previously only been decoding spatial layer S0 decoder which had previously only been decoding spatial layer S0
would be able to decode layer S1 starting at frame 3. would be able to decode layer S1 starting at frame 3.
An illustration of spatial layer refresh of a base layer is shown An illustration of spatial layer refresh of a base layer is shown
below. below. <-- indicates a coding dependency.
... <-- S1 <-- S1 <-- S1 <-- S1 <-- ... ... <-- S1 <-- S1 <-- S1 <-- S1 <-- ...
| | | | | | | |
\/ \/ \/ \/ \/ \/ \/ \/
... <-- S0 <-- S0 S0 <-- S0 <-- ... ... <-- S0 <-- S0 S0 <-- S0 <-- ...
1 2 3 4 1 2 3 4
Figure 2 Figure 2
In Figure 2, frame 3 is a layer refresh point for spatial layer S0; a In Figure 2, frame 3 is a layer refresh point for spatial layer S0; a
decoder which had previously not been decoding the stream at all decoder which had previously not been decoding the stream at all
could decode layer S0 starting at frame 3. could decode layer S0 starting at frame 3.
For temporal layers, layer refresh requires that the layer be For temporal layers, while normal encoding allows frames to depend on
"temporally nested", i.e. use as reference only earlier frames of a earlier frames of the same temporal layer, layer refresh requires
lower temporal layer, not any earlier frames of this temporal layer, that the layer be "temporally nested", i.e. use as reference only
and also promise that no future frames of this temporal layer will earlier frames of a lower temporal layer, not any earlier frames of
reference frames of this temporal layer before the refresh point. In this temporal layer, and also promise that no future frames of this
many cases, the temporal structure of the stream will mean that all temporal layer will reference frames of this temporal layer before
frames are temporally nested, in which case decoders will have no the refresh point. In many cases, the temporal structure of the
need to send LRR messages for the stream. stream will mean that all frames are temporally nested, in which case
decoders will have no need to send LRR messages for the stream.
An illustration of temporal layer refresh is shown below. An illustration of temporal layer refresh is shown below. <--
indicates a coding dependency.
... <----- T1 <------ T1 T1 <------ ... ... <----- T1 <------ T1 T1 <------ ...
/ / / / / /
|_ |_ |_ |_ |_ |_
... <-- T0 <------ T0 <------ T0 <------ T0 <--- ... ... <-- T0 <------ T0 <------ T0 <------ T0 <--- ...
1 2 3 4 5 6 7 1 2 3 4 5 6 7
Figure 3 Figure 3
In Figure 3, frame 6 is a layer refresh point for temporal layer T1; In Figure 3, frame 6 is a layer refresh point for temporal layer T1;
a decoder which had previously only been decoding temporal layer T0 a decoder which had previously only been decoding temporal layer T0
would be able to decode layer T1 starting at frame 6. would be able to decode layer T1 starting at frame 6.
An illustration of an inherently temporally nested stream is shown An illustration of an inherently temporally nested stream is shown
below. below. <-- indicates a coding dependency.
T1 T1 T1 T1 T1 T1
/ / / / / /
|_ |_ |_ |_ |_ |_
... <-- T0 <------ T0 <------ T0 <------ T0 <--- ... ... <-- T0 <------ T0 <------ T0 <------ T0 <--- ...
1 2 3 4 5 6 7 1 2 3 4 5 6 7
Figure 4 Figure 4
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entry applies to a different media sender, identified by its SSRC. entry applies to a different media sender, identified by its SSRC.
[NOTE TO RFC Editor: Please replace "TBD" with the IANA-assigned [NOTE TO RFC Editor: Please replace "TBD" with the IANA-assigned
payload-specific feedback number.] payload-specific feedback number.]
3.1. Message Format 3.1. Message Format
The Feedback Control Information (FCI) for the Layer Refresh Request The Feedback Control Information (FCI) for the Layer Refresh Request
consists of one or more FCI entries, the content of which is depicted 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 in Figure 5. The length of the LRR feedback message MUST be set to
2+3*N, where N is the number of FCI entries. 2+3*N 32-bit words, where N is the number of FCI entries.
0 1 2 3 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 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 | | SSRC |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Seq nr. |C| Payload Type| Reserved | | Seq nr. |C| Payload Type| Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| RES | TTID| TLID | RES | CTID| CLID (opt) | | RES | TTID| TLID | RES | CTID| CLID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5 Figure 5
SSRC (32 bits) The SSRC value of the media sender that is requested SSRC (32 bits) The SSRC value of the media sender that is requested
to send a layer refresh point. to send a layer refresh point.
Seq nr. (8 bits) Command sequence number. The sequence number space Seq nr. (8 bits) Command sequence number. The sequence number space
is unique for each pairing of the SSRC of command source and the is unique for each pairing of the SSRC of command source and the
SSRC of the command target. The sequence number SHALL be SSRC of the command target. The sequence number SHALL be
increased by 1 modulo 256 for each new command. A repetition increased by 1 for each new command (modulo 256, so the value
SHALL NOT increase the sequence number. The initial value is after 255 is 0). A repetition SHALL NOT increase the sequence
arbitrary. number. The initial value is arbitrary.
C (1 bit) A flag bit indicating whether the "Current Temporal Layer C (1 bit) A flag bit indicating whether the "Current Temporal Layer
ID (CTID)" and "Current Layer ID (CLID)" fields are present in the ID (CTID)" and "Current Layer ID (CLID)" fields are present in the
FCI. If this bit is 0, the sender of the LRR message is FCI. If this bit is 0, the sender of the LRR message is
requesting refresh of all layers up to and including the target requesting refresh of all layers up to and including the target
layer. layer.
Payload Type (7 bits) The RTP payload type for which the LRR is Payload Type (7 bits) The RTP payload type for which the LRR is
being requested. This gives the context in which the target layer being requested. This gives the context in which the target layer
index is to be interpreted. index is to be interpreted.
Reserved (RES) (16 bits / 5 bits / 5 bits) All bits SHALL be set to Reserved (RES) (three separate fields, 16 bits / 5 bits / 5 bits)
0 by the sender and SHALL be ignored on reception. All bits SHALL be set to 0 by the sender and SHALL be ignored on
reception.
Target Temporal Layer ID (TTID) (3 bits) The temporal ID of the Target Temporal Layer ID (TTID) (3 bits) The temporal ID of the
target layer for which the receiver wishes a refresh point. target layer for which the receiver wishes a refresh point.
Target Layer ID (TLID) (8 bits) The layer ID of the target spatial Target Layer ID (TLID) (8 bits) The layer ID of the target spatial
or quality layer for which the receiver wishes a refresh point. or quality layer for which the receiver wishes a refresh point.
Its format is dependent on the payload type field. Its format is dependent on the payload type field.
Current Temporal Layer ID (CTID) (3 bits) If C is 1, the ID of the Current Temporal Layer ID (CTID) (3 bits) If C is 1, the ID of the
current temporal layer being decoded by the receiver. This current temporal layer being decoded by the receiver. This
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layer. If C is 0, this field SHALL be set to 0 by the sender and layer. If C is 0, this field SHALL be set to 0 by the sender and
SHALL be ignored on reception. SHALL be ignored on reception.
When C is 1, TTID MUST NOT be less than CTID, and TLID MUST NOT be When C is 1, TTID MUST NOT be less than CTID, and TLID MUST NOT be
less than CLID; at least one of TTID or TLID MUST be greater than less than CLID; at least one of TTID or TLID MUST be greater than
CTID or CLID respectively. That is to say, the target layer index CTID or CLID respectively. That is to say, the target layer index
<TTID, TLID> MUST be a layer upgrade from the current 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 <CTID, CLID>. A sender MAY request an upgrade in both temporal and
spatial/quality layers simultaneously. spatial/quality layers simultaneously.
A receiver receiving an LRR feedback packet which does not satisfy
the requirements of the previous paragraph, i.e. one where the C bit
is present but TTID is less than CTID or TLID is less than CLID, MUST
discard the request.
Note: the syntax of the TTID, TLID, CTID, and CLID fields match, by 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]. design, the TID and LID fields in [I-D.ietf-avtext-framemarking].
3.2. Semantics 3.2. Semantics
Within the common packet header for feedback messages (as defined in Within the common packet header for feedback messages (as defined in
section 6.1 of [RFC4585]), the "SSRC of packet sender" field section 6.1 of [RFC4585]), the "SSRC of packet sender" field
indicates the source of the request, and the "SSRC of media source" 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 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. which the LRR command applies are in the corresponding FCI entries.
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Upon reception of LRR, the encoder MUST send a decoder refresh point Upon reception of LRR, the encoder MUST send a decoder refresh point
(see Section 2.1) as soon as possible. (see Section 2.1) as soon as possible.
The sender MUST respect bandwidth limits provided by the application The sender MUST respect bandwidth limits provided by the application
of congestion control, as described in Section 5 of [RFC5104]. As of congestion control, as described in Section 5 of [RFC5104]. As
layer refresh points will often be larger than non-refreshing frames, layer refresh points will often be larger than non-refreshing frames,
this may restrict a sender's ability to send a layer refresh point this may restrict a sender's ability to send a layer refresh point
quickly. quickly.
LRR MUST NOT be sent as a reaction to picture losses -- it is LRR MUST NOT be sent as a reaction to picture losses due to packet
RECOMMENDED to use PLI [RFC4585] instead. LRR SHOULD be used only in loss or corruption -- it is RECOMMENDED to use PLI [RFC4585] instead.
situations where not sending a layer refresh point would render the LRR SHOULD be used only in situations where there is an explicit
video unusable for the users. change in decoders' behavior, for example when a receiver will start
decoding a layer which it previously had been discarding.
4. Usage with specific codecs 4. Usage with specific codecs
In order for LRR to be used with a scalable codec, the format of the In order for LRR to be used with a scalable codec, the format of the
temporal and layer ID fields (for both the target and current layer temporal and layer ID fields (for both the target and current layer
indices) needs to be specified for that codec's RTP packetization. indices) needs to be specified for that codec's RTP packetization.
New RTP packetization specifications for scalable codecs SHOULD New RTP packetization specifications for scalable codecs SHOULD
define how this is done. (The VP9 payload [I-D.ietf-payload-vp9], define how this is done. (The VP9 payload [I-D.ietf-payload-vp9],
for instance, has done so.) If the payload also specifies how it is for instance, has done so.) If the payload also specifies how it is
used with the Frame Marking RTP Header Extension used with the Frame Marking RTP Header Extension
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The LRR message is applicable to all these mechanisms. For MRST and 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 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 the SSRC of the RTP stream containing the layer indicated by the
Current Layer Index (if "C" is 1), or the stream containing the base Current Layer Index (if "C" is 1), or the stream containing the base
encoded stream (if "C" is 0). For MRMT, it is sent on the RTP 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 session on which this stream is sent. On receipt, the sender MUST
refresh all the layers requested in the stream, simultaneously in refresh all the layers requested in the stream, simultaneously in
decode order. decode order.
6. Security Considerations 6. SDP Definitions
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.
7. SDP Definitions
Section 7 of [RFC5104] defines SDP procedures for indicating and Section 7 of [RFC5104] defines SDP procedures for indicating and
negotiating support for codec control messages (CCM) in SDP. This negotiating support for codec control messages (CCM) in SDP. This
document extends this with a new codec control command, "lrr", which document extends this with a new codec control command, "lrr", which
indicates support of the Layer Refresh Request (LRR). indicates support of the Layer Refresh Request (LRR).
Figure 9 gives a formal Augmented Backus-Naur Form (ABNF) [RFC5234] Figure 9 gives a formal Augmented Backus-Naur Form (ABNF) [RFC5234]
showing this grammar extension, extending the grammar defined in showing this grammar extension, extending the grammar defined in
[RFC5104]. [RFC5104].
rtcp-fb-ccm-param =/ SP "lrr" ; Layer Refresh Request rtcp-fb-ccm-param =/ SP "lrr" ; Layer Refresh Request
Figure 9: Syntax of the "lrr" ccm Figure 9: Syntax of the "lrr" ccm
The Offer-Answer considerations defined in [RFC5104] Section 7.2 The Offer-Answer considerations defined in [RFC5104] Section 7.2
apply. 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 8. IANA Considerations
This document defines a new entry to the "Codec Control Messages" This document defines a new entry to the "Codec Control Messages"
subregistry of the "Session Description Protocol (SDP) Parameters" subregistry of the "Session Description Protocol (SDP) Parameters"
registry, according to the following data: registry, according to the following data:
Value name: lrr Value name: lrr
Long name: Layer Refresh Request Command Long name: Layer Refresh Request Command
Usable with: ccm Usable with: ccm
Mux: IDENTICAL-PER-PT
Reference: RFC XXXX Reference: RFC XXXX
This document also defines a new entry to the "FMT Values for PSFB This document also defines a new entry to the "FMT Values for PSFB
Payload Types" subregistry of the "Real-Time Transport Protocol (RTP) Payload Types" subregistry of the "Real-Time Transport Protocol (RTP)
Parameters" registry, according to the following data: Parameters" registry, according to the following data:
Name: LRR Name: LRR
Long Name: Layer Refresh Request Command Long Name: Layer Refresh Request Command
Value: TBD Value: TBD
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