draft-ietf-avtext-framemarking-07.txt   draft-ietf-avtext-framemarking-08.txt 
Network Working Group M. Zanaty Network Working Group M. Zanaty
Internet-Draft E. Berger Internet-Draft E. Berger
Intended status: Standards Track S. Nandakumar Intended status: Standards Track S. Nandakumar
Expires: November 1, 2018 Cisco Systems Expires: April 26, 2019 Cisco Systems
April 30, 2018 October 23, 2018
Frame Marking RTP Header Extension Frame Marking RTP Header Extension
draft-ietf-avtext-framemarking-07 draft-ietf-avtext-framemarking-08
Abstract Abstract
This document describes a Frame Marking RTP header extension used to This document describes a Frame Marking RTP header extension used to
convey information about video frames that is critical for error convey information about video frames that is critical for error
recovery and packet forwarding in RTP middleboxes or network nodes. recovery and packet forwarding in RTP middleboxes or network nodes.
It is most useful when media is encrypted, and essential when the It is most useful when media is encrypted, and essential when the
middlebox or node has no access to the media decryption keys. It is middlebox or node has no access to the media decryption keys. It is
also useful for codec-agnostic processing of encrypted or unencrypted also useful for codec-agnostic processing of encrypted or unencrypted
media, while it also supports extensions for codec-specific media, while it also supports extensions for codec-specific
information. information.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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 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 November 1, 2018. This Internet-Draft will expire on April 26, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Key Words for Normative Requirements . . . . . . . . . . . . 4 2. Key Words for Normative Requirements . . . . . . . . . . . . 4
3. Frame Marking RTP Header Extension . . . . . . . . . . . . . 4 3. Frame Marking RTP Header Extension . . . . . . . . . . . . . 4
3.1. Extension for Non-Scalable Streams . . . . . . . . . . . 4 3.1. Short Extension for Non-Scalable Streams . . . . . . . . 4
3.2. Extension for Scalable Streams . . . . . . . . . . . . . 5 3.2. Long Extension for Scalable Streams . . . . . . . . . . . 5
3.2.1. Layer ID Mappings for Scalable Streams . . . . . . . 6 3.2.1. Layer ID Mappings for Scalable Streams . . . . . . . 7
3.2.1.1. H265 LID Mapping . . . . . . . . . . . . . . . . 6 3.2.1.1. H265 LID Mapping . . . . . . . . . . . . . . . . 7
3.2.1.2. H264-SVC LID Mapping . . . . . . . . . . . . . . 7 3.2.1.2. H264-SVC LID Mapping . . . . . . . . . . . . . . 7
3.2.1.3. H264 (AVC) LID Mapping . . . . . . . . . . . . . 7 3.2.1.3. H264 (AVC) LID Mapping . . . . . . . . . . . . . 7
3.2.1.4. VP8 LID Mapping . . . . . . . . . . . . . . . . . 7 3.2.1.4. VP8 LID Mapping . . . . . . . . . . . . . . . . . 8
3.2.1.5. Future Codec LID Mapping . . . . . . . . . . . . 7 3.2.1.5. Future Codec LID Mapping . . . . . . . . . . . . 8
3.3. Signaling Information . . . . . . . . . . . . . . . . . . 8 3.3. Signaling Information . . . . . . . . . . . . . . . . . . 8
3.4. Usage Considerations . . . . . . . . . . . . . . . . . . 8 3.4. Usage Considerations . . . . . . . . . . . . . . . . . . 8
3.4.1. Relation to Layer Refresh Request (LRR) . . . . . . . 8 3.4.1. Relation to Layer Refresh Request (LRR) . . . . . . . 9
3.4.2. Scalability Structures . . . . . . . . . . . . . . . 8 3.4.2. Scalability Structures . . . . . . . . . . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 4. Security Considerations . . . . . . . . . . . . . . . . . . . 9
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9 5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
7.1. Normative References . . . . . . . . . . . . . . . . . . 9 7.1. Normative References . . . . . . . . . . . . . . . . . . 10
7.2. Informative References . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
Many widely deployed RTP [RFC3550] topologies [RFC7667] used in Many widely deployed RTP [RFC3550] topologies [RFC7667] used in
modern voice and video conferencing systems include a centralized modern voice and video conferencing systems include a centralized
component that acts as an RTP switch. It receives voice and video component that acts as an RTP switch. It receives voice and video
streams from each participant, which may be encrypted using SRTP streams from each participant, which may be encrypted using SRTP
[RFC3711], or extensions that provide participants with private media [RFC3711], or extensions that provide participants with private media
via end-to-end encryption where the switch has no access to media [I-D.ietf-perc-private-media-framework] via end-to-end encryption
decryption keys. The goal is to provide a set of streams back to the where the switch has no access to media decryption keys. The goal is
participants which enable them to render the right media content. In to provide a set of streams back to the participants which enable
a simple video configuration, for example, the goal will be that each them to render the right media content. In a simple video
participant sees and hears just the active speaker. In that case, configuration, for example, the goal will be that each participant
the goal of the switch is to receive the voice and video streams from sees and hears just the active speaker. In that case, the goal of
each participant, determine the active speaker based on energy in the the switch is to receive the voice and video streams from each
participant, determine the active speaker based on energy in the
voice packets, possibly using the client-to-mixer audio level RTP voice packets, possibly using the client-to-mixer audio level RTP
header extension [RFC6464], and select the corresponding video stream header extension [RFC6464], and select the corresponding video stream
for transmission to participants; see Figure 1. for transmission to participants; see Figure 1.
In this document, an "RTP switch" is used as a common short term for In this document, an "RTP switch" is used as a common short term for
the terms "switching RTP mixer", "source projecting middlebox", the terms "switching RTP mixer", "source projecting middlebox",
"source forwarding unit/middlebox" and "video switching MCU" as "source forwarding unit/middlebox" and "video switching MCU" as
discussed in [RFC7667]. discussed in [RFC7667].
+---+ +------------+ +---+ +---+ +------------+ +---+
skipping to change at page 3, line 41 skipping to change at page 3, line 41
o Furthermore, it is highly desirable to do this in a payload o Furthermore, it is highly desirable to do this in a payload
format-agnostic way which is not specific to each different video format-agnostic way which is not specific to each different video
codec. Most modern video codecs share common concepts around codec. Most modern video codecs share common concepts around
frame types and other critical information to make this codec- frame types and other critical information to make this codec-
agnostic handling possible. agnostic handling possible.
o It is also desirable to be able to do this for SRTP without o It is also desirable to be able to do this for SRTP without
requiring the video switch to decrypt the packets. SRTP will requiring the video switch to decrypt the packets. SRTP will
encrypt the RTP payload format contents and consequently this data encrypt the RTP payload format contents and consequently this data
is not usable for the switching function without decryption, which is not usable for the switching function without decryption, which
may not even be possible in the case of end-to-end encryption of may not even be possible in the case of end-to-end encryption of
private media. private media [I-D.ietf-perc-private-media-framework].
By providing meta-information about the RTP streams outside the By providing meta-information about the RTP streams outside the
encrypted media payload, an RTP switch can do codec-agnostic encrypted media payload, an RTP switch can do codec-agnostic
selective forwarding without decrypting the payload. This document selective forwarding without decrypting the payload. This document
specifies the necessary meta-information in an RTP header extension. specifies the necessary meta-information in an RTP header extension.
2. Key Words for Normative Requirements 2. Key Words for Normative Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Frame Marking RTP Header Extension 3. Frame Marking RTP Header Extension
This specification uses RTP header extensions as defined in This specification uses RTP header extensions as defined in
[RFC5285]. A subset of meta-information from the video stream is [RFC8285]. A subset of meta-information from the video stream is
provided as an RTP header extension to allow an RTP switch to do provided as an RTP header extension to allow an RTP switch to do
generic selective forwarding of video streams encoded with generic selective forwarding of video streams encoded with
potentially different video codecs. potentially different video codecs.
The Frame Marking RTP header extension is encoded using the one-byte The Frame Marking RTP header extension is encoded using the one-byte
header or two-byte header as described in [RFC5285]. The one-byte header or two-byte header as described in [RFC8285]. The one-byte
header format is used for examples in this memo. The two-byte header header format is used for examples in this memo. The two-byte header
format is used when other two-byte header extensions are present in format is used when other two-byte header extensions are present in
the same RTP packet, since mixing one-byte and two-byte extensions is the same RTP packet, since mixing one-byte and two-byte extensions is
not possible in the same RTP packet. not possible in the same RTP packet.
This extension is only specified for Source (not Redunadancy) RTP This extension is only specified for Source (not Redundancy) RTP
Streams [RFC7656] that carry video payloads. It is not specified for Streams [RFC7656] that carry video payloads. It is not specified for
audio payloads, nor is it specified for Redundancy RTP Streams. The audio payloads, nor is it specified for Redundancy RTP Streams. The
(separate) specifications for Redudancy RTP Streams often include (separate) specifications for Redundancy RTP Streams often include
provisions for recovering any header extensions that were part of the provisions for recovering any header extensions that were part of the
original source packet. Such provisions SHALL be followed to recover original source packet. Such provisions SHALL be followed to recover
the Frame Marking RTP header extension of the original source packet. the Frame Marking RTP header extension of the original source packet.
Source packet frame markings may be useful when generating Redundancy
RTP Streams; for example, the I and D bits can be used to generate
extra or no redundancy, respectively, and redundancy schemes with
source blocks can align source block boundaries with Independent
frame boundaries as marked by the I bit.
3.1. Extension for Non-Scalable Streams A frame, in the context of this specification, is the set of RTP
packets with the same RTP timestamp from a specific RTP
synchronization source (SSRC).
3.1. Short Extension for Non-Scalable Streams
The following RTP header extension is RECOMMENDED for non-scalable The following RTP header extension is RECOMMENDED for non-scalable
streams. It MAY also be used for scalable streams if the sender has streams. It MAY also be used for scalable streams if the sender has
limited or no information about stream scalability. The ID is limited or no information about stream scalability. The ID is
assigned per [RFC5285], and the length is encoded as L=0 which assigned per [RFC8285], and the length is encoded as L=0 which
indicates 1 octet of data. indicates 1 octet of data.
0 1 0 1
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID=? | L=0 |S|E|I|D|0 0 0 0| | ID=? | L=0 |S|E|I|D|0 0 0 0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following information are extracted from the media payload and The following information are extracted from the media payload and
sent in the Frame Marking RTP header extension. sent in the Frame Marking RTP header extension.
o S: Start of Frame (1 bit) - MUST be 1 in the first packet in a o S: Start of Frame (1 bit) - MUST be 1 in the first packet in a
frame; otherwise MUST be 0. frame; otherwise MUST be 0.
o E: End of Frame (1 bit) - MUST be 1 in the last packet in a frame; o E: End of Frame (1 bit) - MUST be 1 in the last packet in a frame;
otherwise MUST be 0. otherwise MUST be 0. Note that this SHOULD match the RTP header
marker bit when the latter is reliable.
o I: Independent Frame (1 bit) - MUST be 1 for frames that can be o I: Independent Frame (1 bit) - MUST be 1 for frames that can be
decoded independent of temporally prior frames, e.g. intra-frame, decoded independent of temporally prior frames, e.g. intra-frame,
VPX keyframe, H.264 IDR [RFC6184], H.265 IDR/CRA/BLA/RAP VPX keyframe, H.264 IDR [RFC6184], H.265 IDR/CRA/BLA/RAP
[RFC7798]; otherwise MUST be 0. [RFC7798]; otherwise MUST be 0.
o D: Discardable Frame (1 bit) - MUST be 1 for frames that can be o D: Discardable Frame (1 bit) - MUST be 1 for frames the sender
discarded, and still provide a decodable media stream; otherwise knows can be discarded, and still provide a decodable media
MUST be 0. stream; otherwise MUST be 0.
o The remaining (4 bits) - MUST be 0 for non-scalable streams. o The remaining (4 bits) - are reserved for future use for non-
scalable streams; they MUST be set to 0 upon transmission and
ignored upon reception.
3.2. Extension for Scalable Streams 3.2. Long Extension for Scalable Streams
The following RTP header extension is RECOMMENDED for scalable The following RTP header extension is RECOMMENDED for scalable
streams. It MAY also be used for non-scalable streams, in which case streams. It MAY also be used for non-scalable streams, in which case
TID, LID and TL0PICIDX MUST be 0. The ID is assigned per [RFC5285], TID, LID and TL0PICIDX MUST be 0. The ID is assigned per [RFC8285],
and the length is encoded as L=2 which indicates 3 octets of data. and the length is encoded as L=2 which indicates 3 octets of data.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID=? | L=2 |S|E|I|D|B| TID | LID | TL0PICIDX | | ID=? | L=2 |S|E|I|D|B| TID | LID | TL0PICIDX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following information are extracted from the media payload and The following information are extracted from the media payload and
sent in the Frame Marking RTP header extension. sent in the Frame Marking RTP header extension.
skipping to change at page 5, line 36 skipping to change at page 6, line 4
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ID=? | L=2 |S|E|I|D|B| TID | LID | TL0PICIDX | | ID=? | L=2 |S|E|I|D|B| TID | LID | TL0PICIDX |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The following information are extracted from the media payload and The following information are extracted from the media payload and
sent in the Frame Marking RTP header extension. sent in the Frame Marking RTP header extension.
o S: Start of Frame (1 bit) - MUST be 1 in the first packet in a o S: Start of Frame (1 bit) - MUST be 1 in the first packet in a
frame within a layer; otherwise MUST be 0. frame within a layer; otherwise MUST be 0.
o E: End of Frame (1 bit) - MUST be 1 in the last packet in a frame o E: End of Frame (1 bit) - MUST be 1 in the last packet in a frame
within a layer; otherwise MUST be 0. within a layer; otherwise MUST be 0. Note that the RTP header
marker bit MAY be used to infer the last packet of the highest
enhancement layer.
o I: Independent Frame (1 bit) - MUST be 1 for frames that can be o I: Independent Frame (1 bit) - MUST be 1 for frames that can be
decoded independent of temporally prior frames, e.g. intra-frame, decoded independent of temporally prior frames, e.g. intra-frame,
VPX keyframe, H.264 IDR [RFC6184], H.265 IDR/CRA/BLA/RAP VPX keyframe, H.264 IDR [RFC6184], H.265 IDR/CRA/BLA/RAP
[RFC7798]; otherwise MUST be 0. Note that this bit only signals [RFC7798]; otherwise MUST be 0. Note that this bit only signals
temporal independence, so it can be 1 in spatial or quality temporal independence, so it can be 1 in spatial or quality
enhancement layers that depend on temporally co-located layers but enhancement layers that depend on temporally co-located layers but
not temporally prior frames. not temporally prior frames.
o D: Discardable Frame (1 bit) - MUST be 1 for frames that can be o D: Discardable Frame (1 bit) - MUST be 1 for frames the sender
discarded, and still provide a decodable media stream; otherwise knows can be discarded, and still provide a decodable media
MUST be 0. stream; otherwise MUST be 0.
o B: Base Layer Sync (1 bit) - MUST be 1 if this frame only depends o B: Base Layer Sync (1 bit) - MUST be 1 if the sender knows this
on the base layer; otherwise MUST be 0. If no scalability is frame only depends on the base temporal layer; otherwise MUST be
used, this MUST be 0. 0. If no scalability is used, this MUST be 0.
o TID: Temporal ID (3 bits) - The base temporal layer starts with 0, o TID: Temporal ID (3 bits) - The base temporal layer starts with 0,
and increases with 1 for each higher temporal layer/sub-layer. If and increases with 1 for each higher temporal layer/sub-layer. If
no scalability is used, this MUST be 0. no scalability is used, this MUST be 0.
o LID: Layer ID (8 bits) - Identifies the spatial and quality layer o LID: Layer ID (8 bits) - Identifies the spatial and quality layer
encoded. If no scalability is used, this MUST be 0 or omitted. encoded, starting with 0 and increasing with higher fidelity. If
When omitted, TL0PICIDX MUST also be omitted. no scalability is used, this MUST be 0 or omitted to reduce
length. When omitted, TL0PICIDX MUST also be omitted.
o TL0PICIDX: Temporal Layer 0 Picture Index (8 bits) - Running index o TL0PICIDX: Temporal Layer 0 Picture Index (8 bits) - Running index
of base temporal layer 0 frames when TID is 0. When TID is not 0, of base temporal layer 0 frames when TID is 0. When TID is not 0,
this indicates a dependency on the given index. If no scalability this indicates a dependency on the given index. If no scalability
is used, this MUST be 0 or omitted. When omitted, LID MUST also is used, or the running index is unknown, this MUST be omitted to
be omitted. reduce length. Note that 0 is a valid running index value for
TL0PICIDX.
The layer information contained in TID and LID convey useful aspects The layer information contained in TID and LID convey useful aspects
of the layer structure that can be utilized in selective forwarding. of the layer structure that can be utilized in selective forwarding.
Without further information about the layer structure, these Without further information about the layer structure, these
identifiers can only be used for relative priority of layers. They identifiers can only be used for relative priority of layers. They
convey a layer hierarchy with TID=0 and LID=0 identifying the base convey a layer hierarchy with TID=0 and LID=0 identifying the base
layer. Higher values of TID identify higher temporal layers with layer. Higher values of TID identify higher temporal layers with
higher frame rates. Higher values of LID identify higher spatial higher frame rates. Higher values of LID identify higher spatial
and/or quality layers with higher resolutions and/or bitrates. and/or quality layers with higher resolutions and/or bitrates.
skipping to change at page 8, line 31 skipping to change at page 8, line 47
When an RTP switch needs to discard a received video frame due to When an RTP switch needs to discard a received video frame due to
congestion control considerations, it is RECOMMENDED that it congestion control considerations, it is RECOMMENDED that it
preferably drop frames marked with the D (Discardable) bit set, or preferably drop frames marked with the D (Discardable) bit set, or
the highest values of TID and LID, which indicate the highest the highest values of TID and LID, which indicate the highest
temporal and spatial/quality enhancement layers, since those temporal and spatial/quality enhancement layers, since those
typically have fewer dependenices on them than lower layers. typically have fewer dependenices on them than lower layers.
When an RTP switch wants to forward a new video stream to a receiver, When an RTP switch wants to forward a new video stream to a receiver,
it is RECOMMENDED to select the new video stream from the first it is RECOMMENDED to select the new video stream from the first
switching point with the I (Independent) bit set and forward the switching point with the I (Independent) bit set in all spatial
same. An RTP switch can request a media source to generate a layers and forward the same. An RTP switch can request a media
switching point by sending Full Intra Request (RTCP FIR) as defined source to generate a switching point by sending Full Intra Request
in [RFC5104], for example. (RTCP FIR) as defined in [RFC5104], for example.
3.4.1. Relation to Layer Refresh Request (LRR) 3.4.1. Relation to Layer Refresh Request (LRR)
Receivers can use the Layer Refresh Request (LRR) Receivers can use the Layer Refresh Request (LRR)
[I-D.ietf-avtext-lrr] RTCP feedback message to upgrade to a higher [I-D.ietf-avtext-lrr] RTCP feedback message to upgrade to a higher
layer in scalable encodings. The TID/LID values and formats used in layer in scalable encodings. The TID/LID values and formats used in
LRR messages MUST correspond to the same values and formats specified LRR messages MUST correspond to the same values and formats specified
in Section 3.2. in Section 3.2.
Because frame marking can only be used with temporally-nested
streams, temporal-layer LRR refreshes are unnecessary for frame-
marked streams. Other refreshes can be detected based on the I bit
being set for the specific spatial layers.
3.4.2. Scalability Structures 3.4.2. Scalability Structures
The LID and TID information is most useful for fixed scalability The LID and TID information is most useful for fixed scalability
structures, such as nested hierarchical temporal layering structures, structures, such as nested hierarchical temporal layering structures,
where each temporal layer only references lower temporal layers or where each temporal layer only references lower temporal layers or
the base temporal layer. The LID and TID information is less useful, the base temporal layer. The LID and TID information is less useful,
or even not useful at all, for complex, irregular scalability or even not useful at all, for complex, irregular scalability
structures that do not conform to common, fixed patterns of inter- structures that do not conform to common, fixed patterns of inter-
layer dependencies and referencing structures. Therefore it is layer dependencies and referencing structures. Therefore it is
RECOMMENDED to use LID and TID information for RTP switch forwarding RECOMMENDED to use LID and TID information for RTP switch forwarding
skipping to change at page 9, line 43 skipping to change at page 10, line 16
Note to RFC Editor: please replace RFC XXXX with the number of this Note to RFC Editor: please replace RFC XXXX with the number of this
RFC. RFC.
7. References 7. References
7.1. Normative References 7.1. Normative References
[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, <https://www.rfc- DOI 10.17487/RFC2119, March 1997,
editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC6184] Wang, Y., Even, R., Kristensen, T., and R. Jesup, "RTP
Payload Format for H.264 Video", RFC 6184,
DOI 10.17487/RFC6184, May 2011,
<https://www.rfc-editor.org/info/rfc6184>.
[RFC6190] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
"RTP Payload Format for Scalable Video Coding", RFC 6190,
DOI 10.17487/RFC6190, May 2011,
<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,
<https://www.rfc-editor.org/info/rfc7741>.
[RFC7798] Wang, Y., Sanchez, Y., Schierl, T., Wenger, S., and M.
Hannuksela, "RTP Payload Format for High Efficiency Video
Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, March
2016, <https://www.rfc-editor.org/info/rfc7798>.
[RFC8285] Singer, D., Desineni, H., and R. Even, Ed., "A General
Mechanism for RTP Header Extensions", RFC 8285,
DOI 10.17487/RFC8285, October 2017,
<https://www.rfc-editor.org/info/rfc8285>.
7.2. Informative References 7.2. Informative References
[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", draft-ietf-avtext-lrr-07 (work in progress),
July 2017. July 2017.
[I-D.ietf-payload-vp9] [I-D.ietf-payload-vp9]
Uberti, J., Holmer, S., Flodman, M., Lennox, J., and D. Uberti, J., Holmer, S., Flodman, M., Lennox, J., and D.
Hong, "RTP Payload Format for VP9 Video", draft-ietf- Hong, "RTP Payload Format for VP9 Video", draft-ietf-
payload-vp9-05 (work in progress), March 2018. payload-vp9-06 (work in progress), July 2018.
[I-D.ietf-perc-private-media-framework]
Jones, P., Benham, D., and C. Groves, "A Solution
Framework for Private Media in Privacy Enhanced RTP
Conferencing", draft-ietf-perc-private-media-framework-07
(work in progress), September 2018.
[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>.
[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)",
RFC 3711, DOI 10.17487/RFC3711, March 2004, RFC 3711, DOI 10.17487/RFC3711, March 2004,
<https://www.rfc-editor.org/info/rfc3711>. <https://www.rfc-editor.org/info/rfc3711>.
[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>.
[RFC5285] Singer, D. and H. Desineni, "A General Mechanism for RTP
Header Extensions", RFC 5285, DOI 10.17487/RFC5285, July
2008, <https://www.rfc-editor.org/info/rfc5285>.
[RFC6184] Wang, Y., Even, R., Kristensen, T., and R. Jesup, "RTP
Payload Format for H.264 Video", RFC 6184,
DOI 10.17487/RFC6184, May 2011, <https://www.rfc-
editor.org/info/rfc6184>.
[RFC6190] Wenger, S., Wang, Y., Schierl, T., and A. Eleftheriadis,
"RTP Payload Format for Scalable Video Coding", RFC 6190,
DOI 10.17487/RFC6190, May 2011, <https://www.rfc-
editor.org/info/rfc6190>.
[RFC6464] Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time [RFC6464] Lennox, J., Ed., Ivov, E., and E. Marocco, "A Real-time
Transport Protocol (RTP) Header Extension for Client-to- Transport Protocol (RTP) Header Extension for Client-to-
Mixer Audio Level Indication", RFC 6464, Mixer Audio Level Indication", RFC 6464,
DOI 10.17487/RFC6464, December 2011, <https://www.rfc- DOI 10.17487/RFC6464, December 2011,
editor.org/info/rfc6464>. <https://www.rfc-editor.org/info/rfc6464>.
[RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and [RFC7656] Lennox, J., Gross, K., Nandakumar, S., Salgueiro, G., and
B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms B. Burman, Ed., "A Taxonomy of Semantics and Mechanisms
for Real-Time Transport Protocol (RTP) Sources", RFC 7656, for Real-Time Transport Protocol (RTP) Sources", RFC 7656,
DOI 10.17487/RFC7656, November 2015, <https://www.rfc- DOI 10.17487/RFC7656, November 2015,
editor.org/info/rfc7656>. <https://www.rfc-editor.org/info/rfc7656>.
[RFC7667] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 7667, [RFC7667] Westerlund, M. and S. Wenger, "RTP Topologies", RFC 7667,
DOI 10.17487/RFC7667, November 2015, <https://www.rfc- DOI 10.17487/RFC7667, November 2015,
editor.org/info/rfc7667>. <https://www.rfc-editor.org/info/rfc7667>.
[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, <https://www.rfc-
editor.org/info/rfc7741>.
[RFC7798] Wang, Y., Sanchez, Y., Schierl, T., Wenger, S., and M.
Hannuksela, "RTP Payload Format for High Efficiency Video
Coding (HEVC)", RFC 7798, DOI 10.17487/RFC7798, March
2016, <https://www.rfc-editor.org/info/rfc7798>.
Authors' Addresses Authors' Addresses
Mo Zanaty Mo Zanaty
Cisco Systems Cisco Systems
170 West Tasman Drive 170 West Tasman Drive
San Jose, CA 95134 San Jose, CA 95134
US US
Email: mzanaty@cisco.com Email: mzanaty@cisco.com
Espen Berger Espen Berger
Cisco Systems Cisco Systems
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