RTP Control Protocol (RTCP) Messages for Temporal-Spatial Resolution
draft-ietf-avtcore-rtcp-green-metadata-08

AVTCORE Working Group                                              Y. He
Internet-Draft                                                  Qualcomm
Intended status: Standards Track                             C. Herglotz
Expires: 6 December 2026                                             FAU
                                                             E. Francois
                                                            InterDigital
                                                             4 June 2026

  RTP Control Protocol (RTCP) Messages for Temporal-Spatial Resolution
               draft-ietf-avtcore-rtcp-green-metadata-08

Abstract

   This specification describes an RTCP feedback message format for the
   ISO/IEC International Standard 23001-11, known as Energy Efficient
   Media Consumption (Green metadata), developed by the ISO/IEC JTC 1/SC
   29/ WG 3 MPEG System.  The RTCP payload format specified in this
   specification enables receivers to provide feedback to the senders
   and thus allows for short-term adaptation and feedback-based energy
   efficient mechanisms to be implemented.  The payload format has broad
   applicability in real-time video communication services.

Status of This Memo

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   This Internet-Draft will expire on 6 December 2026.

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   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Conventions . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Abbreviations . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Format of RTCP Feedback Messages  . . . . . . . . . . . . . .   4
     4.1.  Temporal-Spatial Resolution Request . . . . . . . . . . .   4
       4.1.1.  Message format  . . . . . . . . . . . . . . . . . . .   5
       4.1.2.  Semantics . . . . . . . . . . . . . . . . . . . . . .   6
       4.1.3.  Timing Rules  . . . . . . . . . . . . . . . . . . . .   6
       4.1.4.  Handling of Message in Mixers and Translators . . . .   7
     4.2.  Temporal-Spatial Resolution Notification (TSRN) . . . . .   7
       4.2.1.  Message format  . . . . . . . . . . . . . . . . . . .   7
       4.2.2.  Semantics . . . . . . . . . . . . . . . . . . . . . .   8
       4.2.3.  Timing Rules  . . . . . . . . . . . . . . . . . . . .   9
       4.2.4.  Handling of TSRN in Mixers and Translators  . . . . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   6.  SDP Definitions . . . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Extension of the rtcp-fb Attribute  . . . . . . . . . . .  10
     6.2.  Examples  . . . . . . . . . . . . . . . . . . . . . . . .  10
   7.  Operational Considerations  . . . . . . . . . . . . . . . . .  11
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  12
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  12
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  13
   Appendix A.  Change History . . . . . . . . . . . . . . . . . . .  14
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   ISO/IEC 23001-11 specification, Energy Efficient Media Consumption
   (green metadata) [GreenMetadata], specifies metadata that facilitates
   reduction of energy usage in the encoding, decoding, and display
   processes while preserving the user’s quality of experience.  New
   metadata and quality metrics have been specified in the 3rd edition
   of green metadata specification to support H.266 and ISO/IEC 23090-3
   [VVC], and ISO/IEC 23094-1 [EVC] in addition to ITU-T Recommendation
   H.264 and ISO/IEC 14496-10 [AVC], H.265 and ISO/IEC 23008-5 [HEVC].

   Two main types of metadata are defined in the specification.  The
   first type consists of metadata generated by a video encoder which
   provides information about the decoding complexity of the delivered

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   bitstream and about the quality of the decoded content.  This first
   type of metadata is conveyed via the supplemental enhancement
   information (SEI) message mechanism specified in the video coding
   standard ITU-T Recommendation H.264 and ISO/IEC 14496-10 [AVC], H.265
   and ISO/IEC 23008-5 [HEVC], H.266 and ISO/IEC 23090-3 [VVC].

   The second type consists of metadata generated by a decoder as
   feedback conveyed to the encoder to adapt the decoder energy
   consumption.  This specification focuses on this second type of
   metadata which is conveyed as extension of RTP Control Protocol
   (RTCP) feedback messages [RFC4585].  The feedback in the second type
   of metadata specified in ISO/IEC 23001-11 [GreenMetadata] includes
   decoder operations reduction request, coding tools configuration
   request and temporal and spatial scaling request.  This specification
   defines new RTCP payload formats for the temporal and spatial
   resolution request and notification feedback message.

   The carriage of green metadata is specified in ISO/IEC 23001-19
   [GreenMetadataCarriage], including storage and carriage of green
   metadata using the ISO Base Media File Format (ISOBMFF) as specified
   in ISO/IEC 23001-10 [TimedMetadata] and encapsulation, signalling,
   and streaming of green metadata data in a media streaming system,
   e.g., dynamic adaptive streaming over HTTP (DASH) as specified in
   ISO/IEC 23009-1 [DASH].

   The primary use case for RTCP messages for temporal and spatial
   resolution is point-to-point video conferencing.  In such a scenario,
   each endpoint functions as both a transmitter and a receiver, and the
   conferencing session may be scheduled in advance.  A receiver
   operating on battery power can estimate its power consumption rate
   and, if necessary, request a reduction in pixel rate to ensure
   completion of the scheduled session.  Furthermore, when multiple
   tasks share a processing unit and a software decoder is allocated a
   limited portion of the available resources, the receiver can monitor
   real-time throughput and request a lower resolution or frame rate
   that aligns with the decoder’s processing capability.

2.  Conventions

   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 BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

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3.  Abbreviations

   AVPF: RTP Audio-Visual Profile with Feedback [RFC5104]

   CCM: Codec Control Messages [RFC5104]

   FCI: Feedback Control Information [RFC4585]

   FMT: Feedback Message Type [RFC4585]

   PSFB: Payload-specific FB message [RFC4585]

   RTP: Real-time Transport Protocol [RFC3550]

   RTCP: RTP Control Protocol [RFC3550]

   TSRN: Temporal-Spatial Resolution Notification

   TSRR: Temporal-Spatial Resolution Request

   Commonly-used RTP terms are defined in [RFC3550]

4.  Format of RTCP Feedback Messages

   This document extends the RTCP feedback messages defined in the RTP/
   AVPF [RFC4585] and [RFC5104] by defining a temporal-spatial
   resolution feedback message.  The message can be used by the receiver
   to inform the sender of the desirable coding temporal resolution
   (frame rate) and spatial resolution of the bitstream delivered, and
   by the sender to indicate the coding temporal and spatial resolution
   it will use henceforth.

   RTCP temporal-spatial resolution feedback message follows a similar
   message format as RTCP Temporal-Spatial Trade-off Request and
   Notification [RFC5104].  The message may be sent in a regular full
   compound RTCP packet or in an early RTCP packet, as per the RTP/AVPF
   rules.

   This specification specifies two additional payload-specific feedback
   messages: Temporal-Spatial Resolution Request (TSRR) and Temporal-
   Spatial Resolution Notification (TSRN)

4.1.  Temporal-Spatial Resolution Request

   The TSRR feedback message is identified by RTCP packet type value
   PT=PSFB and FMT=12.

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   -- To RFC Editor: please remove this note before publication: These
   assigned value are to be confirmed by IANA ---

   The FCI field MUST contain one or more TSRR FCI entries.

4.1.1.  Message format

   The content of the FCI entry for the Temporal-Spatial Resolution
   Request is depicted in Figure 1.

   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.     |         Reserved          |   Frame Rate      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Picture Width         |   Picture Height          | Rsvd  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Syntax of an FCI Entry in the TSRR Message

                                  Figure 1

   SSRC (32 bits): The Synchronization Source (SSRC) of the media sender
   that is requested to apply the frame rate and picture resolution.

   Seq nr. (8 bits): Request sequence number.  The sequence number space
   is unique for pairing of the SSRC of request source and the SSRC of
   the request target.  The sequence number SHALL be increased by 1
   modulo 256 for each new command.  A repetition SHALL NOT increase the
   sequence number.  The initial value is arbitrary.

   Reserved (14 bits): All bits SHALL be set to 0 by the sender and
   SHALL be ignored on reception.

   Frame Rate (10 bits): The requested frame rate.  This field is
   equivalent to the frames_per_second as defined in clause 6.3 of
   [GreenMetadata].  An integer value between 1 and 1023 that indicates
   the coding frame rate that is requested.  The value of Frame Rate
   equal to 0 is invalid.

   Picture Width (14 bits): The requested picture width in the units of
   luma samples.  This field is equivalent to the
   pic_width_in_luma_samples defined in clause 6.3 of [GreenMetadata].
   An integer value between 1 and 16383 that indicates the coding
   picture width in the units of luma samples that is requested.  The
   value of Picture Width equal to 0 is invalid.

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   Picture Height (14 bits): The requested picture height in the units
   of luma samples.  This field is equivalent to the
   pic_height_in_luma_samples defined in clause 6.3 of [GreenMetadata].
   An integer value between 1 and 16383 that indicates the coding
   picture height in the units of luma samples that is requested.  The
   value of Picture Height equal to 0 is invalid.

   Rsvd (4 bits): Reserved bits.  All reserved bits SHALL be set to 0 by
   the sender and SHALL be ignored on reception.

4.1.2.  Semantics

   A decoder can suggest a temporal-spatial resolution by sending a TSRR
   message to an encoder.  If the encoder is capable of adjusting its
   temporal-spatial resolution, it SHOULD take into account the received
   TSRR message for future coding of pictures.  The temporal and spatial
   resolutions in a TSRR message SHALL be less than or equal to the
   temporal and spatial resolutions negotiated via SDP.

   The reaction to the reception of more than one TSRR message by a
   media sender from different media receivers is left open to the
   implementation.  The selected Frame Rate, Picture Width and Picture
   Height SHALL be communicated to the media receivers by means of the
   TSRN message (see Section 4.2).

   Within the common packet header for feedback messages (as defined in
   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 TSRR applies are in the corresponding FCI entries.

   A TSRR message MAY contain requests to multiple media senders, using
   one FCI entry per target media sender.

4.1.3.  Timing Rules

   The timing follows the rules outlined in section 3 of [RFC4585].
   This request message is not time critical and SHOULD be sent using
   regular RTCP timing.  Only if it is known that the user interface
   requires quick feedback, the message MAY be sent with early or
   immediate feedback timing.

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4.1.4.  Handling of Message in Mixers and Translators

   A mixer or media translator (see Section 2.3 of [RFC3550]) that
   encodes content sent to the session participant issuing the TSRR
   SHALL consider the request to determine if it can fulfill it by
   changing its own encoding parameters.  A media translator unable to
   fulfill the request MAY forward the request unaltered towards the
   media sender.  A mixer encoding for multiple session participants
   will need to consider the joint needs of these participants before
   generating a TSRR on its own behalf towards the media sender.

4.2.  Temporal-Spatial Resolution Notification (TSRN)

   The TSRN message is identified by RTCP packet type value PT=PSFB and
   FMT=13.

   -- To RFC Editor: please remove this note before publication: These
   assigned value are to be confirmed by IANA ---

   The FCI field SHALL contain one or more TSRN FCI entries.

4.2.1.  Message format

   The content of the FCI entry for the Temporal-Spatial Resolution
   Notification is depicted in Figure 2.

   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.     |         Reserved          |   Frame Rate      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Picture Width         |     Picture Height        | Rsvd  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
            Syntax of an FCI Entry in the TSRN Message

                                  Figure 2

   SSRC (32 bits): The Synchronization Source (SSRC) of the source of
   the TSRR that resulted in this notification.

   Seq nr. (8 bits): The sequence number value from the TSRR that is
   being acknowledged.

   Reserved (14 bits): All bits SHALL be set to 0 by the sender and
   SHALL be ignored on reception.

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   Frame Rate (10 bits): The frame rate the media sender is using
   henceforth.

   Picture Width (14 bits): The coding picture width in the units of
   luma samples the media sender is using henceforth.

   Picture Height (14 bits): The coding picture height in the units of
   luma samples the media sender is using henceforth.

   Rsvd (4 bits): Reserved bits.  All reserved bits SHALL be set to 0 by
   the sender and SHALL be ignored on reception.

   It is to note that the returned value (Frame Rate, Picture Width,
   Picture Height) may differ from the requested one, for example, in
   cases where a media encoder cannot change its frame rate or picture
   resolution, or when the requested temporal and spatial resolutions
   are larger than the temporal and spatial resolutions negotiated via
   SDP, or when pre-recorded content is used.

4.2.2.  Semantics

   This feedback message is used to acknowledge the reception of a TSRR.
   For each TSRR received targeted at the session participant, a TSRN
   FCI entry SHALL be sent in a TSRN feedback message.  A single TSRN
   message MAY acknowledge multiple requests using multiple FCI entries.
   The Frame Rate, Picture Width and Picture Height value included SHALL
   be the same in all FCI entries of the TSRN message.  Including an FCI
   for each requestor allows each requesting entity to determine that
   the media sender received the request.  The notification SHALL also
   be sent in response to TSRR repetitions received.  If the request
   receiver has received TSRR with several different sequence numbers
   from a single requestor, it SHALL only respond to the request with
   the highest (modulo 256) sequence number.  Note that the highest
   sequence number could be a smaller integer value due to the wrapping
   of the field.  Appendix A.1 of [RFC3550] has an algorithm for keeping
   track of the highest received sequence number for RTP packets; it
   could be adapted for this usage.

   The TSRN SHALL include the Temporal-Spatial Resolution Frame Rate,
   Picture Width and Picture Height that will be used as a result of the
   request.  This is not necessarily the same Frame Rate, Picture Width
   and Picture Height as requested, as the media sender may need to
   aggregate requests from several requesting session participants.  It
   may also have some other policies or rules that limit the selection.

   Within the common packet header for feedback messages (as defined in
   section 6.1 of [RFC4585]), the "SSRC of packet sender" field
   indicates the source of the Notification, and the "SSRC of media

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   source" is not used and SHALL be set to 0.  The SSRCs of the
   requesting entities to which the Notification applies are in the
   corresponding FCI entries.

4.2.3.  Timing Rules

   The timing follows the rules outlined in section 3 of [RFC4585].
   This acknowledgement message is not extremely time critical and
   SHOULD be sent using regular RTCP timing.

4.2.4.  Handling of TSRN in Mixers and Translators

   A mixer or translator (see Section 2.3 of [RFC3550]) that acts upon a
   TSRR SHALL also send the corresponding TSRN.  In cases where it needs
   to forward a TSRR itself, the notification message MAY need to be
   delayed until the TSRR has been responded to.

5.  Security Considerations

   The defined messages have certain properties that have security
   implications.  These must be addressed and taken into account by
   users of this protocol.

   Spoofed or maliciously created feedback messages of the type defined
   in this specification can have the following implications:

   *  severely reduced picture resolution due to false TSRR messages
      that sets the picture width and height to a very low value;

   *  severely reduced frame rate due to false TSRR messages that sets
      the frame rate to a very low value.

   *  severely increased picture resolution due to false TSRR messages
      that sets the picture width and height to a value that is larger
      than the value negotiated via SDP;

   *  severely increased frame rate due to false TSRR messages that sets
      the frame rate to a value that is larger than the value negotiated
      via SDP.

   To prevent these attacks, there is a need to apply authentication and
   integrity protection of the feedback messages.  This can be
   accomplished against threats external to the current RTP session
   using the RTP profile that combines Secure RTP [SRTP] and AVPF into
   SAVPF [SAVPF].  In the mixer cases, separate security contexts and
   filtering can be applied between the mixer and the participants, thus
   protecting other users on the mixer from a misbehaving participant.

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6.  SDP Definitions

   The capability of handling messages defined in this specification MAY
   be exchanged at a higher layer such as SDP.  This specification
   follows all the rules defined in AVPF [RFC4585] and CCM [RFC5104] for
   an "rtcp-fb" attribute relating to the payload type in a session
   description.

6.1.  Extension of the rtcp-fb Attribute

   This specification defines a new parameter "tsrr" to the "ccm"
   feedback value defined in CCM [RFC5104] to indicate support of the
   Temporal-Spatial Resolution Request/Notification (TSRR/TSRN).  All
   the rules described in [RFC4585] for rtcp-fb attribute relating to
   payload type and to multiple rtcp-fb attributes in a session
   description also apply to the new feedback messages defined in this
   specification.

   rtcp-fb-ccm-param =/ SP "tsrr" ; Temporal-Spatial Resolution

6.2.  Examples

   Example 1: The following SDP describes a point-to-point video call
   with H.266, with the originator of the call declaring its capability
   to support the FIR and TSRR/TSRN codec control messages.  The SDP is
   carried in a high-level signaling protocol like SIP.

   v=0
   o=alice 3203093520 3203093520 IN IP4 host.example.com
   s=Point-to-Point call
   c=IN IP4 192.0.2.124
   m=audio 49170 RTP/AVP 0
   a=rtpmap:0 PCMU/8000
   m=video 51372 RTP/AVPF 98
   a=rtpmap:98 H266/90000
   a=rtcp-fb:98 ccm tsrr
   a=rtcp-fb:98 ccm fir

   In the above example, when the sender receives a TSRR message from
   the remote party it is capable of adjusting the trade-off as
   indicated in the RTCP TSRN feedback message.

   Example 2: The following example describes the Offer/Answer
   implications for the codec control messages.  The offerer wishes to
   support "tsrr", "fir" and "tmmbr".  The offered SDP is

   -------------> Offer

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   v=0
   o=alice 3203093520 3203093520 IN IP4 host.example.com
   s=Offer/Answer
   c=IN IP4 192.0.2.124
   m=audio 49170 RTP/AVP 0
   a=rtpmap:0 PCMU/8000
   m=video 51372 RTP/AVPF 98
   a=rtpmap:98 H266/90000
   a=rtcp-fb:98 ccm tsrr
   a=rtcp-fb:98 ccm fir
   a=rtcp-fb:* ccm tmmbr smaxpr=120

   The answerer wishes to support only the FIR and TSRR/TSRN messages
   and the answerer SDP is

   <---------------- Answer

   v=0
   o=alice 3203093520 3203093524 IN IP4 otherhost.example.com
   s=Offer/Answer
   c=IN IP4 192.0.2.37
   m=audio 47190 RTP/AVP 0
   a=rtpmap:0 PCMU/8000
   m=video 53273 RTP/AVPF 98
   a=rtpmap:98 H266/90000
   a=rtcp-fb:98 ccm tsrr
   a=rtcp-fb:98 ccm fir

7.  Operational Considerations

   *  This is a change that needs to be implemented at both endpoints,
      implementing at only one endpoint will result in no change to the
      RTP service.

   *  Remote support for this RFC is indicated by receiving a a TSRR
      message from a remote party using SDP (see Section 6) and
      confirmed by receiving a valid TSRR feedback message.

   *  A mixer or translator needs to be updated to support the TSRR
      message if it wishes to interact with the protocol (see
      Section 4.2.4).

   *  Operational security considerations are provided in the security
      considerations (see Section 5).

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8.  IANA Considerations

   IANA is requested to allocate the following two FMT Values in
   [IANA-RTCP-FMT-PSFB-PT]:

   Value, Name, Long Name, Reference

   12, TSRR, Temporal-Spatial Resolution Request, Section 4.1 of this
   RFC

   13, TSRN, Temporal-Spatial Resolution Notification, Section 4.2 of
   this RFC.

   IANA is requested to register a new Session Description Protocol
   (SDP) parameters in the “Session Description Protocol (SDP)
   Parameters” registry [IANA-SDP]:

   Value Name, Long Name, Usable with, Reference

   TSRR, Temporal-Spatial Resolution, ccm, this RFC

9.  References

9.1.  Normative References

   [GreenMetadata]
              "ISO/IEC FDIS 23001-11, Information technology - MPEG
              Systems Technologies - Part 11: Energy-Efficient Media
              Consumption (green metadata)", 2023,
              <https://www.iso.org/standard/83674.html>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <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, <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,
              <https://www.rfc-editor.org/info/rfc4585>.

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   [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, <https://www.rfc-editor.org/info/rfc5104>.

   [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>.

9.2.  Informative References

   [AVC]      "Advanced video coding, ITU-T Recommendation H.264", 2021,
              <https://www.itu.int/rec/T-REC-H.264>.

   [DASH]     "Information technology — Dynamic adaptive streaming over
              HTTP (DASH) Part 1: Media presentation description and
              segment formats", 2022,
              <https://www.iso.org/standard/83314.html>.

   [EVC]      "Information technology — General video coding Part 1:
              Essential video coding", 2020,
              <https://www.iso.org/standard/57797.html>.

   [GreenMetadataCarriage]
              "Information technology — MPEG systems technologies Part
              19: Carriage of green metadata", 2025,
              <https://www.iso.org/standard/90211.html>.

   [HEVC]     "High efficiency video coding, ITU-T Recommendation
              H.265", 2021, <https://www.itu.int/rec/T-REC-H.265>.

   [IANA-RTCP-FMT-PSFB-PT]
              "IANA-RTCP-FMT-PSFB-PT", 2025,
              <https://www.iana.org/assignments/rtp-parameters/rtp-
              parameters.xhtml#rtp-parameters>.

   [IANA-SDP] "IANA-SDP", 2026, <https://www.iana.org/assignments/sdp-
              parameters/sdp-parameters.xhtml>.

   [SAVPF]    Ott, J. and E. Carrara, "Extended Secure RTP Profile for
              RTCP-based Feedback (RTP/SAVPF)", 2008,
              <https://datatracker.ietf.org/doc/pdf/rfc5124>.

   [SRTP]     Baugher, M., McGrew, D., Naslund, M., Carrara, E., and K.
              Norrman, "The Secure Real-time Transport Protocol(SRTP)",
              2004, <https://datatracker.ietf.org/doc/pdf/rfc3711>.

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   [TimedMetadata]
              "Information technology — MPEG systems technologies Part
              10: Carriage of timed metadata metrics of media in ISO
              base media file format", 2020,
              <https://www.iso.org/standard/78824.html>.

   [VVC]      "Versatile Video Coding, ITU-T Recommendation H.266",
              2022, <http://www.itu.int/rec/T-REC-H.266>.

Appendix A.  Change History

   -- To RFC Editor: PLEASE REMOVE ThIS SECTION BEFORE PUBLICATION ---

   draft-ietf-avtcore-rtcp-green-metadata-00 ....initial version

   draft-ietf-avtcore-rtcp-green-metadata-01 ....title and editorial
   changes

   draft-ietf-avtcore-rtcp-green-metadata-02 ....editorial changes

   draft-ietf-avtcore-rtcp-green-metadata-03 ....no changes

   draft-ietf-avtcore-rtcp-green-metadata-04 ....no changes

   draft-ietf-avtcore-rtcp-green-metadata-05 ....editorial changes

   draft-ietf-avtcore-rtcp-green-metadata-06 ....no changes

   draft-ietf-avtcore-rtcp-green-metadata-07 ....editorial changes

   draft-ietf-avtcore-rtcp-green-metadata-08 ....editorial changes

Authors' Addresses

   Yong He
   Qualcomm
   5775 Morehouse Drive
   San Diego,  92121
   United States of America
   Email: yonghe@qti.qualcomm.com

   Christian Herglotz
   FAU
   Schlossplatz 4
   91054 Erlangen
   Germany
   Email: christian.herglotz@fau.de

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   Edouard Francois
   InterDigital
   975 Avenue des Champs Blancs
   35576 Cesson-Sevigne
   France
   Email: edouard.francois@interdigital.com

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