Closing the RTP Payload Format Media Types Registry Ericsson
magnus.westerlund@ericsson.com
WIT avtcore The working group process and the authors of RTP payload formats have sometimes failed to ensure that the media types are registered in the IANA "RTP Payload Format Media Types" registry as recommended by RFC 8088. To simplify the process and rely only on the "Media Types" registry, this document closes the RTP payload- specific registry. In addition, it updates the instruction in RFC 8088 to reflect this change.
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Table of Contents
  • .  Introduction
  • .  Update to How to Write an RTP Payload Format
  • .  IANA Considerations
  • .  Security Considerations
  • .  References
    • .  Normative References
    • .  Informative References
  • Acknowledgments
  • Author's Address
Introduction Sometimes, authors defining new Real-time Transport Protocol (RTP) payload formats forgot to specify registration of the format's media type in the "RTP Payload Format Media Types" registry as recommended by . In practice, this has no real impact. This registry is not used for any purpose other than to track which media types actually have RTP payload formats, which can be done through other means. It is required that media types be registered in the "Media Types" registry to identify the format in various signalling usages, avoid collisions, and reference the defining specifications. To resolve this situation, this document:
  • updates the "RTP Payload Format Media Types" registry to include known RTP payload formats at the time of writing,
  • closes the "RTP Payload Format Media Types" registry to future registrations and lists this RFC as a reference, and
  • removes from the instruction to register RTP payload formats in the "RTP Payload Format Media Types" registry.
The origins of the "RTP Payload Format Media Types" registry, as referenced in , are unclear. The registry cites as providing the instructions for its maintenance. However, upon reviewing RFC 4855, no text has been found that defines the registry's purpose and operational rules. Further attempts to trace the registry's creation have failed to uncover any references to its establishment. It is likely that the registry was created based on email correspondence or at the request of an Area Director. Consequently, there is no known specification for this registry that requires updating upon its closure.
Update to How to Write an RTP Payload Format The IANA Considerations section of "How to write an RTP Payload Format" () mandates that RTP payload formats shall be registered in the "RTP Payload Format Media Types" registry. The following paragraph is updated as shown below, thus removing the need for media types to be registered in the "RTP Payload Format Media Types" registry. Note that this update does not impact the rest of RFC 8088's status as an Informational RFC. OLD:
Since all RTP payload formats contain a media type specification, they also need an IANA Considerations section. The media type name must be registered, and this is done by requesting that IANA register that media name. When that registration request is written, it shall also be requested that the media type is included under the "RTP Payload Format media types" sub-registry of the RTP registry (http://www.iana.org/assignments/rtp-parameters).
NEW:
Since all RTP payload formats contain a media type specification, they also need an IANA Considerations section. The media type name must be registered, and this is done by requesting that IANA register that media name in the "Media Types" registry ().
IANA Considerations IANA has added the following RTP payload types to the "RTP Payload Format Media Types" registry . Payload Types Added to the RTP Payload Format Media Types Registry
Media Type Subtype Clock Rate (Hz) Channels (audio) Reference
application flexfec RFC 8627
audio EVRCNW 16000 RFC 6884
audio EVRCNW0 16000 RFC 6884
audio EVRCNW1 16000 RFC 6884
audio aptx RFC 7310
audio opus 48000 RFC 7587
audio G711-0 RFC 7650
audio flexfec RFC 8627
text flexfec RFC 8627
text ttml+xml RFC 8759
video VP8 90000 RFC 7741
video AV1 90000
video HEVC 90000 RFC 7798
video smpte291 RFC 8331
video VVC 90000 RFC 9328
video EVC 90000 RFC 9584
video flexfec RFC 8627
IANA has updated the following entries in the "RTP Payload Format Media Types" registry . Payload Types Updated in RTP Payload Format Media Types Registry
Media Type Subtype Clock Rate (Hz) Channels (audio) Reference
audio MP4A-LATM RFC 6416
video MP4V-ES 90000 RFC 6416
IANA has also closed the "RTP Payload Format Media Types" registry to any further registrations. IANA added the following to the registry note: NEW:
This registry has been closed; it was considered redundant because all RTP payload formats are part of the [Media Types registry]. See RFC 9751 for further details.
In addition, IANA updated the note in the "RTP Payload Format Media Types" registry as follows: OLD:
Registration procedures and a registration template can be found in .
NEW:
It was previously stated that registration procedures and a registration template can be found in . As documented in RFC 9751, this is not the case.
Security Considerations This document has no security considerations as it defines an administrative rule change.
References Normative References video/AV1 IANA Media Types IANA How to Write an RTP Payload Format This document contains information on how best to write an RTP payload format specification. It provides reading tips, design practices, and practical tips on how to produce an RTP payload format specification quickly and with good results. A template is also included with instructions. RTP Payload Format Media Types IANA Informative References Media Type Registration of RTP Payload Formats This document specifies the procedure to register RTP payload formats as audio, video, or other media subtype names. This is useful in a text-based format description or control protocol to identify the type of an RTP transmission. [STANDARDS-TRACK]
Acknowledgments The author thanks , , , , , , , , and for their reviews and editorial fixes.
Author's Address Ericsson
magnus.westerlund@ericsson.com