path: root/doc/rfc/rfc3555.txt

Network Working Group                                          S. Casner
Request for Comments: 3555                                 Packet Design
Category: Standards Track                                     P. Hoschka
                                                           W3C/INRIA/MIT
                                                               July 2003


             MIME Type Registration of RTP Payload Formats

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document defines the procedure to register RTP Payload Formats
   as audio, video or other MIME subtype names.  This is useful in a
   text-based format or control protocol to identify the type of an RTP
   transmission.  This document also registers all the RTP payload
   formats defined in the RTP Profile for Audio and Video Conferences as
   MIME subtypes.  Some of these may also be used for transfer modes
   other than RTP.

Table of Contents

   1. Introduction ..................................................  2
      1.1. IANA Considerations ......................................  2
      1.2. Terminology ..............................................  3
   2. Procedure For Registering MIME Types for RTP Payload Types ....  3
   3. Mapping to SDP Parameters .....................................  5
   4. Registrations for "Audio/Video Profile" .......................  6
      4.1. Audio Type Registrations .................................  6
      4.2. Video Type Registrations ................................. 30
   5. Security Considerations ....................................... 42
   6. Normative References .......................................... 43
   7. Authors' Addresses ............................................ 44
   8. Full Copyright Statement ...................................... 45






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1. Introduction

   The MIME registration procedure described in RFC 2048 [1] was
   originally designed for transport of multimedia information via
   asynchronous Internet mail, but the MIME namespace now provides
   identification for other transport modes as well.  This document
   defines the procedure to register MIME subtype names for use with the
   Real-time Transport Protocol (RTP), RFC 3550 [2], to identify RTP
   payload formats.

   This document also registers all the RTP payload formats defined in
   the RTP Profile for Audio and Video Conferences, RFC 3551 [3], as
   MIME subtypes under the "audio" and "video" MIME types.

1.1. IANA Considerations

   This document registers the following MIME subtypes:

      audio/DVI4
      audio/G722
      audio/G723
      audio/G726-16
      audio/G726-24
      audio/G726-32
      audio/G726-40
      audio/G728
      audio/G729
      audio/G729D
      audio/G729E
      audio/GSM
      audio/GSM-EFR
      audio/L8
      audio/L16
      audio/LPC
      audio/MPA
      audio/PCMA
      audio/PCMU
      audio/QCELP
      audio/RED
      audio/VDVI
      video/BT656
      video/CelB
      video/JPEG
      video/H261
      video/H263
      video/H263-1998
      video/H263-2000
      video/MPV



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      video/MP2T
      video/MP1S
      video/MP2P
      video/BMPEG
      video/nv

   MIME subtype audio/L16 has already been registered via RFC 2586 for
   transports other than RTP.  That registration is incorporated here
   and augmented with additional information for RTP transport.

1.2. Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [4] and
   indicate requirement levels for implementations compliant with this
   specification.

2. Procedure For Registering MIME Types for RTP Payload Types

   Registering an RTP payload type as a MIME type follows the same
   procedures as described in RFC 2048 and uses the registration
   template shown in Section 2.8 of RFC 2048.  Some additional
   parameters are required to specify how a particular payload format is
   transported over RTP:

      Published specification
         A description of the encoding and a specification of the
         payload format must be provided, usually by reference to an RTP
         payload format specification RFC.  That RFC may be separate, or
         the MIME subtype registration may be incorporated into the
         payload format specification RFC.  The payload format
         specification MUST include the RTP timestamp clock rate (or
         multiple rates for audio encodings with multiple sampling
         rates).

         A reference to a further description of the data compression
         format itself should be provided, if available.

      Required parameters
         If the payload format does not have a fixed RTP timestamp clock
         rate, then a "rate" parameter is required to specify the RTP
         timestamp clock rate.  A particular payload format may have
         additional required parameters.







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      Optional parameters
         Most audio payload formats can have an optional "channels"
         parameter to specify the number of audio channels included in
         the transmission.  Any payload format, but most likely audio
         formats, may also include the optional parameters "ptime", to
         specify the recommended length of time in milliseconds
         represented by the media in a packet, and/or "maxptime" to
         specify the maximum amount of media which can be encapsulated
         in each packet, expressed as time in milliseconds.  The "ptime"
         and "maxptime" parameters are defined in the Session
         Description Protocol (SDP) [5].

         A particular payload format may have additional optional
         parameters.

      Encoding considerations
         The fact that the type can be transferred via RTP MUST be
         noted.

   Depending on whether the type has already been registered for
   transfer with a non-RTP protocol (e.g. MIME mail or http) or not,
   several different cases can occur:

      a) Not yet registered as a MIME type

         A new registration should be constructed using the MIME
         registration template.  The registration may specify transfer
         via other means in addition to RTP if that is feasible and
         desired.  The encoding considerations must specify how the type
         is transferred via RTP.

         Optional parameters may be defined as needed, and it must be
         clearly stated whether to which mode(s) of transfer the
         parameters apply.

      b) MIME type exists for a non-RTP protocol

         The encoding considerations of the existing type should be
         changed to indicate that the type can also be transferred via
         RTP.

         RTP-specific parameters may be added, and it must be clearly
         stated that these are only to be used when the media type is
         transmitted via RTP transport.







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      c) Update an existing MIME type for RTP to be used for a non-RTP
         protocol

         The encoding considerations of the existing type should be
         changed to indicate that the type can also be transferred via a
         non-RTP protocol (e.g. SMTP, HTTP).

         Non-RTP-specific parameters can be added, and it must be
         clearly stated that these are only to be used when the media
         type is transmitted via a non-RTP transport.

3. Mapping to SDP Parameters

   The representation of a MIME media type is specified in the syntax of
   the Content-Type header field in RFC 2045 [6] as follows:

      type "/" subtype  *(";" parameter)

   Parameters may be required for a particular type or subtype or they
   may be optional.  For media types which represent RTP payload
   formats, the parameters "rate", "channels", "ptime", and "maxptime"
   have general definitions (given above) that may apply across types
   and subtypes.  The format for a parameter is specified in RFC 2045 as

      attribute "=" value

   where attribute is the parameter name and the permissible values are
   specified for each parameter.  The value may need to be a quoted
   string if it contains any of the special characters listed in RFC
   2045.

   The information carried in the media type string has a specific
   mapping to fields in the Session Description Protocol (SDP) [5],
   which is commonly used to describe RTP sessions.  The mapping is as
   follows:

      o  The MIME type (e.g., audio) goes in SDP "m=" as the media name.

      o  The MIME subtype (payload format) goes in SDP "a=rtpmap" as the
         encoding name.

      o  The general (possibly optional) parameters "rate" and
         "channels" also go in "a=rtpmap" as clock rate and encoding
         parameters, respectively.

      o  The general (and optional) parameters "ptime" and "maxptime" go
         in the SDP "a=ptime" and "a=maxptime" attributes, respectively.




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      o  Any payload-format-specific parameters go in the SDP "a=fmtp"
         attribute.  The set of allowed parameters is defined by the RFC
         that specifies the payload format and MUST NOT be extended by
         the MIME subtype registration without a corresponding revision
         of the payload format specification.  The format and syntax of
         these parameters may also be defined by the payload format
         specification, but it is suggested that the parameters be
         copied directly from the MIME media type string as a semicolon
         separated list of parameter=value pairs.  For payload formats
         that specify some other syntax for the fmtp parameters, the
         registration of that payload format as a MIME subtype must
         specify what the parameters are in MIME format and how to map
         them to the SDP "a=fmtp" attribute.  See Section 4.1.21 for an
         example.

   An example mapping is as follows:

      audio/L16; rate=48000; channels=2; ptime=5; emphasis=50-15

      m=audio 49170 RTP/AVP 97
      a=rtpmap:97 L16/48000/2
      a=fmtp:97 emphasis=50-15
      a=ptime:5

   Note that the payload format (encoding) names defined in the RTP
   Profile are commonly shown in upper case.  MIME subtypes are commonly
   shown in lower case.  These names are case-insensitive in both
   places.  Similarly, parameter names are case-insensitive both in MIME
   types and in the default mapping to the SDP a=fmtp attribute.

4. Registrations for "Audio/Video Profile"

   In the following sections, all RTP payload formats described in the
   RTP Profile for Audio and Video Conferences, RFC 3551 [3], are
   registered as MIME subtypes.

4.1. Audio Type Registrations

   The following sections register all of the RTP audio payload types
   defined in RFC 3551 as MIME types.

   For most audio payload formats, the RTP timestamp clock rate is equal
   to the sampling rate.  Some payload formats operate only at one fixed
   sampling rate, while others are adjustable.







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4.1.1. Registration of MIME media type audio/DVI4

   MIME media type name: audio

   MIME subtype name: DVI4

   Required parameters: rate
        The RTP timestamp clock rate, which is equal to the sampling
        rate.  The typical rate is 8000, but other rates may be
        specified.

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner

















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4.1.2. Registration of MIME media type audio/G722

   MIME media type name: audio

   MIME subtype name: G722

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.3. Registration of MIME media type audio/G723

   MIME media type name: audio

   MIME subtype name: G723

   Required parameters: None

   Optional parameters:
        ptime, maxptime

        bitrate: the data rate in kb/s used or preferred for the audio
        bit stream, with permissible values 5.3 or 6.3.  If
        unspecified, the bitrate may change from frame to frame as
        indicated inband.

        annexa: indicates that Annex A, voice activity detection, is
        used or preferred.  Permissible values are "yes" and "no"
        (without the quotes); "yes" is implied if this parameter is
        omitted.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner









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4.1.4. Registration of MIME media type audio/G726-16

   MIME media type name: audio

   MIME subtype name: G726-16

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.5. Registration of MIME media type audio/G726-24

   MIME media type name: audio

   MIME subtype name: G726-24

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:

        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner



















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4.1.6. Registration of MIME media type audio/G726-32

   MIME media type name: audio

   MIME subtype name: G726-32

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.7. Registration of MIME media type audio/G726-40

   MIME media type name: audio

   MIME subtype name: G726-40

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.8. Registration of MIME media type audio/G728

   MIME media type name: audio

   MIME subtype name: G728

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.9. Registration of MIME media type audio/G729

   MIME media type name: audio

   MIME subtype name: G729

   Required parameters: None

   Optional parameters:
        ptime, maxptime

        annexb: indicates that Annex B, voice activity detection, is
        used or preferred.  Permissible values are "yes" and "no"
        (without the quotes); "yes" is implied if this parameter is
        omitted.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner














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4.1.10. Registration of MIME media type audio/G729D

   MIME media type name: audio

   MIME subtype name: G729D

   Required parameters: None

   Optional parameters:
        ptime, maxptime

        annexb: indicates that Annex B, voice activity detection, is
        used or preferred.  Permissible values are "yes" and "no"
        (without the quotes); "yes" is implied if this parameter is
        omitted.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner














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4.1.11. Registration of MIME media type audio/G729E

   MIME media type name: audio

   MIME subtype name: G729E

   Required parameters: None

   Optional parameters:
        ptime, maxptime

        annexb: indicates that Annex B, voice activity detection, is
        used or preferred.  Permissible values are "yes" and "no"
        (without the quotes); "yes" is implied if this parameter is
        omitted.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner














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4.1.12. Registration of MIME media type audio/GSM

   MIME media type name: audio

   MIME subtype name: GSM

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.13. Registration of MIME media type audio/GSM-EFR

   MIME media type name: audio

   MIME subtype name: GSM-EFR

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.14. Registration of MIME media type audio/L8

   MIME media type name: audio

   MIME subtype name: L8

   Required parameters: rate, the RTP timestamp clock rate

   Optional parameters: channels, ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.15. Registration of MIME media type audio/L16

   MIME subtype audio/L16 has already been registered via RFC 2586 for
   transports other than RTP.  That registration is incorporated here
   and augmented with additional information for RTP transport.

   MIME media type name: audio

   MIME subtype name: L16

   Required parameters
        rate: number of samples per second -- For non-RTP transport,
        the permissible values for rate are 8000, 11025, 16000, 22050,
        24000, 32000, 44100, and 48000 samples per second.  For RTP
        transport, other values are permissible but the aforementioned
        values are RECOMMENDED.  For RTP, the rate parameter indicates
        the RTP timestamp clock rate, which is equal to the sample
        rate.

   Optional parameters
        channels: how many audio streams are interleaved -- defaults
        to 1; stereo would be 2, etc.  Interleaving takes place
        between individual two-byte samples.

        emphasis: analog preemphasis applied to the signal before
        quantization.  The only emphasis value defined here is
        emphasis=50-15 to indicate the 50/15 microsecond preemphasis
        used with Compact Disks.  This parameter MUST be omitted if no
        analog preemphasis was applied.

        channel-order: specifies the sample interleaving order for
        multiple-channel audio streams (see [7] Section 7).
        Permissible values are DV.LRLsRs, DV.LRCS, DV.LRCWo,
        DV.LRLsRsC, DV.LRLsRsCS, DV.LmixRmixTWoQ1Q2,
        DV.LRCWoLsRsLmixRmix, DV.LRCWoLs1Rs1Ls2Rs2, DV.LRCWoLsRsLcRc.
        For interoperation with DV video systems, only a subset of
        these channel combinations is specified for use with 20-bit
        linear encoding in the DV video specification [4]; those are
        DV.LRLsRs, DV.LRCS, DV.LmixRmixTWoQ1Q2.  This parameter MUST
        be omitted when the AIFF-C channel order convention (see RFC
        3551) is in use.

        For RTP, ptime: RECOMMENDED duration of each packet in
        milliseconds.

        For RTP, maxptime: maximum duration of each packet in
        milliseconds.




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   Encoding considerations
        Audio data is binary data, and must be encoded for non-binary
        transport; the Base64 encoding is suitable for Email.  Note
        that audio data does not compress easily using lossless
        compression.

        This type is also defined for transfer via RTP [RFC 3550].

   Security considerations
        Audio data is believed to offer no security risks.
        See Section 5 of RFC 3555.

   Interoperability considerations
        This type is compatible with the encoding used in the WAV
        (Microsoft Windows RIFF) and Apple AIFF union types, and with
        the public domain "sox" and "rateconv" programs.

   Published specification
        RFC 2586 for non-RTP transports, RFC 3551 for RTP

   Applications which use this media
        The public domain "sox" and "rateconv" programs accept this
        type.

        1. Magic number(s) : None
        2. File extension(s) : WAV L16
        3. Macintosh file type code : AIFF

   Person to contact for further information
        1. Name : James Salsman
        2. E-mail : jps-L16@bovik.org

   Intended usage
        Common

        It is expected that many audio and speech applications will
        use this type.  Already the most popular platforms provide
        this type with the rate=11025 parameter referred to as "radio
        quality speech."

   Author/Change controller
        James Salsman for non-RTP transports.
        Stephen Casner for RTP transport.








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4.1.16. Registration of MIME media type audio/LPC

   MIME media type name: audio

   MIME subtype name: LPC

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.17. Registration of MIME media type audio/MPA

   MIME media type name: audio

   MIME subtype name: MPA (MPEG audio)

   Required parameters: None

   Optional parameters:
        layer: which layer of MPEG audio encoding; permissible values
        are 1, 2, 3.

        samplerate: the rate at which audio is sampled.  MPEG-1 audio
        supports sampling rates of 32, 44.1, and 48 kHz; MPEG-2
        supports sampling rates of 16, 22.05 and 24 kHz.  This parameter
        is separate from the RTP timestamp clock rate which is always
        90000 Hz for MPA.

        mode: permissible values are "stereo", "joint_stereo",
        "single_channel", "dual_channel".  The "channels" parameter
        does not apply to MPA.  It is undefined to put a number of
        channels in the SDP rtpmap attribute for MPA.

        bitrate: the data rate for the audio bit stream.

        ptime: RECOMMENDED duration of each packet in milliseconds.

        maxptime: maximum duration of each packet in milliseconds.

        Parameters which are omitted are left to the encoder to choose
        based on the session bandwidth, configuration information, or
        other constraints.  The selected layer as well as the sampling
        rate and mode are indicated in the payload so receivers can
        process the data without these parameters being specified
        externally.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.




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   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner

4.1.18. Registration of MIME media type audio/PCMA

   MIME media type name: audio

   MIME subtype name: PCMA

   Required parameters: rate
        The RTP timestamp clock rate, which is equal to the sampling
        rate.  The typical rate is 8000, but other rates may be
        specified.

   Optional parameters: channels, ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner







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4.1.19. Registration of MIME media type audio/PCMU

   MIME media type name: audio

   MIME subtype name: PCMU

   Required parameters: rate
        The RTP timestamp clock rate, which is equal to the sampling
        rate.  The typical rate is 8000, but other rates may be
        specified.

   Optional parameters: channels, ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner

















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4.1.20. Registration of MIME media type audio/QCELP

   MIME media type name: audio

   MIME subtype name: QCELP

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2658

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.1.21. Registration of MIME media type audio/RED

   MIME media type name: audio

   MIME subtype name: RED

   Required parameters:
        pt: a comma-separated list of RTP payload types.  Because
        comma is a special character, the list must be a quoted-string
        (enclosed in double quotes).  For static payload types, each
        list element is simply the type number.  For dynamic payload
        types, each list element is a mapping of the dynamic payload
        type number to an embedded MIME content-type specification for
        the payload format corresponding to the dynamic payload type.
        The format of the mapping is:

           dynamic-payload-type "=" content-type

        If the content-type string includes a comma, then the
        content-type string MUST be a quoted-string.  If the content-
        type string does not include a comma, it MAY still be quoted.
        Since it is part of the list which must itself be a quoted-
        string, that means the quotation marks MUST be quoted with
        backslash quoting as specified in RFC 2045.  If the content-
        type string itself contains a quoted-string, then the
        requirement for backslash quoting is recursively applied.  To
        specify the audio/RED payload format in SDP, the pt parameter
        is mapped to an a=fmtp attribute by eliminating the parameter
        name (pt) and changing the commas to slashes.  For example,
        'pt="0,5"' maps to 'a=fmtp:99 0/5'.  A more complicated
        example, with a dynamic payload type, is:

           pt = "0, 103 = \"audio/G729D;annexb=yes\" "

           m=audio 49170 RTP/AVP 99 0 103
           a=rtpmap:99 RED/8000
           a=fmtp:99 0/103
           a=rtpmap:103 G729D/8000
           a=fmtp:103 annexb=yes

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none



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   Published specification: RFC 2198

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner

4.1.22. Registration of MIME media type audio/VDVI

   MIME media type name: audio

   MIME subtype name: VDVI

   Required parameters: None

   Optional parameters: ptime, maxptime

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner





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4.2. Video Type Registrations

   For all of the video payload formats registered here, the RTP
   timestamp clock rate is always 90000 Hz, so the "rate" parameter is
   not applicable.  Likewise, the "channel" parameter is not used with
   video, and while "ptime" and "maxptime" could be used with video,
   they typically are not.

4.2.1. Registration of MIME media type video/BT656

   MIME media type name: video

   MIME subtype name: BT656

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2431

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner












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4.2.2. Registration of MIME media type video/CelB

   MIME media type name: video

   MIME subtype name: CelB

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2029

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.3. Registration of MIME media type video/JPEG

   MIME media type name: video

   MIME subtype name: JPEG

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2435

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.4. Registration of MIME media type video/H261

   MIME media type name: video

   MIME subtype name: H261

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2032

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.5. Registration of MIME media type video/H263

   MIME media type name: video

   MIME subtype name: H263

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2190

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.6. Registration of MIME media type video/H263-1998

   MIME media type name: video

   MIME subtype name: H263-1998

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2429

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.7. Registration of MIME media type video/H263-2000

   MIME media type name: video

   MIME subtype name: H263-2000

   Required parameters: None

   Optional parameters:
        profile: H.263 profile number, in the range 0 through 10,
        specifying the supported H.263 annexes/subparts.

        level: Level of bitstream operation, in the range 0 through
        100, specifying the level of computational complexity of the
        decoding process.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2429
        The specific values for the profile and level parameters and
        their meaning are defined in Annex X of ITU-T Recommendation
        H.263, "Video coding for low bit rate communication".  Note
        that the RTP payload format for H263-2000 is the same as for
        H263-1998, but additional annexes/subparts are specified along
        with the profiles and levels.

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner








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4.2.8. Registration of MIME media type video/MPV

   MIME media type name: video

   MIME subtype name: MPV
        MPEG-1 or -2 Elementary Streams

   Required parameters: None

   Optional parameters:
        type: the type of MPEG video, from the set "mpeg1",
        "mpeg2-halfd1", or "mpeg2-fulld1".  The default is "mpeg1".
        The mapping to a=fmtp is identity.

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2250

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner
















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4.2.9. Registration of MIME media type video/MP2T

   MIME media type name: video

   MIME subtype name: MP2T
        MPEG-2 Transport Streams

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2250

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner



















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4.2.10. Registration of MIME media type video/MP1S

   MIME media type name: video

   MIME subtype name: MP1S
        MPEG-1 Systems Streams

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2250

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner



















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4.2.11. Registration of MIME media type video/MP2P

   MIME media type name: video

   MIME subtype name: MP2P
        MPEG-2 Program Streams

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2250

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner



















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4.2.12. Registration of MIME media type video/BMPEG

   MIME media type name: video

   MIME subtype name: BMPEG

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 2343

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner




















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4.2.13. Registration of MIME media type video/nv

   MIME media type name: video

   MIME subtype name: nv

   Required parameters: None

   Optional parameters: None

   Encoding considerations:
        This type is only defined for transfer via RTP [RFC 3550].

   Security considerations: See Section 5 of RFC 3555

   Interoperability considerations: none

   Published specification: RFC 3551

   Applications which use this media type:
        Audio and video streaming and conferencing tools.

   Additional information: none

   Person & email address to contact for further information:
        Stephen Casner <casner@acm.org>

   Intended usage: COMMON

   Author/Change controller:
        Stephen Casner

5. Security Considerations

   The MIME subtype registration procedure specified in this memo does
   not impose any security considerations on its own.  This memo also
   contains several MIME type registrations.  The registrations
   themselves do not impose security risks, but some may state security
   considerations specific to the particular registration.

   Several audio and video encodings are perfect for hiding data using
   steganography.

   The RTP specification, RFC 3550, provides security considerations for
   the transport of audio and video data over RTP, including the use of
   encryption where confidentiality is required.





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6. Normative References

   [1] Freed, N., Klensin, J. and J. Postel, "Multipurpose Internet Mail
       Extensions (MIME) Part Four: Registration Procedures", BCP 13,
       RFC 2048, November 1996.

   [2] Schulzrinne, H., Casner, S., Frederick, R. and V. Jacobson, "RTP:
       A Transport Protocol for Real-Time Applications", RFC 3550, July
       2003.

   [3] Schulzrinne, H. and S. Casner, "RTP Profile for Audio and Video
       Conferences with Minimal Control", RFC 3551, July 2003.

   [4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
       Levels", BCP 14, RFC 2119, March 1997.

   [5] Handley, M. and V. Jacobson, "SDP: Session Description Protocol",
       RFC 2327, April 1998.

   [6] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
       Extensions (MIME) Part One: Format of Internet Message Bodies",
       RFC 2045, November 1996.

   [7] Kobayashi, K., Ogawa, A., Casner, S. and C. Bormann, "RTP Payload
       Format for 12-bit DAT Audio and 20- and 24-bit Linear Sampled
       Audio", RFC 3190, January 2002.

























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7. Authors' Addresses

   Stephen L. Casner
   Packet Design
   3400 Hillview Avenue, Building 3
   Palo Alto, CA 94304
   United States

   Phone: +1 650 739-1843
   EMail: casner@acm.org


   Philipp Hoschka
   INRIA
   Route des Lucioles 2004
   06904, Sophia-Antipolis Cedex
   BP 93, France

   Phone: (+33) 4 92 38 79 84
   Fax:   (+33) 4 92 38 77 65
   EMail: ph@w3.org

   W3C
   http://www.w3.org/people/hoschka



























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8. Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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