RFC 3555
MIME Type Registration of RTP Payload Formats
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
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
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.
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.
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.
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.
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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.
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.
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
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.
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
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
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
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
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 Casner4.1.22. 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
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
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
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
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
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
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
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
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
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
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
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
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
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 Casner5. 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.
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.
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
8. Full Copyright Statement
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