wdiff rfc4856.original rfc4856.txt

Internet Engineering Task Force Audio/Video Transport
Network Working Group
INTERNET-DRAFT S. Casner
draft-ietf-avt-rfc3555bis-part2-02.txt
Request for Comments: 4856 Packet Design
Obsoletes: RFC 3555 (if approved) October 15, 2006
Expires: April 15, March 2007
Category: Standards Track

Media Type Registration of Payload Formats in the
RTP Profile for Audio and Video Conferences

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Abstract

This document specifies media type registrations for the RTP payload
formats defined in the RTP Profile for Audio and Video Conferences.
Some of these may also be used for transfer modes other than RTP.

Table of Contents
1. Introduction .................................................. 3 ....................................................2
1.1. IANA Considerations ...................................... 3 ........................................2
1.2. Terminology .............................................. 4 ................................................3
2. Registrations for "Audio/Video Profile" ....................... 4 .........................3
2.1. Audio Type Registrations ................................. 4 ...................................3
2.2. Video Type Registrations ................................. 25 ..................................24
3. Changes from RFC 3555 ......................................... 26 ..........................................25
4. Security Considerations ....................................... 26 ........................................26
5. References .................................................... 27
6. Author's Address .............................................. 28
7. Intellectual Property Statement ............................... 28
8. Disclaimer of Validity ........................................ 29
9. Copyright Statement ........................................... 29 .....................................................27
5.1. Normative References ......................................27
5.2. Informative References ....................................27

1. Introduction

This document updates the media type registrations initially
specified in RFC 3555 for the Real-time Transport Protocol (RTP)
payload formats defined in the RTP Profile for Audio and Video
Conferences, RFC 3551 [1], as subtypes under the "audio" and "video"
media types. This document does not include media type registrations
for the RTP payload formats that are referenced in RFC 3551 but
defined in other RFCs. The media type registrations for those
payload formats are intended to be updated by including them in
revisions of the individual RFCs defining the payload formats.

The media type registrations specified here conform to the updated
template format and procedures in RFC 4288 [2] and RFC XXXX 4855 [3].
This update makes no technical changes in the registrations.
Together with RFC XXXX, 4855, this document obsoletes RFC 3555.

1.1. IANA Considerations

As a consequence of the generalized applicability of the media types
registry as specified in RFC 4288, some changes in nomenclature are
needed in the RTP Payload Format section of the registry. In the
registry title "RTP Payload Format MIME types" and the introductory
text, "MIME" should be changed to "media". "MIME" should be deleted
from the table headings, leaving just "media type" and "subtype".

This document updates the media type registrations listed below to
conform to the revised registration format specified in RFC 4288 and
RFC
XXXX, 4855, so the reference for these media types should be changed
from RFC 3555 to this document. Some media type registrations
contained in RFC 3555 are omitted from this document; the existing
registrations for those types continue to be valid until updated by
other RFCs. There are no new registrations contained here.

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/PCMA
audio/PCMU
audio/VDVI
video/nv

Media type audio/L16 was initially 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. Registrations for "Audio/Video Profile"

In the following sections, the RTP payload formats defined in the RTP
Profile for Audio and Video Conferences, RFC 3551 [1], are registered
as media types.

2.1. Audio Type Registrations

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.

These audio formats also include the optional parameters "ptime", "ptime" to
specify the recommended length of time in milliseconds represented by
the media in a packet, and "maxptime", "maxptime" to specify the maximum amount
of media that can be encapsulated in each packet, expressed as time
in milliseconds. The "ptime" and "maxptime" parameters are defined
in the Session Description Protocol (SDP), RFC ZZZZ 4566 [5].

2.1.1. Registration of Media Type audio/DVI4

Type name: audio

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 (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550 [6]). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner
Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.2. Registration of Media Type audio/G722

Type name: audio

Subtype name: G722

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.3. Registration of Media Type audio/G723

Type name: audio

Subtype name: G723

Required parameters: None none

Optional parameters:
ptime, maxptime: see RFC ZZZZ 4566

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 media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.4. Registration of Media Type audio/G726-16

Type name: audio

Subtype name: G726-16

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner
Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.5. Registration of Media Type audio/G726-24

Type name: audio

Subtype name: G726-24

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.6. Registration of Media Type audio/G726-32

Type name: audio

Subtype name: G726-32

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.7. Registration of Media Type audio/G726-40

Type name: audio

Subtype name: G726-40

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.8. Registration of Media Type audio/G728

Type name: audio

Subtype name: G728

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.9. Registration of Media Type audio/G729

Type name: audio

Subtype name: G729

Required parameters: None none

Optional parameters:
ptime, maxptime: see RFC ZZZZ 4566

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 media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner
Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.10. Registration of Media Type audio/G729D

Type name: audio

Subtype name: G729D

Required parameters: None none

Optional parameters:
ptime, maxptime: see RFC ZZZZ 4566

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 media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.11. Registration of Media Type audio/G729E

Type name: audio

Subtype name: G729E

Required parameters: None none

Optional parameters:
ptime, maxptime: see RFC ZZZZ 4566

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 media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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
Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.12. Registration of Media Type audio/GSM

Type name: audio

Subtype name: GSM

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.13. Registration of Media Type audio/GSM-EFR

Type name: audio

Subtype name: GSM-EFR

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner
Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.14. Registration of Media Type audio/L8

Type name: audio

Subtype name: L8

Required parameters:
rate: the RTP timestamp clock rate

Optional parameters:
channels: how many audio streams are interleaved -- defaults
to 1; stereo would be 2, etc. Interleaving takes place
between individual one-byte samples. The channel order is as
specified in RFC 3551.

ptime, maxptime: see RFC ZZZZ 4566

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.15. Registration of Media Type audio/L16

Media type audio/L16 was initially registered via RFC 2586 [10] for
transports other than RTP. That registration is incorporated here
and augmented with additional information for RTP transport.

Type name: audio

Subtype name: L16

Required parameters 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 parameters:
channels: how many audio streams are interleaved -- defaults
to 1; stereo would be 2, etc. Interleaving takes place
between individual two-byte samples. The channel order is as
specified in RFC 3551 unless a channel-order parameter is also
present.

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. Discs. This parameter MUST be omitted if no
analog preemphasis was applied. Note that this is a stream
property parameter, not a receiver configuration parameter.
Thus, if parameters are negotiated, it may not be possible for
the sender to comply with a receiver request for a particular
setting.

channel-order: specifies the sample interleaving order for
multiple-channel audio streams (see RFC 3190 [7] [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 [9]; 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 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.

Security considerations considerations:
Audio/L16 data is believed to offer no security risks. This
media type does not carry active content. The encoding is not
compressed. See Section 4 of RFC YYYY. 4856.

Interoperability considerations 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 specification:
RFC 2586 for non-RTP transports, RFC 3551 for RTP

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

Additional information:
Magic number(s) : None number(s): none
File extension(s) : extension(s): WAV L16
Macintosh file type code : code: AIFF

Person to contact for further information
Name : information:
James Salsman
E-mail : jps-L16@bovik.org <jps-L16@bovik.org>
Intended usage 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 parameter, referred to as "radio
quality speech." speech".

Restrictions on usage usage:
In addition to file-based transfer methods, this type is also
defined for transfer via RTP (RFC 3550).

Author

Author:
James Salsman for non-RTP transports.
Stephen Casner for RTP transport.

Change controller controller:
James Salsman for non-RTP transports.
For RTP transport, IETF Audio/Video Transport working group
delegated from the IESG.

2.1.16. Registration of Media Type audio/LPC

Type name: audio

Subtype name: LPC

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.17. Registration of Media Type audio/PCMA

Type name: audio

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.

ptime, maxptime: see RFC ZZZZ 4566

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551
Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.18. Registration of Media Type audio/PCMU

Type name: audio

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.

ptime, maxptime: see RFC ZZZZ 4566

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.1.19. Registration of Media Type audio/VDVI

Type name: audio

Subtype name: VDVI

Required parameters: None none

Optional parameters: ptime, maxptime (see RFC ZZZZ) 4566)

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551
Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

2.2. Video Type Registrations

For most video payload formats, including the one 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, while "ptime" and "maxptime" could be but
typically are not.

2.2.1. Registration of Media Type video/nv

Type name: video

Subtype name: nv

Required parameters: None none

Optional parameters: None none

Encoding considerations:
This media type is framed binary data (see Section 4.8 in RFC
4288).

Security considerations:
This media type does not carry active content. It does
transfer compressed data. See Section 4 of RFC YYYY. 4856.

Interoperability considerations: none

Published specification: RFC 3551

Applications which that 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

Restrictions on usage:
This media type depends on RTP framing, and hence is only
defined for transfer via RTP (RFC 3550). Transfer within
other framing protocols is not defined at this time.

Author:
Stephen Casner

Change controller:
IETF Audio/Video Transport working group delegated from the
IESG.

3. Changes from RFC 3555

RFC 3555 is obsoleted by the combination of RFC XXXX 4855 [3] and this
document. RFC XXXX 4855 retains the specification of procedures and
requirements from RFC 3555, while the media type registrations from
RFC 3555 were extracted into this document. The media type
registrations for the RTP payload formats that are referenced in RFC
3551 [1] [1], but defined in other RFCs RFCs, have been elided from this
document because those registrations are intended to be updated by
including them in revisions of the individual RFCs defining the
payload formats.

The media type registrations in this document have been updated to
conform to the revised media type registration procedures in RFC 4288
[2] and RFC XXXX. 4855. Whereas RFC 3555 required the encoding
considerations to specify transfer via RTP, that is now specified
under restrictions on usage. The encoding considerations now warn
that these types are framed binary data. The change controller is
also now identified according to current conventions. The optional
parameter "channels" was clarified for audio subtypes L8, PCMA, and
PCMU. Finally, reference [9], which was missing from RFC 3555, has
been corrected.

4. Security Considerations

This memo specifies media type registrations for the transfer of
several compressed audio and video data encodings via RTP, so
implementations using these media types are subject to the security
considerations discussed in the RTP specification [8].

None of these media types carry "active content" that could impose
malicious side-effects upon the receiver. The content consists
solely of compressed audio or video data to be decoded and presented
as sound or images. However, several audio and video encodings are
perfect for hiding data using steganography.

A potential denial-of-service threat exists for data encodings using
compression techniques that have non-uniform receiver-end
computational load. The attacker can inject pathological datagrams
into the stream stream, which are complex to decode and cause the receiver
to be overloaded. However, none of the encodings registered here has
an expansion factor greater than about 20, and all are considered
relatively simple by modern standards (some are implemented on
handheld devices and most were implemented on general-purpose
computers ten years ago).

As with any IP-based protocol, in some circumstances a receiver may
be overloaded simply by the receipt of too many packets, either
desired or undesired. Network-layer authentication MAY be used to
discard packets from undesired sources, but the processing cost of
the authentication itself may be too high.

RTP may be sent via IP multicast, which provides no direct means for
a sender to know all the receivers of the data sent and therefore no
measure of privacy. Rightly or not, users may be more sensitive to
privacy concerns with audio and video communication than they have
been with more traditional forms of network communication.
Therefore, the use of security mechanisms with RTP to provide
confidentiality and integrity of the data is important. Because the
data compression used with these media types is applied end-to-end,
encryption may be performed after compression so there is no conflict
between the two operations.

5. References

5.1. Normative References

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

[2] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December, December 2005.

[3] Casner, S., "Media Type Registration of RTP Payload Types",
draft-ietf-avt-rfc3555bis-02.txt, February 2006.
(Companion to this document, referenced herein as RFC XXXX).
4855, January 2007.

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

[5] Handley, M., V. Jacobson Jacobson, V., and C. Perkins, "SDP: Session
Description Protocol", draft-ietf-mmusic-sdp-new-26.txt, January 2006.
(Approved for publication as Proposed Standard to obsolete RFC 2327, so this reference should be to the RFC when published
and that number inserted where RFC ZZZZ appears in this document) 4566, July 2006.

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

[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.

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

5.2. Informative References

[9] IEC 61834, Helical-scan digital video cassette recording system
using 6,35 mm magnetic tape for consumer use (525-60, 625-50,
1125-60
1125-60, and 1250-50 systems), August 1998.

[Note to RFC Editor: References in the media type registrations to RFC
YYYY are to be replaced with the

[10] Salsman, J. and H. Alvestrand, "The Audio/L16 MIME content
type", RFC number of this document itself.
The purpose of the self-references is to make the registrations complete
when extracted.]

6. 2586, May 1999.

Author's Address

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

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