The AVT working group requests a media types review for the updated 3GPP timed text draft. There was much recent discussion on this subject, and this draft is intended to address the concerns expressed. Colin (AVT co-chair) Begin forwarded message:

From: "Jose Rey" <Jose.Rey@eu.panasonic.com> Date: 14 June 2005 08:33:16 BDT To: <avt@ietf.org> Subject: FW: [AVT] I-D ACTION:draft-ietf-avt-rtp-3gpp-timed- text-15.txt

Hi all,

A new version is out. This update includes some very minor editorial changes as well as those changes agreed during the Media Type discussions (below.)

Looking forward to WGLC!

José

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- Section 2.1, p.4: remove paragraph that causes confusion

REMOVED:

The scope of the 3GPP PSS specification (in the following referred to as PSS) includes both downloading and streaming of multimedia content over 3G packet-switched networks. PSS adopts multimedia codecs such as MPEG-4 Visual [22], AMR wide-band [23] or MPEG-4 AAC [24] for encoding content. Other protocols like RTSP [15] for session set-up and control, or SMIL [9] for handling presentation layouts. For transport, HTTP over TCP is used for downloading and RTP for streaming.

- Section 8: OLD: The media subtype for the 3GPP Timed Text codec is allocated from the IETF tree. The top-level media type under which this payload format is registered is 'text'.

The receiver MUST ignore any unrecognized parameter.

Media type: text

NEW: The media subtype for the 3GPP Timed Text codec is allocated from the standards tree. The top-level media type under which this payload format is registered is 'video'. This registration is done using the template defined in [31] and following RFC 3555 [30].

The receiver MUST ignore any unrecognized parameter.

Media type: video

OLD: Encoding considerations:

RTP payloads complying with this payload format contain binary data.

Note that this type is incompatible with the use of text media types in other protocols, e.g. text/html. This is because in order to extract and decode any of the timed text media it is necessary understand the (binary) payload headers defined in RFCXXXX.

Restrictions on usage:

This type is only defined for transfer via RTP.

NEW: Encoding considerations:

This media type is framed (see section 4.8 in [31]) and partially contains binary data.

Restrictions on usage:

This media type depends on RTP framing, and hence is only defined for transfer via RTP [RFC 3550]. Transport within other framing protocols is not defined at this time.

OLD: Interoperability considerations:

The 3GPP Timed Text media format and its storage is specified in Release 6 of 3GPP TS 26.245 "Transparent end-to-end packet switched streaming service (PSS); Timed Text Format (Release 6)". The 3GPP file format (3GP) and the SMIL language profile used can be found in Release 5 of 3GPP TS 26.234 and in the corresponding specifications for later Releases. Note also that 3GPP may in future Releases specify extensions or updates to the timed text media format in a backwards-compatible way, e.g. new modifier boxes or extensions to the sample descriptions. The payload format defined in RFCXXXX allows for such extensions. For future 3GPP Releases of the Timed Text Format, the parameter "sver" is used to identify the exact specification used.

NEW: Interoperability considerations:

The 3GPP Timed Text media format and its file storage is specified in Release 6 of 3GPP TS 26.245 "Transparent end- to-end packet switched streaming service (PSS); Timed Text Format (Release 6)". Note also that 3GPP may in future Releases specify extensions or updates to the timed text media format in a backwards-compatible way, e.g. new modifier boxes or extensions to the sample descriptions. The payload format defined in RFCXXXX allows for such extensions. For future 3GPP Releases of the Timed Text Format, the parameter "sver" is used to identify the exact specification used.

The defined storage format for 3GPP Timed Text format is the 3GPP File Format (3GP) [32]. 3GP files may be transferred using the media type video/3gpp as registered by RFC 3839 [33]. The 3GPP File Format is a container file that may contain, e.g., audio and video which may be synchronized with the 3GPP Timed Text.

- Section 12.2: New informative references

REMOVED:

References 22, 23 and 24

NEW:

[30] Casner, S. and P. Hoschka, "MIME Type Registration of RTP Payload Formats", RFC 3555, July 2003.

[31] Freed, N. and J. Klensin, "Media Type Specifications and Registration Procedures", draft-freed-media-type-reg-04, April 2005.

[32] Transparent end-to-end packet switched streaming service (PSS); 3GPP file format (3GP) (Release 6), TS 26.244 V6.3. March 2005.

[33] Castagno, R. and D. Singer, "MIME Type Registrations for 3rd Generation Partnership Project (3GPP) Multimedia files", RFC 3839, July 2004.

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-----Original Message----- From: avt-bounces@ietf.org [mailto:avt-bounces@ietf.org] On Behalf Of Internet-Drafts@ietf.org Sent: Monday, June 13, 2005 9:37 PM To: i-d-announce@ietf.org Cc: avt@ietf.org Subject: [AVT] I-D ACTION:draft-ietf-avt-rtp-3gpp-timed-text-15.txt

A New Internet-Draft is available from the on-line Internet-Drafts directories. This draft is a work item of the Audio/Video Transport Working Group of the IETF.

Title : RTP Payload Format for 3GPP Timed Text Author(s) : J. Rey, Y. Matsui Filename : draft-ietf-avt-rtp-3gpp-timed-text-15.txt Pages : 59 Date : 2005-6-13

This document specifies an RTP payload format for the transmission of 3GPP (3rd Generation Partnership Project) timed text. 3GPP timed text is a time-lined decorated text media format with defined storage in a 3GP file. Timed Text can be synchronized with audio/video contents and used in application such as captioning, titling and multimedia presentations. In the following sections the problems of streaming timed text are addressed and a payload format for streaming 3GPP timed text over RTP is specified.

A URL for this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-avt-rtp-3gpp-timed- text-15.txt