ACTION-282: Add MPEG liaison to agenda for 24/3 TTWG meeting

Add MPEG liaison to agenda for 24/3 TTWG meeting

State:
closed
Person:
Nigel Megitt
Due on:
April 24, 2014
Created on:
April 17, 2014
Related emails:
  1. {agenda} TTWG Meeting 14/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-13)
  2. Re: {agenda} TTWG Meeting 7/8/2014 (from pal@sandflow.com on 2014-08-06)
  3. {agenda} TTWG Meeting 7/8/2014 (from nigel.megitt@bbc.co.uk on 2014-08-06)
  4. {agenda} TTWG Meeting 31/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-30)
  5. {agenda} TTWG Meeting 17/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-16)
  6. {agenda} TTWG Meeting 10/7/2014 (from nigel.megitt@bbc.co.uk on 2014-07-09)
  7. RE: {agenda} TTWG Meeting 19/6/2014 (from mdolan@newtbt.com on 2014-06-18)
  8. {agenda} TTWG Meeting 19/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-18)
  9. RE: {agenda} TTWG Meeting 12/6/2014 (from mdolan@newtbt.com on 2014-06-12)
  10. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
  11. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  12. Re: {agenda} TTWG Meeting 12/6/2014 (from pal@sandflow.com on 2014-06-11)
  13. Re: {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  14. {agenda} TTWG Meeting 12/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-11)
  15. RE: {agenda} TTWG Meeting 5/6/2014 (from mdolan@newtbt.com on 2014-06-04)
  16. {agenda} TTWG Meeting 5/6/2014 (from nigel.megitt@bbc.co.uk on 2014-06-04)
  17. {agenda} TTWG Meeting 29/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-28)
  18. {agenda} TTWG Meeting 22/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-21)
  19. {agenda} TTWG Meeting 15/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-14)
  20. Re: {agenda} TTWG Meeting 8/5/2014 (from tmichel@w3.org on 2014-05-08)
  21. {agenda} TTWG Meeting 8/5/2014 (from nigel.megitt@bbc.co.uk on 2014-05-07)
  22. {agenda} TTWG Meeting 1/5/2014 (from nigel.megitt@bbc.co.uk on 2014-04-30)
  23. {minutes} TTWG Meeting 24/4/2014 (from nigel.megitt@bbc.co.uk on 2014-04-24)
  24. {agenda} TTWG Meeting 24/4/2014 (from nigel.megitt@bbc.co.uk on 2014-04-23)

Related notes:

Liaison email can be viewed at http://lists.w3.org/Archives/Public/public-tt/2014Apr/0005.html

Text of liaison is:

Title Liaison template on MIME type parameter for TimedText

MPEG has identified the need to define a MIME “Codecs” parameter for timed text and metadata streams stored in ISOBMFF, possibly based on the MIME type and “Codecs” parameter of the carried data. This would allow distinguishing between different ISOBMFF files containing different XML subtitle formats during HTTP exchanges or within a DASH MPD. This is particularly relevant to identify the different profiles of TTML along with other related namespaces (e.g. SMPTE-TT). MPEG believes it is the responsibility of MPEG to specify the format of this “Codecs” parameter for streams carried in ISOBMFF. However, MPEG would like to coordinate with affected organizations on the best way to achieve it.

MPEG currently envisages using the value “mett.<mime_type>” and “sbtt.<mime_type>” for text-based formats, where <mime_type> is the MIME type for the given format, possibly including a (properly escaped) “Codecs” parameter on its own.

For XML-based formats, it has been considered to use the tuple list of {namespace, schema-location} in the “Codecs” parameter, as this is information readily available from the XMLSubtitleSampleEntry and XMLMetaDataSampleEntry. However, this would generate very long strings. MPEG is also considering using the <mime_type> for XML-based streams, but this would require modification of the sample entry to make it readily available for generation of the “codecs” string from an ISOBMFF file.

In particular, for the case of TTML, MPEG believes the definition of a parameter for the TTML MIME type is needed, to enable identifying the different configurations of TTML. We take note of the content profile work in W3C TTML2, which may be relevant. If a parameter were defined by the owning organizations (e.g. W3C as the owner of the base TTML specification), MPEG would probably reuse it.


Nigel Megitt, 23 Apr 2014, 13:31:55

Display change log.


David Singer <singer@apple.com>, Nigel Megitt <nigel.megitt@bbc.co.uk>, Chairs, Thierry Michel <tmichel@w3.org>, Philippe Le Hégaret <plh@w3.org>, Atsushi Shimono <atsushi@w3.org>, Staff Contacts
Tracker: documentation, (configuration for this group), originally developed by Dean Jackson, is developed and maintained by the Systems Team <w3t-sys@w3.org>.
$Id: 282.html,v 1.1 2019/11/12 10:02:14 carcone Exp $