[Bug 22137] New: changes in number of audio tracks during advert insertion

https://www.w3.org/Bugs/Public/show_bug.cgi?id=22137

            Bug ID: 22137
           Summary: changes in number of audio tracks during advert
                    insertion
    Classification: Unclassified
           Product: HTML WG
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Media Source Extensions
          Assignee: adrianba@microsoft.com
          Reporter: oipfjon@gmail.com
        QA Contact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-media@w3.org

In many cases, the main content will have more than one audio track. This could
be multiple languages (depending on the market) as well as accessible audio
such as either audio description for the visually impaired or clean audio for
the hearing impaired (see section E.4 of TS 101 154 for the latter) or indeed
both. In many cases, the audio in adverts may not include any of these tracks
and could easily just include one track for audio in the most common language. 

In cases where more than one audio track is combined in the same byte stream
(e.g. MPEG-2 Transport Stream), it is unlikely to be practical or economic to
produce versions of each advert supporting each combination of audio tracks
matching the content that the advert could be used with.

We request the W3C relax the restrictions in section 11 that “apply to all
initialization segments in a byte stream” – particularly requirements #1 (“The
number and type of tracks must be consistent”) and #3 (“Track IDs must be the
same across initialization segments if the segment describes multiple tracks of
a single type”) – at least for audio tracks.

NOTE: This issue arises from joint discussions between the Open IPTV Forum,
HbbTV and the UK DTG. These organizations originally sent a liaison statement
to the W3C Web & TV IG which is archived here;

https://lists.w3.org/Archives/Member/member-web-and-tv/2013Jan/0000.html (W3C
member only link)

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Received on Wednesday, 22 May 2013 14:14:30 UTC