[Bug 26778] New: Section 3 MPEG-2 TS should handle the closed captions case where the caption_services_descriptor is not signaled when caption data is present in the transport stream.

https://www.w3.org/Bugs/Public/show_bug.cgi?id=26778

            Bug ID: 26778
           Summary: Section 3 MPEG-2 TS should handle the closed captions
                    case where the caption_services_descriptor is not
                    signaled when caption data is present in the transport
                    stream.
           Product: HTML WG
           Version: unspecified
          Hardware: PC
                OS: Windows NT
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Sourcing In-band Media Resource Tracks
          Assignee: silviapfeiffer1@gmail.com
          Reporter: Pat_Ladd2@cable.comcast.com
        QA Contact: public-html-bugzilla@w3.org
                CC: mike@w3.org, public-html-admin@w3.org

Existing MPEG-2 TS content does not always contain the
‘caption_services_descriptor’ to signal when captions are present. Caption
tracks should be sourced in this case. This can be done as follows:

Section 3.2. The CEA 708 caption service [CEA708] as identified by:
- A 'Caption Service Descriptor' [ATSC65] in the 'Elementary Stream
Descriptors' in the PMT entry for a video stream with stream type 0x02 or 0x1B.

- For stream type 0x02, the presence of caption data in the ‘user_data()’ field
[ATSC52].

- For stream type 0x1B, the presence of caption data in the ‘ATSC1_data()’
field [SCTE128-1].

Section 3.3. Language: @kind is “captions”:

- Content of the 'language' field for the caption service in the 'Caption
Service Descriptor’.

- If a ‘caption_service_descriptor()’ is not present:

o @language of the audio track where @kind is “main” for the first caption
service
o The empty string for all other caption services

[ATSC52] http://www.atsc.org/cms/standards/a53/a_53-Part-1-6-2007.pdf
[SCTE128-1]
http://www.scte.org/documents/pdf/Standards/ANSI_SCTE%20128-1%202013.pdf

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Received on Wednesday, 10 September 2014 20:52:53 UTC