[Bug 25005] Add MPEG-2 TS metadata text track cue generation guideline

https://www.w3.org/Bugs/Public/show_bug.cgi?id=25005

--- Comment #2 from Bob Lund <b.lund@cablelabs.com> ---
(In reply to Silvia Pfeiffer from comment #1)
> Bob, I don't really understand what the table in [2] means.
> 
> I don't follow how a cue is created in DASH or MPEG-4.

I don't think there is a general rule - it's dependent on the MIME. For
example, WebVTT (text/vtt) has a cue format, TTML (application/xml+ttml) has
another cue format. Don't the specs for these formats define how a UA would
create a cue?
> 
> Even for MPEG-2 the statement is strange. What is the time that the cue is
> created? Where can I find that in the file? Would it be better to say
> something like "Every PSI section is encapsulated in a DataCue with the
> cue's start time provided by the activation time of that PSI section and the
> cue's end time by the deactivation time of that PSI or by a repeat PSI
> packet."
> 
> Does that make sense?

There is no explicit presentation/activation and deactivation time - the cue
should fire as soon as the UA can create it, which implies the UA has received
all TS packets comprising the section data; hence,the proposed language.
endTime is not defined so could be same as start, a really big number or an
indication of infinity/no endTime.

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Received on Monday, 17 March 2014 16:59:00 UTC