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[media-source] ISO BMFF bytestream: how can CEA 608 / 708 embedding be supported?

From: wolenetz via GitHub <sysbot+gh@w3.org>
Date: Tue, 22 Mar 2016 22:12:38 +0000
To: public-html-media@w3.org
Message-ID: <issues.opened-142796113-1458684757-sysbot+gh@w3.org>
wolenetz has just created a new issue for 
https://github.com/w3c/media-source:

== ISO BMFF bytestream: how can CEA 608 / 708 embedding be supported? 
==
If I understand correctly, CEA 608 / 708 embedding of text track data 
is one option for sourcing text track data described within 
https://dev.w3.org/html5/html-sourcing-inband-tracks/#mpeg4
However, such embedding/signalling of the embedding occurs after the 
ISO BMFF initialization segment.
Since track types and counts must remain consistent across 
initialization segments for a SourceBuffer, and the initialization 
segment received algorithm is the sole place in MSE where various 
track attributes (like SourceBuffer.TextTracks and 
HTMLMediaElements.TextTracks) are populated, is it impossible to 
support CEA 608 / 708 embedding of text track data in ISO BMFF in any 
compliant MSE implementation?

@silviapfeiffer : Am I missing some part of signalling for CEA 608 / 
708 in ISO BMFF that actually occurs within an MSE initialization 
segment?

@jdsmith3000 / @mwatson2 / other MSE user agent implementors: Do you 
have this working somehow? Does the MSE ISO-BMFF bytestream spec 
and/or https://dev.w3.org/html5/html-sourcing-inband-tracks/#mpeg4 
need some update, or am I indeed missing some simple signalling within
 the defined MSE ISO BMFF initialization segment which allows such 
embedded text tracks to be known at the time of executing the 
initialization segment received algorithm?

Please view or discuss this issue at 
https://github.com/w3c/media-source/issues/58 using your GitHub 
account
Received on Tuesday, 22 March 2016 22:12:40 UTC

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