[Bug 18921] append(data) should accept any part of media segment

https://www.w3.org/Bugs/Public/show_bug.cgi?id=18921

Mark Watson <watsonm@netflix.com> changed:

           What    |Removed                     |Added
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                 CC|                            |watsonm@netflix.com

--- Comment #1 from Mark Watson <watsonm@netflix.com> 2012-09-19 19:14:40 UTC ---
(In reply to comment #0)
> From step 6 of the append method, as defined in the spec:
> If data is part of a media segment and timestampOffset is not 0:
> 1.Find all timestamps inside data and add timestampOffset to them.
> 2.If any of the modified timestamps are earlier than the presentation start
> time, then call endOfStream("decode"), and abort these steps.
> 3.Copy the contents of data, with the modified timestamps, into the source
> buffer.
> 
> The definition of "part of a media segment" have several conditions that needs
> to be addressed. In particular, a part of a media segment that is not
> continuous to a previously appended buffer.
> 
> In seeking scenario, after the current source buffer is aborted, a user might
> append a buffer which is not a beginning of a segment. 

No, at the beginning, or after flushing the buffer, appending must begin at the
start of a segment.

It's not an assumption that the media file format supports 'discovery' of
segment boundaries.

> In that case, the
> browser should discard all the bytes that are prior to a beginning of a
> segment. 

It may not have any way to recognize segment boundaries. The application should
be aware of segment boundaries and append only from the beginning of a segment.

> This will protect the playback from failing. In some cases, there can
> be several "small" appends which are part of previous segment which should all
> be discarded, until the append of buffer the contain the start of a segment.
> 
> Without that, js developers must employ parsers to have the accurate offset of
> all segments.

Yep.

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Received on Wednesday, 19 September 2012 19:14:41 UTC