[foms] Chunks

Steve Lhomme slhomme at matroska.org
Thu Nov 11 06:37:48 PST 2010

On Thu, Nov 11, 2010 at 3:29 PM, Andoni Morales <ylatuya at gmail.com> wrote:
> 2010/11/11 Steve Lhomme <slhomme at matroska.org>:
>> Interresting. To clarify things on the MKV/WebM side that you don't
>> support yet. I think it's easier to send Matroska chunks on the fly
>> that MP4. Basically these chunks don't need a Cues section (nor
>> chapters, tags, etc or even Meta Seek). So the header is fixed and the
>> same for all chunks (all you need it set an "unknown" on the high
>> level Segment structure). They copy as much Clusters you need from the
>> source file. I think that's basically what Fluendo/GStreamer are doing
>> on their HTTP server of live WebM content. They don't even bother
>> cutting the source file on Cluster boundaries, but in the case of
>> chunks that are supposed to join correctly, you want to avoid some
>> false alarm in trying to find the boundary you want.
> On GStreamer, the webm muxers starts a new cluster for each keyframe
> and unset the DELTA_UNIT flag on this buffers, which makes it a
> "keyframe". The streamer, multifdsink, allows syncing new clients
> connections on keyframes, so a client will always receive a stream
> completely decodable.

OK, I wasn't sure it had been changed. It's obviously better that way.
But some other live streamers may still want to use that "lazy"
technique in the future. Now that GStreamer doesn't do that anymore,
maybe it should become illegal in WebM to do that.

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