[Matroska-devel] Re: [xine-devel] Re: synchronized playback of several videos

Thibaut Mattern thibaut.mattern at gmail.com
Fri Jul 22 18:19:00 CEST 2005

On 7/21/05, ChristianHJW <christian at matroska.org> wrote:
> Oliver Koenig schrieb:
> > About two years ago - working for a summer job - I started looking for a
> > possibility to play back stereoscopic videos in 720p HD resolution.
> > Therefore
> > it was necessary to play back two different streams perfectly simultanuous.
> > As all available and affordable solutions were only able to handle PAL
> > or  NTSC
> > (normal DVD-playback) I decided to create my own solution.
> Just so you know :
> matroska multimedia container can hold any number of video streams
> inside a single file, and will even allow for different codecs and/or
> resolutions.

yes, other containers can do that too (at least more than one video or
audio track).
> mkvmerge supports muxing of these files already since more than a year,
> and on DirectShow we recently added video stream switching into our
> current matroska splitter filter. Sad tough, that DShow will not easily
> allow displaying two video streams simultaneously, Xine would definitely
> be much better suited for this.

the engine cannot decode two tracks from the same stream simultaneously.
I think the engine could easily be enhanced to allow multiple
video/audio decoders per stream. That would involve a new API entry to
wire a video track to a video port, and a big decoder loop rewrite to
handle that.
Thinking about it, it should not be too complicated.

> I dont know if Xine's matroska parser code would allow to add playback
> of more than one video track from a single MKV file at the same time
> easily, or switching between the tracks. Responsible dev to answer.

It's not a parser problem, the engine is simply not designed to use
more than one video decoder per stream. Switching between audio tracks
is handled correctly, it should be easy to port that feature to the
video decoder loop.

> Christian
> matroska project admin
> http://www.matroska.org


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