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List:       kde-multimedia
Subject:    Re: Arts::Video
From:       Matthias Welwarsky <matze () stud ! fbi ! fh-darmstadt ! de>
Date:       2002-04-11 6:10:28
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On Thursday 11 April 2002 06:06, Martin Vogt wrote:
> On Wed, Apr 10, 2002 at 06:10:52PM +0200, Nikolas Zimmermann wrote:
> > Hi there,
> >
> > Please look into kdenonbeta/arts-video and it's docs.
> > Whitepaper can be found there.
>
> Ok, I read it.
> As already said, I like to contribute the image support.
> The image structure is the most important one for the
> framework. (From my experience with mpeglib I already
> know the problems which can occur)

welcome on board :)

>
> Back to the whitepaper.
> The videodecoder pushes the images to the syncer in the
> graphic. bad from my experience. mpeglib does it this way
> and xine as well.(mpeg2dec pushes the images to the image api)
> The reason is, that this needs callbacks to the syncer.
> A better solution is a push/pull approach.

Well the original idea is a pulling system. The Master stops the worker if 
enough frames are queued.

> The "idea ot the sync system", needs more.
> mpeg system streams carry DTS,PTS information and
> they have a timeshift between audio/video. Synchronistion
> works here against a reference clock, feed with timestamps
> from the mpeg stream.
> (its a bit complex.)
> "calculate audio time and render some frames" wont work.
> Usually you carry a "byte postion/pts token" for every
> frame from the demux to the syncer.

So you say the video frame rate is not a constant? If this is true, the Master 
indeed needs some more information to sync audio and video. If there's only 
an offset, we can compensate by prefilling the audio queue of the Master.

regards,
	Matze
- -- 
Matthias Welwarsky
Fachschaft Informatik FH Darmstadt
Email: matze@stud.fbi.fh-darmstadt.de

"all software sucks equally, but some software is more equal"
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