[gst-devel] AV SYNC Problem of gstreamer when using customized dsp decoder

[Stefan Kost]

Quoting Volter Yen <volter619 at 163.com>:

>  Hi Sameer,
>  now the problem is that the dsp decoder is blackbox(put encoded datum in,
> and get decoded datum out)for me ,It is obvious that it would no set the
> outbuffer's TIMESTAMP, so how should I set the correct timestamp of video
> outbuffer in my application? how to decide the  timestamp value of the video
> outbuffer from my dsp decoder?
I would just copy the timestamp from the input. That works quite fine for me.

Stefan

> I have an idea, set the timestamp of audio
> out buffer from the alsasink to the videooutbuffer and update it dynamicly
> with the bus-message mechanism of that the sink element, is that fesible and
> resonable?there is a new question :
>   say that datum from the audio and video buffers with same   
> timestamp(the demuxer set the timestamp and duration on the buffer
> before it is pushed out to the decoder),if the timestamp of audio   
> and video decoder outbuffer putted to the sink element, must be the   
> same?thanks!volter
> ?2007-10-24?"Sameer Naik" <sameer at damagehead.com> ???
> first of, the demuxer would set the timestamp and duration on the   
> buffer before it is pushed out to the decoder. these timestamps have  
>  to be applied to the decoded buffer before you push them further,   
> unless you decide to change the framerate and stuff. next, if your   
> using a your own videosink plugin, make sure you subclass the   
> basevideosink, at it implements av synchronization mechanisms. if   
> you dont subclass the the basevideosink, then you will have to write  
>  your own av sychronization code in the videosink plugin. lastly, if  
>  your already doing the above and still don't get synchronization,   
> then set the "max-lateness" property (inherited from the   
> basevideosink) to some reasonable amount. xvimagesink for example   
> sets the default value of this property to 20000000, which is half   
> the duration of a frame at 25 fps. and yes, also make sure you push   
> a valid play segment (GstSegment) before you push any buffers out of  
>  the decoder..this is very important. or else gstreamer will flash a  
>  message saying buffer received without new segment, assuming   
> timestamps start from 0. and this will effect your av sync if the   
> timestamps do nor start from 0. ~sameer On Mon, 2007-10-22 at 23:50   
> -0400, pritesh wrote: > hi, > if timestamp from decoder plugins are   
> proper , > then av sync is done in video/audio sink plugins > > if u  
>  have custom videosink plugin , is it subclassed from videosink >   
> base class, which derives from basesink. > > > > > > --- On Mon   
> 10/22, Volter Yen < volter619 at 163.com > wrote: > From: Volter Yen   
> [mailto: volter619 at 163.com] > To:   
> gstreamer-devel at lists.sourceforge.net > Date: Tue, 23 Oct 2007   
> 10:55:56 +0800 (CST) > Subject: [gst-devel] AV SYNC Problem of   
> gstreamer when using > customized dsp decoder > > Hi all, > > > >   
> Recently, I want to implement a simple mpeg2-ts palyer using >   
> gstreamer framework,and the decodec element are customized > with   
> dsp, and my demuxer is flutsdemux, Gaurav have told me > that the   
> demux will push the two on seperate pads in buffers > after applying  
>  the same timestamp ,and the the sinks (audio > and video ) will  
> play  the buffers depending on the stream time > and timestamps... >  
> > and  I have read the source code of mpeg2dec which used >  
> libmpeg2, it  will adjust the outbuffer's timestamps with the >  
> related pts if  necessarybut when I use a dsp decoder,It seem > that  
> I can get only  the decoded data from it's outbuffer,how > to adjust  
> the  videooutbuffer's timpstamps in order to avoid > meeting av sync  
>  problem? > > I could not find the av sync sample demo ,can anyone   
> guide me > and/or give me some sample codes on the related   
> subject?thanks > a lot! > > > > Best Regards > > Volter > > > > > >   
> > > > ===================================================== > > > >   
> Happy everyday $ Best Regards! > > > > msn:volter619 at 163.com > > > >  
>  Focus on embed linux software! > > > >   
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