[gst-devel] A/V sync issues

[Wim Taymans]

On Fri, 2006-12-15 at 18:09 +0000, Pavan Kumar Patale wrote:
> Hi Zaheer,
> 
> I tried to localise the problem and observed that if set the 
> max-size-time=700 for demux_audio_queue the A/V sync is perfectly achieved.
> 
> gst-launch-0.10 filesrc location=test.avi ! queue ! avidemux name=demux 
> demux.video_00 ! queue ! video_decoder ! ffmpegcolorspace ! timeoverlay ! 
> xvimagesink sync=false demux.audio_00 ! queue max-size-time=700 ! 
> audio_decoder ! audio_sink
> 
> But, I am just wondering will this be a permanent solution ?
> If this kind of queue manipulation has to be done at recording itself so 
> that other players will playback with A/V sync, what would be the better 
> approach ?
> Third query is before sending to avimux should we explicitly handle A/V sync 
> ?

see docs/design/draft-latency.txt for the draft proposal
see also bug #340842.

Wim
> 
> Thanks,
> Pavan.
> 
> 
> >On 12/12/06, Pavan Kumar Patale <pavanpatale at hotmail.com> wrote:
> >>Hi,
> >>
> >> >Firstly, you have a live source at the end going to a synchronised sink. 
> >>  This will produce exactly  >> >what you mentioned, ie. not  smooth 
> >>playback and frames being dropped.
> >>
> >>Ok
> >>
> >> >Also remember framerate is a fraction, so better to specify framerate as
> >> >15/1.
> >>
> >>Ok
> >>
> >> >
> >> >You are better off recording to a file, and then trying to playback the
> >> >file.  The file is not a live >source and you'll be able to tell better 
> >>the
> >> >a/v sync and the quality of the recording and resulting
> >> >playback than by capturing, encoding, muxing, demuxing, decoding and
> >> >playing back in the same >pipeline.
> >>
> >>Yes, actually i recorded to a file using the below pipeline :-
> >>
> >>gst-launch-0.10 avimux name=mux ! filesink location=test.avi v4l2src !
> >>ffmpegcolorspace ! tee name=t t.src0 ! queue ! timeoverlay ! xvimagesink
> >>t.src1 ! queue ! video/x-raw-yuv, width=176, height=144, framerate=15/1 !
> >>videorate ! video_encoder ! mux. audio_source ! queue ! audio_encoder ! 
> >>mux.
> >>
> >>using the below pipeline playback is very smoth, but there is 2 seconds of
> >>audio lag :-
> >>
> >>gst-launch-0.10 filesrc location=test.avi ! queue ! avidemux name=demux
> >>demux.video_00
> >>! queue ! video_decoder ! ffmpegcolorspace ! timeoverlay ! xvimagesink
> >>sync=false demux.audio_00 ! queue ! audio_decoder ! audio_sink
> >>
> >>
> >>Then to analyze the problem tried to directly demux instead of  writing to
> >>the file as mentioned in my previous mail.
> >>
> >>Is there a way to reduce this audio lag?
> >>
> >>Thanks,
> >>Pavan.
> >>
> >>_________________________________________________________________
> >>Get up-to-date with movies, music and TV. Its happening on MSN 
> >>Entertainment
> >>http://content.msn.co.in/Entertainment/Default
> >>
> >>
> >
> >Please could you file a bug in bugzilla actually stating the pipeline
> >with the encoders and decoders you use so we can try to reproduce.
> >
> >Zaheer
> 
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-- 
Wim Taymans <wim at fluendo.com>