[gst-devel] A/V sync issues

Pavan Kumar Patale pavanpatale at hotmail.com
Tue Dec 12 04:48:35 CET 2006


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.

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