[gst-devel] How can I synchronize video and audio

[Stefan Kost]

Zelalem Sintayehu schrieb:
> Hi Stefan, thank you for your response. You know when I didn't get help for some time, I had lost my hope and abandon it. 2 second is considerable time. Anyway, I am sorry for my sily question, but I don't understnad what you mean by "narrow it down"? Also how can I "Check if you receive the material properly timestamped"?.
> 
> Thank you again for your help.

Don't expect that everything is ready. I don't have an explanation for the
problem you see. As nobody else was answering, it seems that you will have to
figure our what the probelm is. With "narrow it down", I was suggsting to try to
make simpler/different variants to see if you can pinpoint the problem. E.g.
recod to a mp4 with mp4mux to see if it might be a problem in avimux.

Also you should not start two pipelines on the src side, instead of
Source:
Audio:
gst-launch-0.10
-v alsasrc ! queue ! audio/x-raw-int,rate=8000,channels=1,depth=8 !
audioconvert ! alawenc ! rtppcmapay ! udpsink port=5002
Video:
gst-launch
v4l2src ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate !
video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace! ffenc_h263p ! rtph263ppay
! udpsink port=5000

just do

Source:
gst-launch-0.10
-v alsasrc ! queue ! audio/x-raw-int,rate=8000,channels=1,depth=8 !
audioconvert ! alawenc ! rtppcmapay ! udpsink port=5002
v4l2src ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate !
video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace! ffenc_h263p ! rtph263ppay
! udpsink port=5000

Then both livesource use the same clock to timestamp buffers.

Stefan


> 
> - Zelalem S. 
> 
> 
>> Date: Sat, 18 Jul 2009 19:03:10 +0300
>> From: ensonic at hora-obscura.de
>> To: gstreamer-devel at lists.sourceforge.net
>> Subject: Re: [gst-devel] How can I synchronize video and audio
>>
>> Zelalem Sintayehu schrieb:
>>> Hi guys, I wanted to record video coming from network into avi file,
>>> and wrote some code. The file is created but it is unsynchronized (by
>>> almost 2 second) and it is annoying. I am using avimuxer. I also used
>>> buffer for the audio source hoping to reduce the time difference. The
>>> following is the source and destination codes (the command line version
>>> of my code). Is there anything that I should consider to avoid this
>>> problem. Please help me. If you think that I should use other file
>>> formats and video muxer, please advice me.
>>>
>>> Source:
>>> Audio: 
>>> gst-launch-0.10
>>> -v alsasrc ! queue ! audio/x-raw-int,rate=8000,channels=1,depth=8 !
>>> audioconvert ! alawenc ! rtppcmapay ! udpsink port=5002
>>> Video:
>>> gst-launch
>>> v4l2src ! video/x-raw-rgb,width=320,height=240 ! queue ! videorate !
>>> video/x-raw-rgb,rate=15/1 ! ffmpegcolorspace! ffenc_h263p ! rtph263ppay
>>> ! udpsink port=5000
>>>
>>> Destination:
>>> gst-launch-0.10 -v
>>> avimux name=mux ! filesink location=videoandaudio.avi sync=true {udpsrc
>>> port=5000
>>> caps="application/x-rtp,media=(string)video,clock-rate=(int)90000,encoding-name=(string)H263-1998" 
>>> ! queue ! rtph263pdepay !
>>> 'video/x-h263,width=320,height=240,framerate=(fraction)25/1' ! queue} !
>>> mux.video_0 {udpsrc port=5002
>>> caps="application/x-rtp,media=(string)audio,payload=(int)96,
>>> rate=(int)8000, encoding-name=(string)PCMA" num-buffers=5000 ! queue !
>>> rtppcmadepay ! 'audio/x-alaw, rate=(int)8000, channels=(int)1' ! queue}
>>> ! mux.audio_0;
>>>
>> try to narrow it down. Check if you receive the material properly timestamped.
>> Check if avimux handles timestamping correctly when muxing.
>>
>> STefan
>>
>>> Thank you.
>>>
>>> - Zelalem S. 
>>>
>>>