[FFmpeg-user] Audio Video Lip Sync Problem - IPhone mov

belcampo belcampo at zonnet.nl
Fri Dec 2 11:59:46 CET 2011

On 12/02/2011 10:47 AM, Gagandeep Bawa wrote:
> Hi Guys,
> I am compressing IPhone recorded mov file in to mpeg4 file with in my
> IPhone app itself. For this i compiled ffmpeg libraries for IPhone and
> doing compression programmatically using ffmpeg libraries with in IPhone
> app. Everything working fine except video audio lip sync problem. Video
> seems to be running slow and not proper sync with audio, however output
> file duration comes correct same as it was in original file. I checked for
> 12 sec video and 1 min video both. I am setting 15 frame rate for video. I
> am just compressing video frames and not compressing audio frames, i am
> writing audio frames as it is in out put stream.
That's because you set it to 15fps, the source will be 25 or 30fps. So 
get what you asked for. Leave out the fps setting or set it the same as 
the source.
> It would be great if some one can help me to resolve this audio video lip
> sync problem. I need to fix this programmatically only not from ffmpeg
> command line options.

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