[FFmpeg-user] Video and audio out of sync - general question

Frank Häfemeier ffmpeg at frank.haefemeier.eu
Sun Nov 18 21:11:54 CET 2012

I am converting HD video (H264, mp2/ac3, TS container) captured from
cable TV into mp4 container (x264, aac). I am also copy (if existing the
original ac3 stream as an additional stream into the mp4 container,
especially in case of a 5.1 audio.

Sometimes happens the audio is not in sync with video. In this case I
use the asyncts filter with 'first_pts=0'. This works well but only if I
encode all audio streams.

Is it really necessary to encode instead of copy? I tried to copy the
stream and using the filter, but the audio was still not in sync. Is
there a special order of parameter relevant?

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