[Libav-user] Transcoding Decoding_Encoding to MP4/h264 - asynchron tracks

Silver marco_sie at web.de
Thu Mar 13 18:01:48 CET 2014

Can i somehow prevent this video/audio sync drift? 
I'm going back to Zero... is there a way to narrow it down?

Im done with Trial and Error... if such oldschool mail list can't help me...
is there some other place where i can look? It seems People are rar with
some insight and KnowHow?
I started to read different things.. and somehow i feel that this whole
time_base,pts/dts, keyframes has something to do with it. 
Is there no Bulding-Plan? Step A, Step B, Step C? 


I use the avcodec libs which comes from ffmpeg 1.2.4.  What is the different
between 1.2 and 2.1 ffmpeg? Because it makes such a huge jump 1.2 -> 2.0,
instead 1.3,1.4,....   is it somewhere explained? Maybe i found it already
and forgot it...
Should i try the new avcodec libs from 2.1 ?

Im a Newbie i totally have no clue..  

totally agree:

Silver wrote
> Hello,
> i dont have a solution now, why my video files gets out of sync after
> 2-4mins.
> If you use the scrubbing tool or play and pause, it gets back to sync.
> I heard something that you have to set a sync point for a certain i-frame,
> for the encoder. 
> Isn't this the pts? I mean Video 1-Frame doesnt mean it has the same
> length like 1 Audioframe, but if the pts/dts aren't correct should it be
> asynchron the entire clip? The weird thing is that it is sync for at least
> 1-3 min and so more you play, so more it gets asynchron.
> But still ... im confused why play/pause, scrubbing brings it back to
> sync.
> ---
> If im searching for sync points here... there are some attributes.
> ffmpeg source
> <https://gitorious.org/ffmpeg/ffmpeg/source/28240a60c1b5ce276e947ba013271ec009adc078:libavcodec/avcodec.h>  
> But i have no clue at all... what i can do. 
> Any help possible?

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