[FFmpeg-user] mpeg-ts to mkv without sound delay

Peter Bašista pbasista at gmail.com
Sat May 21 20:05:12 CEST 2011

> Hi,
> thanks a lot for your reply Peter.
>>Explain in more detail what kind of delay you experience.
> I think video and audio streams are not synchronized at all. The delay is
> huge (about 2s) and it's present during the whole movie. Maybe "delay" is
> not the correct word, sorry for my poor English.

You can use that word. But you should also say what is delayed (audio or video).

> I read somewhere this append because some errors in the input file (due to
> transmission) lead to frame deletion while audio stream is not modified.

That sounds reasonable, but I don' have any experience with fixing
this kind of problems. However, if your video and audio streams differ
by a constant time throughout the whole file, I believe you can use
simple -itsoffset option to shift the audio stream appropriately.

>>I do not have any bright ideas about that. However, since the source
>>is h264, I would try very hard to avoid reencoding, unless it is
>>absolutely necessary. I don't know how much you care about the
>>resulting file size, but I doubt that you can achieve significant file
>>size reduction (say, 50%) while maintaining the video quality. On the
>>other hand, I may be wrong. I am no expert in this field.
>>Another question is whether it is worth to reencode the video if you
>>know that it will reduce its size only by, say 20%. Would you sitll
>>want to do it? Most of the time, I would not.
> I expect a significant file size reduction, at least 50%. I know it will be
> probably time consuming but it's not a problem.

Okay, then I can suggest you look up some advanced libx264 presets and
options. I too wish I knew how to set up libx264 to produce small and
quality videos. It would be nice to have something like a competitive
libx264 presets database. Maybe it already exists, but I am not aware
of it.

Peter Basista

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