For the pros: Different length in audio- and file of the same stream

[sebastian]

Hi guys,

when downloading and merging the video files of be-at.tv (e.g. hxxp://www.be-at.tv/brands/wmc/surfcomber/waveform-with-victor-calderone-guests/ida-engberg.go ), the video and audio file (which are splitted) do have different lengths.

In my shown example, the downloaded mp3 is 01:28:36, but the video is 01:28:49! Also the video slider at the website itself shows 2nd length.

So how can I get the video and audio in sync? And what is the master lenght?

I guess this is a question for the pros. ;-)

Thanks in advance!

[Bahman]

2nd one is master length, for sure!!
Avidemux can do this trick(sync) I think without re-encoding!!

[sebastian]

Originally Posted by Bahman

2nd one is master length, for sure!!
Avidemux can do this trick(sync) I think without re-encoding!!

Ok, and do you know how?

[svnpenn]

Just use FFmpeg

ffmpeg -i video.flv -i audio.mp3 -c copy out.flv

[greenythebeast]

What codec is the audio?

[svnpenn]

Originally Posted by greenythebeast

What codec is the audio?

In my shown example, the downloaded mp3

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[greenythebeast]

Originally Posted by svnpenn

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ah, i see. when using ffmpeg try adding "-async 1" without the quotes.

[sebastian]

Okay, so this is the solution?

ffmpeg -i video.flv -i audio.mp3 -c copy out.flv -async 1

My 2nd question is: Is there also a solution for first demuxing the video? I muxed them with mencoder.exe.

Now I'd like to write a batch file, that first splits the audio and video, and after that muxes it again via the code you told me.

[svnpenn]

You should be able to just "remux" the file.

Say you have a file with 1 video stream and 1 audio stream. You can do

ffmpeg -i bad-video.flv -c copy good-video.flv

If indeed you need to do it in 2 steps you can do this

ffmpeg -i bad-video.flv -map a -c copy astream.mp3
ffmpeg -i bad-video.flv -map v -c copy vstream.flv
ffmpeg -i vstream.flv -i astream.mp3 -c copy good-video.flv

[sebastian]

Okay, but I'd have to add -async 1? Like

ffmpeg -i bad-video.flv -c copy good-video.flv -async 1

?