How to extract audio from avi

[JConnor]

Is it possible to extract the audio file from .avi into m2v format so i can later mux it into dvd? And how?

[mats.hogberg]

You can extract the audio from an AVI yes. But it will be in whatever format it was in the AVI; mp3, AC3, wav... Use Goldwave or VirtualDub. Or you can load the AVI in ffmpeggui and save out the audio as DVD compliant AC3 in one go. Many ways to skin a cat.
Then you can convert it to whatever format you want (but not m2v, as that's mpeg2 video!) using some audio encoder.
The AC3 file can then be used as audio source for creating a Video DVD.
I took the liberty of changing your subject to better reflect what you want.

/Mats

[JConnor]

You know I have some problems the avi files from which I need to extract the audio from are 2... THerefore I need to join them first. Im using AVI MPEG RM WMV JOINER but it doesn't recognize the avi files. Any ideas for other programs to try or maybe software that will join the extracted audio files.

P.S. When I load the avi file into ffmpeg ffmpeggui All i get is 2 channels for output although the original file is 5 channel. What's up with that?

[mats.hogberg]

If the original audio is 5 channels already, just demux them from the AVIs one by one with VirtualDubMod (from the stream list).
Then join them using DOS copy command:

copy /B audio1.ac3+audio2.ac3 audio1plus2.ac3

As you've discovered, ffmpeggui only encodes to stereo (2 cannels) AC3.

/Mats

[JConnor]

When I load the avi file do Vdub here's what I get:

Couldnt locate decompressor for format 'DIV3' (Microsoft High-Speed MPEG-4 V3 [Hack: Divx Low Motion])
Virtual Dub requires Video for Windows (VFW) compatible codec to decompress video. DirectShow codecs, such as those used by Windows Media Player, are not suitable.


Really confusing what's next? Or is that the end of the line for me?

[guns1inger]

Install FFDShow and use the vfw decoders in that to help Virtualdub along. You can set which decoders will be used by setting the options form the Start menu.

[mats.hogberg]

You could also try AviMux GUI - I don't think it needs the codec(s) to work.
As an addition to my previous post, you may have to run your final AC3 file (audio1plus2.ac3 in my example) thru AC3Fix.

/Mats

[JConnor]

Okay I managed to extract the audio files but im not really into that DOS thing so if u would be so kind mats.hogberg to guide me through the process step by step? You see i named the 2 audio files audio1.ac3 and audio2.ac3 is this right?

[mats.hogberg]

The names as such doesn't matter - as long as you know them. But as you've followed my example, let's stick to audio1.ac3 and audio2.ac3. (I'm making the assumption the AVI audio is really AC3?)
Ayway, open up a command prompt. (Start -> Run... and enter cmd)
This will start a DOS window, where all action from here on will take place. (You haven't used a computer until you've mastered the command prompt! )
Now change to the directory where your two AC3 files are:
(Let's say they are in d:\video\audio\)
Type d: and hit enter
Type cd video\audio and hit enter
Type dir and hit enter
Now, you should see audio1.ac3 and audio2.ac3 in the directory listing.
OK so far?
Now it's time to concatenate them, and that's already described:
copy /B audio1.ac3+audio2.ac3 audio1plus2.ac3
Type dir again, and you should have audio1.ac3, audio2.ac3 and audio1plus2.ac3 in the directory list.
Done.

/Mats

[JConnor]

Okay everything is cool now I even muxed the audio file with the new video file but the audio is out of sync any other ideas how to fix that?

P.S. The video is PAL.

[mats.hogberg]

Ah - I was just waiting for that. If you expected to be able to just take the audio from a couple of AVIs, and have it sync with a m2v of a different origin, your expectations are somewhat off base.
Depending on what you use to multiplex, you may be able to set an audio offset. Sorry I am not of much more help here, as I'd never dream of attempting what you're trying to do. Too much may mis match between the AVI and mpg versions.

/Mats

[JConnor]

Well thanks for everything so far. I think i have an audio offset on MuxMan. I'll try it.

[JConnor]

Would it help if i convert the video to NTSC? It might then be in sync with the audio?

[mats.hogberg]

Depends on the audio source. If it's from NTSC video, it'd sure be easier to fit to another NTSC video...

/Mats