I have 10 xvid/mp3 avi videos which I would like to merge into one long video (each is like 10 minutes). I've successfully used avidemux to merge the video and the audio, but they get ridiculously out of sync as the video goes on. Does anyone know a simple way to do this? I suppose I could even just split each audio visual into its respective raw codec and copy /b the files together, but I'm not entirely sure how to extract the raw data stream, and I'm not entirely certain it will stay in sync.

I'm not sure if it would work, but you could try chopping the last frame off from the end of each to be sure you get exactly the same length for the video and audio in each video before you combine them. You might need to convert the audio track to an uncompressed format before you do this.

Manual correction isn't an option? I mean couldn't you use a video editing tool to add a few ms of silence, or another video frame where it gets out of synch?

mkvtoolnix is your best bet. Vdub works too, really, but mkvmerge is much faster and more effective.

And, as SF says, make sure the audio/video streams are exactly the same length. This is a big deal for merging. If the audio is even a second longer/shorter major desyncing will occur.

Alright, it looks like avidemux sucks for a lot of things, but mkvtoolnix worked perfectly.

I can't ever get things to import correctly into Vdub.

I'm actually cropping a TV show into a full length film and cutting out intro/commercials, so the audio should be lined up perfectly, assuming avidemux (what I used to crop) didn't fuck up the lengths of the video and audio track. What's really amazing is that one of the videos was on divx, but mkvtoolnix managed to make it work just fine. I'm not sure if it remuxed it, or if divx=xvid in some cases.

Dvix should work fine.

If you want to be sure about cutting out commercials you could go through a (annoying) process of cutting stuff out of it using the split by time function in mkvmerge (through the Global) tab. It isn't always perfect (it seems to have a limit on how small of a section it can cut so it might be off by a few seconds), but I did this to cut parts out of videos before. The logistics could be irritating if you aren't accustomed to it.

Basically...

*Show*-commercial-*Show*

You split at the first show stream when the commercial begins, then split the second show stream when the commercial ends. Thus, cutting out the commercial and getting two show streams you can later merge back together.

There's faster/easier ways to do it but they would require other programs and re-encoding which can be annoying.

On that topic, if you allow my hijack, what's a good program to extract parts of the audio of avi files? (preferably without recoding)

Audition can lift stuff from videos if you drag-drop the video onto it and it supports the codec. If it's something like AAC or whatever that is not natively supported, a google search can usually yield a plugin that enables that support.

I think mkvmerge can extract audio as well but I forget the exact process.

Not sure if it would work for you, but you could try blender's video sequence editor.

Blender's video sequence editor is actually pretty good, I've used it for stop mo films among other things, mostly because vdub sux IMHO and the stop mo alternatives are extremely laggy.

When I first started to use blender's video sequence editor, I was also pretty amazed, I didn't think I would ever find something that good to edit my videos. Since it has a compositor, you can do a lot of cool things too.

windows live movie maker. it's the best thing ever. i made all of my youtube videos with it.

I can't even figure out how to save an AVC video in movie maker.

Also nude, I don't think there's anything stuck in avi except for audio and video (though I wouldn't know because that's what mp4 and mkv are good at). So if you want to simply extract the video or the audio, you can use avidemux to copy the video stream and disable the audio, or save the audio.

There's a really nice flv splitter if you ever need to split flash, but often times the output data is containerless (.264 and .aac files).

Movie maker is awful. If you want to use an editor you should start with Vegas and then work up to After Effects, but the latter is considerably more difficult to break into.