How to extract complete audio track from an mpeg

[dalecooper]

Help, I'm losing my mind. I've been going round and round with a movie I am trying to edit for two solid weeks now. I figured out how to piece scenes together, make the audio flow, and generate a finished mpeg (which came out beautifully). I tried to take it into Ulead and author a new DVD, but then I found out the file was too large. I tried to have Ulead reencode it for me and it turned the movie into a jittery mess.

So I took it into Womble's MPEG Video Wizard and reencoded it there. Took most of a day (a 24 hour day - yeesh) but it eventually spit out a good-looking mpeg which is over a gig smaller than the original. Problem is, the audio cuts off 17 minutes and 5 seconds into the movie. I don't know why. I figured something happened in the reencoding, but it took so long that I didn't want to do it again. So I set my new mpeg up in Womble as the video, set my ORIGINAL mpeg up as the audio, and created a new mpeg from that. And what happens? Sound cuts off 17 minutes and 5 seconds into the movie. It plays fine in the editor itself, but the finished mpeg file is missing most of its sound in all applications I try to play it in.

This is driving me crazy. I need any kind of hypothetical solution. My first, best guess is to extract just the audio from the original mpeg, then Ulead will let me replace the audio with whatever audio track I have. That should work, in theory, unless Ulead's program is a bigger piece of crap than I think it is (and right now I'm already not-delighted about how it botched the reencoding). Hence the subject line.

Another idea I'm playing with is to split my original mpeg into a bunch of smaller files, then bring them into Womble as a series of audio tracks running against my reencoded video. This idea is based on the (perhaps false) notion that Womble is having trouble with getting audio out of an mpeg that is almost 2 hours long. Although frankly, I have no idea why that would be the case since it created the original mpeg with almost 2 hours of audio, and had no problems doing so.

I have already tried splitting the video and audio at 17 minutes exactly and just making an mpeg from that point forward. Guess what - it cuts off 5 seconds in.

What the hell is wrong with my mpeg? Or is it Womble? How can I get around this? I'm tearing my friggin' hair out. I don't think any video editing or authoring software I have tried so far (out of about ten popular applications) has worked 100% as advertised.

[dalecooper]

Oh, and I should mention: I tried using VOBedit on the original master mpeg. It demuxed an ac3 file, but that file was 0 KB and contained no sound.

[mats.hogberg]

You could try demuxing the audio with TMPGEnc. And as for making your too big DVD smaller, many seem to just go ahead and author it anyway, then use DVDShrink to bring it down to DVD5 size.

/Mats

[Nelson37]

Editing MPEG is a bear.

SFAIK, there are timecodes embedded in both the video and audio streams, and anything which gets these de-synchronized, or any other errors therein, causes problems.

What works for me, almost every time, is this. Take a working, synchronized file (your first mpeg). Strip the audio as a WAV using VdubMOD or something similar. Demux the video portion of the new, smaller re-encoded mpg. Encode the audio seperately, then remux.

Alternately, frameserve the original video to an encoder using the stripped WAV as the audio source. You may want to encode seperately and remux last.

What you have to do is rebuild the timecodes and/or GOP headers. I have had great success using TMPGenc Merge & Cut, which apparently does this rebuilding. Re-encoding also accomplishes this, hence the frameserve option.

[rhegedus]

How about running the DVD files through DVD2ONE or DVDshrink?

[dalecooper]

Thanks for the suggestions, guys. I haven't tried VdubMod yet, so that's where I'm going to start. Hopefully I'll be able to just demux the audio as a wav and then Ulead will be able to use that in place of the truncated audio I have for my smaller mpeg... otherwise, I'll try remuxing everything into a new mpeg. I was really hoping to be able to do that actually, just to have one finished mpeg in the right size, but if I can skip a step at this point, I will do so gladly.

I haven't played much with TMPGEnc... I downloaded it and tried a few things, but I found the interface kind of frustrating compared to Womble's two programs, so I gave up on it. For this sort of non-editing procedure though, I'll try it again. I didn't realize it did demuxing - I had been trying to use it to split up an mpeg into scenes.

[dalecooper]

How about running the DVD files through DVD2ONE or DVDshrink?

As I understand the uses of these tools, they usually just eliminate unnecessary extras from ripped DVDs. That won't help me here - the master mpeg is lean and mean, just 105 minutes of (pretty high quality) video and a matching stereo audio track. DVDShrink will also reencode, but considering how long reencoding seems to take in ANY program, I'm trying to avoid doing it again. I've got a cleanly reencoded video already - it's just the audio that's giving me headaches now.

[rhegedus]

It would probably be easier to generate the mpeg again from the source filrs using a lower audio bitrate - just run the TMPGEnc wizard and set the audio bitrate there.

Demuxing/remuxing will just make sync problems more likely.

[louv68]

I'm not sure, but I think DVD2AVI can extract audio from MPEG's.
I've extracted audio from DVD Soundtracks and the results sound great.

[mats.hogberg]

DVDShrink will also reencode, but considering how long reencoding seems to take in ANY program, I'm trying to avoid doing it again

Shrink doesn't reencode, but transcode. It's a much speedier process, taking about 1/10 of the time compared to reencoding.

/Mats

[Shudder]

Yeah, dvdshrink can probably transcode it in 20 minutes if you've got a decent new machine, if you have a great mpeg that is simply too large, I'd say give it a shot first before you do any of the other time-consuming methods.

What's "too big" anyway? are we talking 4.6 gigs size or 7? If it's under 10% you should use dvdshrink without even questioning it.

[dalecooper]

It's about 5 gig, so if I can knock off 15-20% I should be in good shape. Pardon the newb question, but what's the difference between transcoding and reencoding? Can DVDshrink get my file down to about 4 gigs? (There are a few other elements that will be on the DVD, and I don't care to press my luck by recording the entire disc full, so I'd like the mpeg w/ audio for the movie itself to only be about 4 gig in all.)

I *may* have resolved this problem just now. Final results aren't in yet, but I managed to extract the audio as mp2 using TMPGEnc, and I am trying to make a new mpeg based on that + the video that I reencoded. The sync looked fine in Womble MPEG Video Wizard, and I did a test run of just the first 20 minutes and found that it did not drop the audio after 17:05. So hopefully when I get back home in a few hours, I'll have a usable mpeg that slides in at just under 4 gig. If not, it's off to DVDshrink I go.