editing audio in VOB files

[djdust]

hi all

I have got a new DVD recorder and have been having tons of fun recording stuff with it then transferring the VOB files to my PC using DVD Decrypter. I now want to edit the audio on these files...

I gether I have to 'demux' the VOB files into their component M2V (video) and WAV (audio) files first - is that correct? Once I've finished editing the audio (making sure it stays exactly the same length) what's the process called where you stick the two WAV/M2V files back together into a VOB file again (and is there a good piece of software to do it?)

Hope someone can help...

Cheers

daz

[Baldrick]

You can demultiplex to m2v,wav,mp2 files with dvd decrypter directly or use pgcdemux.

Edit the audio. Be sure to save to a dvd compliant format, wav pcm, mp2, ac3.

Reauthor / multiplex back to a vob file with muxman and add back it to the dvd structure. Or reauthor and make new menus using tda, ulead dvd workshop, etc.

[guns1inger]

If you alter the length of the file, then you really need to reauthor. This can be simple, with no menus, using something like muxman, or more complex with menus, chapters etc.

I would suggest you look at a dedicated mpeg editor such as Video Redo or Womble to make your cuts.

[djdust]

Erm, I'm not altering the length of the audio files as I've already specified and have already got video cutting sorted. That isn't what I asked...

Demuxing directly from the DVDR isn't an option as the VOB files I wish to audio-edit have been trimmed down (using Video Redo)

I'll give muxman a try...

[djdust]

ok, a bit stuck here trying to demux the VOB files.... Is it possible to demux the VOB files on my hard drive with DVD Decrypter or does that only work for files that are actually on a DVD..? I've tried PGCDemux but it only seems to want to open .IFO files...?

[guns1inger]

Rejig can demux VOBs from the HDD without the ifo files, as can VOB2MPG, I believe.

[djdust]

no joy whatsoever with VOB2MPG - it only seems to work with the VIDEO_TS folder, not individual VOB files...

I tried rejig - after a bit of fiddling with a test VOB file, I've ended up with an .m2v and an .ac3 file. I don't know much about .ac3 files and don't seem to have anything that allows me to edit them eiher. I was expecting a .m2v file and a .wav file.. Can someone tell me a bit more about ac3s..?

[guns1inger]

AC3 = Dolby Digital encoded. Most likely two channels if coming off a DVD Recorder.

You can use something like belight to convert this to wav

[djdust]

Thanks for all your help so far guns1inger..

Actually, I've just found DGIndex and that demuxes brilliantly AND converts the AC3 to WAV so I can actually edit the sound. I've used muxman to stick the M2V and WAV files back together too and the resulting new VOB files seems to play perfectly so it all seems fine now (though the VOB files are now larger but I guess that's to be expected...)

Another question though, is AC3 a compressed format? Ideally I'd like to work with non-compressed files but I guess, if my DVD recorder is creating the VOB files like this then, I guess there's nothing I can do about it, is there..?

[guns1inger]

Yes, AC3 is compressed. If you want to just put everything back the way it was, you should re-encode your audio to AC3 at the same bitrate as the original before muxing. If you don't, you may have a couple of problems.

1. There is a maximum size that a compliant VOB may be (1000MB, I believe), and muxing in uncompressed audio will make your VOBs too big.

2. Uncompressed PCM audio is 1536kbps, as opposed to your AC3 file which is probably 224 or perhaps 384 kbps. This additional bitrate could push the total bitrate above the allowed limits for compliance.

Unless you are going to re-author to ensure that all the structures are correct, you need to make sure that your edited VOB remains identical to the original in length and bitrate, or you will have problems.

[Cunhambebe]

You can load your VOB files (AC-3 will load too) in Sony Vegas 6.0. Please understand that Vegas is not freeware.