Problem with decoding LPCM audio

[slipslide]

Hey there-

I'm trying to back up a dvd, which has audio encoded both in LPCM (main music track) and AC3 (commentary track). However, the LPCM track, when encoded to wav (via DVD2AVI), is just noise. The AC3 tracks decode just fine.

Is there a way to get the LPCM track to decode to wav properly? I've looked through posts here, and nothing I've tried worked (using Smartripper instead of DVD Decrypter; opening the wav file in CoolEdit...).

Any help would be great - thanks!

Chris

[fccHandler]

Just an idea...

Open the noisy .wav in Cool Edit, and save it as "PCM raw data." Now open the .pcm file, and two dialogs will pop up asking you how to interpret the data. In the first dialog, choose 48000 Hz, stereo, 16-bit. In the second dialog, choose "16-bit Motorola PCM," offset 0.

[slipslide]

Nope, no luck with that...

Chris

[fccHandler]

Well, it was a shot in the dark. :)

Does the DVD box give any indication about the format of the PCM track? Like sampling rate, channels...

Maybe it's 96K and/or multi-channel LPCM. I've never seen one of these DVDs myself, but I know they're out there.

[slipslide]

It's actually the new Sonic Youth dvd, which is 24-bit LPCM. I found this related question on another forum (http://article.gmane.org/gmane.comp.video.mplayer.user/30033), but no answers there either... :(

Chris

[fccHandler]

24-bit is messy. :(

I believe most DVD LPCM tracks (all the ones that I've seen, anyway) are 48K 16-bit mono/stereo, and I suppose most ripping software expects that format. They probably aren't designed to handle the rare exceptions (like your Sonic Youth DVD). But even if you could demux the audio correctly, I doubt that Cool Edit (and others?) can handle a 24-bit WAV file. I'm not really sure, though, since I've never encountered such a thing...

My modified VirtualDub version (called VirtualDub-MPEG2 (http://fcchandler.home.comcast.net/stable)) can demux LPCM from VOBs, but not 24-bit LPCM. However, if you can provide me with a small sample of a decrypted VOB (about 50K is fine) I'm pretty sure I can make it possible for VirtualDub-MPEG2 to convert the audio to 16-bit for the "Save WAV" function.

[dutchfudge]

the best things are always free. Go to download.com and search for audacity in the audio tools. Has a ton of different wav format options up to and including 32 bit float and several variations.

it may work for you?

good luck

[fccHandler]

Bump...

I still hope you will send me a ~50K sample of your 24-bit LPCM VOB file. If you want my email address, please send me a private message.

[vip]

fccHandler, you could try this tool: http://www.rarewares.org/files/others/lpcm24.zip
It helps me a lot in processing 24bit lpcm streams ripped from dvd :)

[fccHandler]

Thanks, but I think you misunderstood. I'm saying I don't have any DVDs with 24-bit audio. I want to get a tiny sample of a VOB from someone so I can see what the format looks like, then I can fix my VirtualDub-MPEG2 to support it.

Hmm, I used to like Sonic Youth in the 80's. Maybe I'll just buy the thing... ;)

[vip]

fccHandler, sorry. my post should be for slipslide, dunno why i put your nick there... And it seems like i dont have any dvd atm with 24bit lpcm stream, but those tool had a source code inside and i hope that may help you also...

[fccHandler]

Wow, I didn't know the .zip contained source code. I would still like to have a sample for testing purposes, but at least this will get me started. Thanks for the link!

[bumpa]

Well I am very happy this works, with VDub Mpeg2. I can load the ripped VOB in and then save back to a 16 bit Microsoft Stream as a RAW .AVI file. Then I use TMPGENC to make it an mpeg-2.

Is there a quicker way around this?

Thanks