Topic: How can you separate 24/48 audio and video in mpegs?

[libfab]

I ran into serious trouble today using LPlex 02beta to build a DVD-V out of my 24/48 wav files. The software is free and does a good job--but for some reason the batch stopped and I was stranded with just .mpg files in the temp directory.

As I was silly enough to erase the original wav files in the process, now I'm screwed. I can neither burn the mpegs nor retrieve the audio: ordinary multiplexers/DAW downsample to 16bits at best. Ordinary DVD-V burning soft will reencode the mpegs so that the audio's bit rate falls within their restricted limits. As for separating audio and video (de-multiplexing), even Audition2 downsamples the audio to 16bits on importing the mpeg.

I've heard there's a  Sound Forge MPEG plug-in that could work, but as I don't own it and it's about a hundred bucks I wonder if any of you tried that out, or came by a cheaper alternative.
The very last resort would be to play the mpegs through my sound card and record the digital stream back to my laptop...hugh, a day's work. Not sure the files would come off unspoilt.
Hope a cleverer computer specialist will help me out! 
Fab

[aval57]

Hi Fab, I'm the writer of lplex.

There should also be a file called "something_DVD_dvdauthor.xml"  in the temp folder.  If so, try this:

• first replace 'mplex.exe' and 'dvdauthor.exe' in the 'Lplex\Bin' program folder with the newer versions here (this likely lsn't necessary, but can't hurt).
• EDIT: open 'something_DVD_dvdauthor.xml' in notepad and make sure the folder referred to in the second line (e.g dest="c:\path\to\something_DVD") exists and is empty.
• now open up a commandline box (Start>Run>type "cmd" in the textbox and hit enter)
• change directory to the 'Lplex\Bin' folder and run dvdauthor:

Code: [Select]

cd "c:\wherever\lplex\bin"
dvdauthor -x "c:\full\path\to\tempfolder\something_DVD_dvdauthor.xml"

• If all goes well, (assuming the mpegs aren't incomplete) you should end up with the completed dvd files in the folder 'something_DVD' as usual.
• to restore the original wavs, drop the 'something_DVD' folder onto lplex.exe and it should  output the original wavs to a folder called 'something_DVD_UNPACKED'

If this doesn't work, and assuming you haven't run lplex again since the mishap, attach the file 'Lplex.log' (located in your user home directory - type %USERPROFILE% in the explorer address box to go there).  There's another more tedious method you could try, which I can describe in that case.

good luck,
Bahman

[ethan]

Don't know about 24 bit but I can separate audio from video using VirtualDub. Select Audio->Full Processing Mode. Then File -> Save WAV.

http://www.virtualdub.org/

[libfab]

Hi Bahman,
your trick worked real well, thanks a lot for your speedy reply. It really restored the files in a handful of minutes, I'm very grateful. It's stunning how free soft sometimes works better than costly stuff. I wish Lplex all the best for future developments. Fab

[aval57]

Glad to hear it!

[libfab]

Hi again--for Ethan: virtualdub is a cool soft yet it doesn't open Mpeg2s...so it doesn't read mpegs from Lplex. Perhaps next version?

[libfab]

A "bonus" remark to conclude this thread: if you either

- impair a DVD-V with 24bit-audio, like when you scratched off the system file structure (IFO/BUP files), so you can't play it nor "rip" it back to your computer;
- or if you were stranded like me with VOBs, but with the additional mishap of having lost everything else...wav files, mpegs, IFO/BUP, and even xml instructions...

you're in a pretty mess, yet your situation is not quite as desperate as it may seem. Just do as follows:

1) use Nero Vision 4 VOB-stitching option

 ("Make Movie>open several VOBS at a time>do NOT save as new mpegs, otherwise you'll loose time and probably audio>retrieve the "VTS_01.0001.mpg" file in the folder "NeroVision\ImportedVideo" in My documents)

or any other good VOB-stitcher (Bahman, d'you know a free one?)
Vision 4 converts you the VOBs into one clean mpg with no audio loss (I double checked on that after "ripping")

2) copy this mpg file to the folder "Temp\something_DVD" in "Local settings"
3) correct the xml file in Temp by leaving just one single "VTS_01.0001.mpg" file (as in the text file attached)
4) run the "Bahman procedure" as explained above
5) Just burn the "something_DVD" file structure "as is" --I checked there is no reencoding with Nero 7, burning proceeds at once (you can rip back part of the VOB and check it's 24bits).

The direct conversion procedure to wav by Lplex would not unpack more than very first VOB that was stiched to the others to make the big chunk. I think it's the stitching done by Vision that blocks full ripping--that's for future improvements of your great software, B.
Likewise when you play your DVD, you'll find just one track onscreen, then the time count STOPS at the end of what was the first audio file. BUT wait! My player goes on playing the whole stuff, with the count stuck at 00:00 ...so you can possibly get back digital audio through SPDIF/optical!

Mind you, this lifesaving procedure is much more speedy than you might think--about 30 minutes to recover and burn off a whole 4.7 DVD-V. Bahman, it's now up to U to fix that damn' stitching issue...

 Fab

[aval57]

with the additional mishap of having lost everything else...wav files, mpegs, IFO/BUP, and even xml instructions...

Um, you never mentioned this part before, Fab!

Shorter version:

• A vob file is just an mpeg 2 file under another name.
• A sequence of vobs tacked together back-to-back form a valid mpeg file.
• You can't navigate the vobs without an ifo file, neither can lplex.
• Without navigation info an mpeg stream will play but isn't seekable.

Going by the attached xml file it seems you've now produced a dvd with just one chapter spanning the entire disk.  Your new ifo file is telling lplex there's only one chapter, so lplex is finding its previously embedded tag for the first audio file (which was the original chapter 1 when the mpeg was first produced) and extracting the number of bytes it specifies.  If you had used the original xml, then the other chapters would be known and therfore extracted as well.  But it seems you're saying that it's extracted more than the first file, which is curious.  Can you pm me the "lplex.log" file in your extraction folder (something_DVD_UNPACKED) + the xml file you used if different from the attached one + the new ifo file?

Anyway the rest of Lplex's tags are still embedded in the mpeg stream, so you could still find and read them "by hand" using a hex editor, which would give you the necessary info to reconstruct the original xml file with all the chapters listed, and you could rerun the "Bahman" procedure all over again.  Let me know if you want to try this and I'll describe it in detail.  I don't know if Vision's stitching might complicate things, though.

Also, are you using the updated or original dvdauthor to produce your dvd?  (This may explain the clock stopping).

Bahman

[libfab]

Hi again
this is just to publicly thank Bahman, as I can't +T yet...I learnt a lot on DSP in the interaction.

Also, in the course of exchanging PMs, we have come up with a few ideas that might be useful to DVD-V addicts. This is just a practical summary--there are arcane details and complications that I will skip here, and many other possible cases.
Let's suppose the original wav files were erased.

Case 1 : you have the mpegs, but something went wrong while processing the vobs with Lplex
Follow Bahman's procedure posted May 29 10:37.

Case 2 : you have neat vob and ifo/bup files, but you've lost the mpegs.
You can use a neat app called vstrip that converts vobs into raw PCM files. Use the "demux" setting, unselect all streams, select just the first audio PCM substream. Then use another app called lpcm24 that swiftly unpacks the 24-bit audio wav track. (To get the apps, see the sticky thread "where do I find"?) Bahman tells me you're likely to get a few more bits in the process because vstrip adds "padding", but it isn't much of an issue.

Case 3 : you just have neat vobs...or don't want the padding. Well then there's a way of recovering your files by hand using an hex editor. It's a bit time-consuming. But if it isn't that useful to you to neatly restore the full monty with time labels, and you just want to store the music away on DVD, then in this case you can get off lightly with the procedure I proposed in my previous post. Here is a simplification suggested by Bahman : instead of using Vision or any other costly software, just tack the vobs together using a DOS command line like this :
C:\full path to temp folder\something_DVD> copy /b VTS_01_1.VOB+VTS_01_2.VOB+VTS_01_3.VOB VTS_01.0001.mpg
in which the vobs are copied from the output _DVD folder (there may be more than just 3), and you use the boiled-down xml file I attached earlier. I tested all the above tips and they do the job just fine.
Hope this helps, Fab.