Extracting DVD audio

I’m looking to edit the audio of a DVD movie. Is AC3 the sound file you need to edit even if all I want to edit is the stereo (2 channel)? Also, do I need to extract the sound file from each vob or does software like vobedit just need the first vob file 01_01?

David

What exactly are you trying to do with the audio?

Normally I would demux the audio from the video, work with the audio stream then remux. You can use PGCDemux to get a complete audio stream from the entire dvd movie: http://www.videohelp.com/tools/PgcDemux Make sure to save the video stream as well.

You can then use an audio editing program on the audio stream, which will probably be ac3 format. Audacity with the ffmpeg plug-in should be able to do this, depending on what you intend to do in your editing.

If you don’t change the timing, you can then reauthor the dvd. Many free authoring tools require demuxed streams, so you can use one of them to rebuild the dvd. Something like DVDAuthorGui would be a simple authoring tool. GUIforDVDAuthor is another, though more complex.

If you cut sections of the audio, then you open a whole can of worms in retiming the audio to fit the video. So it really comes down to what you are attempting to do.

Thanks for your help so far. I have a DVD movie with crazy dynamic sound range and all I want to do is normalize the audio. Could I join the 7-8 vob files together as one large vob to make it easier to work with? Or should deal each vob file seperately.

You won’t be able to work effectively with individual vob files. It really is easier to remove the entire dvd audio stream with PGCDemux and run that ac3 file through the normalization process in Audacity. Make certain to save (export) the file as ac3 48khz at no more than 448 kpbs. Do [B]not[/B] save as 44khz, which is the normal setting for cd audio.

Then rebuild the dvd using the video and normalized ac3 file from Audacity. Either of those DVDAuthor gui’s will be able to remux the streams for you without issues and give you dvd-video as the output.

All of the tools I’ve mentioned so far are free to download and use.

I’m new to all of this. What options do I choose in PGCDemuxto? demux all audio streams obviously? What about demux video stream and and demux all subpic stream (not sure what is)? Thanks.

You might want to try it this way :

You’ll need to demux the audio and video streams from the dvd-video.

Get DGIndex .
http://www.videohelp.com/tools/DGMPGDec
Under the file pulldown select " Save Project and Demux Video" .
This should give you 3 files .ac3 , .d2v .m2v .

The tool I would use to adjust the sound is Audacity, a free audio editing program. You can find it here: http://audacity.sourceforge.net/
Get the 1.3.13 beta, and get the ffmpeg and lame libraries as well. http://lame.buanzo.com.ar/
http://manual.audacityteam.org/index.php?title=FAQ:Installation_and_Plug-Ins#installffmpeg

By using the ffmpeg library in Audacity, you should be able to import an AC3 audio stream.

At this point you’ll want to import the AC3 file into Audacity and follow this guide for amplify & normalize from your audio stream. :

http://wiki.audacityteam.org/wiki/Amplify_and_Normalize

http://wiki.audacityteam.org/index.php?title=Noise_Removalhttp://wiki.audacityteam.org/index.php?title=Noise_Removal

Once you have normalized the audio , click on File–>Export and save as an AC3 file. It will need to be 48khz to be dvd compliant and no more than 448kbps.
I still have the 1.3.12 beta version installed as I didn’t know the newer version is out. I will be updating to it but have no reason to beleive the older one would work better.

Now you need DVDAuthorGUI.
http://www.videohelp.com/tools/DVDAuthorgui
File pulldown / Add New Title… It will ask for the .m2v first then the .ac3.
Then File pulldown select Author DVD.
I would put the DVD files in a new different folder on your HDD. The movie name usually.
I would just test to see how the sync was with a player like VLC or MPC-HC. From the HDD.
DVDAuthorGUI does have a Edit A/V Delay which can be used positive or negative time .
After you view & listen this could be used to adjust the sync by repeating the process again.

Part of this information is from t0nee1 & Kerry56 with some addition by me.

Thanks for all your help. I really appreciate it. I seemed to figure out how to use PGCDemux but why are two ac3 files? Are they split or are they different?

Read the two .ac3 files with a software named MediaInfo .
http://mediainfo.sourceforge.net/en
This should tell you a lot of information . The legnth & number of channels for example.
Second open the .ac3 files with VLC player or other software that will play it .
Listen to it . There could be different languages or one may be the directors comment .ac3. You will have to determine the correct one.

Language was the difference…one is english the other french.

I realize now that what I actually require is compression of the dynamic range not normalization. Any ideas what settings to set the Audacity’s compressor effect to? I’m not very technical so I have no clue where to start.

Someone else could instruct you better for the settings to use.
dynamic range compression (see “Compressor” under the Effect menu in Audacity).
This has adjustments. A short Preview which seems to be only a short clip of the begining of the .ac3 file lets you listen to some of the adjustment. I didn’t work with it long enough to seeif it would let me hear any specific part .

[QUOTE=debrock;2591902]Thanks for your help so far. I have a DVD movie with crazy dynamic sound range and all I want to do is normalize the audio. Could I join the 7-8 vob files together as one large vob to make it easier to work with? Or should deal each vob file seperately.[/QUOTE]

Thats kinda normal because its ac3 which is 5.1 and NOT 2channel stereo.

BTW, maybe even your player downmixes the audio and creates that weird sounding audio output?!