Editing AC3 audio?

[AarontheRipper]

I'd like to be able to edit some DVD movies I have so that they are a little more child friendly (I don't want my 4 year old coming up to me and saying WTF?). Cutting out scenes, etc. is fairly straight forward, but I'd like to also be able to edit the audio. I'd like to be able to cut out words said by people without losing much music or other background noise in the movie.

My questions are:

1) What are some programs that would give me the capability to do this?

2) What format should the audio be in so that I can edit it?

3) Can I get it back to AC3 audio, or will I have to burn it back onto a DVD with a different audio format?

[FOO]

If you can hire the original actor to say "WTF" into a microphone
you could subtract that from the audio.

What you want is very difficult. It might be done in the frequency domain
if the background is fairly constant.

You should do whatever you do as a WAV and convert back to AC3
with besweet

[wizzy]

the things you need to do are:
downsampled the AC3 to wav (you cannot return to full AC3 DD5.1!!)
open a wav editor and mute or put in silence in the parts you want to add
importent!: do not cut parts!
if you do so you will not have a perfect synch between audio/video
after you done you can use besweet to make wav2AC3 (2 channels)

Tools:
any kind of DVDripper that can rip directly to m2v and ac3 file
wav editor, like wavlab or soundforge
Muxing back all together with authoring software like:
ifoedit (very simple)
DVDmaestro
Etc.

[FOO]

without losing much music or other background noise in the movie.

The man doesn't want blank audio

[AngusMacGyver]

I would try using filters "range reject". You can cut out the voice frequency, keeping part of the background and music audio. You won't get a perfect cut, but it's woth a try.

I think it's not my business, but... If a film has bad language, I think it's not good to your child. If it has bad language, probably has violence scenes too.

But, as I said, it's not my business.

[freestyler]

What's wrong with letting kids learn the facts of life? I don't believe in censorship, if the movies are bad they shouldn't be watching them. If he/she knows WTF already, what more harm can be done?

Bust out the Lion Kings dude and put the smut away, it'll save you much valuable time you could otherwise be spending with your child.

[Kelso]

I have successfully re-edited a DVD movie AND I was able to keep the 5.1 digital audio. I was not trying to make a CHILD friendly version of a movie....instead I was upset at a badly edited / overly long movie. So I re-edited the movie to make it flow smoother and shorter. And I am so glad I did. The movie works so much better.



Anyway... Here is how to do it.
I used the following programs.

DVD-Decrypter
Ulead MediaStudio 7 Pro
TMPGENC
Adobe Premiere 6.0
BeSweet
Sonic Scenarist (not necessary - but if you know someone who owns a copy, ask them if you can use itt!!)
And a DVD authoring program of your choice



1..Make sure you have LOTS of free harddrive space. (NTFS format)
I'm talking LOTS !!!!! 200GB would be great.




2..Rip the DVD to your harddrive with DVD-Decrypter.
Use stream proccessing, and select only the video, and only one 5.1AC3 audio track.

(Use IFO mode. And set "file splitting" to NONE.)

You will end up with one large VOB file containing all of the movie.





3..Using TMPGENC... Demux the VOB file to a M2V video file and the 5.1 AC3 file.





4..Now you need to convet the M2V (Mpeg-2 video) file for editing.
I used Ulead MediaStudio 7 Pro. You can download a 30 day working trail for free. I am sure there are other programs that will do this job just as well. But I found the MediaStudio process very simple, and it handles bad and corrupt files extremely well.

Start the program. Under the "FILE" menu is a "CONVERT" option.

It will ask you for the source file. Load in the M2V file of the movie.

You then select what type of video you want to convert it to.

If you have tons of harddrive space... select "uncompressed" to keep the best quality.

If you are like regular people, select "HUFFY". The file size will still be big, but not outrageous like "uncompressed". (you can download the HUFFY codec off of the internet)

Give the new video file a name, and start the conversion process.
Sit back.. it will take a while.
You will end up with a really big AVI file.




5..Using BESWEET, convert the 5.1AC3 audio file into 6 PCM-WAV files. (48000 KHZ)
LEFT.wav
RIGHT.wav
CENTER.WAV
SUB.WAV
LEFT SURROUND.wav
RIGHT SURROUND.wav





6..Now for the editing.
I used Adobe Premiere 6.0

Start a new project, using the correct video codec setting to match your AVI file. Adjust the audio setting to match the wav files.(Remember each of the 6 wav files is 48000KHZ MONO... so set the project to mono)

Import the video file and 6 wav files.

Put the video on an editing track.
Put the each wav file on it's own track.

Edit accordingly.

If you cut a section of video out, cut the same section of audio on all 6 audio tracks as well.

If you just want to take out a bad word, you can just cut a hole into the CENTER channel audio. The rest of the audio tracks will still play and for the most part will cover the center channel how. (ie.. you will probably not notice a drop.. because the music and effects will still play in the other channels)

CAUTION.. remember what ever you do to the video, you must do the same to the audio. If you do not, you will lose sync.




7..After you are done editing.
select the entire project, with the yellow timeline ruler.

Enable only 1 audio track to play.
click the "EXPORT TIMELINE" / "AUDIO" to export the first channel of sound.
Remember to export as 48000KHZ MONO.

When done, turn off that channel and enable another.
Export that channel of audio.

Do this for all six channels, and you should end up with 6 new wav files on your hard dive. Remember to keep the names so you know what is what. (left, right, center, sub, left surround, right surround)




8..Export the video from the editor.
Remember to export with the same codec it started in... HUFFY, uncompressed, etc.....




9..Recompress the edited AVI video back to DVD-MPEG2-video.
I used TMPGENC. for a 2 hour video, make sure you use Variable bitrate to make sure it will fit on a DVD-R.
Tell the program to make you an "elementary video stream".
You will end up with a M2V file.





10..Now you need to take the 6 edited wav audio files, and convert them back to a 5.1AC3 audio file. There are many programs to do it. Each with it problems. Sonic Foundry's SOFT ENCODE is easy to use... but the sound quailty is not the best. I think BESWEET can do it, but haven't tried it.

If you can, use the AC3 Encoder built into Sonic Scenarist. It does a great job, and the recompressed AC3 file sounds very close to the orginal.

Make sure to set the bitrate for the AC3 file to 448... to preserve as much quailty as you can. (do not go higher, as it is not allowed in the DVD standard)






11..Now the video and audio are ready. You can load the M2V video and AC3 file into your DVD authoring software, and make your new DVD.



Enjoy.

[hiphats2003]

I did some experiments with ripping AC3 soundtracks with BeSweet and it was successful (got the 6 separate mono .wavs for surround channels).

Now someone said you could remix those surround channels back to true AC3 with BeSweet but that someone never tried it. Well, I did try it myself, and unfortunately you can only either do AC3 to AC3 or AC3 to .wav (I think you can also do AC3 to DTS). Is there other software out there that can remix the 6 .wavs to AC3 without paying thousands of dollars for it?

[hiphats2003]

Update...yes, it can be done. With a little elbow grease you can re-convert stereo .wav files to AC3 audio...or as close to it as possible, using BeSweet. All you have to do is input your .wav file and output to AC3 and that's it.

The rest is up to you.

Thanks!

[hiphats2003]

Update:

Well, I successfully ripped AC3 5.1 into 6 mono .wavs. The problem today is I have truly been unsuccessful at making 2.0 AC3 files and remixing 6 mono wavs back to its original AC3 5.1.

Can anyone tell me what inexpensive software or freeware that can do this?

Thanks.