Restoring Audio in AC3 format?

Superstar · #1 08-04-2010, 03:03 AM

I'm ripping clips off a DVD with the intention to put them on a new DVD. Is it possible to edit the audio of a clip that is already in AC3 format? When I import it into TMPEG, it tells me that it's already AC3, and it won't let me seperate it. The clips have staticy audio, and I'd like to get rid of that, but I'm not sure if I can?

Also, should I encode a clip that I rip from another DVD before I put it on a new DVD? Or will that lower the quality of it? If it does, should I just leave it alone?

admin · #2 08-04-2010, 06:25 AM

Nope. Process with standard procedure:

Extract from DVD properly
Demux video and audio (separate/split audio and video)
Convert audio to WAV
Restore
Re-convert back to AC3
Author new DVD

Best to leave footage alone. Only re-encode when necessary.

Superstar · #3 08-20-2010, 12:50 PM

It's not letting me do it that way. I extracted the ac3 audio with TMPEG as I always do, I saved it as .wav in Goldwave, and what was weird is I noticed when I brought the ac3 into Goldwave, the screen had no lines on it, it always has red and blue audio lines, but there was nothing there. I saved it as wav and opened that in SF, and it said that it contains no data...

admin · #4 08-20-2010, 12:58 PM

Don't do a simple demux. Do the normal one.

It may also be a 6-channel (5.1) Dolby AC3. You'll have to downconvert that to stereo first. I don't have a method for you, off the top of my head. I don't deal with that too often, as I tend to create new content, not redo commercial DVDs.

Besweet should work. You'll have to just wing it on the settings. I don't have any 5.1 sources readily available that I can test with right now. Even most of my commercial DVDs are just 2/0 stereo.

Superstar · #5 08-20-2010, 01:02 PM

I always do the normal demux, I've never done the simple one. All of that sounds pretty complicated and I have a lot of clips to do this on, do you think I should just leave them alone? A lot of them have staticy backgrounds which I don't want..but it looks like I'm going to have to leave it that way unfortunately

admin · #6 08-20-2010, 01:12 PM

I just don't have enough information to give further input.

Superstar · #7 08-20-2010, 01:18 PM

If I uploaded one of them to the FTP site, would that help you at all?

admin · #8 08-20-2010, 02:33 PM

What does Gspot say about both the MPEG file (pre-demux) as well as the audio file after demux?
Gspot: http://www.digitalfaq.com/forum/show...ysis-2305.html ... if you don't have it already.

Superstar · #9 08-20-2010, 03:11 PM

All that it said is
Path - the name of it ac3 format
Size - 2.76 mb

Container
File Type : Elementary ac3 audio
Mime Type : n.a.

Audio
Codec- AC3
Stat - Codec installed
Info - 48000Hz 256 kb/s total (2 chnls)

It didnt say anything in the video section on the right, because I seperated this clip from the video clip, so I could try to do all the restoration to it.

Was this the info that you were looking for? I uploaded the audio clip to the FTP program under my folder.

admin · #10 08-23-2010, 12:58 PM

I was able to open the AC3 in Goldwave with no problem. I just dragged and dropped it, and it opened. I can hear bad microphone work. There's a nice clean noise print at the start of the audio, too. I first ran the aggressive pop/click default in Goldwave, and it knocked out most of the bad audio fuzzles. And then I did a noise reduction, still in Goldwave, with the default it pulled up, using the clean noise print already at the header of the file. It cleaned up well, with no artifacts that I could hear.

But the audio was a tad low, so I opened it in SoundForge, did a normalize curve at 60%.

Converted to AC3 in TMPGEnc AC3 encoder (Sound Player app).

All in all, this is an easy one.

I can only guess that maybe you've installed some software or codecs that have disrupted how your system is handling AC3 audio? That's what it sounds like.

Superstar · #11 09-20-2010, 12:01 AM

Since a lot of the clips that I have are similiar to the one that you restored here, should I do the same methods that you described that you used to restore that clip?
I've never used Goldwave for this stuff, so I'm not familiar with the methods you described...
Can you tell me how to use Goldwave for these things...AND...how will I know if I should use the exact steps that you told me you used?

Also, still having this problem..
It's not letting me do it that way. I extracted the ac3 audio with TMPEG as I always do, I saved it as .wav in Goldwave, and what was weird is I noticed when I brought the ac3 into Goldwave, the screen had no lines on it, it always has red and blue audio lines, but there was nothing there. I saved it as wav and opened that in SF, and it said that it contains no data...

admin · #12 10-08-2010, 02:59 AM

The "lines" are the audio waveform. If the audio has no waveform, then it's silent. Or the computer's AC3 decoder has somehow been broken. What has changed, or been installed, since the last time an AC3 file opened okay? Consider opening an old file that you know had worked, to be very sure it's not simply the file.

Then again ....

You cannot open 5.1 AC3 in Goldwave, using this method. You'll have to downconvert the audio to 2.0 stereo. Surround sound is not supported by Goldwave or most other audio apps.

You may have to downconvert to stereo using Besweet. That's been my tool of choice for 5/1 > 2/0 in the past year.