Ac3 mono to simulated stereo?

[Arkay]

Hi All,

My apologies if this has been covered, I have searched the forums and read the FAQ's and didn't come up with anything.

I have a DVD here (V The Final Battle), that is encoded as 1.0 AC3. The original series was at least 2.0. What I would like to know is if there are any processing tools available that can (with any semblance of acuracy), take a mono source and convert it to some sort of spacial stereo.. Kind of like the old "Stereo Wide" switches you you used to get on old amps.

I don't know if there is anywhere near enough audio data in a mono stream to generate anything of use but I am constantly amazed at what mathematicians and DSP coders come up with out of basically nothing so maybe there is a way to get something alot nicer than mono.

Any help would be much appreciated.

Cheers,
Arkay.

[DSPguru]

maybe ambisionic can help.. :
http://forum.doom9.org/showthread.php?s=&threadid=29277

[DJ Bobo]

Senseless anyway.
You better keep the mono track as is (besides, there is no reason for them to encode a stereo track in mono)

[Arkay]

Not necessarily senseless. It is usually possible to take a crap image and turn it into something better, the same should apply to audio.

For instance you can rip the mono AC3 to wav, run a low pass over it and extract a perfectly good LFE. Why you say? Well, so that there is an LFE getting fed to my subs instead of just the centre channel. The subs after all are the things designed to output those frequencies.

Now, if you can take the mono and do this:

1. Run a voice removal filter over the wav, use the resultant wav for left and right discrete channels.
2. Do the opposite, keeping human voice freqencies and use that wav for centre.
3. Play around with mixing/amplifing the channels (inc LFE) until happy.

At least you would end up with more voice where voice should be and possibly better sounding (still mono but from L & R channel) music/background noise. It's untested at the moment, just wondering what effect it would have. Not saying that it's possible to generate anything remotely similar to stereo from a mono source, it's not. But with AC3 there is room to play with discrete channels and I may just get better sound out of it than what is on the original.

No harm in trying :)

Cheers,
Arkay

[specise_8472]

There is one good program for doing this. The Fireverb suite from Catt.
http://www.catt.se/
It has very good presets:
Mono -> Stereo: Basic 1 to 2 reverb as if stereo microphines are picking up the sound of a single source in a room.

Mono -> 5 channel

Mono -> B-Format: For Ambisonic decoding.

[Arkay]

Cool, thanks for the link. Now if I can get a license for it.... I'll send of for the demo but I dunno if that will give me everything I need.

Bloody complex looking piece of software too. But I'll give it a go!

Cheers,
Arkay