Convert .ac3 (384 Kbps) to Dolby 5.1 (448 Kbps) ????

[christopheramos]

Hello!

Does anyone know of a good program to use to convert .ac3 (384 Kbps) audio files to Dolby 5.1 (448 Kbps) ???

Thanks!
Chris

[guns1inger]

AC3 is Dolby Digital. At 384 kbps, it most likely is 5.1. You will gain nothing by re-encoding it to 448 kbps, and may well decrease the quality simply through re-encoding.

What are you trying to do with the file that you think you need to change it ?

[christopheramos]

Hi!

I am compiling a DVD using DVD Lab Pro 2. One of the audio files is 448 Kbps, and Lab Pro says it's Dolby 5.1. But the other audio files I load in, Lab Pro says they are Dolby 2 (384 Kbps).

I was trying to even out the audio by having all of the files in Dolby 5.1 format.

[jman98]

Bit rate has nothing at all to do with whether your files are in 5.1 sound or not. You could have 5.1 sound with a bit rate of 320, for example. Don't re-record it at a higher bit rate as that will only make it sound worse. I think there are programs available (do a web search) that can convert one or two channel inputs into fake 5.1 sound, but having fake 5.1 sound won't make it be any better in reality. I'd leave it in 2 channel sound on the DVD. Good amplifiers should have a setting that can take 2 channel sound and output a fake surround sound from it and that will probably give you just as good results for a lot less work than trying to convert the 2 channel sound you have into a fake 5.1 surround file before burning the DVD.

BeSweet with the right AC3 programs might be able to convert your file into a fake 5.1 file. That will give you a place to start.

Fake 5.1 sound is arguably worse than the original 2 channel or mono soundtrack a lot of movies have. There are a lot of fans of various films or directors who have reacted very angrily when DVDs have come out with only fake 5.1 soundtracks when the original soundtrack was either mono or stereo. They caused such an uproar over Ruscico's re-issuing of some classic Andrei Tarkovsky films for only including fake 5.1 soundtracks and not the original mono soundtrack that Ruscico had to redo a bunch of Tarkovsky DVDs and include the original mono soundtrack or people wouldn't buy them. I see a lot of complaints all the time on a forum for Asian films because it's very rare to have the original mono soundtracks available on DVD for pre-1990 movies and the fans of such films are not happy about it.

[3dsnar]

It is worth to add, that some sound tracks may be in stereo (i.e. two channels to be more precise), however down-mixed from multichannel source in a special way, which allows for roughly recreating the surround panorama during decoding. Example of such a technology is Dolby Pro Logic I/II, etc.

It is not a fake surround, but true surround (with some limitations, when compared to discrete multichannel encoding technologies).

Cheers, 3d.

[zee944]

Forget it, don't touch your stereo/surround AC3 for god's sake!

There's no way to make a 5.1 mix from it. It is already downmixed to stereo or surround, so you can't remix it in 5.1 "automatically". You could extract it then put together as a 4.0, 4.1, or 5.1 file, but it would be fake and sound only worse. FORGET IT.

[3dsnar]

Actually, what the home theatre amplifier does, is upmixing from prologic (stereo) to multichannel on-the-fly.
So if you have a software which does similar thing, and your home theatre equipment does not have the prologic decoding engine, then it makes sens to do such a conversion.

Moreover, if the stream is stereo/prologic, and if your HTC amplifier decodes that, and your DVD player is capable of decoding mp3, it makes sens to convert such AC3 to MP3 for reducing bitrate.

Cheers, 3d