Stereo to 2-channel AC-3? How? And why?

[Colmino]

Reading through a DVD authoring tutorial, I encountered a reference to an app called "Sonics Soft" or something like that, which the author said was good to use for converting the normal stereo audio (associated with DV video) into two-channel Dolby AC-3.

Well, the true name of the app must be a little different, because I'm not finding it. But before even looking into the matter further, I have to wonder what the point is of performing such a conversion. It seems to me that you start with stereo audio and you end up with stereo audio. Can anyone offer possible explanations as to why someone might want to do this?

And assuming it's a good idea for whatever reason, what app should one actually use to do the conversion?

Thanks!

[FulciLives]

A DVD can have PCM WAV audio (which is what DV uses) or AC-3 audio or MP2 audio.

PCM WAV is the best sounding since it is basically uncompressed but since it is uncompressed it can take up a MASSIVE about of space on the DVD ... so much so that it is INSANE!

AC-3 and MP2 use compression. AC-3 is preferred because technically MP2 is only supported by PAL format DVD players where as all DVD players support both PCM WAV and AC-3

AC-3 uses compression but chanes are you won't be able to tell at all unless you have a damn good ear and are an "audiophile" to the nth degree.

The highest bitrate most people use for 2.0 AC-3 is 256kbps

You can use higher birates (AC-3 maxes out at 448kbps) but anything over 256kbps for normal 2 channel Stereo is considered extreme. Usually only multi-channel formats (like 5.1 DOLBY DIGITAL) use 448kbps.

The program you probably read about was called SOFT ENCODE but you can't get it anymore.

Right now most people seem to use BeSweet or ffmpeg to encode to AC-3 format.

TMPGEnc DVD Author has an AC-3 plug-in you can buy and I think the plug-in works even if you don't have or use TMPGEnc DVD Author.

Right now those are your 3 cheapest solutions (actually the first two are free only the TMPGEnc DVD Author AC-3 encoding module costs money).

- John "FulciLives" Coleman

P.S.
Oh yes the main benefit of using AC-3 is that it takes up a lot less space on the DVD so you can use more bits on the video. As I said PCM WAV is huge at a fixed bitrate of 1536kbps compared to 256kbps for AC-3

*** EDIT ***
Wanted to add one more thing there ...

DVD Video generally can't go above 8000kbps for the video. That bitrate with 1536kbps PCM WAV audio will only put about 60 minutes on a standard DVD recordable. So really the only time you would probably want to use PCM WAV audio is when you are putting around 60 minutes or less per DVD. Otherwise it makes a hell of a lot more sense to use AC-3 audio.

[daamon]

FulciLives advice and info is spot on.

To add just a little to it:

Right now most people seem to use BeSweet or ffmpeg to encode to AC-3 format.

I think that the latest version of BeSweet has AC3 encoding disabled, not 100% sure (don't use it). Also, ffmpeg is a DOS command line app. Baldrick, the site administrator, has written a nice front-end GUI for it. You can get the complete package by downloading ffmpeggui.

[adam]

AC3 support in BeSweet was removed, literally for sucking as the author put it, but it was re-implemented in at least the latest version.

[Colmino]

This forum is great. Thanks, everyone.

[daamon]

AC3 support in BeSweet was removed, literally for sucking as the author put it, but it was re-implemented in at least the latest version.

Useful to know - cheers adam.

@ Colmino - You're not wrong there! No problem.