No Dolby Pro Logic from AC3Machine

[jonghyunchung]

Every time I select "surround" or "surround2", my Audio Decoder only says "Dolby Digital 2.0" without the Surround encoding when I play a DVD I just burned from DVD-Lab Pro. I mean, the "surround" encoding works for DVDs from other sources, but on the disc I recently burned, it doesn't appear.

Are there any bugs for that?

[minidv2dvd]

if the source material was stereo then there wouldn't be any surround channel audio. 2.0 would play like a cd.

[jonghyunchung]

if the source material was stereo then there wouldn't be any surround channel audio. 2.0 would play like a cd.

So what am I supposed to do to make sure this doesn't happen? In other words, get real 2.0 surround sound? I want full directions, please, so that I don't lose my place.

[minidv2dvd]

first you would need to know whether or not the source audio you are using has "surround sound" encoded into or not. if not, there isn't any point in trying to make it so. artificial surround made from a 2 ch. source doesn't sound good.

so the questions are what is the source? where'd it come from, what format is it in, how was it encoded?

[jonghyunchung]

first you would need to know whether or not the source audio you are using has "surround sound" encoded into or not. if not, there isn't any point in trying to make it so. artificial surround made from a 2 ch. source doesn't sound good.

so the questions are what is the source? where'd it come from, what format is it in, how was it encoded?

It came from an Ac3 (Dolby Digital) file, not an MP3.

[Cornucopia]

The doesn't necessarily make any difference.

You can have surround in 3 ways: Discreet, Matrixed, or Synthesized.

Discreet surround requires all 5.1, 7.1 etc. channels--no matter which format used (AC3, AAC/MP4, MP3pro, WAV, etc)

Matrixed (aka pre-mixed down) surround (nearly always Dolby Surround/ProLogic/ProLogicII) requires 2 channels only. Also doesn't matter the format (AC3, AAC/MP4, MP3, WAV, etc). It's like surround MASQUERADING as stereo.
* Note that because it's masquerading, when a decoder sees a stereo signal it will try to "recover" the surround info (which isn't really there in a non-matrixed stereo recording--this can sometimes be good "synthetic" surround, or sometimes bad).

Synthesized surround requires 1 or 2 channels only (any format like above). The surround synthesis engine/algorithm determines what it will work with and how it will process to come up with some semblance of surround. Some are better than others, none are all that great. The worst ones are so crappy it's better to listen in mono or stereo than to hear what they put out.

What you've got there is an AC3 2.0ch source. No designation on whether it actually is surround (if it is, it's "matrixed"), so you decoder must be set up manually--and hopefully there actually is some surround info there to decode. If there isn't, don't bother going to the trouble.

HTH,
Scott

[minidv2dvd]

well the op in his header lists ac3machine as the source of the problem. what i am looking for is info on the input audio file he gave to ac3machine to produce the ac-3 2.0 file if in fact that is what he did.

[jonghyunchung]

well the op in his header lists ac3machine as the source of the problem. what i am looking for is info on the input audio file he gave to ac3machine to produce the ac-3 2.0 file if in fact that is what he did.

I'm talking about the four (left - center - right - surround) channels that's impossible with AC3Machine. What can fix this?

[Cornucopia]

Using whatever AC3 encoder at your disposal, whether it is AC3Machine/BeSweet, or Aften, etc, you need to:

1. Start off with a multichannel source. (4ch, 5ch, 7ch)
2. Downmix/Matrix to 2.0ch.
3. Set your AC3 encoder's "Surround Mode" to "Dolby Surround encoded" (the other options are "Normal/Stereo/Not-encoded" and "Not Indicated/Don't Know")

Did you do all those steps when creating your discs???

How do you know those other discs that you're comparing yours to aren't 5.1 ch? What tool are you using to check the file info?

More info, please.

Scott


<<<<<edit>>>>>

As AC3 Machine is just a front end to BeSweet which is a front end to other command line tools, you have to find out if (each of) those tools support:
1. Multichannel input
2. Downmixing/Matrixing
3. Surround mode flag setting

[jonghyunchung]

Even with a 5.1-channel WAV source, it still converts to Dolby 2.0, especially when I told it to do 5.1.