Subject:What happens to AC-3 when played in stereo.

Posted by: decrink

Date:10/28/2003 1:07:46 AM

What happens to an AC-3 5.1 mix that is played on a DVD system with only stereo? Will it automatically revert to become a stereo file for these listeners or do I need to render and include seperate AC-3 and stereo files for all possible listening situations.

What happens to the rear speakers when its played in stereo? Do you lose them? How do you mix for both type systems as I'm well aware that many people who might not have 5.1 will be listening to these DVD projects.

Subject:RE: What happens to AC-3 when played in stereo.

Reply by: Tampa

Date:10/28/2003 5:55:09 AM

That's one of the great things about Dolby Digital. The Dolby Digital chipset down mixes the bit stream and sends it out the analog ports as stereo. Of course the player has to have the analog ports hooked up. If your user has his DVD player just hooked up analog to the TV he will be fine even though the sound track is AC3 (dolby digital). The only requirement is that your user's DVD player be Dolby Digital compatible. He does NOT need an AV AMP to decode Dolby Digital, but he does need a Dolby Digital compatible player. Yes, when not decoding Dolby Digital the user will lose the rear speakers. Unless they are running some sort of matrix with their AV AMP, but that has nothing to do with your DVD's soundtrack.

Subject:RE: What happens to AC-3 when played in stereo.

Reply by: SonyEPM

Date:10/29/2003 1:05:14 PM

You have some control over the 5.1>stereo downmix behaviors in the AC3 custom settings> ext. bitsream page. We provide defaults based on Dolby's suggested settings, but because so much of AC3 encoding is material dependent, you'll need to do some experimenting.

Before you dive into that, you might want to do some reading on the subject- lots of info at : http://www.dolby.com/tech

Subject:RE: What happens to AC-3 when played in stereo.

Reply by: thrillcat

Date:11/3/2003 5:30:21 PM

Every DVD Player is Dolby Digital compatible. That was the original DVD Spec. It was DTS that wasn't available in all DVD players, but is in virtually all new models.

Most receivers will automatically mix the downmixed 5.1 file from the analog outputs and fake it with Dolby Pro Logic. And the new Dolby ProLogic II, while not enough a reason to buy a new receiver, has really impressed me.

Subject:RE: What happens to AC-3 when played in stereo.

Reply by: Tampa

Date:11/4/2003 6:04:52 AM

NO, sorry not every DVD player is DD compatible! My Dad has an early Phillips 1996 model that is not. I'll grant you that most if not all since 2000 are DD compatible, but prior to that it's anybody's guess. You also have to be careful about defaulting to Dolby pro logic mode. A lot of amps will default into protection mode if you try to send signals to speakers that aren't wired. A lot of people have amps, but never bought the rear speakers. Another "my dad" situation.

Subject:RE: What happens to AC-3 when played in stereo.

Reply by: thrillcat

Date:11/7/2003 10:20:11 AM

Maybe it didn't have Dolby Digital 6-channel outputs, but it would have to pass the DD signal through the digital output.

Dolby Digital was the standard before dvds were released.

From the dolby website:

December 1995

Dolby Digital AC-3 audio mandatory for NTSC countries, optional elsewhere, in final DVD specifications.

http://www.dolby.com/company/chronology1990_1999.html