Dolby Digital - 2.0 mono vs. 1.0 mono?

[DarthMarklar]

I realize that 2.0 mono is just 2 channels of the same mono track, but what advantage does 2.0 mono have over 1.0 mono?

Both 1.0 and 2.0 (on DVD's) are encoded at 192k/sec, so what's the deal?

Do they sound different? Is there more ease with the Dolby Pro-Logic conversion on a 2.0 rather than a 1.0? Is there a thing with the DVD authoring programs where some won't allow anything smaller than 2.0?

[Cornucopia]

Given that you're specifically talking about MONO soundtracks...

AC3 2.0 mono has actually NO benefit over 1.0 mono.
-AND-
It is either a waste of disc space
-OR-
It is a non-necessary waste of usable bitrate (and thus of lower quality)

Your AC3 decoder will output both kinds of mono files and you'll get an identical sonic experience with either (although the 2.0 might be 3db louder), so stick to the 1.0 configuration when using mono files. You'll be maximizing your quality and minimizing your disc requirements that way.

HTH,
Scott

[Cornucopia]

Oh, yeah, and...

Marklar, marklar, marklar the marklar marklar.

Scott

[DarthMarklar]

Scott, do you know why Hollywood DVD's are authored this way? Why would they use 2.0 mono? It just seems like there's an advantage that we don't realize.

p.s. Marklar is the marklar way to marklar your marklar.

[FOO]

Maybe the players can't get mono to both speakers

[Jeff Muller]

Well, there are 3 threads about this over at the Home Theater Forum:

http://www.hometheaterforum.com/htforum/showthread.php?s=&threadid=193097

Or is that you again?

[Cornucopia]

Scott, do you know why Hollywood DVD's are authored this way? Why would they use 2.0 mono? It just seems like there's an advantage that we don't realize.

p.s. Marklar is the marklar way to marklar your marklar.

Yes, I know why H'wood does this. and No, no advantage.

It's a "workplace habit" or industry workflow sort of thing.

Most of the studios contract with encoding companies. They have HARDWARE AC3 digitizer/encoders, that are either 2.0- or 5.1-capable. They also have preset encoding templates, most of which are also designed for 2.0 or for 5.1. If they send audio tracks through an SDI (Serial Digital Interface) or AES cable, then the choice of audio channels is probably determined by the source tape deck (usually D1, DigiBeta, Betacam, DVCam/DVCPro, etc).
They usually have an output switch on the deck of [Separate Tracks] or [Mixed Tracks].
This will then give you either a 2.0 stereo stream or a 2.0 mono stream. They often don't have time to tweak EVERY audio program output that comes through (especially with the flood of old catalog re-issues).

Hope that Marklar's you,

Scott

[Nilfennasion]

Actually, there IS an advantage, but it is one of pure subjectivity and end-user level only.

The majority of centre speakers in use today are not that well-specified. When they have the entire soundtrack coming out of them, they will sound compressed or severely frequency-limited.

Emperor's Emperial Live Ceremony DVD is a good example of this. The original release was in 1.0, and purchasers were often complaining of the results of having the entire song coming out of one speaker that was really only intended to place the dialogue so it would always sound like it came from the screen regardless of where the audience were seated. When it was rereleased in Dolby 2.0 (never bothered to check whether it was mono or stereo), the complaints ceased because left and right speakers are usually designed to handle a lot more than the centre. At least until you start spending over $500 on a centre.

So, to put it in the terms of the professional author, these soundtracks are designed with the majority of the DVD-Video market in mind rather than the audiophiles who can afford to spend $10K on a receiver and $2K on a centre speaker.

[Cornucopia]

As somebody who does this kind of work for a living, but has a modest setup at home (<$1k total speakers & receiver), your argument doesn't completely hold water.
Especially when, as was mentioned in the referred link, many receivers would automatically steer a AC3 2.0 mono stream to the center speaker.

Scott

[Nilfennasion]

If a receiver steers a 2.0 soundtrack that doesn't have the Puke-Logic flag set, it isn't worth buying, end of story. I used to wonder if Yamahas were worth buying until my old man bought one that did exactly that.

I've also listened to enough 2.0 mono soundtracks to know that a decent receiver will not play the two channels through anything other than the fronts. It was intended to come from the fronts by those who mixed the soundtrack.

Okay, so I sound ornery about this one, but nothing irritates me more than people who think "stereo" means "you can play it as 5.1 if you fiddle with your receiver's settings". The same people who wonder why their subwoofers start to drown out the other channels when they adjust their receivers on a soundtrack-by-soundtrack basis.

The centre channel was intended only to place the dialogue so it would sound like it was coming from the screen. Dolby's own product literature says exactly the same thing.

[Cornucopia]

Food for thought:

Just got this direct from the DOLBY site...

"Encoding Guidelines for Professionals" (pdf)

Decoders output 1/0 mode (mono) signals to either the Center channel or Left and
Right channels when the Center channel is not available. It is unnecessary and
therefore not recommended to encode mono signals in 2/0 mode.

Scott

[Nilfennasion]

They're right, it isn't necessary, but there are reasons why professional encoders like to do it anyway.

The Emperor DVD I once reviewed is a good case in point. Little to my knowledge, it had been originally encoded in Dolby 1.0 because the source was mono. Which might have been great for a film, but when you're showing a live performance of a band that features two guitarists and keyboards, things tend to get muddy unless the centre speaker is a 300W dynamo like the one my old man continually refuses to calibrate properly.

The record label was very quick to reissue the disc with the soundtrack recoded as 2.0 after European customers complained that it sounded like crap coming out of a singular speaker.

Dolby also released a statement claiming their codec was so much better than DTS, mentioning three tests that were done by experts they never named in locations they never named, with no sources, references, or indeed anything other than their own blanket statements offered. I therefore take everything that Dolby say about their own product with a grain of salt.

[Cornucopia]

You do realize that a straightforward solution exists for 1.0 mono tracks...

Change the setup of the DD/PLII decoder and tell it that you don't have a Center channel speaker. Even if you do.

Then it will automatically steer mono to both L+R. (That's what Dolby Labs was talking about)

Scott

[Nilfennasion]

Of course, the quality of steered sound is heavily dependent upon the quality of the receiver/processor doing the steering.

[Cornucopia]

Aye

[nick1977]

On my receiver, if you just turn surround processing off, it has the effect of sending 1.0 signals to the L + R channel. Turning off surround on most setups should make it ignore centre, rear, and sub channels.

Nick

[Nilfennasion]

My old man's receiver has this annoying habit of taking 2.0 soundtracks like the one from Still Smokin', and steering them into the rears. While it is somewhat novel the first time, hearing the entire soundtrack out of the rears, it gets on the nerves.

It also appears that many different receivers will do many different things, too. [/i]