I think we are getting some (admittedly very confusing) things conflated.

1. The encoding and processing of the actual bit stream representing the audio that is sent to the speakers.
2. The encoding and processing of the bit streams that represent the metadata headers that describe the format of the contents.

I think they are almost entirely independent. The digital processing that creates, say Dolby, don't require any knowledge derived from metadata to know what to do.

And for another example, the process that creates ATMOS effects works regardless of whether the audio bit streams are coming from a disc or from the network.. All of the necessary content headers and metadata are encoded within the stream, to tell the codecs in the Xbox or A/V receiver what to do.

The metadata we have been talking about is different, albeit encoded in a complex bit stream on the DVD or BD, this data is not actually a part of the audio stream itself, and does not have any relevance to the actual codec processing - it is information for humans (and programs such as players) only.

Now that is the way I understand it to work. There may be other ways for it to work. If someone has actual technical knowledge or experience that would inform me better on this, it would be appreciated. Otherwise, any other reasonable conjecture would be just that - and I am pretty comfortable with my own, semi-informed version.

The "it" you are talking about is the amalgamation of the codec being used, and your receiver settings, including manual adjustments (e.g. "balance", or a "mono" switch, or down-mix settings and the list goes on).

Based on all the discussions, I'm coming to a very simple way of thinking about it. If there is one channel in the audio stream, the source is mono. If there are 2 channels, the source is stereo (seems to borne out by the code I am looking at - that Dual Mono code seems never to be hit). And so forth.

Now, what you HEAR in which speaker is totally dependent on setup , configuration, and actual channel content.

Quoting GSyren:

Quote:
Quoting mediadogg:

Quote:
The "it" you are talking about is the amalgamation of the codec being used, and your receiver settings, including manual adjustments (e.g. "balance", or a "mono" switch, or down-mix settings and the list goes on).

That may well be so, but the bottom line is - is listening to the center speaker vs the left/right ones a reliable way to determine if it's mono or stereo. And my understanding is that it is not, if you're looking for a quick determination.

Correct. Although there is a "DIRECT" setting that some A/V receivers have that i think turns off the codecs. That might be a way ...

Gunnar, I have to issue a retraction. DVDPca, as I think you know, is an augmented mashup of a bunch of other programs, such as DVDInfo, BDInfo, two different IFO scanners, two different movies players, and a bunch of other snippets. During the testing, which a bunch of people contributed to, I experimented with various mixes and matches, fixed some bugs and added some new features. I stopped when I was getting mostly reports that the metadata matched exactly other tools such as PowerDVD, and running times were computed exactly. Extra features included extracting other metadata from the IFO files and off the disk.

As a result, when I looked at the code the other day, I posted a snippet containing "DualMono". That code, as far as I can tell, will never be hit in the current version of DVDPca, whose code is a jumbled mess.

DVDPca, for DVDs will only designate "Mono", if there is only 1 channel. period.

I am currently looking at some updates, and I might experiment with at least putting in the logic that is capable of outputting "Dual Mono." Whether there is a DVD out there, with metadata that will trigger the code, is anybody's guess.

By the way, the IFOs you sent, when parsed, identifies an AC3 codec (Dolby) and 2 channels.

I was trying to find an analogy for what we are dealing with. This is as close as I could come:

Quote:

A car is registered as a 5 passenger car, if it can legally carry a maximum of 5 passengers. It retains that designation, no matter how many people are actually traveling.

However, in a "high occupancy" lane, you are required to have at least 2 passengers, otherwise get a ticket from police.

There is no policeman that prevents, while mastering the DVD, two identical mono sources from being passed to the Dolby AC3 encoder as a "stereo" signal. You get pseudo surround, unless you turn off the Dolby processing of the receiver. In this case, if the cover says "Mono", then depending on your point of view, both the cover and the metadata are correct.

Quoting GSyren:

Quote:
For what it's worth: All discs I looked at, whether 1 or 2 channels, were identified as AC3 by DVDPca. But that was only maybe half a dozen discs, so that could be just coincidence.

Barring a good way to display channel difference (l-r), it still seems to me that an educated guess is the best way to identify 2-channel mono. Not sure how well that would fare with voters/scanners though.

I would only be concerned if DVDPca produced different metadata than other trusted tools. If you find such a case, then let me know, and send me the IFOs.

Also, you have actual 1 channel discs? Wouldn't mind taking a look at those IFOs as well. Thanks.

In terms of displaying (L-R), a simple hardware circuit will do it. I have an old Radio Shack voice remover that was used for Karaoke, if you want to play with it. Pay for shipping and you can borrow it.

Or, I could build you a little custom circuit that works with headphones. let me know.

But again, if during mastering, the mono signals are passed thru a Dolby encoder, there is pseudo surround info added to the 2 channels. Check the Wiki for Dolby for a full discussion. So then you go from M->L and M->R, to stereo AC3 Lt and Rt, where Lt and Rt are the augmented pseudo surround channels. In that case, I think the subtraction trick still works, but I am not 100% sure.

I was going to say that I do have several 1 channel discs, bur the problem would be to find them.
But now that AiAustria has provided an example maybe I don't have to?
If you need further examples, mediadogg, I can certainly take a look.

Quoting GSyren:

Quote:
For what it's worth: All discs I looked at, whether 1 or 2 channels, were identified as AC3 by DVDPca. But that was only maybe half a dozen discs, so that could be just coincidence.

Barring a good way to display channel difference (l-r), it still seems to me that an educated guess is the best way to identify 2-channel mono. Not sure how well that would fare with voters/scanners though.

Quote:
I was going to say that I do have several 1 channel discs, bur the problem would be to find them.
But now that AiAustria has provided an example maybe I don't have to?
If you need further examples, mediadogg, I can certainly take a look.

Not sure how to interpret this. If you used some 1 channel discs, then you obviously could find them.  What did I miss?

Never mind everybody regarding examples. The nose on my face got in the way of the obvious.

A simple filter search on my own collection, identified a whole bunch of DVDs and BDs with MONO audio tracks. I will just run a few through DVDPca and compare what it finds to the existing DVDP profiles. If I find a difference, I wil examine the code and the actual IFO bits.