Dolby Surround 2.1 software?

[guns1inger]

Scott - if you read back through some of the posts regarding the OP's rational, it doesn't seem to be based on the nest audio experience, but rather a warm and fuzzy psychological feeling of actually have some signal in the LFE, needed or not.

[Cornucopia]

I know, I figured as much. Just hoping that one more appeal for scientific rationality might be enough to sway his opinion...

Scott

[SingSing]

As the title suggest, I am trying to find out if there is a software that allows me to create Dolby Surround 2.1 audio to be placed on a DVDR disc as part of DVD-compliant MPEG2 files.

There is an application "AudioDVD Creator" that can encode 2 channel wave file to DVD compliance Dolby 2.0. The tool also claimed it can matrix mixed to Dolby 5.1. Check it out.

[greymalkin]

your are asking reasonable people who are thinking this out logically to help you with an unreasonable, illogical plan to magically create subwoofer channels.

You say you want to keep the pure audio qualities of the 2.0 track, then leave it alone! There's nothing you can do to it other than mess it up.

Also, as has been said many many many many times over in this thread, if you want to reduce the file size to fit on a single layer dvd, recompress the video! The audio is negligible. How much time have you already wasted posting these huge baffling comments about making 3.1 tracks (???) when you could have copied it to a single layer dvd using dvdshrink and be done with it!

[Disco Makberto]

Dear all,

Thank you very much for your responses. I appreciate all opinions, although some of you obviously disagree with what I am after. I respect everybody's opinions, and in no way I am going to say that "his" or "her" is better opinion than "her" or "his". All opinions are equal in importance to me, and I am proud to say it. That's the way I am.

Why I am still (though I could change path) interested in this "Dolby Surround 2.1"? I will ask you this same question though in a different way, "Why there are some or more than some original factory-pressed DVD's with "Dolby Surround 2.1"? Again, why? Is it because the creators of those original factory-pressed DVD's are not following the "scientific method", and they decided to add "Dolby Surround 2.1" based on a layman's opinion like mine?

Okay, I understand that those factory-pressed DVD's have very little information for the ".1" channel. Well, how can I add that very little information to my "Dolby Stereo 2.0".

I don't understand something. Why this topic is going back and forth and around and everything in between? The answer is simple. It should be something like this:

1) Yes, you can do it. Use such and such and do it this way.
2) No, you cannot do it because you don't have a "master" or whatever.

If you read some previous posts, some of you say it's possible while some others say it's not possible.

About degradation? Yes, it could be the case. But I still want to know how to do it if it is indeed possible.

Returning to the case of original DVD's, I know, some of you will say that they have the "masters", and that they created the subwoofer channel before encoding it or something in that vein to create the "Dolby Surround 2.1". And they do this professionally or with expensive hardware, etc.. That's fine with me. However, that doesn't change the basis of my original question, "is there a software that can help me create "Dolby Surround 2.1" or not? If possible, how do I do it?".

Oh, I forgot! The difference between Subwoofer and LFE channels. Okay, my question is, what is the definition of "Dolby Surround 2.1"? As I understand it, though I could be wrong, it is full left channel, full right channel, plus subwoofer channel. Or is this definition wrong on my part? If I am wrong, I would highly appreciate that anybody correct me and let me know the correct definition.

Another important question. Why most people is saying that it is possible to create "Dolby Surround 5.1" based on a stereo or mono source while leaving out the fact if it is is possible or not to create "Dolby Surround 2.1" based on a stereo or mono source? Yes, I know, "Dolby Surround 5.1" is better than "Dolby 2.1", but I am not asking you which one is better or why should I go with this Dolby something or with the other Dolby something. I am asking you how to do "Dolby Surround 2.1", and if it is not possible, why is it so?

Before I close, I have some idea about how to do it based on a previous post. But again, I am highly interested in any reaffirmation of its creation whether it is "yes, it is completely possible" or "no, it is absolutely impossible".

Thank you all for your time and attention.

Sincerely,

Carlos "Shale" Lacaye

P.S.: I forgot something else. The Dolby ProLogic II amplifier discussion. Okay, this kind of amplifier upgrades the "Dolby Stereo 2.0", so I don't need any "Dolby Surround 2.1", right? So why manufacturers of some original DVD's do not think the same way and instead of adding "Dolby Surround 2.1", they just add "Dolby Stereo 2.0"? What do they gain by adding "Dolby Surround 2.1"? Okay, again, they have very little information on that ".1" channel, so I paraphrase my question, what do manufacturers of some original DVD gain by adding that very little information on a "Dolby Surround 2.1" instead of forgetting this and just add a "Dolby Stereo 2.0" channel?

[guns1inger]

Working backwards through your last post

Over the years there have been dozens of different methods of recording and playing back audio tracks for cinema release. These have entailed different physical methods of applying the audio to the film media, different methods of mixing the channels, and different ways of encoding audio. Depending on the age of the film and the masters that remain, it may simply be that someone has found elements in that configuration.

Yes, you can certainly mix 2.1 if your encoder supports it. Some do, some don't. Softencode does, as does Vegas with the AC3 plugin or DVD Architect.

That said, as has been pointed out several times, you have to create the content of this channel for these encoders to use it, and it isn't just a simple matter of sending all the bass there. If you look at the LFE channel of some of the commercial blockbusters, you will find that the LFE is dormant most of the time, with only specific signals at very precise times. However depending on the cutover point you have set in your amplifier, your subwoofer may well be a lot more active than the LFE channel would indicate it should be.

How do you create a 2.1 AC3 file ?

It depends on your software. In Vegas you would load you stereo mix, create a new channel for the LFE and designate it as an LFE channel, then set the AC3 encoder to 2.1 and save.

For SoftEncode you need to create the mono channels for left, right and LFE and load them accordingly.

The guide I posted earlier in this thread has one method for the creation of an LFE channel.

I suspect if you take the time to read up on ffmpeg you will find it can also encode 2.1, if you have the 3 mono channels ready for it. It is a command line tool, and the guis for it only seem to support 2.0.

[Cornucopia]

Your Q: "Can it be done or can't it?"

Answer: Yes and No! It's just not that simple. People who are saying so aren't telling you the whole story.

IF you have the ***original*** multitrack masters, sure it can be done! Without them, it can only be done even SEMI-decently by a long, laborious, REDICULOUS amount of effort to separate and isolate individual elements (while simulatneously trying to maintain quality), just to get "back" to a Multitrack state and mix as intended.

Possible? ~yes Workable? NOT LIKELY (so much so, that most would say it ISN'T possible). I know some methods that might help, but you still might not get what you're thinking you're going to get, so I don't really want to tell them to you. (sorry)

Your Q: "2.1 = Full Left + Full Right + Subwoofer, right?"

Answer: NO. 2.1 = Full Left + Full Right + LowFrequencyEffects (only). These channel choices only PARTIALLY affect what comes out of the Subwoofer speaker. THAT'S WHY I SAID TO LOOK AT MY OLD POST! It explains that there.
But to summarize...

• L = Left High + Left Mid + Left Low frequencies
  R = Right High + Right Mid + Right Low frequencies
  LFE = LFE low frequencies --- Almost always quite rare (supposed to be that way)

That is just the arrangement of the encoding...

Then there's the decoding...

• Left Channel = Left High + Left Mid frequencies for sure
  Right Channel = Right High + Right Mid frequencies for sure
  ***Subwoofer output is determined by settings of your AC3 decoder and your 5.1 ch amplifier/receiver -- which can vary ALOT***

Usually, Subwoofer = Left Low + Right Low + LFE low frequencies (but it doesn't necessarily have to be that way). This is what I was talking about concerning "Bass Management".

Obviously, if it's going to get mixed BACK to the same single/mono subwoofer channel, it doesn't make much sense to separate it.

***Note: Hollywood/factory DVD's are following the "scientific method", because they've got a few LF effects they would like to be separate, AND they have the original multitrack masters.
Specifically, they are NEVER taking a 2.0 signal and "creating/generating" an LFE signal by extracting it from the main signal.

Your Q: "If it's possible to create 5.1 ch from 2.0 source, why not 2.1?"

Answer: It's possible to SYNTHESIZE a psuedo-5.1 signal (aka -FAKE-) from 2.0, and in the same vein one could create the psuedo-5.1 signal and drop the center and rear channels, creating a psuedo-2.1 signal. But that's still not the real thing. Can't be done--that way.

HTH,
Scott[/list]

[Disco Makberto]

Dear Gus1Inger,

Thank you a million times for your answer! That is exactly the kind of response that I needed: Exemplarily helpful!!!

Now I understand 99.99% percent of what I should do. I will probably go via Vegas, but I will also consider the other options.

One final thought for those who care: the fact the I will encode to "Dolby 2.1" doesn't mean that I will necessirly like it. Maybe I will, maybe I won't. But to know the answer, I have to try. If I never create a "Dolby 2.1" stream, how will I know if I like it or not?

All the best to all of you,

Carlos Albert "Shale" Lacaye
Disco Mak

[Cornucopia]

Disco Mak,

Here's something that may make some sense to you...

When 5.1 signals are Downmixed (often in DVD players that aren't sending out all 6 channels, etc) to 2, the LFE is meant (by Dolby) to be completely ignored/lost!

This is probably also true of any .1 signal--it will be lost in the auto-downmix.

And if more has been created/diverted from the main signals, MORE will be missing when downmixed. ESPECIALLY for those who don't have subwoofers!

Scott

[guns1inger]

True. The LFE is excluded from all stereo downmixes - 5.1 or 2.1

[Disco Makberto]

Curnocopia & Gus1Inger,

Thanks for your further comments.

I am looking at this from another angle. So, when the LFE is extracted from the main channel of a 2.0 left and right to be sent somewhere else (sub-woofer, etc.), does that mean that the output of the main channels are now deprived of the LFE? And now the LFE are only available through the ".1" channel?

This is a better scenario if I didn't explain sufficiently enough before:

1) Let's say that I am decoding a "Dolby Stereo 2.0" through two normal speakers only. In this case, I get:
a) L = Left High + Left Mid + Left Low frequencies
b) R = Right High + Right Mid + Right Low frequencies

2) Let's say that I am decoding/dowmixing a "Pseudo Dolby Stereo 2.1" through two normal speakers only and no sub-woofer. In this case, I get:
a) L = Left High + Lef Mid (No Left Low frequencies)
b) R= Right High + Right Mid (No Right Low frequencies)
c) No LFE because there is no sub-woofer

Hence, if 1) and 2) are correct, downmixing a 2.1 stream or even a 5.1 stream is worse than playing the original 2.0 stream. Is this correct?

See ya',

Disco Mak or CAL

[Cornucopia]

In 1st part of scenario, you've got a standard 2.0 signal (assuming AC3 here). In this case, there's no such things as "downmix to stereo" because that's what you've already got. So it passes the signals as-is along to your bass management part of the amp.

If you have no subwoofer (and amp set accordingly), speakers should play each channel as-is.
If you DO have a subwoofer (+amp set correctly with crossover, etc), L, R speakers will play their respective Hi & Mid freq., while Subwoofer will play the combined/mono/sum of L+R Low frequencies. This is to be expected.

In the 2nd part of scenario, with that extra ".1", you're probably going to expect a downmix situation in some circumstances (DVD players w/o 6ch out or raw dig out). The downmix WILL LOSE all of the .1.

This won't be a problem if you "copied" the Low freq. from L+R to make the LFE, as it'll still be in the regular 2 channels, though if you did that, it would be a problem for players/amps that do support 6ch/dig out because they'll be doubling the volume of the low frequencies (either in the sub or in the mains).
Of course, if you go the other way and "steal" the Low freq. from the L+R to make the LFE, you'll have NO Low freq. whether in mains or in sub because of the downmix.
Players/Amps that have a raw/non-dowmixed path should work correctly as long as the sub setting and crossover is set correctly.

See why it's best to leave LFE alone? It can get messy real quick!

Scott

[Disco Makberto]

Dear Cornucopia,

Thanks very much for your detailed explanation.

Yes, I concur with you that going from Dolby Stereo 2.0 to Dolby Surround 2.1 results in a Dolby Surround 2.1 that is hard to deal with, via downmixing or upmixing...

However, what about going via Dolby ProLogic II 2.1 or higher? If I understand correctly, there is no loss in quality when downmxing to stereo in Dolby ProLogic II. And the upmixing can be taken care of by using a Dolby ProLogic IIx amplifier.

Surcode encodes Dolby ProLogic II. Please read about it here:

http://www.surcode.com/low/prologic2/prologic2.htm

As for the actual process, I think I can create the LFE via Vegas, then I place the two stereo sources along with the LFE to Surcode, and encode. This will give me a Dolby Prologic II 2.1. As for Dolby Prologic II 5.1, I need to read more.

But to be concise, do you think that Dolby Prologic II 2.1 is a better alternative than Dolby Surround 2.1 (I mean the pseudo versions, of course)?

Take good care of yourself,

Disco Mak or CAL

[guns1inger]

There is no such thing as a Dolby Prologic II 2.1 or 5.1 audio track. You can encode 2.0 with a Dolby Prologic flag using some AC3 encoders, but Dolby Prologic II is a hardware based matrixing system to create a pseudo-surround mix from a 2 channel source. Your 2.1 or 5.1 will be AC3 (Dolby Digital) encoded, If you play it back through a non-digital stereo connection to a ProLogic II amplifier, the amplifier will receive only the left and right channels, minus the LFE, and it will create the surround distribution in hardware.

If you do a multi-track mix with careful placement of sounds in the full field in Vegas, and save this as a 2.0 audio track with the Dolby prologic flag set, the encoded audio will be able to aid the ProLogic or PrLogic amplifier to better matrix the surround field, however anything that goes to the subwoofer will be due to the corssover settings in the amplifier, not because of any LFE channel you have built. ProLogic does not have an LFE channel like AC3.

[Disco Makberto]

Guns1Inger,

With all due respect, I cordially tell you that I think there is indeed a software encoder for Dolby Prologic II. From

http://www.surcode.com/manuals/proLogic2_manual.pdf

it reads,

"

1
1 Overview
SurCode for Dolby Pro Logic II converts your 5.1 surround soundfiles
to the Dolby Pro Logic II format by matrix-encoding the Center, Surround,
and LFE tracks into the Left and Right tracks. The L and R tracks
then become Lt/Rt, which stands for Left total/Right total - meaning that
Lt/Rt tracks contain the matrix-encoded Center, Surround and LFE
tracks. These Lt/Rt tracks can be distributed and played in stereo, and
also decoded by a Dolby Surround/Pro Logic/Pro Logic II decoder and
played back in surround.
SurCode can accept up to 6 master surround soundfiles in either .WAV
or .AIFF format. SurCode outputs an Lt/Rt .wav file that can be used in
any stereo transmission medium.
Audio files encoded by Surcode for Dolby Pro Logic II are fully compatible
with all branded Dolby Surround, Pro Logic, and Pro Logic II
decoders, either in software or hardware format.
SurCode for Dolby Pro Logic II contains a decoder, which is essential
for properly setting the encode parameters. Also, the encoder/decoder in
SurCode can work in real-time, enabling you to monitor the results of
encoder option changes while making them.

"

About the buidling of the endoded material, I can start with Dolby Stereo 2.0 with all my files if that is helpful (or Dolby Surround 5.1).

Again, what is my "perceived" advantage of having the final product as Dolby ProLogic II? If what I have been reading is correct, the stream can be downmixed without losing quality or sub-channels. Then, again, if I am correct, it can be upmixed using a Dolby ProLogic IIx amplifier without overloding some channels.

Gotta go for now... but I will check back soon.

Disco Mak or CAL

[Disco Makberto]

Gus1Inger wrote in response to my previous post:

>Vegas will also do this, which I pointed out in your original thread. However what you get a 2 >channel file which has matrixing information in it. You don't get an LFE channel - whatever >might have been in it is distributed to the front L and R. If you play it back through a >standard stereo amp, you get a standard stereo signal, as the matrixing data is ignored. If >you play it back through a ProLogic amplifier you get Front L and R, C and mono rear. >Through a ProLogic II amp you get Front L and R, C and stereo rears. You still don't get true >LFE, only what the crossover provides. You don't have a true 5.1 mix, just a matrixed >facsimile.

Yes, I think you are absolutely right. However, this stereo signal is also compatible with Dolby Surround amplifiers. What do I get there? I am not quite sure, but the stream is supposed to be decodable with such amplifiers as well.

Also, I certainly understand that whatever the end product is, it is not "true Dolby 5.1" or "true Dolby 2.1", but rather "pseudo Dolby 5.1" or "pseudo Dolby 2.1", etc.

>So what do you have ? a stereo file with some matrixing hints embedded in it. It is not a 5.1 >file, it is a stereo file.

Agreed.

>If you are starting out with a Dolby ProLogic (Dolby stereo) 2.0 original you gain absolutely >nothing at all, as ProLogic II will do a much better job on it's own that anything you will do >with it. If you have a 5.1 original then you lose all the benefits of 5.1 for the sake of a couple >of hundred MB of space.

Well, when I talk about "Dolby Stereo 2.0", I am talking about my Rockamerica DVD only. I have other DVD's that have mp1, mp2, lpcm...

And, to compare apples with apples and not apples with oranges, my question is, "what is more desirable (within its limitations), "Pseudo Dolby 2.1"/"Pseudo Dolby 5.1" or "Pseudo Dolby ProLogic II". We are leaving out any "real Dolby" here because I don't have any multitrack masters, and in the very few cases that I have "true Dolby" (as in my Robert Palmer DVD), I will leave it like that or add an extra "Pseudo Dolby ProLogic II" without messing up the original "Dolby Surround 5.1".

Until soon,

Carlos "Disco Mak"

[Disco Makberto]

Returning to Dolby ProLogic II...

If "Dolby ProLogic II" audio encompasses a stereo stream with Center, Surround, and LFE incorporated in the leff and right channels as Lft and Rft (Left Total and Right Total), why when we downmix it with a regular stereo amplifier the LFE is said to be lost? I mean, when the LFE is a separate channel like in "Dolby Surround", I understand it...But in "Dolby Prologic II", I don't. Is there a way to circumvent this limitation, maybe by distributing the right and left channel "evenly", as some claim? But how do I achieve this?

All the best,

Carlos "Disco Mak"

P.S.: Or perhaps it's better to leave them as they are and use the "bass management" of the amplifier.

[Disco Makberto]

Guns1Inger writes,

>If you are starting out with a Dolby ProLogic (Dolby stereo) 2.0 original you gain absolutely >nothing at all, as ProLogic II will do a much better job on it's own that anything you will do >with it. If you have a 5.1 original then you lose all the benefits of 5.1 for the sake of a couple >of hundred MB of space.

In technical specifications, I agree with you, for there is nothing to be gained. However, in conveniency terms, I am of the opinion that there is. A "Dolby ProLogic II" stream with 5.1 matrix information is supposed to be decodable with "Dolby Surround" receivers at the 5.1 level while a naked "Dolby Stereo 2" stream cannot be reproduced at the 5.1 level with a "Dolby Surround" receiver. At least, that is how I understand it. Let me confirm it.

Thank you for your understanding and patience.

Carlos "Shale" Lacaye
Disco Mak