Dolby Pro Logic II Encoding

[velocity3k]

As many know if you parse a standard 2 channel file through a Dolby Pro Logic II decoder you get somewhat a decent 5.1 emulated sound. I was wondering whether there was a program that would do this emulation at the encoding stage and thus provding a 5.1 emulated AC3 file from a 2 channel stereo source.

[funkguy4]

I know there is, but the name just isn't coming to me right now! Sorry I couldn't help more, but at least now you can rest assured that it exists. Someone here's bound to know it.

[debennett2]

I am also interested if this is possible. It might breathe life into some of my otherwise boring home movies.

[jester1x]

Actually, a program that can do this does exist, but unfortunately it is no longer sold. It's called Sonic Foundry's Soft Encode. It can make a two channel stereo file into pseudo-Dolby Digital 5.1. It actually works quite well!

[freestyler]

Sonic Foundry's Vegas Video 4 has fully integrated AC3 capabilities such as those found in Soft Encode.

[turk690]

First let's be clear about a few things. There is only one such standard for encoding 4-ch (L, R, C, S) audio information into 2-ch that Dolby Labs has created and that is Dolby Surround. This is an analogue matrixing scheme that tries to (impossibly) retrieve 4 discrete values from 2 unknowns at the decoding end. Since it's not possible, COMBINATIONS of those values can be solved for and we can have convincing playback of 4-ch with early Dolby Surround decoders. Decoder design has matured by several steps in the past years through the use of logic circuitry in directional enhancement and we had Dolby Pro-Logic, and now Dolby Pro-Logic II. The latter has even more sophisticated algorithms so as to detect and provide a wider, much more convincing sound field in 2-ch sources that WERE NOT even Dolby Surround-encoded to begin with, like ordinary music CDs. Dolby Surround encoding HAS NOT changed, and if you know the exact equations involved (they can be seen in the help text of DVD2AVI), you will know that to create a genuine Dolby Surround-encoded 2-ch track you will need 4 channels to begin with. Otherwise you can get along with your existing stereo 2-ch track as it is and decode and listen with a Dolby Pro-Logic II decoder. However you do it you can't get away with NOT using the Dolby PLII decoder. With the advent of Dolby Digital up to 5.1 discrete channels can be encoded and retrieved with fidelity indistinguishable from the original making Dolby Surround look positively jurassic but this related topic requires another post (maybe in another forum).

[funkguy4]

Does BeSweet do it? I can't remember which app, AHHHH!!!

I just looked it up, I heard CoolEdit will do it.

[turk690]

CoolEdit will do WHAT? Just to reiterate, there IS NO such thing as Dolby Pro-Logic encoding, or for that matter DPL II. There is only one such thing and that is Dolby Surround encoding. Dolby Stereo (as it appears on 80s movie credits), Dolby Pro-Logic, and Dolby Pro-Logic II are variations on DECODING the matrixed 2-ch Dolby Surround-encoded audio track. This means that to get the 5.1-ch back (even in fact if the 2-ch stereo track IS NOT Dolby Surround encoded) one can't get away from using a Dolby Pro-Logic II decoder. There are certain virtual Dolby Surround decoders that purport to give surround effects, etc with only two speakers. That's still a decoder and it gets back to that: no escape from using a DPL II decoder as a fact to get surround output.
CoolEdit is no more because Syntrillium has been bought by Adobe. It is now known as Adobe Audition.

[funkguy4]

What I meant was that you can get output that, when decoded using the Dolby Prologic matrix, will get back the 5.1 sound. Personally, I think 2 channel to 5.1 channel is stupid, just go to 2 channel MPEG and use your prologic decoder matrix on your amp.

[sazanon]

Well, in fact there's a new procedure to convert a normal stereo 2 channel wav file to a 5.0 prologic2 encoded file. The output is a 6 channel 5.0 PLII encoded file that then you can load it into Cool Edit Pro 2.1 and get 6 different mono waves files and finally encode these to AC3 or DTS.

The thing is :Is it really worth too much trouble ?. If you have a hardware PLII decoder amplifier, then just run your plain stereo file on cd and you'll get the same result.

Anyway, here is the link :

http://forum.doom9.org/showthread.php?s=192eea1197a81491b84edf371a4b6733&threadid=57736

[debennett2]

I think ti is a great idea for those who author movies that might go to a familymember that doesn't have the latest and greatest in surround decoding (specifically PLII). You have to remember that it is a pretty new thing and that a lot of folks still have some of the first DD/DTS/andreglar PL receivers still. This would alllow for something at least a step about regualr Prologic at least.

[EddyH]

syntrillium no more?

rats, just as i was getting close to having the cash to register my copy of CE.. cant help feeling somehow responsible.. now i have to buy an adobe product

[funkguy4]

That's bunny is UGLY .
:P

[EddyH]

Funny, everyone either spots it as a (occasionally 'demonic', or now 'ugly') Bunny or as an Evee (from Pokémon), neither of which it is. Not sure which of those misidentifications I like more (bunny is amusing; evee understandable)!!

A positive ID from *someone* *sometime* would be nice though

And... um... your cow is also quite hideous. I think. So there!



Throwaway question: Any way to trick an auto-sense decoder into switching to ProLogic mode, even with no actual prologic sound in the stream? And preventing it from decoding any apparent surround effects? (apart from maybe putting shared L/R info to the centre speaker?)...

Switching into ProLogic is the only way I've found of getting my cheap DVD player to send filtered signal from a stereo stream down the Subwoofer cable but it usually comes, with VCD audio, at the expense of having a generally mangled and false surround soundstage appearing to the back.. (yeah i could just unplug the rear speakers.. but i'm lazy, and anyone else in this house using the machine wouldn't even *think* of that let alone do it / dodge it).

Oddest thing ever was when a *mono* film somehow triggered it off, and all the sound came solely from the centre and bass speakers!

[funkguy4]

I know my cow is hideous, but it's funny also. Your whatever it is is just UGLY . No hard feeling either way, I hope.

I supposed you could just tell your program to use the Pro Logic decoder matrixon a regular file and hope for the best......

[EddyH]

not entirely sure what you mean by using the matrix on a plain WAV and all, so i think i'll just risk being (re)moved to the offtopic forum with a warning:

my avatar has something to say to yours



hmm... seeing as its effectively my public face on the forum, may as well include some variety....



cheers to the butaconnection ( www.buta-connection.net ) for unwittingly supplying the source images for these quite severe crops ^_^

[dogmatix]

My cents worth

Why don't you use DVD2(S)vcd and use the MPEG 5.1 in the audio option.

Maybe I am way off track here - my knowlegde about his stuff is not to great.

Cheers

[funkguy4]

@EddyH

My post wasn't off topic. Someone asked if they could take a standard, Pro Logic incompatible audio source and get a 5.1 file out of it. The way Pro Logic decodes is it uses a specialized matrix to retrieve the lost information. So I said they could try and put it through the Pro Logic matrix and get the file. Not off topic.

[flaninacupboard]

those images are from the dungeons and dragons cartoon, right?
First time i saw your avatar i thought it was a fluffy version of the evil rabbit in donnie darko.

why oh why did the unicorn in dungeons and dragons baa like a sheep?!

[EddyH]

Between this and the toolame posts, i sometimes wonder if im speaking an alien language Where did i say your post was offtopic? I only meant about what i was about to do, as in posting a load of unrelated pictures without any useful text!

(plus i was a little confused on "just tell your program to use the Pro Logic decoder matrix on a regular file and hope" as well, i dont have any programs that can do that, or any PL matrices either)

Fuh...

Flan, right era, wrong country, totally wrong genre (and etc). Dungeons and Dragons is all well and good but this is something (traditionally reported as being) on another level... though i can somehow feel a bond between them, to think of it, just in a low down superficial 'feel' of the things. Erm.

Wonder if anyone can put those pics and my Name That Movie picture/hints together and get the "five" which will explain em both

[funkguy4]

not entirely sure what you mean by using the matrix on a plain WAV and all, so i think i'll just risk being (re)moved to the offtopic forum with a warning:

THIS IS WHERE YOU SAID IT WAS OFF TOPIC. Now that I read it again, looks like I miscomprehended what you said. .

[EddyH]

yeah... like i said... i meant i was about to engage 4-low and hit the ditches... not that you'd already stuffed the corvette into a hedge.

[BJ_M]

i just noticed this thread -- and to clear up the wrong info and such --

yes there is a Dolby ProLogic II Encoder

This is a screen shot

[flaninacupboard]

Ahhh, intersting. thanks BJ_M!
I'm going to have to hunt it down......

[EddyH]

hey... thats got full 5.1 encoding... couldn't DPL/DS only do 3.0 / 4.0?

[flaninacupboard]

DS has 4 channels, and a prologic decoder has 4 channels. Pro logic 2 decoders have 5.1 so it makes sense to use a newer encoder that supports them all.
Heh, imagine sticking it on casette! 5.1 channels on casette!

[EddyH]

Well you point me towards an AC-3 splitter and the download source for that program, and i'll give it a shot. My dad's stereo has a prologic decoder on it
That has never, up to this point, seen any kind of active service apart from some 'spatial stereo' on music CDs. Results could be... interesting. Put a film soundtrack on there, can try it out next time i'm over his house. Even if it doesn't support decoding from the tape deck, I can plug my walkman into the 'video/aux' sockets and away we go!

Still don't quite grasp what you mean by it supporting all 5.1 channels. Wouldn't the decoder still be 'faking' the LFE channel and the difference between the left-rear and right-rear speakers (if PL2 is left, centre, right, and surround?)?? Or are we onto Pro Logic 3 now?

[funkguy4]

Still don't quite grasp what you mean by it supporting all 5.1 channels. Wouldn't the decoder still be 'faking' the LFE channel and the difference between the left-rear and right-rear speakers (if PL2 is left, centre, right, and surround?)?? Or are we onto Pro Logic 3 now?

I know that Prologic 2 does 5.1 channel (I got a pretty new system). I think maybe Prologic 1 is 4 channel, not sure.