Not to worry. You won't be over processing the sound. Here's what Dolby said about PLII encoding of analog stereo sources when it introduced the technology to stereo TV broadcasts a few years ago:

Dolby Pro Logic II decoding, rapidly becoming a standard feature in A/V receivers and home-theater-in-a-box (HTIB) systems, transforms any high-quality two-channel source content (such as compact discs, MP3 files, and stereo broadcasts) into a lush surround sound experience. When Dolby Pro Logic II encoding is applied by a broadcaster or content provider, and later decoded by a Dolby Pro Logic II receiver in the home environment, listeners are afforded an even more exact and realistic surround sound experience.

 



Quote:
Originally Posted by BIslander /forum/post/13535782


Not to worry. You won't be over processing the sound. Here's what Dolby said about PLII encoding of analog stereo sources when it introduced the technology to stereo TV broadcasts a few years ago:

Dolby Pro Logic II decoding, rapidly becoming a standard feature in A/V receivers and home-theater-in-a-box (HTIB) systems, transforms any high-quality two-channel source content (such as compact discs, MP3 files, and stereo broadcasts) into a lush surround sound experience. When Dolby Pro Logic II encoding is applied by a broadcaster or content provider, and later decoded by a Dolby Pro Logic II receiver in the home environment, listeners are afforded an even more exact and realistic surround sound experience.

Thanks for the Reply BIslander, so I feel like I understand the concepts of what the Dolby PL's and the DTS's Neo:6 do by taking a two channel source and creating a simulated surround field.

I'm just trying to figuring out the best setup from the AVR's perspective....should I Let the Reciever Decode a Stereo Signal or a "Surround" signal from the Wii. I've tried both, I can't really appreciate a big difference. I'm just trying to understand why the "Surround" is even an option for the Wii, when you are going to hook it up to a decoder anyway....?????

 

Look up "Dolby Surround" in Wikipedia or something. It's a way of encoding surround information into a 2-channel, stereo-compatible signal.


If you enable the "surround" option in the Wii, it mixes its 2-channel output so that if you run it through a Dolby Pro Logic decoder, then sounds from behind will come out from the rear speakers.


If fed a proper Dolby Surround encoded signal, Dolby Pro Logic doesn't create a "simulated surround field" - it extracts the surround information that was deliberately encoded in the signal.


The same applies for 2-channel TV broadcasts - a lot of stuff on TV will be Dolby Surround encoded and thus you'll get real surround information. Dolby Pro Logic isn't making it up.


To test this, you need to find some way to get the Wii to output a "behind you" sound. It may well be that many games don't really support surround sound. But if there is something that does, there should be a really clear difference behind the "stereo" and "surround" modes with the receiver set to Dolby Pro Logic.

 

The issue at hand for you is whether the games are encoded in a way that will improve the sound experience if you select the surround mode on the Wii rather than stereo. Here's a link to the Dolby web site explaining PLII encoding. It mentions the gaming implementation:

Dolby Pro Logic II also enables video game consoles to encode five-channel surround sound information into a stereo signal with virtually no impact on the console's CPU, which means all this extra audio won't slow your game down.


I am not a gamer and have no idea about the audio quality differences. I also don't know whether there's anything on the game case that indicates whether a particular game uses PLII encoding where you would hear an improvement.

 

Thanks Guys for your time and Info! BIslander, the link didn't work for me but I get the idea. Yes, Most all Wii games have the "Dolby Prologic II" logo on the back of their game case, for that matter most PS2 games do as well (I only have experience on PS2 and Wii)......

so what i'm learning is: the Wii can output it's audio over 2 channels in either 1.) Stereo or 2.) in a 2channel encoded surround mix. The AVR that is set to DPLII will play both. But, the the 2.) option will have the proper encodings for a Surround Field. Whereas the 1.) option will still be in surround but without the proper encodings. I'm assuming that in therory the 2.) will sound better. I guess I'm realizing that the DPLII decoders in the AVR will do their magic with both DPLII sources and Stereo sources. I suppose one is just more complete than the other, but, both surround, Ya? It's hard to do A and B switching with the Wii because of the process you have to take to get back to the settings and switch between "Surround" and "Stereo", and then re-load the game. But, I think after all this I will use the "Surround" setting on the Wii, and feel a little better that this is what my AVR wants

Thanks again guys for your answers.

Tom.

 



Quote:
Originally Posted by greenhill /forum/post/13540140


BIslander, the link didn't work for me but I get the idea.

The link is fixed.


I am a bit perplexed about this myself, actually. Everything I have ever read on the subject says ProLogic II is a decoder that produces 5.1 by matrixing the stereo signal. I've never seen anything to indicate there was also a Pro Logic II encoder. Dolby Surround is an encoding technique dating back to the A/V dark ages whereby a center channel and a single surround channel were folded into the L/R stereo signals and then pulled back out by a Dolby Surround or Pro Logic decoder. The Dolby web site description makes it sound like Pro Logic II encoding is a relatively new technique that can fold five discrete channels into a stereo signal, which would likely produce a better output than just applying Pro Logic II decoding to a regular stereo signal.


Perhaps someone with more technical knowledge in this area can shed some light on the subject.

 

allright BIslander, I re-read the PLII page on the Dolby site http://www.dolby.com/consumer/techno...ologic_II.html ..... and it still sounds to me that the AV Reciever wants a High Quality Stereo Signal which will process to ''five playback channels of full-bandwidth surround sound" using the PLII decoder.

(I know all this info has allready been referenced in this thread, i'm just trying to put it all together.)

"Dolby Pro Logic II detects the directional cues that occur naturally in stereo content and uses these elements to create a five-channel surround sound playback experience".... ???????

but then, and to me this is the confusing part.......

"Dolby Pro Logic II also enables video game consoles to encode five-channel surround sound information into a stereo signal with virtually no impact on the console's CPU, which means all this extra audio won't slow your game down."

So the point of the PLII decoder is taking a Stereo source and making a 5.1 sound field.

so, why the need to encode PLII info into a source (such as a video game) and then sending to an decoder, to do the same thing?????

I guess, my confusion is that I always thought the PLII Decoders wanted a clean Stereo Signal to Manipulate to a surround field (with 5 channels), (6, 7 channels with PLIIx.)

am i making sense or am I missing something.....

thanks again BIslander.

Tom.

 

If the source has no deliberate sound encoding, then the DPLII decoder won't do much. Some diffuse sounds will head backwards, but nothing spectacular.


But if there is deliberate encoding, then the source can very precisely steer effects to particular speakers. This can be shown by playing a multichannel speaker test DVD, and hooking it up to the receiver via 2-channel stereo (after ensuring that the player is outputting a Dolby Surround encoded downmix). The various speaker identifications will still come out pretty much isolated to the correct speakers, even though you're only using a 2-channel link.


In the example of a sound in a game that is notionally from directly behind you - if you tell the console you are using simple 2-channel stereo, then it will just output it equally to left and right channels. If you then run that through a DPLII decoder, it will come out of the front centre speaker.


But if you tell the console to Dolby Surround encode, then it will send the sound equally to left and right channels, but 180 degrees out-of-phase. That will then be detected by the DPLII decoder, and it will send that sound to the surround speakers instead of the fronts. You see? Steering in other directions are achieved by adjusting the phases and relative levels of the two channels.


Now, I think some of your confusion about real encoded information and "inventing" surround information may be down to the different modes of DPLII.


DPLII cinema/movie is the "genuine" mode designed to extract real Dolby Surround information - it won't do much with non-encoded material, apart from collapse things to the centre speaker. DPLII music is a rather more liberal mode designed to also pick up any accidental surround cues from non-encoded sources, without collapsing to the centre speaker. I'm not sure what exactly DPLII game does.


So what a DPLII decoder wants as input is a Dolby Surround encoded signal. It wants information to decode. That will give the best results. But it won't go horribly wrong with unencoded information. All of this has been designed to be compatible - a DPLII decoder won't output weird effects if given unencoded information, and a simple 2-channel non-DPL TV won't output weird effects if given encoded information.

Quote:
I've never seen anything to indicate there was also a Pro Logic II encoder.

This is fairly new - up to recently Dolby consistently used Pro Logic to refer only to the decoder - to distinguish it from the primitive Dolby Surround decoders. Dolby Surround was a cheap-and-cheerful decode of the information that was done for home kit. The later Pro Logic is similar to the more advanced cinema Dolby Stereo decoder.


But more recently Dolby have marketed a Dolby Pro Logic II encoder to the computer/console market. It's a real time Dolby Surround encoder that takes a 5-channel input and produces a Dolby Surround encoded mix. When decoded with a DPL decoder, you get a good discrete 5-channel result.


Why this is being marketed under the DPLII name, I'm not sure. Presumably to indicate that it's equipped to encode stereo surround channels, rather than the mono surround of basic Dolby Stereo?

 



Quote:
Originally Posted by KMO /forum/post/13545591


more recently Dolby have marketed a Dolby Pro Logic II encoder to the computer/console market. It's a real time Dolby Surround encoder that takes a 5-channel input and produces a Dolby Surround encoded mix. When decoded with a DPL decoder, you get a good discrete 5-channel result.

Thanks, KMO. That's helpful information.


One more question - is the sound track recorded on the disc as five discrete channels which are then encoded on the fly during playback? Or, does the PLII encoding happen when the disc is recorded so that there's only a two channel sound track on the disc?


I can see the application of this technique for analog TV, which allows for surround sound over stereo. But, its usefulness for games and such is less clear. Why not just use DD? If a game console is hooked up to more than two speakers, chances are there's a digital audio connection on the receiver.

 

Thanks KMO! that is great. thank you for your time, to help me understand this. I'm getting it now. I'm definately going to go with the "Surround" setting on the Wii, and will set my Reciever to DPLII Movie, this seems to be optimal..... I liked the explanation about the "phase", that was great. I never really understood the Pro Logic's. I think alot of times the ProLogic stuff get overshadowed by the newer formats (DD, DTS....and now all the new lossless HD formats.., crazy), I had a hard time finding chatter about two channel encoded surround. hence the thread

You mentioned a Multichannel disc......I do have the DVE calibration disc (you might have it too), and there is a Very Cool Stereo demonstration on it. with only the two front mains ON, there is a Surround demonstration and it is impressive how the guys voice moves around the room, even towards the rear. The first time i did it I kept running to center and rear speakers because i could'nt believe it was just the two fronts. I also did the same demonstration with the DPLII decoder ON and was very discrete when his voice went to the Center, Front and Rear. So I'm sure this is Encoded information, being processed by the proper Decoder, which gave a good result............. but again, before this thread, I did'nt realized there was info encoded. I thought it was simply lt and rt stereo being processed by a decoder.....

Since were on this topic...... is the DPLII encoding protected??? I guess what i'm asking is, will DTS's Neo:6 (Cinema/Music) pick up the DPLII's encoding????.... i mean if it is just a matter of detecting signals and flipping phases, right?...... not that this is important to me but just curious. I've never seen software (like games) with a Neo:6 logo on the back, It's always DPLII. my understanding is that Neo:6 is the same thing as the PLII, just DTS's version.

again, Thanks!

Tom.

 

DTS just came in the game later and doesn't use the marketing prowress that Dolby Labs uses.


Dolby is stamped everywhere and people then assume anything else is a gimmick.


As for your question; Neo:6 uses the same in-phase out-of-phase information that Pro-Logic uses it's just DTS's version of decoding the signal sent.


So for instance, if you went in your game and chose the Pro-Logic II setting, you could then switch your receiver to Neo:6 Cinema and have the proper decoding where ambience and movement can be heard from your rear speakers.


In my setup I find Neo:6 to be a little more discrete on certain sources... it seems to seperate the channels a little more.


That being said, I actually use Pro-Logic II most of the time; reason being, I find it to "mesh" better overall, I think Neo:6 tries to be a little "too" discrete.


Really, it's just a matter of what your currently listening to, and wether you actually want to switch modes or not.

 



Quote:
Originally Posted by BIslander /forum/post/13546713


One more question - is the sound track recorded on the disc as five discrete channels which are then encoded on the fly during playback? Or, does the PLII encoding happen when the disc is recorded so that there's only a two channel sound track on the disc?

Well, if it's a 3D-type game, then sounds are usually created on-the-fly. A sound effect could come from in-front, to the side, or from behind. That's why you need this live encoding, unlike on a DVD which has the 5 channels laid down already.


A Dolby ProLogic encoder takes a 5-channel input, which can be live as in a game, or prerecorded as in a DVD, and then turns it on-the-fly into 2-channel output.


However, some parts of a game, such as loader music, may be pre-encoded 2-channel info. (Much like DVDs where often the menus are 2-channel Dolby Surround).

Quote:
I can see the application of this technique for analog TV, which allows for surround sound over stereo. But, its usefulness for games and such is less clear. Why not just use DD? If a game console is hooked up to more than two speakers, chances are there's a digital audio connection on the receiver.

Lots of consoles, and indeed PCs, don't have digital links. The Wii doesn't, for example.


And also, Dolby Digital encoding is another step of complexity. That means also doing real-time compression of the signal; quite CPU intensive (akin to MP3 encoding). It's not as easy as chucking raw 6 PCM streams up an HDMI link.


Also, in PCs the ability to output Dolby Digital isn't ubiquitous - and even if they have a digital output they can often only stream a pre-encoded source, as from a DVD. There isn't a native OS mechanism to do real-time encoding.


However, the facility does exist - it's called "Dolby Digital Live". Some sound cards have it - they take a 5-channel input from the OS and turn it into a Dolby Digital output on the fly.

 



Quote:
Originally Posted by BIslander /forum/post/13546713


Why not just use DD? If a game console is hooked up to more than two speakers, chances are there's a digital audio connection on the receiver.

I don't know the first part of your question BIslander, but i do know a little about this one.... The Wii is the only Console, of the newer game Consoles, left that does'nt support DD. Both the new Xbox and the new PS3 support games with DD. the PS2 had a optical digital audio out, and supported DD for Movies (standard DVD) only.... but all the PS2 software game discs were Dolby PLII only...

 

Thanks, again, KMO. I now have a much better understanding of Pro Logic II encoding and its real world applications.

 



Quote:
Originally Posted by greenhill /forum/post/13547956


Since were on this topic...... is the DPLII encoding protected??? I guess what i'm asking is, will DTS's Neo:6 (Cinema/Music) pick up the DPLII's encoding????.... i mean if it is just a matter of detecting signals and flipping phases, right?...... not that this is important to me but just curious. I've never seen software (like games) with a Neo:6 logo on the back, It's always DPLII. my understanding is that Neo:6 is the same thing as the PLII, just DTS's version.

No, the encoding isn't protected. Indeed, the encoding is very, very, very simple. Almost childish. The matrixing was brought in as part of "Dolby Stereo" in the cinema, but to be honest it was only a minor part of the entire package - a lot of it was optical-film-specific optimisation. (And a similar matrixing trick was also in Quadraphonic records, so a DPL decoder will generate decent surround from most quad formats).


The clever bit is in the decoding, and extracting and steering the separate sounds from the 2-channel downmix. That's why the decoders in the home market have gone through several generations (Dolby Surround, Dolby Pro Logic, Dolby Pro Logic II, Dolby Pro Logic IIx) while the encoders have hardly changed at all.


And as part of this idea of trying to improve the decode, in steps DTS. DTS Neo:6 is DTS's own-brand decoder for the Dolby-style matrixing. It works on the same encoded source material, using their own algorithms, to try to do the same basic job. Whether it does a better job is for you to judge - it's a matter of taste. All we can say is that Dolby Pro Logic is the "reference" implementation, and it's what downmixes are more likely to have been tested against.

 

As KMO said it's not a software limitation, it's a hardware limitation.


The original XBOX was able to ENCODE games in 5.1 via the D.I.C.E. (Dolby Interactive Content Encoder) which was later changed to Dolby Digital Live.


I personally use a Dolby Live sound card and it's truly incredible what it's capable of... I can't fathom how they do it... taking a two channel MP3 and making sound like discrete 5.1... It's insane!!


I use the Auzentech X-Meridian sound card which is now discontinued.


I thought for sure when I upgraded my speakers to the SVS 5.1 system I would finally see the faults with the sound card.


Not at ALL!! It's sound jaw-droppingly amazing, some almost sound like a SACD!!!!


It's amazing where technology has lead us...