Questions about Wii Pro Logic 2.

[ninzel]

Just wondering if Wii is PL2x because that means it's 7.1 surround.
Also I was wondering about the audio tools that Factor 5 developed for GC, I heard these were superior to what 360 is using as 360 is using WMA and compression but of course it get's discrete channels.
The last thing is the most confusing.Everyone knows that PL2x allows for older 2 channel(stereo) sound to be decoded to simulate 5.1 or 7.1 surround,but can it also work with a sound created for 4 channel? I ask because PL2 is backward compatible with Pro Logic and that could simulate 4.1. So can devs, when making games for Wii actually develop the sound with more than 2 channels in mind?And can they develop the sound to specifically target towards any speaker,or is it a case where it's always just developed in stereo,and the decoder is always "guessing" where the sound should go?

 

[StefanS]

It looks like it's Dobly ProLogic II. Here's the official press release from Dobly.

 

[Bohdy]

It's just matter of how they mix the sound. F5 supported PLIIx on the GC with Rebel Strike. And yes PLIIx mixed sound should be compatible with PL and PLII.

 

[Guden Oden]

So can devs, when making games for Wii actually develop the sound with more than 2 channels in mind?

Yes, they can. If you've played any game with DPLII on the GC with a surround decoder capable of handling it, you can easily track sounds as they move from speaker to speaker. The effect isn't perfect, it tends to sort of break up when the audio gets very busy, but in Metroid Prime for example it's pretty startlingly effective much of the time.

And can they develop the sound to specifically target towards any speaker,or is it a case where it's always just developed in stereo,and the decoder is always "guessing" where the sound should go?

The decoder isn't guessing per se. It's decoding, as best it can, from a pre-mixed analog signal... The pre-mix, made by the sound DSP, is fully programmable by the developers, so in theory you have full surround sound on the GC/Wii. However, as we're dealing with analog signals, decoding won't be as good as with a digital signal where channels are discrete from the outset. Still, it's good enough I'd say.

 

[ninzel]

Yes, they can. If you've played any game with DPLII on the GC with a surround decoder capable of handling it, you can easily track sounds as they move from speaker to speaker. The effect isn't perfect, it tends to sort of break up when the audio gets very busy, but in Metroid Prime for example it's pretty startlingly effective much of the time.


The decoder isn't guessing per se. It's decoding, as best it can, from a pre-mixed analog signal... The pre-mix, made by the sound DSP, is fully programmable by the developers, so in theory you have full surround sound on the GC/Wii. However, as we're dealing with analog signals, decoding won't be as good as with a digital signal where channels are discrete from the outset. Still, it's good enough I'd say.

Cool thanks,that's the info I was looking for. Alot of people think that the sound from PL2 is derived from only a basic stereo sound,since that one of the biggest advertising points of PL2. I don't think enough people realize that the develper can do much more to enhance the final output.

 

[KOF]

Right. DLP was originally developed as a simple stereo expansion technology. When DPLII was created, not only the outputting channel be increased to 5 from 4, it also allowed sound engineers to encode rear channels into the fronts as well so that they could be decoded back into 5 channels. That IMO, is what sets DPLII apart from any other stereo expansion technologies. It's true that so many are confusing these two. Play Resident Evil 4 in pure stereo than roll out DPLII decoder, it'll only sound like it's supposed to do for any other stereo sources that aren't created with DPLII decoding in mind.

DLPIIx is just a further matrixing technique that can matrix up to 7 channels. I don't think GC/Wii developers will develop games with 7.1 output per se, but rather a directional coding in the similiar vein as Direct Sound, as it's extremely difficult to pack 7 different (let alone discrete) channels into two. It's pretty useful for matrixing 4.1/5.1/6.1 sources into 7.1, especially 6.1 sources as DD-ES as 6.1 positioning can bring in psychoaccoustically incorrect sounds. (even Dolby recommends using DPLIIx for DD-ES tracks)

 

[ninzel]

Plus I understand it takes less of a hit to the CPU and the sound is uncompressed. So does that mean that even though DD5.1 has better discrete seperation,the sound quality is potentially better using PL2?
On a side not I just read the Factor 5 did support PL2x. Not that I'll ever hear it,I will be using 5.1 for some time to come.

 

[ninzel]

. Play Resident Evil 4 in pure stereo than roll out DPLII decoder, it'll only sound like it's supposed to do for any other stereo sources that aren't created with DPLII decoding in mind.

Could you clarrify this.

 

[archie4oz]

Plus I understand it takes less of a hit to the CPU and the sound is uncompressed. So does that mean that even though DD5.1 has better discrete seperation,the sound quality is potentially better using PL2?
On a side not I just read the Factor 5 did support PL2x. Not that I'll ever hear it,I will be using 5.1 for some time to come.

Dunno about sound quality, the discrete digital transports allow you stuff a pretty high dynamic range signal into the data stream that I'm not sure you can do with DPLII/IIx (it's really more of how much does the digital compression affect the audio quality). But it does have lower latency. "Real-time" Dolby Digital and DTS encoding typically added about 35-100ms (50ms is the claimed worse case, but I've seen worse) of latency to the audio. You don't have any of the transform and compression latency with DPLII/IIx. Personally I'd rather not deal with any of them and just pump out discrete analog channels to the reciever (almost any receiver made that supports Dolby Digital has at least a 5.1 analog input and many with 7.1 these days). Granted that does put the onus for really good D/A conversion on the console itself instead of the reciever. The other current sexy option would be (at least in the case of the PS3) to spit out 6-8 channel LPCM, then you get the nice, high-quality audio, no compression/decompression latency (outside of what the game audio and your engine does), and you offload the D/A conversion to the reciever.

 

[sfried]

Play Resident Evil 4 in pure stereo than roll out DPLII decoder, it'll only sound like it's supposed to do for any other stereo sources that aren't created with DPLII decoding in mind.

Are you sure you put the settings to "Surround" after you set up the decoder?

 

[KOF]

I compared RE4 using both stereo and PLII surround in the game option. (while running DPLIIx on my receiver) When using stereo, I get absolutely no sense of directional sounds in games at all, meaning when I'm around a welping dog and I go around in 360 circle, the welping sounds remain constant in all my speakers. The waterfalls sound, Ganados shouting all sounded mostly equal on my rear speakers as well as fronts. (this is by no means to imply that all DPLII is doing to a regular stereo source is to duplicate the fronts to the rears, but rather that you won't be getting EAX like sound directions no matter what)

Switching to DPLII on the menu, the volumes for the fronts and rears differ depending on where I move. When I'm facing the dog, the fronts sound the same but the rear is much quieter, when I'm facing away behind the dog, the welping sound sounds normal from the rear, but quieter on the fronts. The individual channels will never be silent because PLII works by filtering the original stereo sound by frequencies.

Even if DD/DTS use lossy compressions, it will always triumph over PLII when it comes to positioning because they are discrete. As sound quality in games and movies keeps improving, it makes sense to send it digitally to be processed by better DACs. I hope Dolby HD or DTS MS becomes the standard from next-gen.

 

[Guden Oden]

The individual channels will never be silent because PLII works by filtering the original stereo sound by frequencies.

The way I understand it is DPL(II,x) works by phase-shifting the various channels compared to each other, not 'filtering by frequencies'. How could you filter sound so it would go to a particular speaker, when it's the same frequency sound that goes to each speaker?

Like, sound destined for left rear is phase-shifted 90 degrees from the normal left channel, sound for center channel is shifted 90 degrees between left and right channel, and so on. I'm sure this isn't a totally accurate description, it's just an example.