A stereo LtRt (PLII encoded) file could be built into an fsb and played from an 2D event that has output set to L and R speakers only.
Fmod would have to be mixing to stereo, and NOT encoding its multichannel mix into ProLogic II. Also, depending on what else is getting mixed in on top of the PLII file, the resultant output will vary in quality of surround steering / imaging by the decoder.
The users computer has to be set to stereo output and connected to a PLII decoding receiver.
If all of these are true will a pre-encoded PLII signal might make it to the decoder correctly.
If the PC speakers are in any other mode, it will not work 100%, and as far as I know, there isn’t a polite way to force this configuration on the user.
Safest bet is to use multichannel source files and let the various playback systems handle it individually per user.
So, and correct me if I’m wrong, are you saying that you can’t simultaneously play LtRt file and have FMOD mix to DPL at the same time?
Example: ambiance track pre-encoded for DPL and the rest of 3D sounds encoded to DPL on the way out.
I was wondering how other people mix in FMOD on Wii if you want to take advantage of DPL. Do you mix in stereo and let the encoder/decoder take care of DPL when the user switches to surround? Or you mix to DPL II and stereo still plays fine?
Now that you have mentioned Wii as your console of interest in this thread, it narrows the problem down some – 6 channel out from pcs and DolbyDigital out from an Xbox360 have an entire other set of issues in regard to pre-encoded PLII.
What you describe might work reasonably well on the Wii; I recall doing that trick some on the Ps2 and Gamecube.
The Wii has a built-in PLII encoder on its output, and playing a pre-encoded PLII signal though this encoder is feasible so long as you assure that no part of the pre-encoded signal gets sent to the center or surround channels of the Wii’s mixer; only direct through left to left and right to right. All other game sounds can pan around in surround as needed and the Wii will encode them into PLII for you.
Best course for technical verification of this approach would be to use a phase meter to A/B the original encoded signal vs the same signal played through the Wii/Fmod mixer.
Also do a lot of listening tests with various density of sounds being mixed together and check for decoder surround steering glitches.
Thanks for the information jcobb. You wouldn’t care to elaborate on the PC and 360 issues would you? The last couple projects I did were for the PS2 and dropping in PL2 encoded two channel ambient tracks worked great, playing back in stereo or surround depending of course on the user selection.
But for this project the target is 360, PC and eventually PS3 using fmod as a front end to the Unreal 3 engine. I’m just getting familiar with fmod, so what would you suggest to be the best method? Should I skip PL2 encoding and create multichannel layers in fmod? I was hoping PL2 encoding would simplify things for my ambient tracks.
Thanks in advance for any advice.
To get PLII to work through a pc 6channel out, it must be decoded inside the pc. You would need a PLII decode DSP effect in fmod to accomplish that.
With Dolby Digital, playing an LtRt will just result in a stereo signal out of the digital decoder of the playback system. Again, unless there is a PLII decoder DSP to split out the channels inside the console before the Dolby Digital encoder.
You could double up layers in your events and use the new layer export flags to build only the LtRt for Wii and only the multichannel for Xbox360, Pc, etc…
Or just take regular stereo and pan it to surround a bit in fmod – works reasonably well across all platforms.
It would be cool to have a PLII decode DSP effect in fmod though; it is similar to principal to a [url=http://www.fmod.org/forum/viewtopic.php?t=8427&highlight=midside:15e7edir]m-s deocde[/url:15e7edir], but a lot more complex.
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