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November 13, 2011

Is it possible to get "true" 5.1 surround sound from a PC game?

I'm working with an older mobo, P35C-DS3R and using optical to AVR for 5.1 decoding in Dolby, DTS, etc. The ALC889A chip can carry through pre-encoded signals just fine, but PC games are bothersome. What is the reality these days for the 'source audio' of PC releases? I recall often seeing highly compressed MP3, OGG..

I also see these chipsets like X-Fi and CMI8770 on Newegg for sound cards with "Dolby Digital Live" (DDL) - some on-the-fly encoding into a compressed DD stream that can be carried by optical (2.0 PCM). Sounds interesting and I'm seeing a lot of great reviews on it, but remain skeptical.

Is this just a 5.1 virtual matrix of a 2.0 source? Some sort of play with psychoacoustics, as best as I can describe? Or if I see the DD logo on the back of a PC box, should I expect the same positional audio I experience playing the PS3 equivalent? Recent titles like Skyrim come to mind...

I understand that many games use something like OpenAL, I think? Something that can utilize multichannels and send them as discrete signals, but that would be analog stereo plugs. Is "DDL" considered a method to 'combine' these otherwise discrete channels and compress them live to feed to the AVR?

Also, is EAX 5.0 really that important? I'm liking the OMEGA Striker models, ~$76 but Creative shares similar features with EAX 5.0 included -- worth it?

Thanks for any advice.

TLDR - Is "Dolby Digital Live" the PC hardware equivalent of what PS3/360 uses to deliver positional/theatrical in-game audio?

Source audio is usually a mono source, sometimes compressed and sometimes uncompressed, which is blended between channels based on a positional algorithm. EAX is just a standardized toolkit which includes libraries of the maths required to do this sort of positional calculation, in addition to things like reverb, muting, other waveform transformations. The problem you are having has nothing to do with the source: it arises because your onboard chipset is sharing resources with your CPU, which can be subject to delays and stutters when dealing with something like PC-gaming.

What you seem to be describing would require a separate recording for each position of a sound, and would be a stupid waste of space. As for EAX 5.0, sure, get it if you want it, some games are bound to use it, but I can't distinguish between 128 meticulously processed sounds and 64. Creative leads the industry for hardware acceleration, but isn't necessarily the best thing for recording/fidelity.

Dolby Live is just a standard for passing digital sources to home theater or other professional sound pre-processing equipment. If you're trying to integrate into an existing home theater setup then maybe this will simplify things for you, but most systems I know just pass shit off to an analogue amplifier setup and then feed it to their speakers.

Some games support Dolby Digital Live or DTS Connect! These games will give you matrixed 5.1 audio through your system.

If you want true uncompressed 5.1 channel surround, you'll need to step up to HDMI, DP, or a 6 connector analog output. I believe some games do support true surround but the list is probably very short. IIRC Battlefield: Bad Company 2 supported true 6-channel surround.

And I believe EAX has been deprecated. Support for hardware acceleration of Directsound/Directsound 3D was dropped in Vista so unless you're running XP your fancy EAX-accelerated card will just be outputting the same OpenAL EFX effects that any other solution can produce. EFX requires no hardware acceleration.

Creative (and other card manufacturers) has had a DirectX wrapper which intercepts directx calls and handles them in openAL it's standard driver package for years now, and windows 8 is expected to allow direct hardware sound manipulation again. Hardware acceleration is still very much alive.

get a Radeon and output 5.1 over HDMI to your decoder. That will give you true 5.1

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