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Thread: PSA/Guide: Real directional audio through Pro Logic

  1. #1
    New Member
    Registered: Jun 2007

    PSA/Guide: Real directional audio through Pro Logic

    So everyone here already knows that they can get amazing HRTF binaural (for headphones) or ambisonic 7.1 positional audio in Dark Engine games like Thief: Gold, Thief 2, and System Shock 2 through OpenAL, but... Wait, did you already know that? If you didn't and like to play games with headphones, stereo speakers, or surround speakers (I think that covers all possibilities), you should try these games with the latest version of OpenAL Soft, or better yet, the proprietary Rapture3D OpenAL driver with additional bells and whistles which I can't recommend highly enough.

    ...But back on subject: Directional audio is also possible in classic Deus Ex. A lot of you probably know this, but because matrixed surround gets a bad wrap due to its two very different applications which people tend to conflate, it's worth mentioning.

    One use of Pro Logic, Pro Logic II, Pro Logic IIx or Pro Logic IIz is to take a normal signal and upmix it to play over all speakers in one's system. This is a sort of blunt object approach, and there will always be noticeable cross-talk between channels. It's not exactly indiscriminate like expanded stereo is, but there just isn't enough information in a common stereo signal to make miracles possible. I don't use this application of Pro Logic for anything but upmixing a 5.1 movie or console game up to 7.1 so that two of my speakers aren't hanging from the wall idle.

    The more interesting use of Pro Logic is upmixing a stereo signal that is actually engineered to be upmixed to 5.1. The effect achieves very good channel separation and can be every bit as convincing as conventional discrete Dolby Digital or DTS 5.1 audio. This is the means by which certain games for the Nintendo GameCube and Wii provide legitimate positional audio over the systems' simple stereo analog outputs. Is this true discrete positional audio in the technical sense? No. Is it real positional audio that will give you an advantage in situational awareness and contribute significantly to your immersion in the game? Absolutely.

    Here's how to make it work provided you have some means of outputting Pro Logic and are on Windows XP/Vista/7/8/8.1 using any kind of soundcard or onboard chipset at all:

    • Go to the Sound control panel in Windows and configure your playback device's speaker settings to Stereo. If you use HDMI and get PCM 7.1, change it to stereo. If you use SPDIF with real-time 5.1 DDL/DTSI encoding, disable the encoding and set the speakers to stereo.
    • Launch Deus Ex and set Dolby Surround Sound to On. Make sure "Hardware 3D Support" is disabled. This option won't make any difference at all if you're using Vista or later unless you use Alchemy or 3D SoundBack to restore DirectSound3D support to Deus Ex. I know, that sounds attractive, but the game lacks any sort of multichannel positional audio beyond what I've already detailed. Enabling "Hardware 3D Support" will override the Dolby Pro Logic signal we depend on and all will be lost and nothing gained. Your life won't be worth living. Then you'll disable the option and move on to the next step.
    • Set your receiver* to Pro Logic, Pro Logic II, IIx, IIz, or whatever version you have. The exact setting on my Pioneer AVR is Pro Logic IIx Movie, which I find preferable to Pro Logic IIx Game mode. The x in my case means it upmixes from stereo to 5.1 and then onto 7.1. The 5.1->7.1 in this case is "blunt object" style as the matrixed stereo signal the game sends out is designed for clean upmixing to 5.1. Due to only so much phase-shifting being possible in a single stereo signal, we can't produce a realistic 7.1 signal from it. However, no damage is done in upmixing from 5.1 to 7.1--it's just as if you'd upmixed a 5.1 DD/DTS track to 7.1 using the same algorithm.
    • Start a new game, run up to Paul and talk to him, then stand still while Paul and the mech walk around so that you know it's working.

    *If you have a soundcard that can provide Pro Logic upmixing itself, this should work in the absence of an actual receiver. For example, say you have an analog 5.1 setup and a soundcard that supports Pro Logic II. I think what you would do is keep the speaker settings on 5.1, set the Dolby Surround Sound option in-game to On as directed above, and then activate Pro Logic II in the soundcard driver settings. The outcome should be the same.

    That's it. No, it isn't as impressive as what's possible with OpenAL, but an OpenAL engine modification for Deus Ex is currently in early development elsewhere. Maybe one day we'll be able to play Deus Ex with OpenAL Soft or Rapture3D. Until then, don't discount what Deus Ex is capable of. I assure you it sounds just as good, and probably better, than the discrete support found in many modern AAA titles using simplistic 'modern' sound solutions like XAudio2.
    Last edited by galneon; 15th Feb 2015 at 18:51.

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