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WASAPI vs ASIO vs Windows Volume Control

Discussion in 'Sound Science' started by Niouke, Jul 30, 2018.
  1. Niouke
    Hello guys,

    On numerous occasions I have stumbled upon people insisting on using WASAPI or ASIO for media playback on windows computer, claiming it was the only way to obtain "bit perfect" playback...my experience with FruityLoops is that it sounds the same whatver mean I use for output...

    Is there any measurable improvement using WASAPI or ASIO for media playback on PC? Thank you!
  2. jiiteepee
    Depends on your HW, SW, setup, source and settings.
  3. Niouke
    can you tell me what you mean by HW and SW, thank you!

    EDIT : nvm you mean hardware and software
  4. Niouke
    let's say I output from my computer in digital via HDMI to a TV that converts the signal to Toslink SPDIF, for conversion and amplification by a Yamaha A-S701 DAC/AMP, what would WASAPI and ASIO bring to me?
  5. jiiteepee
    If it already works for you as expected then nothing extra. If you hear just static then you would need to use ASIO (or maybe WASAPI Exclusive).
  6. VNandor
    I've messed around with some of the settings on my computer (without really knowing what I was doing) when I tried to play back some supposedly high-resolution audio and measured the output of my soundcard. The way I set up windows/foobar absolutely made measurable differences, sometimes even audible like not working at all or cracking while playing back music.
  7. jiiteepee
    Maybe that was because of "messing around without knowing what you were doing" then.
    Instead of just telling of those results you got, to back up, it would be good to post some graphs of results and info of methods/settings used and info of HW used.
  8. Niouke
    "cracking" sounds like an ASIO buffer underrun
  9. VNandor
    Sure, I have an STX soundcard. The driver was set to 192kHz. Windows is also set to 192kHz, both the playback and recording.
    I connected the output of the sound card to the input, and I also used an analogue oscilloscope to measure the output directly (so the signal wouldn't go through an A/D conversion).

    This is the file I was playing with foobar:

    Foobar's output set to primary sound driver:


    Output set to kernel streaming, wasapi was identical to this:

    Output set to ASIO:

    At the time I had xonar essence stx asio, fl studio asio and asio4all and I don't remember which one I was using.

    There's also those notes about the oscilloscope, the same with scope note means that I've seen the signal to sweep up and then back down with mostly a constant amplitude except for the highest and lowest frequencies, the amplitudes dropped there.

    Anyways, I'm not sure about the WASAPI vs ASIO thing but misconfiguration can certainly cause some problems and if someone makes changes without really knowing what's going on, they are likely to run into it.

    My guess is that an incorrect setup might make asio and wasapi work differently but with a correct setup they are probably identical.
  10. Roseval
    WASAPI or ASIO allows you to bypass the Win mixer.

    WASAPI in shared mode (Direct Sound) uses the settings in de win audio panel.
    If you set Win to 24 bit 192 kHz, all audio will be resampled to this format.
    Likewise if you set Win to 16/44 all hires recordings will be downsampled.
    The win mixer is not very good at resampling
    See http://www.thewelltemperedcomputer.com/Intro/SQ/SampleRateConversion.htm for an example.

    As the mixer is active, all audio is converted to float, mixed (even if 1 stream is playing), dithered and converted back to integer.
    Dither is adding noise but as most of our DACs are 24 bit, dither at -144 dBFS is probably not audible.

    If you use WASAPI in Exclusive mode, the media player talks straight to the sound card as the mixer is bypassed.
    You also get automatic sample rate switching in the process (if your hardware supports this).
    Technically I do think Excluive a better method (ASIO works more or less the same but you do need hardware that is ASIO enabled).

    You might experience a slight increase in transparency under some conditions when using Exclusive mode but don’t expect the world.
    obileye obiyemi, GearMe and VNandor like this.
  11. Niouke
    OK if windows resamples everything I see how that could upset diehard audiophiles. I personnally use spotify, so there is no possibility to choose my output method. I'll stick to 44/16 PCM in windows options. I have never been able to pick up dither noise so I'm safe on that side.

    Thank you for the info.
  12. jiiteepee
    You could try Voicemeeter BANANA as default audio device to bypass WASAPI Shared mode ... (BANANA playback device options include ASIO and Windows native APIs to bypass the Audio engine 'routines').
    bfreedma likes this.
  13. bfreedma
    Interesting toolset - will have to test drive it. Thanks!
  14. smodtactical
    Switching my foobar to wasapi from directsound, I gained a clear 5% in sound quality...and for free! :D

    Maybe its placebo but Im confident I can hear it. Increase soundstage, layer separation and more nuanced and detailed sound. Decays more perceptible.
  15. bigshot
    Your description of the difference sounds more like placebo than an actual difference in sound reproduction. Perhaps if you use criteria that refer to specific aspects of sound, like response, dynamics, distortion, etc. A controlled comparison test would be good too.
    Last edited: Sep 4, 2018

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