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Author Topic: Question about WASAPI and other audio output modes  (Read 5973 times)

mesue

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Question about WASAPI and other audio output modes
« on: April 27, 2009, 02:46:34 pm »

I enabled WASAPI for the audio output mode in MC13 just to see if it was better or worse than the other settings. It worked fine for MC playback, but I was not able to hear any other computer audio. When I changed back to Wave Out, the computer audio returned. Why did this happen?

And is there somewhere that explains the differences and pros and cons of all the audio output modes?
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Sue

JimH

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Re: Question about WASAPI and other audio output modes
« Reply #1 on: April 27, 2009, 03:25:40 pm »

There is a thread on WASAPI.  I think you can find it from here:
http://wiki.jrmediacenter.com/index.php/WASAPI

It may be the "Exclusive Mode" option.  It's set just below where you set WASAPI in Playback options.
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Alex B

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Re: Question about WASAPI and other audio output modes
« Reply #2 on: April 27, 2009, 03:43:33 pm »

I enabled WASAPI for the audio output mode in MC13 just to see if it was better or worse than the other settings. It worked fine for MC playback, but I was not able to hear any other computer audio. When I changed back to Wave Out, the computer audio returned. Why did this happen?

As Jim said, probably you have the exclusive mode option enabled (Output mode settings > Open device for exclusive access). It is called WASAPI Exclusive Mode for a reason. The windows mixer gets bypassed and only one stream at a time can be played. It really is an option only for audiofools audiophiles. It doesn't miraculously make the system sound better, it just bypasses the quite useful OS level software audio mixer that is of high quality in Vista.

Quote
And is there somewhere that explains the differences and pros and cons of all the audio output modes?

ASIO an older method that is functionally similar to WASAPI Exclusive Mode and can be used only if the sound device has ASIO support (it is not provided by Microsoft).

WASAPI in shared mode, DirectSound and Wave Out use the Windows mixer and don't have practical audio quality differences. These are standard Windows audio modes. WASAPI is the latest and Wave out is the oldest.
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mesue

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Re: Question about WASAPI and other audio output modes
« Reply #3 on: April 27, 2009, 07:17:41 pm »

Thanks, guys!
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Sue

jmone

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Re: Question about WASAPI and other audio output modes
« Reply #4 on: April 28, 2009, 02:43:20 am »

Don't listen to Alex B ... he uses a couple of tin cans for speakers  ;D

For me WASAPI Excl Mode has one terrific benefit over all the other options (and it is NOT "quality") it will automatically change the windows output speaker configuration to match the number of changes in the Audio stream.  This means you can have Windows set to 5.1 and when you play a 2Ch recording it will swap to 2ch for the playback allowing your Receiver to do it's thing and NOT recieve a 5.1 stream with 3 "Blank" Channels.

WASAPI Excl Mode is the "Go"!

Thanks
Nathan
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Alex B

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Re: Question about WASAPI and other audio output modes
« Reply #5 on: April 28, 2009, 04:40:31 am »

It's nice that we have various options. Not everyone uses a dedicated HTPC and a HDMI connection.*

The Windows mixer is useful on an all-round computer when you, for instance, want to pause playback and receive a skype call.

(*I don't use HDMI audio. My HTPC is connected by 5.1 analog and SPDIF. Usually I play 2 channel stereo audio only through the two bigger tin cans in front instead of letting the receiver to do its thing and remix & spread the output to the other tin cans. I can keep the sound card and amp set to discrete 5.1 channels all the time, unless I want to use SPDIF and decode DD or DTS on the receiver. In addition, I have another setup in another room with only a pair of rather nice tin cans. And jmone, you are right, I prefer to use that setup when I listen to music.)
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jmone

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Re: Question about WASAPI and other audio output modes
« Reply #6 on: April 28, 2009, 07:07:14 am »

I agree with Alex (and I was just teasing him), if I want to listen to a stereo audio recording then my prefered output is also 2ch (I don't use my receiver to warm up the other channels) ... and that is the beauty of WASAPI Exclusive, it will change the output configuration to match the number of audio tracks present - no button pressing...it just works.  The downside Alex mentioned of WASAPI Exclusive is that you lose Windows Sounds (or other sound output) when your app has exclusive control of the sound card.

Alex, I take your point about various set-ups and uses, so this is not for everyone.  FYI - My HTPC is connected to my Receiver using HDMI for both Audio and Video.  I have configured Vista Audio Mixer for 5.1 (as the default) and have all my software apps decoding and outputing LPCM using WASAPI Exclusive as the audio renderer (JR WASAPI for Audio Files and Reclock for DirectShow playback).  I use my HTPC for playback of all media types including Audio (CD, CD Rips, mostly in 2CH), DTV (can be in 2ch or 5.1), DVD / BluRay / Movie files (can be in 2ch or 5.1) and this is where WASAPI Exclusive is terrific as it will configure the output to the correct number of channels.  The real problems it has solved for me is 2ch TV and Movie playback where the "blank" 3.1 channels stoped the Reciever using the Subwoofer for base mgt and the Center Channel for dialogue.  At my age I certainly will not claim "goldern ears" and can not say that the quality between the available renderers is apparant to me.  I do however easly notice the incorrect handling of 2CH material broadcast over a 5.1 configuration (edit: what being said even 2ch audio sounds "better" to me when the Receiver is just getting 2ch input not 5.1 form MC)

Thanks
Nathan
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JimH

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Re: Question about WASAPI and other audio output modes
« Reply #7 on: April 28, 2009, 08:02:56 am »

jmone,
Thanks for your story.  I added it to the wiki:
http://wiki.jrmediacenter.com/index.php/WASAPI
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