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Author Topic: WASAPI Stuttering  (Read 3247 times)

Coolhighend

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WASAPI Stuttering
« on: September 16, 2009, 11:35:04 am »

I am experiencing a strange phenomena. Maybe somebody has an idea what I could do. My setup:
Windows 7, Lynx AES16, JR MC 14.0.67. I use WASAPI as it gives the best results regarding sound in my setup.

When I play different music with different sample rates, I get many times stuttering when the sample rates changes. For example, I listen to 24/96 and then choose a tune with 24/176, I get stuttering. When I then choose a second tune with 24/176, the stuttering has gone and output is perfect.

This problem only happens with WASAPI, not with ASIO for example.

This only happens if the music is on local drives (internal sata, usb, ndas) and not on network drives. I assume that this is a buffering or timing issue with JR using disk.sys.

Any ideas?
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JimH

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Re: WASAPI Stuttering
« Reply #1 on: September 16, 2009, 11:57:22 am »

There are some WASAPI options.  Try Exclusive.  Also look at this:

http://wiki.jrmediacenter.com/index.php/DAC_Settings

Yours isn't the same device, but it's worth trying.

I had some non-WASAPI stuttering problems that went away when drivers were updated.  I think the video driver update was the key.

If you're using any visualizations, try disabling them.  Try minimizing the program so there is no display.
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Matt

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Re: WASAPI Stuttering
« Reply #2 on: September 16, 2009, 12:50:55 pm »

Have you tried increasing the buffering in the WASAPI options dialog?  It's worth a shot.

Increasing the default hardware buffer size of your card might also help in the card's control panel.
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Matt Ashland, JRiver Media Center

Coolhighend

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Re: WASAPI Stuttering
« Reply #3 on: September 16, 2009, 04:33:56 pm »

I went trough again, thank you very much for your input. The hardware buffers are on max, I played with all the Lynx options and with all your suggestions as well. It is still the same. Changing the sample rates between the songs causes stuttering in many cases. I meanwhile found out that this only is the case if I am playing WAV files (what I usually do). If I convert the files to FLAC, the problem is gone. So, I can imagine that there might be an issue with the in_wav.dll and WASAPI. The stuttering is definitely not coming from the converter, as I can see it already in the Lynx volume control - it there is stutter, the bars go up -  what shows me that it is coming right out of the card.
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Alex B

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Re: WASAPI Stuttering
« Reply #4 on: September 16, 2009, 05:11:08 pm »

That is quite odd. My understanding is that the lossless input plugins and wave input plugins provide identical decoded PCM signals to the next component and there should be no differences in outputted signal that could affect WASAPI or any other output mode. (Assuming the lossless file is directly created from the wave file, i.e. the files have identical PCM contents.)
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Matt

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Re: WASAPI Stuttering
« Reply #5 on: September 16, 2009, 05:18:26 pm »

That is quite odd. My understanding is that the lossless input plugins and wave input plugins provide identical decoded PCM signals to the next component and there should be no differences in outputted signal that could affect WASAPI or any other output mode. (Assuming the lossless file is directly created from the wave file, i.e. the files have identical PCM contents.)

This is exactly right.  The WASAPI part has no idea if the input is WAV, MP3, APE, etc.

You mentioned it's only when playing from a certain drive.  Perhaps you have a drive in PIO mode, and the increased disk activity with playing a WAV file causes trouble?
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Matt Ashland, JRiver Media Center

Coolhighend

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Re: WASAPI Stuttering
« Reply #6 on: September 17, 2009, 04:22:50 am »

The problem exists on local drives only. I use internal SATA, external USB with SATA Drive, and NDAS with SATA Drives. All these drives deliver well over 20 Megabytes per second and there is definitely no PIO mode used.

The processor load is at about 1% playing 16/44 and about 5 % or less playing 24/176. So, this can't be a restriction due to processor or disk issues. Using process explorers, I can't see any bottlenecks at any time.

If I do the playback from my Win2003 Server, the problem is gone.

So, I believe it is more a problem coming from buffer handling or maybe you have any other idea.
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Matt

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Re: WASAPI Stuttering
« Reply #7 on: September 17, 2009, 04:48:30 am »

Is the stutter only at the transition when the card is changing sample rates, or in the middle of the songs too?
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Matt Ashland, JRiver Media Center

Coolhighend

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Re: WASAPI Stuttering
« Reply #8 on: September 17, 2009, 05:11:18 am »

The stutter only happens at the moment where sampling rate changes. For example, I listen to 16/44 and then I play a HRx 24/176 file. The Lynx AES16 switches correctly to the new sample rate. In all cases, I get the stutter there and it will not go away if I don't stop the playout. But if I then stop and play another file with the same new sampling rate, the playout usually will just be fine.

There is never stutter if the playout starts correctly until the next time sampling rate changes.
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