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Windows 7/2008 have bug in SRC when recording via MME—hotfix available, [was “Windows 7 Audio Performance↵Audio Kernel Sample-Rate Conve
Greg
post Aug 29 2012, 07:32
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Just because audio is in the digital domain, you cannot assume that digital-domain audio processors such as sample rate converters and equalizers provide excellent performance. The Windows 7 and Windows Server 2008 R2 Audio Kernel has a bug that can degrade its record sample rate converter performance. I strongly urge any users of these operating systems to update the Windows Audio Kernel with the Microsoft Hotfix that is described and explained here:

http://www.indexcom.com/tech/WindowsAudioSRC/

In summary, the bug affects all audio record/capture/encoder applications that use the Microsoft MME API. These applications include Audacity, SoundForge, CoolEdit, older versions of Adobe Audition, and all streaming encoders that do not include their own resampling. This problem appears when the destination audio sample rate does not match the hardware sample rate. This can be confusing because these parameters are set in the Windows 7 Sound Control Panel, under Device Properties/Advanced, and unless you know to look there (which many production personnel will not), audio quality can be compromised.

Testing sample rate converters requires paying attention to many details, including what the audio hardware supports. Many do not know that the new Microsoft WASAPI Audio API DOES NOT provide sample rate conversion, so developers are required to include their own sample rate converters within each application. Not all sample rate converter designs preserve the signal to noise ratio of their input signals; some add nasty-sounding aliasing or other junk. Choose your audio software wisely!

Here is an informative and revealing link to SRC Comparisons:

http://src.infinitewave.ca/

After viewing this, you are likely to look at digital audio software much more critically. I urge everyone to learn how to analyze and edit audio in the spectral domain. Most audio editor packages offer this mode and some amazing things can be done there.

I have worked with Microsoft to make this Hotfix available. This was a huge effort. This is NOT a problem with Windows 8, but good luck with that for a multitude of other reasons. We thank Microsoft for making this Hotfix available.

Greg Ogonowski
orban
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punkrockdude
post Aug 29 2012, 12:48
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May I ask where on InfiniteWave is Windows' resampling comparison? I see no such thing. Excuse me, I saw that you posted two links and one probably contains that information. Regards.

This post has been edited by punkrockdude: Aug 29 2012, 12:50
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Alexey Lukin
post Aug 29 2012, 16:59
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Good call Greg. I wish this was available automatically through Windows Update. Would you like to volunteer to have the conversion posted to InfiniteWave? It'd be interesting to compare before and after your fix.
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C.R.Helmrich
post Aug 29 2012, 17:46
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FYI, this hotfix has been mentioned and discussed in thread "Windows 7's resampling sucks" in March.

http://www.hydrogenaudio.org/forums/index....st&p=788882

Chris


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bennetng
post Aug 29 2012, 17:52
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After applying KB2653312 sound quality is MUCH better in MME applications.

I uploaded some test samples and video demo to show the artifacts before using the hotfix last year:
http://www.hydrogenaudio.org/forums/index....st&p=774695
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