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Modified VoodooHDA 2.7.3: No noise, pops, 192kHz sample rate

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Joined
Dec 3, 2010
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Motherboard
Gigabyte GA-H55M-S2V
CPU
Intel i3-530
Graphics
HIS HD 6570
Mac
  1. iMac
Mobile Phone
  1. Android
After a lengthy battle trying to get audio to "just work" on my Lion upgrade, I settled on compiling my own version of the latest VoodooHDA kext as a Lion 64bit kext (very few choices for 888b users) with a couple modifications. My issues were:
  • Noise at load from iGain=90
  • Sample and bit rates always set to maximum causing pops, overlaps (fixable with Audio MIDI Setup until reboot)
  • Unused HDMI chosen by default
  • Low volume
A couple of these were fixed with Info.plist edits, but the sample rate was the worst as my system struggled to output 192kHz audio in time with video/animation. Instead, this extension automatically chooses the lowest sample and bit rate, usually 44.1kHz and 16bit. What I wanted was a kext I could install that would "just work", so I'm posting it here in case others (especially 888b users!) would like it. I also hated the bulk of the PrefPane which Multibeast doesn't allow you to leave out.
For users with unused HDMI audio, change the Info.plist entry "IOPCIClassMatch" to "IOPCIPrimaryMatch" and enter your device id + vendor id (my 888b was device 3B56 vendor 8086, which is Intel, for an entry of 0x3B568086). This forces the kext to focus only on your audio card, and leave out HDMI audio (which would have been selected by default). Example:
Before said:
<key>IOPCIClassMatch</key>
<string>0x04030000&amp;0xffff0000</string>
After said:
<key>IOPCIPrimaryMatch</key>
<string>0x3B568086</string>
I'm also posting the (slightly) modified source for those curious.

--edit
Both the source and binary have been updated for Lion 10.7.4 using LLVM-GCC 4.2
--edit
The rebuild wasn't strictly necessary for 10.7.4, but if you're getting KPs at boot, remove/disable the new AppleHDA.kext from /S/L/E, and clear the Extension cache.
--edit
The minimum sample rate has now been clipped to 44.1kHz, which just about every sound card since the 90's can handle. Any users experiencing 22kHz, or any other rate under 44.1kHz should try this new version.
--edit
Now releasing a rebuilt project with the same source files, fixed all warnings, etc, for both Mountain Lion and Lion 64bit.
 

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Does aggregate work? Or are you only getting 2 channel output? Just wondering if I should give this a shot as I already have 2 channel output.
 
It's the "multichannel" branch, i.e. 2.7.3, if that makes a difference. My setup is just stereo monitor speakers, but aggregate devices appear to work in AMS.
 
Where do I find my device and vendor ID's? And would that help in recognizing my outputs? I'm getting 4 HDMI digital-outs, a line-out (green rear), headphones (green front), microphone pink rear and pink front.
 
if you're actually using a GA-H55M-S2V, it should be the same as mine, otherwise an app like DPCIManager would give you a full readout.
 
hmm.. and you're using onboard audio or a sound card? What readout are you getting?
 
GA-H55M-S2V onboard ALC888b which is 0x3B568086
 
Seems to work great, thanks very much.. Ill do a few restarts and see if my settings stick
:)

Update: so now the issue is that it defaults to 8000Hz so everything sounds like its down a telephone :)

Is there a way to get it to stick at 41400.00HZ?
 
All I did was reverse the normal bitrate detection mechanism, to choose the lowest rate which is normally 44.1kHz, but if your audio supports a lower one, that will be selected. If you want it to stick to 44.1kHz, I suggest you edit the source manually.
 
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