briankendall
commented
5 months ago There's not too much domain knowledge I can impart. The way I've been doing logging -- and mind you this is probably not the best way to do it -- is to open Console and filter it for the string "proxyaudiodevice". Debug builds of the HAL driver will print to the console (see any place in the code where DebugMsg is used) and I set up every log statement to include that bit of text so it's easy to filter for.
I've been using the following shell script to copy in new builds of the driver and reload CoreAudio each time I make a build:
#/bin/bash
rm -rf /Library/Audio/Plug-Ins/HAL/ProxyAudioDevice.driver
cp -rf ./DerivedData/proxyAudioDevice/Build/Products/Debug/ProxyAudioDevice.driver /Library/Audio/Plug-Ins/HAL
launchctl kickstart -k system/com.apple.audio.coreaudiodBear in mind I have Xcode configured to put the DerivedData directory in the root of my project folder, so modify that path to the build products as necessary.
If you can find out anything about why things keep going out of sync, that would be great! I've sunk hours into trying to figure out this issue and didn't make any progress. I feel like I'm missing something basic, but I myself don't have that much experience working with CoreAudio and HAL plug-ins (this project is literally the extent of it) so I easily could be doing something wrong that someone with more experience would be able to spot quickly.
Most of my investigation was in ProxyAudioDevice::outputDeviceIOProc() since that's where the desync happens. I put in tons of print statements to notify when the number of samples that are left in the ring buffer gets smaller than the previous cycle, and can just watch it slowly run out until audio stops working. I haven't been able to figure out what configurations are the trigger either.
Can you say more about what your configuration is that causes the sync issue to happen within five minutes?
I don't think I'll have any time for live sessions all that soon -- both my work and personal life keep me plenty busy right now. But I'll try to assist you however else I can and answer any questions.
za-creature
First off, a big thank you @briankendall for this awesome piece of hackery. I've had this issue since about 2018 and it's surprising to me that digital volume control is still not supported natively by Apple. I've been using your code since I found out about it (was previously using another solution that stopped working sometime around Catalina iirc), mostly successfully.
Regarding #14 and #19, I've recently stumbled upon a setup that goes out of sync after <5 minutes instead of hours. Not sure what's causing it, but I'll refrain from making any system changes for at least a week or so to give you some time to answer. I can confirm this behavior with both latest version and an older one (1.0.5)
I cloned and built both driver and config app locally and I sort of know what I'm doing but I haven't worked all that much (read: at all) with HAL or other Mac specific driver code so I'd most likely need some support here.
I'm fairly flexible about how to go about this: we can set up a live session (including, if you want, granting you supervised access to my machine) or we can go back and forth via text here. I'm primarily interested in domain knowledge, such as how to quickly deploy builds from xcode into the running kernel, where to collect logs from, etc.
Let me know when you have some availability. If need be, we can exchange credentials here using a DH exchange (disclaimer: I wrote the above)