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Dec 14, 2016
dual w5580
dual r9270

Not sure if this is the right place for this post, seeing that I have an actual MacBook Pro (MacBookPro13,2).

I'm trying to do some experimentation with the 'DSPFuncLib' (or something similar, forgot what it was called) included in AppleHDA. The provided layouts which I assume are for my computer model appear to instantiate a long chain of effects in the layout xml file and I'm wondering if it would be possible to change or edit this file to change the effects applied to the output.

Right now, from the file, it looks like there are multiple stages of dynamic range compression/volume levelling applied. This has the result of actually causing clipping when there is a sudden peak in the audio input signal, when played through the internal speakers. The path layout of the headphone port doesn't have these 'features', so the output signal is as expected.

In particular, for now, I simply want to experiment with removing some blocks of the signal chain.

I'm wondering about a few things that I couldn't find a good way to do:
1) How to identify which pathmap/layout is currently in use by the system
2) Tips on editing the layouts, keeping current port layouts intact and modifying the DSPFuncLib parts
3) How to pack the layouts back into the kext
4) How to reload the kext (when I tried, it wouldn't load. Loading manually or on startup doesn't work, and I have tried disabling SIP and/or removing the signing).
5) How to restore the original kext without reinstalling the OS (moving a backup back or renaming the backup still results in failure to load/system not detecting any audio devices)

Any help or direction would be greatly appreciated

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