Don't kill pulseaudio's mixer thread if it's already killed
Set a couple pulse callbacks to NULL during reset, and minor cleanups
Assert that there's a buffer for mixing

For Clang's static analysis.
Avoid duplicate calculations
Offset to the buffer's channel start first
Inline a couple functions
Do up to 256 samples at a time with multi-step loops
Set the right variable when assuming CPU extensions
Handle logging Unicode strings on Windows
Support capture with mmdevapi
Fix logging on Windows