Audio flows in MXL use mxlFlowWriterOpenSamples/CommitSamples, not
the grain API (mxlFlowWriterOpenGrain is for discrete video flows).
Using the grain API silently did nothing — hence "last published index: 0".
MXL audio is float32 planar: each channel occupies its own ring buffer
region accessed at base.fragments[*].pointer + c * slice.stride.
Two fragments handle ring buffer wraparound. No int32 conversion needed.
Also log continuous.channelCount/bufferLength instead of the discrete
sliceSizes field (wrong union member for audio).
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
JohannesItten
aa39a821db