ReadonlyfftReadonlyreferenceOptional ReadonlyreferenceHow many samples into its OWN PAST the reference window was read (omx_ring_read_at).
Absent or 0 is the ordinary reading: both windows taken at the same instant. A non-zero offset is how a LATE arrival is measured with the two windows still overlapping — see fitAlignment's "the offset is inside the answer". It rides on the FRAME rather than beside the run because a run averaged across two offsets is two measurements of two different things, and fitAlignment refuses that by shape rather than trusting a caller to remember.
ReadonlysampleReadonlytarget
One paired reading, both sides snapshotted in the same pass (the pair is the unit).