Change #275176

Comments

avcodec/aacpsy: sync block switching across channel pairs
Implement the window_pair() hook: detect both channels of a CPE, then
decide together - if either channel attacks, both switch, with one
merged attack map so the grouping matches across the pair and
common_window survives transients. Pairs the encoder has flagged as
decoupled (joint tools dead) keep independent per-channel decisions,
where forcing the steady channel short at every event in the other
only costs quality.

Attacks must also be NOVEL against the trailing high-pass max-envelope:
a steady pitch-pulse train repeats its peak every period and re-fires
the ratio test forever, producing long false short runs on periodic
content (low brass and the like); a genuine onset towers over the
recent past.

The pre-echo threshold relaxation for gentler isolated onsets is kept,
and START frames entering a short sequence clamp their thresholds
toward the previous long frame's per-band values on the mapped long
grid.

Changed files

• libavcodec/aacpsy.c