The third planner in this crate, and the foundation every AV1 rung will
consume. Same contract as its H.264 and H.265 siblings: an access unit in, a
plan out, with the vendored cros-codecs parser reading the bitstream and this
module owning the reference ledger, the output bookkeeping and the
concealment posture.
AV1's reference model is simpler than H.264's and entirely explicit — eight
numbered slots, `ref_frame_idx` naming what a frame reads and
`refresh_frame_flags` naming what it writes — so the planner is bookkeeping
rather than derivation, and a frame naming an empty slot is a lost reference
with no spec process that might legitimately have emptied it.
Two things measurement changed, both before a line of backend code depends on
them.
`plan_au` returns a VECTOR. An AV1 temporal unit may carry several frames,
and the vendored vector does: 250 units, 274 frames, 24 units carrying two.
Measured, those 24 extras are not `show_existing_frame` (there are none in
this vector) but HIDDEN frames — decoded, never displayed, referenced later.
A planner that took the last header in each unit would have decoded 250
frames and silently dropped 24 REFERENCES, and the damage would have
surfaced as missing-reference concealment on frames that were never damaged.
A picture is not removed until its LAST slot goes. One picture routinely
occupies several slots at once — a key frame refreshes all eight — so a slot
being overwritten does not mean its picture is gone. Reporting it removed
would free a surface under a live reference, which is precisely the shape
this program exists to catch. Tested directly, and asserted to report once
rather than once per slot.
What this does not cover is written down rather than left to be assumed: the
vector uses `show_existing_frame` zero times, so the display-only path and
its key-frame slot reset are exercised by no test here, and the test asserts
that count is zero so the day it changes the claim gets revisited.
Per-backend conversions are deliberately absent. Vulkan, DXVA and libva
disagree about what a reference list indexes — the disagreement that made
HEVC unplayable on every driver — so each belongs beside its siblings in
pf-vkdecode / pf-dxvadec / pf-vaadec, where its own convention is written
down and tested.
Gates: macOS fmt/clippy/344 tests, container clippy -D warnings over six
crates, 799 tests, workspace check.
enricobuehler
7f83ec6c2f