Commit Graph
5 Commits
Author SHA1 Message Date
enricobuehler cdd1f3efce fix(vkdecode): AV1 is bit-exact — the bug was a use-after-free, not the driver
250/250 frames bit-identical to libavcodec on NVIDIA 610.57.04, and all four
other parity legs (H.264, H.265, Main 10, both four-byte-prefix twins) still
green.

session_av1 built the sequence header, handed pStdSequenceHeader to
vkCreateVideoSessionParametersKHR, and dropped the backing the instant the
call returned — on the documented assumption that Vulkan copies parameter
data before returning. NVIDIA does not. It keeps the pointer and dereferences
pColorConfig when a decode is RECORDED. The freed block became our own next
allocation, whose bytes read back as mono_chrome = 1, and a monochrome frame
skips exactly loop_filter_level[2..3] (AV1 7.14).

That is the whole fingerprint two earlier rounds chased: luma bit-exact,
chroma off by small amounts, and rewriting the chroma levels in the bitstream
changing nothing — the driver read them correctly and then discarded them,
because it believed the stream had no chroma. StoredParamsAv1 now holds the
parameters object and its Std backing in one value, so an object whose
backing is gone is unrepresentable.

The road there is worth recording, because two well-evidenced conclusions
were wrong before this one was right. A software oracle reproduced the
divergence exactly by disabling chroma deblocking, and a GPU probe showed
chroma levels [8,12] and [63,63] producing byte-identical output — which
looked conclusive and was not. libavcodec's own Vulkan AV1 hwaccel is
bit-exact on this same driver, which proved the hardware fine and the defect
ours. ffmpeg never hits it: with VK_KHR_video_maintenance2 it uses inline
session parameters and never creates a parameters object at all.

The proof is direct rather than inferred: a throwaway Vulkan capture layer
dumped both submissions and every byte of our AV1 picture info already
matched libavcodec's, including the loop filter block; only the session
parameters layer differed. Watching the block's address showed correct bytes
at create and our next allocation at decode.

Ruled out on hardware, so nobody re-tests them: filmGrainSupport,
maxCodedExtent, maxDpbSlots/maxActiveReferences, VkVideoDecodeUsageInfoKHR,
the tile-start sentinel, the setup slot's SavedOrderHints, a NULL
pTimingInfo, and heap luck.

Two earlier fixes are confirmed against libavcodec's captured wire bytes and
kept: CDEF secondary strengths carry the coded value rather than the spec's
in-place fixup, and LoopRestorationSize is log2-based. The refuted
driver-ignores-chroma-levels claim is corrected everywhere it was written
down, and that probe test now passes and points at the lifetime of everything
a submission points at before blaming a vendor.

⚠ Adjacent and NOT fixed: session.rs and session_h265.rs drop their Std
backings the same way, and those sets carry embedded pointers too. Both are
measured bit-exact on four drivers, so nothing is known to be wrong — but the
contract now rests on a driver behaviour measured FALSE for AV1 on a shipping
driver. The SAFETY comments asserting it have been corrected; the structure
is deliberately untouched pending its own pass.

Gates: macOS fmt/clippy/336 tests, container clippy -D warnings, all green;
8/8 gpu_parity and 3/3 gpu_smoke legs verified on the RTX 5070 Ti.
2026-08-07 00:39:34 +02:00
enricobuehler 96fc3eca10 test(vkdecode): the AV1 rung finally has pixels to answer to
A parity and smoke harness for AV1, mirroring the H.264 and H.265 legs that
proved those rungs bit-identical to libavcodec on four drivers before either
ran on glass. This was the milestone's largest test gap: the adversarial
review found four blocking defects in the AV1 conversion — flags unset on
274 frames of 274, a units error in LoopRestorationSize, per-reference info
describing the wrong picture, film-grain fields left zero — and every one of
them would have shown on frame 1 of a parity run, while clippy and 164 green
unit tests said nothing at all.

The golden is 250 per-frame SHA-256s in DISPLAY order, not 274. The vector
carries 274 coded frames in 250 temporal units; the 24 extras are hidden
ALTREFs, decoded and referenced but never shown, and the rung delivers what
dpb.outputs names. The count is re-derived from the planner rather than
assumed.

Cross-checked between ffmpeg 8.1.1 on macOS arm64 and 8.0.1 on Linux x86_64,
whose raw outputs are byte-identical — and then against a third party neither
build knows about: the vendored vector ships upstream's own per-frame MD5s,
and re-running those reproduces all 250. The golden agrees with a decode
nobody in this program performed. I reproduced both independently before
committing.

8-bit NV12, traced from the sequence header rather than presumed
(seq_profile 0, high_bitdepth 0, mono_chrome 0), so the P010 scar does not
apply here — and the header says which check to make if a Main 10 golden is
ever added. film_grain_params_present is 0, which is load-bearing: grain
synthesis is part of the Vulkan decode profile, so this golden is only
comparable against a grain-less profile key.

Anti-vacuity is the point of the exercise, so it is structural. The golden
guard asserts the exact count, that every line is a bare digest, and that all
entries are DISTINCT — 250 copies of one digest would let a decoder frozen on
a single frame pass parity. The parity body asserts the golden set and the
access-unit count before it touches hardware, so an IVF reader returning
nothing cannot become "0 frames compared, pass". The agent verified the
guards fire by mutating the golden three ways.

assert_bit_identical now names the FIRST divergent frame, which is what
localises a defect; that improves all six legs, not just AV1.

AV1 has no four-byte-start-code twin, deliberately: OBUs are
length-delimited, so there is no prefix for a driver to mis-skip. Documented
where a reader would otherwise see an omission.

Nothing here has run on a GPU. The harness exists precisely so the four
review defects can be answered by measurement instead of argument.
2026-08-06 22:38:04 +02:00
enricobuehler c91a482b4e test(vkdecode): the ten-bit path finally has pixels
Every golden set in this program was eight-bit. So the strongest thing anyone
could say about ten-bit decode was that a Main10 session BUILDS and streams
clean — which is not the same claim, and is exactly the shape of claim this
program has been burned by. A Main10 stream decoding to garbage logs just as
cleanly: HEVC Main10 on D3D11VA has no per-picture status query at all, and on
the Vulkan side the devices that matter report queryResultStatusSupport=false.
The HDR legs were measuring that the pipe ran, not that the pixels were right.

So: a Main10 vector and its goldens, and a ten-bit leg that runs them.

The vector is 50 frames of 320x240 HEVC Main 10 4:2:0 from libx265 — 48 KB,
generated by a command recorded in the golden file's header along with
everything else needed to regenerate it. The goldens come from libavcodec's
software decoder and were cross-checked between two independent builds on two
architectures (ffmpeg 8.1.1 Homebrew/macOS-arm64 and 8.0.1 Ubuntu/x86_64),
which agreed on all 50.

The goldens are P010, NOT yuv420p10le, and that distinction is the whole
reason this could have quietly gone wrong: P010 puts the ten bits in the HIGH
bits of each little-endian 16-bit word with the low six zeroed, which is what
a D3D11 P010 surface and Vulkan's G10X6_B10X6R10X6_2PLANE_420_UNORM_3PACK16
both contain. Hashing LSB-aligned samples against MSB-aligned ones would fail
on every frame on every driver, for a reason that has nothing to do with
decoding. One golden file therefore serves both native rungs.

The readback is now depth-aware. Its only eight-bit assumption was the second
region's buffer_offset, which is a BYTE offset where the extents around it are
TEXELS — that plus the buffer size are the whole change, because
bufferRowLength = 0 already packs rows at the copy extent. The expected pool
format moved onto the readback so the sizing and the per-frame assertion come
from one source; a readback sized for eight bits that then accepted a ten-bit
frame would hash half a picture and blame the decoder.

A CPU guard asserts the vector really is ten-bit — 4:2:0, both depths
minus8 == 2, 320x240, 50 access units, 50 planned outputs. Without it a
regenerated eight-bit vector would turn the ten-bit leg into a second run of
the eight-bit path wearing a ten-bit name, and it would PASS, because its
goldens would have been regenerated alongside it. That guard is not ignored,
so it runs on macOS and in the container rather than only on the fleet.

Hardware: HEVC Main 10 50/50 bit-identical on NVIDIA 610.43.03 (Linux) and on
the Steam Deck's RADV/VanGogh — first run on both, which also confirms the
P010/3PACK16 layout match rather than assuming it. The four eight-bit legs are
unchanged and still green on both boxes.
2026-08-06 13:32:31 +02:00
enricobuehler c985438db1 test(pf-bitstream): replay real host captures through the planners + HEVC goldens
M0's capture hook has been in since 119ec0dd with nothing consuming its
output. corpus_replay.rs is that consumer: point PF_CORPUS at an
au-<stamp>.<codec> capture and every AU walks back through the H.264 or
H.265 planner, asserting no errors and no warnings — a clean capture of
a healthy session must plan whole. Ignored by default (captures are
hundreds of MB and live outside the repo).

It earns its keep immediately. Captured on .173 against the live host
(NVENC, 2800x1260, ~30 s each, client-side codec pin only — no host
config touched):

  h265  1133/1133 AUs planned, 0 errors, 0 warnings
  h264  1514/1514 AUs planned, 0 errors, 0 warnings

The HEVC number is the point: it is the FIRST validation of the WP-1
h265 planner against real host output rather than the vendored
conformance vectors, and it lands before the client's HEVC rung exists
to produce on-glass evidence.

Two real-capture facts the harness had to learn, both from this run:
ending a capture means killing the client, so the final .idx line is
routinely half-written and the final AU's bytes may not all have landed.
Both are tolerated at the TAIL only — a malformed line anywhere else, or
a gap the data cannot cover mid-file, still fails loudly rather than
silently replaying a subset.

Also adds tests/data/test-25fps-h265.nv12.sha256: 250 per-frame NV12
hashes of the vendored HEVC vector from libavcodec's software decoder,
cross-checked frame-for-frame between two independent FFmpeg builds
(8.0.1 in pf-lxcheck2, 8.1.1 from Homebrew) — the sibling of the H.264
goldens, ready for WP-2's parity leg.

Gates: fmt clean; pf-bitstream clippy clean, 69 tests green (the replay
stays ignored in normal runs).
2026-08-06 01:08:50 +02:00
enricobuehler e6d6498a49 test(pf-vkdecode): frame-hash parity vs libavcodec — bit-exact on the whole fleet
WP-D parity A/B. gpu_parity (ignored) decodes the conformance vector,
reads every frame back through the presenter's exact contract (wait,
layout round-trip, signal-back, release), crops at the copy so pitch
can never leak, and compares SHA-256s in display order against goldens
from ffmpeg software decode — cross-checked bit-identical between
ffmpeg 8.0.1 (linux) and 8.1.1 (macOS), so the reference is the spec,
not one build. PF_VKD_TEST_READBACK=1 is the one test-only hook (ORs
TRANSFER_SRC into pool usage; production pools stay zero-copy-tight).

Fleet verdict: 250/250 frames bit-identical to libavcodec on RADV
(Mesa 26.0.3, distinct), AMD proprietary Windows (25.10.30.02,
distinct) and NVIDIA Windows (610.88, coincide) — H.264 decode is
exactly specified, and the native path meets the spec on every driver
and both DPB arrangements.
2026-08-05 20:23:18 +02:00