Commit Graph
8 Commits
Author SHA1 Message Date
enricobuehler d25a20a233 feat(vkdecode): the AV1 rungs meet a second tile for the first time
Every AV1 frame either decode rung has ever been measured against is `tile_cols =
tile_rows = 1`. The vendored vector is single-tile on all 274 of its frames, so every
tile array the conversions fill — `tiles.widths`, `tiles.heights`, the per-tile records
— had only ever been written at index 0, and a conversion that wrote tile 0 and left
the rest zero would pass the whole suite. Our encoder splits 4K into TWO TILE ROWS.

**The fixture.** `lowdelay-3840x2160.ivf.av1`, 261 KB, 60 frames — `punktfunk-host
spike --source synthetic --codec av1 --width 3840 --height 2160 --fps 60 --seconds 1
--bitrate 1` on .21 (NVENC, RTX 5070 Ti), wrapped to IVF with `ffmpeg -f obu … -c copy`
so `common::split_av1_aus` (the vendored parser's own `IvfIterator`) frames it exactly
as it frames the vector, with no second splitter that could disagree.

**4K is not a size choice, it is the only shape with the property.** Measured on the
same box with the same command: 1280x720, 1920x1080 and 2560x1440 all give `tile_cols =
tile_rows = 1`; 3840x2160 gives `tile_cols = 1, tile_rows = 2` with
`width_in_sbs_minus_1 = [59]`, `height_in_sbs_minus_1 = [16, 16]`, and both tiles in ONE
Tile Group OBU. 60 frames instead of 120 pays for the resolution: 261 KB, under both the
282 KB H.264 and 270 KB H.265 low-delay fixtures.

Goldens are libavcodec's software decode, cross-checked between ffmpeg n8.1.2 (Arch
x86_64, libdav1d) and 8.1.1 (Homebrew, macOS arm64, libdav1d) whose 746,496,000-byte raw
outputs are BYTE-IDENTICAL, not merely equal per frame. 60 of 60 digests distinct.

**AV1's frame accounting is asserted, never derived.** The vendored vector is 250
temporal units carrying 274 coded frames of which 24 are hidden; this stream is 60 units,
60 coded, 60 shown, 0 hidden, 0 `show_existing_frame`, 1 key frame. Neither is the
general case, so both parity harnesses now take units / decoded / shown as three
independent parameters instead of computing one from another, and the CPU guard states
all six numbers.

**A CPU gate that needed no hardware at all.** `pic_av1`'s new
`a_two_tile_frame_fills_both_row_entries_and_leaves_the_rest_zero` pins the second row
entry against its OWN `height_in_sbs_minus_1`, requires the two rows to tile the frame
exactly, and requires TWO tile RECORDS out of ONE tile group with rows (0,0) and (1,0) —
the transposition a square grid could never reveal — each spanning real bytes. The
existing one-tile test asserts index 0 is right and `1..` are zero, which a broken
multi-tile conversion also satisfies.

⚠⚠ **This is a file, and on AV1 that distinction has already cost a release.** "250/250
delivered frames bit-identical to libavcodec" was true for the entire period the host was
shipping only the FIRST TILE of every 4K frame: the verification ran against a vendored
file while the truncation lived in packetisation, and the suite stayed green throughout.
This fixture closes the multi-tile gap on the DECODE rungs and closes nothing about
fragmentation, reassembly, loss or AU boundaries — the golden header, both module docs
and the leg docs all say so, at length, so the next reader does not inherit the same
false confidence.

Legs: `low_delay_host_av1_every_frame_hashes_bit_identical_to_libavcodec` on the Vulkan
rung (11 ignored legs now) and on the D3D11VA rung, plus two non-ignored CPU tests.

Verified: 11/11 Vulkan parity legs on .21 (RTX 5070 Ti, 610.57.04), the new one 60/60
bit-identical; workspace clippy `-D warnings` and `cargo fmt --all --check` clean on .21.
2026-08-07 23:09:12 +02:00
enricobuehler f0702f3e06 feat(vkdecode): HEVC's exemption stops being an argument and becomes a vendored stream
`fd6241a2` made HEVC's freedom from the release-ordering defect falsifiable on CPU and
recorded what was still missing: no low-delay HEVC stream was vendored, so the exemption
rested on a structural argument plus one throwaway measurement. This vendors the stream,
and the exemption HELD.

**The fixture.** `lowdelay-640x480.h265`, 270 KB, 120 pictures — `punktfunk-host spike
--source synthetic --codec h265 --width 640 --height 480 --fps 60 --seconds 2 --bitrate 1`
on .21 (NVENC, RTX 5070 Ti, driver 610.57.04). Deliberately the H.264 sibling's resolution
and frame count: the two are then directly comparable, 640 and 480 are both multiples of
MinCbSizeY so there is no conformance window and a hash mismatch can only be decode rather
than readback geometry, and 270 KB sits alongside the 282 KB already accepted for H.264.
Goldens are libavcodec's software decode, cross-checked BIT-IDENTICAL across ffmpeg n8.1.2
(Arch, x86_64) and 8.1.1 (Homebrew, macOS arm64), 120 of 120 digests distinct.

**The exemption held, measured rather than argued.** `sps_max_dec_pic_buffering_minus1 = 4`
against the four pictures 8.3.2 keeps marked in steady state, `sps_max_num_reorder_pics = 0`,
`numRefL0 = 1` — a five-picture DPB filled exactly by four references plus the current
picture. 115 of the 120 access units retire a picture, and `removed ∩ dpb_refs` is **0 of
120**. A 300-picture 1080p stream from the same host reports the same shape: 295
retirements, 0 intersections. It is the encoder and not the resolution, exactly as for
H.264.

**A zero proves nothing on its own, so the fixture is pinned by its counterfactual.**
`test-25fps.h264` reported zero for two milestones while every stream we ship aliased on
99% of its frames. So the guarantee here is not "we looked and it was fine": hand
`plan_to_dxva_h265` the marked DPB as it stood BEFORE `decode_rps` — the mutation a
snapshot move would cause, reconstructed exactly as `dpb_refs(N-1) ∪ {stored(N-1)}` — and
the alias appears on **115 of 120** access units, driven through the real conversion rather
than through planner arithmetic. If a regeneration ever produced a stream that reordered,
or a DPB deeper than its reference count, that 115 collapses to 0 and the tests say so
instead of continuing to pass.

**The two rungs are exempt for different reasons, and the asymmetry is now a gate.** DXVA
binds the whole marked DPB — `RefPicList` is spec-defined that way, and an RFI long-term
anchor has to survive in it — so its exemption really is `H265Planner`'s snapshot ordering,
one call away from being untrue. `plan_to_vk_h265` never reads `dpb_refs` at all:
`pReferenceSlots` is the slots the operation uses, so it binds the current RPS sets, which
`decode_rps` itself derives and which therefore cannot name a picture that same RPS just
dropped. A new test feeds that conversion the identical widened snapshot and asserts
nothing changes, so a future change making the Vulkan rung bind the marked DPB — a
legitimate thing to want, since a *Foll* anchor invisible to the hardware is the RFI
failure shape — fails loudly instead of silently acquiring the defect.

What the Vulkan pixel leg adds is therefore NOT aliasing coverage, and its docs say so:
it is the first HEVC frame either rung has decoded from our own encoder, under a DPB that
retires and reissues a slot on 115 of 120 access units back to back, where the vendored
vector's reordering keeps that eviction slack.

Legs: `low_delay_host_h265_every_frame_hashes_bit_identical_to_libavcodec` on the Vulkan
rung (10 ignored legs now, up from 9) and on the D3D11VA rung, plus three non-ignored CPU
guards that run in ordinary CI.

Verified: 10/10 Vulkan parity legs on .21 (RTX 5070 Ti, 610.57.04), the new one 120/120
bit-identical; workspace clippy `-D warnings` and `cargo fmt --all --check` clean on .21.
2026-08-07 22:53:22 +02:00
enricobuehler 834b244301 fix(client): the H.264 twin was real — every low-delay picture decoded into a surface it predicted from
The AV1 review round flagged the H.264 leg as "plausibly the same defect, traced in
source, not reproduced" and deliberately did not touch it. It is reproduced now, and
it is worse than the AV1 one: it fires on 297 of 300 access units of every stream a
punktfunk host emits, at 720p, 1080p and 2160p alike, on BOTH the DXVA rung and the
Vulkan one.

**Decided on the CPU, no GPU needed.** `H264Planner` snapshots `dpb_refs` in
`begin_picture`, BEFORE `finish_picture` runs 8.2.5's marking and C.4.5.3's bump, so a
picture the sliding window unmarks and the bump then evicts lands in both `dpb_refs`
(which `RefFrameList` is built from) and `dpb.removed`. The conversion released the
whole `removed` list and then assigned the decode target a slot; `SlotMap::assign`
takes the lowest free slot, which is the one just vacated. `CurrPic = N` and
`RefFrameList[k] = N`, in one submission.

The two conditions have to coincide in ONE access unit, and low-delay H.264 is exactly
what makes them: `max_num_reorder_frames = 0` means the evicted picture has already
been output, which is what makes it evictable at all. NVENC seals it by writing
`max_num_ref_frames = 3` ALONGSIDE `max_dec_frame_buffering = 3` — a DPB exactly as
deep as its reference count — so the window unmarks the oldest reference in the very
unit whose bump drops it. The aliased picture is `ref_idx 2` of a three-entry
`num_ref_idx_l0_active` list: addressable by any macroblock, not a spare.

**Why two hardware-proven codecs and four GPUs never saw it.** `test-25fps.h264` is
level 1.3 with no VUI `bitstream_restriction`, so `dpb_limit` falls back to A.3.1's
level ceiling and gives a 7-frame DPB against 2 reference frames — the window unmarks
two units before the bump can evict — and it REORDERS, which keeps an unmarked picture
alive past the unit that unmarked it. Two independent reasons, both properties of that
vector rather than of H.264. It measured zero and passed 250/250 throughout.
`data/lowdelay-640x480.h264` is vendored to close exactly that: our own host's output,
120 pictures, goldens from libavcodec cross-checked bit-identical across two ffmpeg
builds on two architectures.

**The fix is the AV1 fix.** `DecodePlanDxva` and `DecodePlanVk` grow
`release_after_decode`, the conversions hand the removals back instead of applying
them, and the callers release them once the decode op is issued. It costs no slot the
map does not have: `SlotMap::new` allocates `max_dpb_frames + 1` and the DPB never
exceeds `max_dpb_frames`, so a free slot always exists with the whole `removed` list
still held — measured, peak 4 of 4 on the stream that defers on 117 of 120 units.

The Vulkan rung breaks on it in both DPB modes and neither loudly: DISTINCT hands the
aliased reference the same array layer the setup writes; COINCIDE clears
`slot_image[setup]` in the binding sync and the reference then resolves to no bound
image, dropping out of `pReferenceSlots` with a `trace!`. Its deferred release runs on
the FAILURE paths too — the fallible region's Result is held rather than `?`-ed,
because seven exits sat between the conversion and the release and each would have
leaked a slot.

`a_full_dpb_bump_reuses_the_slot_but_the_pool_model_binds_a_fresh_image` asserted the
aliasing as "the planner's normal behaviour": an authored depth-1 stream whose AU1
references the picture it evicts. It now asserts the opposite, which is the defect in
two lines.

New evidence, all of it runnable: the CPU proof pins BOTH numbers (0 on the vector,
117 of 120 on the low-delay stream) so neither can drift silently; the ledger-pressure
test measures the peak; and a low-delay parity leg is added to `pf-vkdecode`'s
`gpu_parity` and `pf-client-core`'s `video_d3d11_native::parity` so both rungs are held
to what they stream rather than only to what they conform to.
2026-08-07 22:09:44 +02:00
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