forked from unom/punktfunk
enricobuehler
5d1556132e
The blocker on this rung was never the code — it was that `dxva.rs` is the most safety-critical file in the backend and nothing in it is type-checked against Windows, so M5's layouts only became trustworthy once a libavcodec byte capture had verified them field by field. AV1 turns out not to need that capture: `DXVA_PicParams_AV1` ships in the Windows SDK's OWN `dxva.h` (10.0.26100.0 and 10.0.28000.0 on .173), which is the declaration the driver was compiled against and therefore outranks any mirror. So `layout-probe-av1.c` is committed beside pf-vaadec's probe, compiled with MSVC against that header on .173, and every number below came out of it: DXVA_PicParams_AV1 is 912 bytes with alignment 1, PicEntry 36, Tile 16, and each offset is a compile-time assertion. The nested blocks are asserted through their own types too, so a wrong internal layout cannot hide behind a right outer one. Every assertion passed on the first build, which is the result worth having: the transcription and the compiler agree. The bit-field words are measured, not assumed. C bit-field allocation order is ABI-defined rather than standardised, so the probe sets one member at a time and prints the word, and the tests check each packer against what MSVC produced — tx_mode at bits 22-23, reference_frame_update at 26, film grain's sixteen-bit word with matrix_coeff_is_identity at 12, and so on. Two places AV1 puts things where the other two codecs would not, both now written down where a conversion will read them: Global motion is per REFERENCE, inside DXVA_PicEntry_AV1 — where Vulkan hangs one global-motion block off the picture info. A conversion carrying the Vulkan shape across would leave every warped reference at identity. CDEF strengths are packed two-to-a-byte, primary in the low six bits and secondary in the top two, where both the AV1 syntax and Vulkan's Std block keep parallel arrays. A zeroed block names NO reference: 0 is a valid surface index, so a memset-style default would quietly point every unused reference at surface 0, which decodes, and decodes wrong. Gates: macOS fmt/clippy/347 tests, container clippy -D warnings over six crates, 802 tests, workspace check.