forked from unom/punktfunk
enricobuehlerandClaude Fable 5
40030e90c8
Intel's Windows driver advertises Vulkan Video (Arc drivers since 2023), so the capability gate alone no longer keeps Intel off FFmpeg-Vulkan — and that combination is broken in the field (B580 report: strobing + 7.2 ms p50 decodes at 4K120) and on glass (Arc Pro iGPU: 29-33 ms p50 decodes at 4K60 where D3D11VA does 2.5 ms on the SAME GPU). Mirror the Linux vendor order on Windows: NVIDIA/AMD keep Vulkan Video first, Intel/unknown take D3D11VA first; vulkan stays reachable by explicit preference and as auto's fallback. Also: - Vulkan→D3D11VA mid-session demotion rung (the Windows analog of Linux's Vulkan→VAAPI rung) — a failing Vulkan backend lands on hardware, not on software, which cannot survive 4K120. - The demotion streak now needs 1 s of age as well as 3 consecutive errors: a startup loss burst produced 3 errors in 20 ms and stranded the session on software decode (one-way) before the IDR requested on the first error could possibly arrive — live-hit on the Intel iGPU leg. - Stale "Intel's Windows driver has no Vulkan Video" comments corrected, docs updated to the per-vendor order, vendor-order test extended with discrete/iGPU Arc cases. Verified on an Arc Pro iGPU + RTX 3500 Ada laptop against a CachyOS/NVENC host: auto now picks d3d11va on Intel (60 fps, 2.5-2.8 ms decode, e2e 26 ms vs 50 ms before) and still picks vulkan on NVIDIA. 27/27 pf-client-core tests, clippy clean. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>