Direct-SDK AMF encoder (encode/windows/amf.rs), the AMD analogue of the
direct-NVENC path, replacing the libavcodec *_amf dispatch. C-vtable FFI
pinned to AMF headers v1.4.36, runtime-loaded from the driver's amfrt64.dll
(no build feature, no new dependency) exactly as NVENC loads its DLL.
- AVC/HEVC (SDR NV12 + 10-bit HDR P010) and AV1 (RDNA3+, probed); a bounded
poll retires the libavcodec ~2-frame output hold; native in-place reset().
- Intra-refresh wave (PUNKTFUNK_INTRA_REFRESH), in-band HDR mastering/CLL
metadata (*InHDRMetadata -> HEVC SEI / AV1 OBU), and a native codec probe
feeding the GameStream advertisement (windows_backend_is_ffmpeg ->
windows_backend_is_probed).
- AMD dispatch / advertisement / 4:4:4 are native-only; the libavcodec AMF
fallback and the PUNKTFUNK_AMF_FFMPEG hatch are removed. FFmpeg serves QSV
only (its AMF path retained solely as the latency A/B comparator).
- Overload back-pressure: submit bounds in-flight surfaces below the input
ring, draining finished AUs (buffered for poll, FIFO-preserved) to free a
slot and retry on AMF_INPUT_FULL instead of tearing the encoder down and
forcing an IDR; this also closes a latent ring-overwrite corruption seen
under load on-glass.
Validated on the lab Ryzen iGPU (AMF runtime 1.4.37): HEVC/AVC across a
native reset, HEVC Main10 mastering+CLL SEIs byte-verified, intra-refresh
accepted, a backpressure burst FIFO-clean, and end-to-end via the macOS
client. Measured §5.2 latency A/B: native encode_us p50 ~5 ms (0.31 frame
periods) vs libavcodec ~17 ms (1.01). 4:4:4 stays unsupported (VCN hardware
limit). Live-gated tests skip cleanly on non-AMD boxes.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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