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punktfunk/crates
enricobuehlerandClaude Fable 5 05868ef634 fix(encode): Vulkan-HEVC full-RPS reference retention + AV1 feature gate (RFI review)
2026-07-12 review of the host encoders / client decoders / RFI plane.
NVENC (both), AMF-LTR, the session glue, and the client RfiTracker came
out clean; every fix lands in the Vulkan Video backend + dispatch:

1. HEVC: author each P-frame's short-term RPS to retain ALL resident DPB
   pictures (minus the setup slot), not just its one reference. HEVC
   8.3.2 evicts unlisted pictures, and clients keep FEEDING the decoder
   while frozen — so with the old single-pic RPS, a conforming parser
   (FFmpeg = the Linux VAAPI/Vulkan and Windows D3D11VA clients) had
   already discarded the picture an RFI recovery anchor references
   whenever a fed post-loss frame preceded it: generate_missing_ref, and
   the "clean" anchor plus everything chained after it decodes as
   garbage. Pure builder (`build_h265_rps_s0`) + unit tests; AV1 needs
   nothing (slot-based retention). The smoke test now encodes a fed
   post-loss frame between loss@4 and anchor@6 so an ffmpeg decode of
   the dropped dump exercises exactly this (expect ONE POC-4 complaint,
   never POC 3) — revalidate on the AMD box; this NVIDIA dev box fails
   the backend earlier at HEVC header retrieval (pre-existing).

2. AV1: chain PhysicalDeviceVideoEncodeAV1FeaturesKHR (videoEncodeAV1 =
   TRUE, stype 1000513004) into device creation — spec-required for the
   ENCODE_AV1 codec op; RADV tolerated the omission, validation layers
   and stricter drivers do not.

3. RFI decline no longer self-arms force_kf — that bypassed the session
   glue's 750 ms IDR cooldown, turning a storm of hopeless RFI requests
   into one full IDR each. Decline like NVENC/AMF and let the caller's
   coalesced keyframe path own the fallback; add the missing
   first>last guard for parity.

4. open_video_backend now returns the label of the branch that ACTUALLY
   opened, so the mgmt API / web console reports "vulkan" instead of
   "vaapi" for the default-on Vulkan sessions (the old dispatch-mirror
   resolved_backend_label went stale when the backend gained its VAAPI
   fallback; deleted).

Structure: the ~230-line inline HEVC coding block moves to
record_coding_h265 (symmetric with record_coding_av1) and the duplicated
pre-encode barriers dedupe into begin_encode_cmd.

Follow-up plan (separate, punktfunk-planning): bring the post-loss
freeze + RECOVERY_ANCHOR/POINT lift to the Android/Windows/Apple clients
via a shared ReanchorGate (design/client-reanchor-freeze-parity.md).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-07-12 23:12:12 +02:00
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