Mesa gates RADV's video-decode support — the VK_KHR_video_decode_* device
extensions AND the decode-capable queue family — behind
RADV_PERFTEST=video_decode (Steam Deck / VANGOGH included). Without it the
presenter's device advertises no decode queue, Decoder::new's auto chain
skips Vulkan Video, and the session silently lands on VAAPI.
punktfunk-session now appends the token to RADV_PERFTEST before the driver
loads (all streams run through this binary, so every launch path and package
is covered). RADV-only knob: other drivers ignore it, and a Mesa where
decode is already default just no-ops. Verified on the Deck: decode_qf=2,
H264/H265/AV1 caps, first frame path="vulkan-video", 90 fps at 1.9 ms decode.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
8bef4e27f9