marfrit-packages/arch/mesa-panvk-bifrost-video

mesa-panvk-bifrost-video

Patched Mesa libvulkan_panfrost.so that adds VK_KHR_video_decode_h264 on Mali Bifrost SBCs (PAN_ARCH 6/7, RK3566/RK3568 class hardware), backed by the SoC's V4L2-stateless hantro VPU.

This is a sibling of mesa-panvk-bifrost (the r4 package that exposes Bifrost to Chromium's Vulkan compositor). Pick this one when the consumer wants Vulkan video decode in addition; pick r4 for compositor-only.

Status

Phase 4 byte-exact validated 2026-05-21: 48/48 unique BBB display frames decoded by this package are byte-identical to ffmpeg+libva-v4l2-request-fourier running on the same hantro hardware. Phase 5 second-model review completed; all load-bearing findings addressed.

How to use

# Co-installs alongside r4 and stock mesa.
sudo pacman -S mesa-panvk-bifrost-video

# Opt in (not on the default loader search path).
export VK_ICD_FILENAMES=/usr/lib/panvk-bifrost-video/icd.json
export PAN_I_WANT_A_BROKEN_VULKAN_DRIVER=1   # mesa-upstream gate

# Run a Vulkan video consumer.
vulkan-video-dec-simple-test -i your.h264 --codec h264 --noPresent --maxFrameCount 50
# or
ffmpeg -hwaccel vulkan -i your.mp4 ...

Phase 1 limitations

Documented in source comments and worth knowing before relying on this in production:

• Single video session per device. Concurrent VkVideoSessionKHR on the same device clobber each other (active_video singleton). Sufficient for current single-stream consumers.
• Synchronous decode at record time. The full V4L2 ioctl dance runs to completion inside vkCmdDecodeVideoKHR. No pipelining. Throughput is bounded by hantro's ~1.16× realtime on 1080p H.264.
• Hardcoded /dev/video1 + /dev/media0. Matches RK3566/68 but won't work on other SoCs without a topology-walk port (see libva-v4l2-request-fourier for the full version).
• Bitstream source buffer assumed HOST_VISIBLE. True on panvk-bifrost (no DEVICE_LOCAL-only memory types exist), but the code silently skips decode if the app bound the buffer to non-host-visible memory.

Co-existence

• Installs to /usr/lib/panvk-bifrost-video/ — parallel to r4's /usr/lib/panvk-bifrost/ and stock /usr/lib/.
• Opt-in via VK_ICD_FILENAMES; does NOT register itself in /usr/share/vulkan/icd.d/.
• Three drivers coexist without conflict; the user picks at runtime which to use.