Foundation for hardware video decode in BOTH preview and export: wgpu textures
can't cross devices, and a hardware-decoded frame is a DMA-BUF-imported texture
that needs the import extensions (only addable via wgpu-hal device_from_raw). So
eframe + the compositor + decode + encode must share ONE custom device.
- vk_device::create_windowed(): the existing import-capable DrmDevice plus
VK_KHR_swapchain (the WSI surface instance extensions are already enabled by
Instance::init), for use as the editor's main device.
- main.rs: on Linux, build the shared device and inject it into eframe via
WgpuSetup::Existing (the egui fork supports it); fall back to wgpu's normal
device + software decode on any failure, on other platforms, or via
LB_NO_SHARED_DEVICE. The DrmDevice's wgpu handles are cloned into eframe
(Arc-backed), so the VkDevice persists with them.
Runtime-verified: the editor launches and renders identically (canvas/vello,
video, panels) on the shared device, and the env-var fallback works.
Headless decode primitive, the mirror of the encoder: VaapiDecoder opens a file,
hardware-decodes H.264 into VAAPI NV12 surfaces (hw_device_ctx + a get_format
callback selecting AV_PIX_FMT_VAAPI), maps each surface to a DRM-PRIME DMA-BUF,
and imports it as two wgpu plane textures via the existing dmabuf::import_raw —
the same path the encoder uses, in the read direction. Frames stay GPU-resident
(no CPU copy).
Validated by a round-trip test: encode solid gray with ZeroCopyEncoder, decode
it back, read the Y plane (mean ≈ 128). All 9 crate tests pass on the container's
Intel GPU.
Next (Stage 3): wire this into VideoManager/get_frame so the compositor consumes
a GPU texture directly (no write_texture upload), with software decode fallback.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
The zero-copy VAAPI encoder emitted full-range BT.709 NV12 but wrote no color
tags, so players assumed limited range and stretched it — the H.264 output
looked dark and oversaturated (preview and VP9/software were fine).
- Rgba2Nv12 takes `full_range` and applies the matching Y/chroma scale+offset
(limited 16-235 / full 0-255) via a uniform; the encoder sets color_range +
bt709 colorspace/primaries/transfer tags to match. ffprobe-confirmed.
- New ColorRange { Limited, Full } on VideoExportSettings (default Limited, the
universally-correct choice; serde(default) so saved settings still load),
surfaced as a "Color range" dropdown in advanced export settings for H.264.
The swscale software fallback still emits Limited regardless of the toggle
(Full only affects the VAAPI zero-copy path).
Three fixes found while running the zero-copy export on real Intel hardware:
- vaapi::create_device() retries LIBVA_DRIVER_NAME in order iHD -> auto ->
i965 -> radeonsi. libva was auto-selecting the legacy i965 driver, which
fails on newer Intel GPUs; the modern iHD (intel-media-driver) is needed.
encoder.rs now builds its hwdevice through this helper.
- vk_device: request the adapter's full limits instead of downlevel_defaults.
Vello's compute pipelines need max_storage_buffers_per_shader_stage >= 5
(downlevel caps at 4), which panicked Vello's shader init on the export
device. This device only ever runs on a real VAAPI GPU.
- ZeroCopyEncoder: unsafe impl Send. It owns its FFmpeg/Vulkan handles
exclusively and is only moved (onto the export thread), never shared.
ZeroCopyEncoder::new now takes an output path and writes a real container
(format inferred from the extension, e.g. .mp4): create an output format
context, add the h264 stream from the encoder, write header; encode_rgba
rescales each packet's ts and av_interleaved_write_frame's it; finish
flushes + writes the trailer + closes. Sets AV_CODEC_FLAG_GLOBAL_HEADER for
mp4/mov so SPS/PPS land in extradata. This lets the editor's existing
mux_video_and_audio consume the temp video file unchanged.
The zerocopy_encode test now writes a .mp4 and ffprobe-verifies the codec,
dimensions, and frame count. Also let wgpu own the imported plane-image
destruction via texture_from_raw drop callbacks (clears two warnings).
Build the full end-to-end zero-copy encoder, validated on Intel/VAAPI:
- render_nv12: fragment-shader RGBA->NV12 that renders luma/chroma into
the imported R8/RG8 plane render targets (compute storage can't write
the DMA-BUF-backed planes; render attachments can).
- dmabuf: import_raw imports an NV12 DMA-BUF by explicit layout; the two
plane images + shared memory are now destroyed by wgpu via texture_from_raw
drop callbacks (Arc MemoryGuard frees the memory once both images are
gone, in wgpu's wait-idle'd deferred pass) -- fixes the teardown segfault.
- encoder::ZeroCopyEncoder: renders an RGBA texture straight into a pooled
VAAPI surface (imports cached by VASurface id) and encodes with h264_vaapi.
encode_rgba + finish; the caller renders on device().
Tests: real-frame render into the surface matches the CPU NV12 reference,
and a 30-frame encode produces valid H.264 (ffprobe-verified) with clean
teardown. Not yet wired into the editor.
New workspace crate isolating the unsafe GPU<->encoder interop for
zero-copy hardware video encoding. Every link is validated by a test on
real Intel/Mesa/iHD hardware:
- nv12: GPU RGBA->NV12 compute (BT.709 full-range), byte-exact vs a CPU
reference.
- vaapi: VAAPI hwcontext + h264_vaapi encode (CPU-fed NV12 -> valid H.264),
and DRM-PRIME surface layout probing.
- vk_device: a custom wgpu Vulkan device that adds
VK_EXT_image_drm_format_modifier (+ external-memory fd/dma-buf) via the
wgpu-hal device-from-raw path, so a tiled VAAPI surface can be imported.
- dmabuf: import a VAAPI NV12 surface's tiled DMA-BUF as two aliasing wgpu
textures (Y=R8, UV=RG8) at the plane offsets.
- zerocopy test: render values via Vulkan straight into the VAAPI surface
and read them back 100% correct -- proving the GPU writes into the
encoder surface with no CPU copy.
Not yet wired into the editor; real-frame render + encode-from-surface +
fallback wiring follow. Linux-only (libva); other platforms fall back.
Skyler Lehmkuhl