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fix(compositor): decode 10-bit and non-4:2:0 H.264 in software on Windows #1530

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Merged
EtienneLescot merged 1 commit into from
Nov 11, 2026
Merged

fix(compositor): decode 10-bit and non-4:2:0 H.264 in software on Windows #1530

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6 changes: 3 additions & 3 deletions crates/compositor/src/cpu_frames_windows.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -24,9 +24,9 @@ use windows::Win32::Graphics::Dxgi::Common::{DXGI_FORMAT_NV12, DXGI_SAMPLE_DESC}

/// Le flag d'algorithme de swscale. Bindgen ne génère pas les `SWS_*` d'algorithme (des
/// macros), et leurs valeurs sont figées par l'ABI de libswscale. `POINT` (plus proche
/// voisin) est le choix honnête : la conversion se fait à dimensions ÉGALES, donc aucun
/// rééchantillonnage n'a lieu — seul le convertisseur de format travaille, et le filtre
/// choisi n'a aucun effet sur la sortie.
/// voisin) est le choix honnête : la conversion se fait à dimensions ÉGALES, donc la luma
/// n'est jamais rééchantillonnée. Seule exception : une source 4:2:2 ou 4:4:4 (H.264
/// importé) perd sa chroma pleine en passant en NV12, et POINT la décime par voisin.
const SWS_POINT: i32 = 0x10;

/// Source de frames du backend CPU, attachée à un `Decoder` quand `Backend::Cpu`.
Expand Down
38 changes: 34 additions & 4 deletions crates/compositor/src/pipeline_windows.rs
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Expand Up @@ -380,6 +380,21 @@ fn d3d11va_for_codec(codec_id: AVCodecID::Type) -> bool {
codec_id == AVCodecID::AV_CODEC_ID_H264
}

/// Per-stream refinement of `d3d11va_for_codec`: FFmpeg only offers a D3D11
/// NV12 surface for 8-bit 4:2:0 H.264. High 10 (yuv420p10le) and 4:2:2 / 4:4:4
/// get none, `get_hw_format` rejects everything and `send_packet` fails with
/// AVERROR_INVALIDDATA, so those streams take the software `CpuFrames` path.
/// An unknown pixel format (`AV_PIX_FMT_NONE`) keeps the hardware path.
fn d3d11va_for_stream(codec_id: AVCodecID::Type, format: AVPixelFormat::Type) -> bool {
d3d11va_for_codec(codec_id)
&& matches!(
format,
AVPixelFormat::AV_PIX_FMT_NONE
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| AVPixelFormat::AV_PIX_FMT_YUV420P
| AVPixelFormat::AV_PIX_FMT_YUVJ420P
)
}

unsafe fn require_decoder_id(
codec_id: AVCodecID::Type,
) -> Result<(*const AVCodec, *mut AVCodecContext)> {
Expand Down Expand Up @@ -847,10 +862,12 @@ impl Decoder {
)?;
allow_d3d11va_h264_baseline(resources.dctx);

// Hardware D3D11VA is the H.264 capture path. WARP has no video decoder
// (`tests/warp_device_cannot_decode.rs`). AV1/VP9 (legacy WebMs, #554)
// take the same software CpuFrames axis as Backend::Cpu.
let want_hw = gpu.backend != Backend::Cpu && d3d11va_for_codec(codec_id);
// Hardware D3D11VA is the H.264 8-bit 4:2:0 capture path. WARP has no video
// decoder (`tests/warp_device_cannot_decode.rs`). AV1/VP9 (legacy WebMs, #554)
// and H.264 High 10 / 4:2:2 / 4:4:4 (no D3D11 surface exists for them) take
// the same software CpuFrames axis as Backend::Cpu.
let want_hw = gpu.backend != Backend::Cpu
&& d3d11va_for_stream(codec_id, (*codecpar).format as AVPixelFormat::Type);
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let cpu = if want_hw {
None
} else {
Expand Down Expand Up @@ -2168,6 +2185,19 @@ mod tests {
assert!(!d3d11va_for_codec(AVCodecID::AV_CODEC_ID_VP9));
}

#[test]
fn d3d11va_is_8bit_420_h264_only() {
use AVPixelFormat::*;
let h264 = AVCodecID::AV_CODEC_ID_H264;
assert!(d3d11va_for_stream(h264, AV_PIX_FMT_YUV420P));
assert!(d3d11va_for_stream(h264, AV_PIX_FMT_YUVJ420P));
assert!(d3d11va_for_stream(h264, AV_PIX_FMT_NONE));
assert!(!d3d11va_for_stream(h264, AV_PIX_FMT_YUV420P10LE));
assert!(!d3d11va_for_stream(h264, AV_PIX_FMT_YUV422P));
assert!(!d3d11va_for_stream(h264, AV_PIX_FMT_YUV444P));
assert!(!d3d11va_for_stream(AVCodecID::AV_CODEC_ID_AV1, AV_PIX_FMT_YUV420P));
}

#[test]
fn require_decoder_rejects_none() {
let err = unsafe { require_decoder_id(AVCodecID::AV_CODEC_ID_NONE) }
Expand Down
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