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Merged
richiemcilroy merged 2 commits into from
Oct 18, 2026
Merged

fix(rendering): preserve chroma at odd frame edges #2613

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f665cfd
fix(rendering): preserve chroma at odd frame edges
yashranaway Oct 15, 2026
62aacd4
Merge branch 'main' into fix/decode
richiemcilroy Oct 18, 2026
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18 changes: 11 additions & 7 deletions crates/rendering/src/decoder/ffmpeg.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,9 @@ use super::{
record_pts_hole,
};

#[cfg(test)]
mod tests;

#[derive(Clone)]
struct ProcessedFrame {
number: u32,
Expand Down Expand Up @@ -96,7 +99,7 @@ fn extract_yuv_planes(frame: &frame::Video) -> Option<(Vec<u8>, PixelFormat, u32
let v_stride = frame.stride(2) as u32;

let y_size = (y_stride * height) as usize;
let uv_height = height / 2;
let uv_height = frame.plane_height(1);
let u_size = (u_stride * uv_height) as usize;

let mut data = Vec::with_capacity(y_size + 2 * u_size);
Expand Down Expand Up @@ -128,7 +131,7 @@ fn extract_yuv_planes(frame: &frame::Video) -> Option<(Vec<u8>, PixelFormat, u32
let uv_stride = frame.stride(1) as u32;

let y_size = (y_stride * height) as usize;
let uv_size = (uv_stride * (height / 2)) as usize;
let uv_size = (uv_stride * frame.plane_height(1)) as usize;

let mut data = Vec::with_capacity(y_size + uv_size);
data.extend_from_slice(&frame.data(0)[..y_size]);
Expand Down Expand Up @@ -275,13 +278,14 @@ impl CachedFrame {
frame
.stride(1)
.saturating_add(frame.stride(2))
.saturating_mul(height / 2),
.saturating_mul(frame.plane_height(1) as usize),
)
}
format::Pixel::NV12 => frame
.stride(0)
.saturating_mul(height)
.saturating_add(frame.stride(1).saturating_mul(height / 2)),
format::Pixel::NV12 => frame.stride(0).saturating_mul(height).saturating_add(
frame
.stride(1)
.saturating_mul(frame.plane_height(1) as usize),
),
_ => (frame.width() as usize)
.saturating_mul(height)
.saturating_mul(4),
Expand Down
233 changes: 233 additions & 0 deletions crates/rendering/src/decoder/ffmpeg/tests.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,233 @@
use super::*;
use crate::yuv_converter::{YuvConversionError, YuvConverterPipelines, YuvToRgbaConverter};

#[test]
fn odd_yuv_frames_preserve_every_chroma_row() {
for format in [format::Pixel::YUV420P, format::Pixel::NV12] {
for (width, height) in [(1, 1), (3, 4), (4, 3), (17, 9), (18, 10)] {
let mut source = frame::Video::new(format, width, height);
for plane in 0..source.planes() {
for (index, byte) in source.data_mut(plane).iter_mut().enumerate() {
*byte = (index * 37 + plane * 59) as u8;
}
}
let expected: Vec<_> = (0..source.planes())
.map(|plane| source.data(plane).to_vec())
.collect();
let expected_bytes: usize = expected.iter().map(Vec::len).sum();
let mut cached = CachedFrame::Raw {
frame: source,
number: 7,
};
let raw_bytes = cached.estimated_bytes();
let output = cached.produce(&mut FrameConverter::new());
assert_eq!(output.number, 7);
let decoded = output.frame;
assert_eq!(decoded.byte_len(), expected_bytes);
assert_eq!(raw_bytes, expected_bytes);
assert_eq!(cached.estimated_bytes(), expected_bytes);
assert_eq!(decoded.y_plane().unwrap(), expected[0]);
for (plane, data) in match format {
format::Pixel::YUV420P => vec![
(1, decoded.u_plane().unwrap()),
(2, decoded.v_plane().unwrap()),
],
_ => vec![(1, decoded.uv_plane().unwrap())],
} {
assert_eq!(
data, expected[plane],
"{format:?} {width}x{height}, plane {plane}"
);
}
}
}
}

fn read_pixels(
device: &wgpu::Device,
queue: &wgpu::Queue,
texture: &wgpu::Texture,
width: u32,
height: u32,
) -> Vec<u8> {
let stride = (width * 4).div_ceil(wgpu::COPY_BYTES_PER_ROW_ALIGNMENT)
* wgpu::COPY_BYTES_PER_ROW_ALIGNMENT;
let buffer = device.create_buffer(&wgpu::BufferDescriptor {
label: None,
size: u64::from(stride * height),
usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
mapped_at_creation: false,
});
let mut encoder = device.create_command_encoder(&Default::default());
encoder.copy_texture_to_buffer(
texture.as_image_copy(),
wgpu::TexelCopyBufferInfo {
buffer: &buffer,
layout: wgpu::TexelCopyBufferLayout {
offset: 0,
bytes_per_row: Some(stride),
rows_per_image: Some(height),
},
},
wgpu::Extent3d {
width,
height,
depth_or_array_layers: 1,
},
);
queue.submit([encoder.finish()]);
let (sender, receiver) = mpsc::channel();
buffer
.slice(..)
.map_async(wgpu::MapMode::Read, move |result| {
sender.send(result).unwrap();
});
device.poll(wgpu::PollType::Wait).unwrap();
receiver.recv().unwrap().unwrap();
let pixels = buffer
.slice(..)
.get_mapped_range()
.chunks(stride as usize)
.flat_map(|row| row[..width as usize * 4].iter().copied())
.collect();
buffer.unmap();
pixels
}

#[test]
fn odd_yuv_gpu_conversion_matches_even_frame_edges() {
let instance = crate::create_wgpu_instance_sync();
let Ok(adapter) =
pollster::block_on(instance.request_adapter(&wgpu::RequestAdapterOptions::default()))
else {
eprintln!("no GPU adapter available, skipping YUV edge regression");
return;
};
let (device, queue) =
pollster::block_on(adapter.request_device(&wgpu::DeviceDescriptor::default())).unwrap();
let pipelines = Arc::new(YuvConverterPipelines::new(&device));

for planar in [true, false] {
for (width, height) in [(1_u32, 1_u32), (3, 4), (4, 3), (17, 9), (18, 10)] {
let even_width = width.div_ceil(2) * 2;
let even_height = height.div_ceil(2) * 2;
let y_stride = even_width + 8;
let uv_stride = even_width / 2 + 8;
let y = vec![128; (y_stride * even_height) as usize];
let u: Vec<_> = (0..uv_stride * even_height / 2)
.map(|index| (index * 37 + 64) as u8)
.collect();
let v: Vec<_> = (0..uv_stride * even_height / 2)
.map(|index| (index * 59 + 192) as u8)
.collect();
let uv: Vec<_> = u.iter().zip(&v).flat_map(|(&u, &v)| [u, v]).collect();
let mut expected = Vec::new();

for (w, h, batched) in [
(even_width, even_height, false),
(width, height, false),
(width, height, true),
] {
let mut converter =
YuvToRgbaConverter::new_with_shared_pipelines(&device, Arc::clone(&pipelines));
let mut encoder = device.create_command_encoder(&Default::default());
match (planar, batched) {
(true, false) => converter
.convert_yuv420p(&device, &queue, &y, &u, &v, w, h, y_stride, uv_stride),
(true, true) => converter.convert_yuv420p_to_encoder(
&device,
&queue,
&mut encoder,
&y,
&u,
&v,
w,
h,
y_stride,
uv_stride,
),
(false, false) => converter.convert_nv12(
&device,
&queue,
&y,
&uv,
w,
h,
y_stride,
uv_stride * 2,
),
(false, true) => converter.convert_nv12_to_encoder(
&device,
&queue,
&mut encoder,
&y,
&uv,
w,
h,
y_stride,
uv_stride * 2,
),
}
.unwrap();
queue.submit([encoder.finish()]);
let actual = read_pixels(
&device,
&queue,
converter.output_texture().unwrap(),
width,
height,
);
if expected.is_empty() {
expected = actual;
} else {
assert_eq!(
actual, expected,
"{width}x{height}, planar={planar}, batched={batched}"
);
}
}
}
}

for batched in [false, true] {
for uv_stride in [3, 4] {
let mut encoder = device.create_command_encoder(&Default::default());
let mut converter =
YuvToRgbaConverter::new_with_shared_pipelines(&device, Arc::clone(&pipelines));
let result = if batched {
converter.convert_nv12_to_encoder(
&device,
&queue,
&mut encoder,
&[128; 9],
&[128; 4],
3,
3,
3,
uv_stride,
)
} else {
converter.convert_nv12(&device, &queue, &[128; 9], &[128; 4], 3, 3, 3, uv_stride)
};
if uv_stride == 3 {
assert!(matches!(
result,
Err(YuvConversionError::PlaneStrideTooSmall {
plane: "UV",
expected: 4,
actual: 3,
})
));
} else {
assert!(matches!(
result,
Err(YuvConversionError::PlaneSizeMismatch {
plane: "UV",
expected: 8,
actual: 4,
})
));
}
}
}
}
6 changes: 3 additions & 3 deletions crates/rendering/src/decoder/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -591,7 +591,7 @@ impl DecodedFrame {
}

let y_bytes = (self.y_stride as usize).saturating_mul(self.height as usize);
let uv_bytes = (self.uv_stride as usize).saturating_mul((self.height / 2) as usize);
let uv_bytes = (self.uv_stride as usize).saturating_mul(self.height.div_ceil(2) as usize);

match self.format {
PixelFormat::Rgba => (self.width as usize)
Expand Down Expand Up @@ -648,7 +648,7 @@ impl DecodedFrame {
.and_then(|v| usize::try_from(v).ok())?;
let u_size = self
.uv_stride
.checked_mul(self.height / 2)
.checked_mul(self.height.div_ceil(2))
.and_then(|v| usize::try_from(v).ok())?;
let u_end = y_size.checked_add(u_size)?;
self.data().get(y_size..u_end)
Expand All @@ -666,7 +666,7 @@ impl DecodedFrame {
.and_then(|v| usize::try_from(v).ok())?;
let u_size = self
.uv_stride
.checked_mul(self.height / 2)
.checked_mul(self.height.div_ceil(2))
.and_then(|v| usize::try_from(v).ok())?;
let v_start = y_size.checked_add(u_size)?;
self.data().get(v_start..)
Expand Down
26 changes: 14 additions & 12 deletions crates/rendering/src/yuv_converter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -932,11 +932,12 @@ impl YuvToRgbaConverter {

upload_plane_with_stride(queue, &self.y_texture, y_data, width, height, y_stride, "Y")?;

let half_height = height / 2;
if uv_stride < width {
let half_height = height.div_ceil(2);
let uv_row_bytes = width.div_ceil(2) * 2;
if uv_stride < uv_row_bytes {
return Err(YuvConversionError::PlaneStrideTooSmall {
plane: "UV",
expected: width,
expected: uv_row_bytes,
actual: uv_stride,
});
}
Expand Down Expand Up @@ -964,7 +965,7 @@ impl YuvToRgbaConverter {
rows_per_image: Some(half_height),
},
wgpu::Extent3d {
width: width / 2,
width: width.div_ceil(2),
height: half_height,
depth_or_array_layers: 1,
},
Expand Down Expand Up @@ -1021,11 +1022,12 @@ impl YuvToRgbaConverter {

upload_plane_with_stride(queue, &self.y_texture, y_data, width, height, y_stride, "Y")?;

let half_height = height / 2;
if uv_stride < width {
let half_height = height.div_ceil(2);
let uv_row_bytes = width.div_ceil(2) * 2;
if uv_stride < uv_row_bytes {
return Err(YuvConversionError::PlaneStrideTooSmall {
plane: "UV",
expected: width,
expected: uv_row_bytes,
actual: uv_stride,
});
}
Expand Down Expand Up @@ -1053,7 +1055,7 @@ impl YuvToRgbaConverter {
rows_per_image: Some(half_height),
},
wgpu::Extent3d {
width: width / 2,
width: width.div_ceil(2),
height: half_height,
depth_or_array_layers: 1,
},
Expand Down Expand Up @@ -1210,8 +1212,8 @@ impl YuvToRgbaConverter {

upload_plane_with_stride(queue, &self.y_texture, y_data, width, height, y_stride, "Y")?;

let half_width = width / 2;
let half_height = height / 2;
let half_width = width.div_ceil(2);
let half_height = height.div_ceil(2);

upload_plane_with_stride(
queue,
Expand Down Expand Up @@ -1285,8 +1287,8 @@ impl YuvToRgbaConverter {

upload_plane_with_stride(queue, &self.y_texture, y_data, width, height, y_stride, "Y")?;

let half_width = width / 2;
let half_height = height / 2;
let half_width = width.div_ceil(2);
let half_height = height.div_ceil(2);

upload_plane_with_stride(
queue,
Expand Down
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