add yuyv (#181)

nokhwa-core/src/pixel_format.rs

@@ -399,3 +399,125 @@ impl FormatDecoder for LumaAFormat {
         }
     }
 }
+
+
+
+/// let image: ImageBuffer<Rgb<u8>, Vec<u8>> = buffer.to_image::<YuyvFormat>();
+/// ```
+#[derive(Copy, Clone, Debug, Default, Hash, Ord, PartialOrd, Eq, PartialEq)]
+pub struct YuyvFormat;
+
+impl FormatDecoder for YuyvFormat {
+    type Output = Rgb<u8>;
+    const FORMATS: &'static [FrameFormat] = color_frame_formats();
+
+    #[inline]
+    fn write_output(
+        fcc: FrameFormat,
+        resolution: Resolution,
+        data: &[u8],
+    ) -> Result<Vec<u8>, NokhwaError> {
+        match fcc {
+            FrameFormat::YUYV => {
+                let i420 = private_convert_yuyv_to_i420(
+                    data,
+                    resolution.width() as usize,
+                    resolution.height() as usize,
+                );
+                Ok(i420)
+            }
+            _ => Err(NokhwaError::GeneralError("Invalid FrameFormat".into())),
+        }
+    }
+
+    #[inline]
+    fn write_output_buffer(
+        fcc: FrameFormat,
+        resolution: Resolution,
+        data: &[u8],
+        dest: &mut [u8],
+    ) -> Result<(), NokhwaError> {
+        match fcc {
+            FrameFormat::YUYV => {
+                convert_yuyv_to_i420_direct(
+                    data,
+                    dest,
+                    resolution.width() as usize,
+                    resolution.height() as usize,
+                )?;
+                Ok(())
+            }
+            _ => Err(NokhwaError::GeneralError("Invalid FrameFormat".into())),
+        }
+    }
+}
+
+fn private_convert_yuyv_to_i420(yuyv: &[u8], width: usize, height: usize) -> Vec<u8> {
+    assert!(
+        width % 2 == 0 && height % 2 == 0,
+        "Width and height must be even numbers."
+    );
+
+    let mut i420 = vec![0u8; width * height + 2 * (width / 2) * (height / 2)];
+    let (y_plane, uv_plane) = i420.split_at_mut(width * height);
+    let (u_plane, v_plane) = uv_plane.split_at_mut(uv_plane.len() / 2);
+
+    for y in 0..height {
+        for x in (0..width).step_by(2) {
+            let base_index = (y * width + x) * 2;
+            let y0 = yuyv[base_index];
+            let u = yuyv[base_index + 1];
+            let y1 = yuyv[base_index + 2];
+            let v = yuyv[base_index + 3];
+
+            y_plane[y * width + x] = y0;
+            y_plane[y * width + x + 1] = y1;
+
+            if y % 2 == 0 {
+                u_plane[y / 2 * (width / 2) + x / 2] = u;
+                v_plane[y / 2 * (width / 2) + x / 2] = v;
+            }
+        }
+    }
+
+    i420
+}
+
+fn convert_yuyv_to_i420_direct(
+    yuyv: &[u8],
+    dest: &mut [u8],
+    width: usize,
+    height: usize,
+) -> Result<(), NokhwaError> {
+    // Ensure the destination buffer is large enough
+    if dest.len() < width * height + 2 * (width / 2) * (height / 2) {
+        return Err(NokhwaError::GeneralError(
+            "Destination buffer is too small".into(),
+        ));
+    }
+
+    // Split the destination buffer into Y, U, and V planes
+    let (y_plane, uv_plane) = dest.split_at_mut(width * height);
+    let (u_plane, v_plane) = uv_plane.split_at_mut(uv_plane.len() / 2);
+
+    // Convert YUYV to I420
+    for y in 0..height {
+        for x in (0..width).step_by(2) {
+            let base_index = (y * width + x) * 2;
+            let y0 = yuyv[base_index];
+            let u = yuyv[base_index + 1];
+            let y1 = yuyv[base_index + 2];
+            let v = yuyv[base_index + 3];
+
+            y_plane[y * width + x] = y0;
+            y_plane[y * width + x + 1] = y1;
+
+            if y % 2 == 0 {
+                u_plane[y / 2 * (width / 2) + x / 2] = u;
+                v_plane[y / 2 * (width / 2) + x / 2] = v;
+            }
+        }
+    }
+
+    Ok(())
+}