vf_colorspace: add floyd-steinberg dithering option to full conversion.

1 files changed, 128 insertions, 0 deletions

diff --git a/libavfilter/colorspacedsp_template.c b/libavfilter/colorspacedsp_template.c
index f225391301..db4a8d2361 100644
--- a/libavfilter/colorspacedsp_template.c
+++ b/libavfilter/colorspacedsp_template.c
@@ -199,6 +199,134 @@ static void fn(rgb2yuv)(uint8_t *_yuv[3], ptrdiff_t yuv_stride[3],
     }
 }
 
+/* floyd-steinberg dithering - for any mid-top pixel A in a 3x2 block of pixels:
+ *    1 A 2
+ *    3 4 5
+ * the rounding error is distributed over the neighbouring pixels:
+ *    2: 7/16th, 3: 3/16th, 4: 5/16th and 5: 1/16th
+ */
+static void fn(rgb2yuv_fsb)(uint8_t *_yuv[3], ptrdiff_t yuv_stride[3],
+                            int16_t *rgb[3], ptrdiff_t s,
+                            int w, int h, const int16_t rgb2yuv_coeffs[3][3][8],
+                            const int16_t yuv_offset[8],
+                            int *rnd_scratch[3][2])
+{
+    pixel **yuv = (pixel **) _yuv;
+    pixel *yuv0 = yuv[0], *yuv1 = yuv[1], *yuv2 = yuv[2];
+    const int16_t *rgb0 = rgb[0], *rgb1 = rgb[1], *rgb2 = rgb[2];
+    int y, x;
+    const int sh = 29 - BIT_DEPTH;
+    const int rnd = 1 << (sh - 1);
+    int cry = rgb2yuv_coeffs[0][0][0];
+    int cgy = rgb2yuv_coeffs[0][1][0];
+    int cby = rgb2yuv_coeffs[0][2][0];
+    int cru = rgb2yuv_coeffs[1][0][0];
+    int cgu = rgb2yuv_coeffs[1][1][0];
+    int cburv = rgb2yuv_coeffs[1][2][0];
+    int cgv = rgb2yuv_coeffs[2][1][0];
+    int cbv = rgb2yuv_coeffs[2][2][0];
+    ptrdiff_t s0 = yuv_stride[0] / sizeof(pixel);
+    const int uv_offset = 128 << (BIT_DEPTH - 8);
+    unsigned mask = (1 << sh) - 1;
+
+    for (x = 0; x < w; x++) {
+        rnd_scratch[0][0][x] =
+        rnd_scratch[0][1][x] = rnd;
+    }
+    av_assert2(rgb2yuv_coeffs[1][2][0] == rgb2yuv_coeffs[2][0][0]);
+    w = AV_CEIL_RSHIFT(w, SS_W);
+    h = AV_CEIL_RSHIFT(h, SS_H);
+    for (x = 0; x < w; x++) {
+        rnd_scratch[1][0][x] =
+        rnd_scratch[1][1][x] =
+        rnd_scratch[2][0][x] =
+        rnd_scratch[2][1][x] = rnd;
+    }
+    for (y = 0; y < h; y++) {
+        for (x = 0; x < w; x++) {
+            int r00 = rgb0[x << SS_W], g00 = rgb1[x << SS_W], b00 = rgb2[x << SS_W];
+            int y00;
+#if SS_W == 1
+            int r01 = rgb0[x * 2 + 1], g01 = rgb1[x * 2 + 1], b01 = rgb2[x * 2 + 1];
+            int y01;
+#if SS_H == 1
+            int r10 = rgb0[x * 2 + 0 + s], g10 = rgb1[x * 2 + 0 + s], b10 = rgb2[x * 2 + 0 + s];
+            int r11 = rgb0[x * 2 + 1 + s], g11 = rgb1[x * 2 + 1 + s], b11 = rgb2[x * 2 + 1 + s];
+            int y10, y11;
+#endif
+#endif
+            int u, v, diff;
+
+            y00 = r00 * cry + g00 * cgy + b00 * cby + rnd_scratch[0][y & !SS_H][x << SS_W];
+            diff = (y00 & mask) - rnd;
+            yuv0[x << SS_W]      = av_clip_pixel(yuv_offset[0] + (y00 >> sh));
+            rnd_scratch[0][ (y & !SS_H)][(x << SS_W) + 1] += (diff * 7 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][(x << SS_W) - 1] += (diff * 3 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][(x << SS_W) + 0] += (diff * 5 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][(x << SS_W) + 1] += (diff * 1 + 8) >> 4;
+            rnd_scratch[0][ (y & !SS_H)][(x << SS_W) + 0]  = rnd;
+#if SS_W == 1
+            y01 = r01 * cry + g01 * cgy + b01 * cby + rnd_scratch[0][y & !SS_H][x * 2 + 1];
+            diff = (y01 & mask) - rnd;
+            yuv0[x * 2 + 1]      = av_clip_pixel(yuv_offset[0] + (y01 >> sh));
+            rnd_scratch[0][ (y & !SS_H)][x * 2 + 2] += (diff * 7 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][x * 2 + 0] += (diff * 3 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][x * 2 + 1] += (diff * 5 + 8) >> 4;
+            rnd_scratch[0][!(y & !SS_H)][x * 2 + 2] += (diff * 1 + 8) >> 4;
+            rnd_scratch[0][ (y & !SS_H)][x * 2 + 1]  = rnd;
+#if SS_H == 1
+            y10 = r10 * cry + g10 * cgy + b10 * cby + rnd_scratch[0][1][x * 2 + 0];
+            diff = (y10 & mask) - rnd;
+            yuv0[x * 2 + 0 + s0] = av_clip_pixel(yuv_offset[0] + (y10 >> sh));
+            rnd_scratch[0][1][x * 2 + 1] += (diff * 7 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 - 1] += (diff * 3 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 + 0] += (diff * 5 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 + 1] += (diff * 1 + 8) >> 4;
+            rnd_scratch[0][1][x * 2 + 0]  = rnd;
+
+            y11 = r11 * cry + g11 * cgy + b11 * cby + rnd_scratch[0][1][x * 2 + 1];
+            diff = (y11 & mask) - rnd;
+            yuv0[x * 2 + 1 + s0] = av_clip_pixel(yuv_offset[0] + (y11 >> sh));
+            rnd_scratch[0][1][x * 2 + 2] += (diff * 7 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 + 0] += (diff * 3 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 + 1] += (diff * 5 + 8) >> 4;
+            rnd_scratch[0][0][x * 2 + 2] += (diff * 1 + 8) >> 4;
+            rnd_scratch[0][1][x * 2 + 1]  = rnd;
+#endif
+#endif
+
+            u = avg(r00, r01, r10, r11) * cru +
+                avg(g00, g01, g10, g11) * cgu +
+                avg(b00, b01, b10, b11) * cburv + rnd_scratch[1][y & 1][x];
+            diff = (u & mask) - rnd;
+            yuv1[x] = av_clip_pixel(uv_offset + (u >> sh));
+            rnd_scratch[1][ (y & 1)][x + 1] += (diff * 7 + 8) >> 4;
+            rnd_scratch[1][!(y & 1)][x - 1] += (diff * 3 + 8) >> 4;
+            rnd_scratch[1][!(y & 1)][x + 0] += (diff * 5 + 8) >> 4;
+            rnd_scratch[1][!(y & 1)][x + 1] += (diff * 1 + 8) >> 4;
+            rnd_scratch[1][ (y & 1)][x + 0]  = rnd;
+
+            v = avg(r00, r01, r10, r11) * cburv +
+                avg(g00, g01, g10, g11) * cgv +
+                avg(b00, b01, b10, b11) * cbv + rnd_scratch[2][y & 1][x];
+            diff = (v & mask) - rnd;
+            yuv2[x] = av_clip_pixel(uv_offset + (v >> sh));
+            rnd_scratch[2][ (y & 1)][x + 1] += (diff * 7 + 8) >> 4;
+            rnd_scratch[2][!(y & 1)][x - 1] += (diff * 3 + 8) >> 4;
+            rnd_scratch[2][!(y & 1)][x + 0] += (diff * 5 + 8) >> 4;
+            rnd_scratch[2][!(y & 1)][x + 1] += (diff * 1 + 8) >> 4;
+            rnd_scratch[2][ (y & 1)][x + 0]  = rnd;
+        }
+
+        yuv0 += s0 * (1 << SS_H);
+        yuv1 += yuv_stride[1] / sizeof(pixel);
+        yuv2 += yuv_stride[2] / sizeof(pixel);
+        rgb0 += s * (1 << SS_H);
+        rgb1 += s * (1 << SS_H);
+        rgb2 += s * (1 << SS_H);
+    }
+}
+
 #undef IN_BIT_DEPTH
 #undef OUT_BIT_DEPTH
 #define OUT_BIT_DEPTH BIT_DEPTH