Add support for Y'CbCr output.

[movit] / ycbcr_conversion_effect.frag

diff --git a/ycbcr_conversion_effect.frag b/ycbcr_conversion_effect.frag
new file mode 100644 (file)
index 0000000..6bc29b1
--- /dev/null
+++ b/ycbcr_conversion_effect.frag
@@ -0,0 +1,24 @@
+uniform sampler2D PREFIX(tex_y);
+uniform sampler2D PREFIX(tex_cb);
+uniform sampler2D PREFIX(tex_cr);
+
+vec4 FUNCNAME(vec2 tc) {
+       vec4 rgba = INPUT(tc);
+       vec4 ycbcr_a;
+
+       ycbcr_a.rgb = PREFIX(ycbcr_matrix) * rgba.rgb + PREFIX(offset);
+
+#if YCBCR_CLAMP_RANGE
+       // If we use limited-range Y'CbCr, the card's usual 0–255 clamping
+       // won't be enough, so we need to clamp ourselves here.
+       //
+       // We clamp before dither, which is a bit unfortunate, since
+       // it means dither can take us out of the clamped range again.
+       // However, since DitherEffect never adds enough dither to change
+       // the quantized levels, we will be fine in practice.
+       ycbcr_a.rgb = clamp(ycbcr_a.rgb, PREFIX(ycbcr_min), PREFIX(ycbcr_max));
+#endif
+
+       ycbcr_a.a = rgba.a;
+       return ycbcr_a;
+}