// uniform sampler2D PREFIX(tex_cbcr); // If CB_CR_SAME_TEXTURE.
// uniform sampler2D PREFIX(tex_cb); // If not CB_CR_SAME_TEXTURE.
// uniform sampler2D PREFIX(tex_cr); // If not CB_CR_SAME_TEXTURE.
+// uniform mat3 PREFIX(ycbcr_matrix);
+// uniform vec3 PREFIX(offset);
+// uniform vec2 PREFIX(cb_offset);
+// uniform vec2 PREFIX(cr_offset);
vec4 FUNCNAME(vec2 tc) {
// OpenGL's origin is bottom-left, but most graphics software assumes