Save a mul in YCbCrInput by folding the scaling into the matrix.

diff --git a/ycbcr_input.cpp b/ycbcr_input.cpp
index 22d689d2a04997edf43fd8a7e768720a176a25be..25fb97932129ca0f7bcb804a59ea4b8b3b9de191 100644 (file)
--- a/ycbcr_input.cpp
+++ b/ycbcr_input.cpp
@@ -143,7 +143,8 @@ void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, uns
 
 string YCbCrInput::output_fragment_shader()
 {
-       float coeff[3], offset[3], scale[3];
+       float coeff[3], offset[3];
+       double scale[3];
 
        switch (ycbcr_format.luma_coefficients) {
        case YCBCR_REC_601:
@@ -209,11 +210,13 @@ string YCbCrInput::output_fragment_shader()
        // Inverting the matrix gives us what we need to go from YCbCr back to RGB.
        Matrix3d ycbcr_to_rgb = rgb_to_ycbcr.inverse();
 
+       // Fold in the scaling.
+       ycbcr_to_rgb *= Map<const Vector3d>(scale).asDiagonal();
+
        string frag_shader;
 
        frag_shader = output_glsl_mat3("PREFIX(inv_ycbcr_matrix)", ycbcr_to_rgb);
        frag_shader += output_glsl_vec3("PREFIX(offset)", offset[0], offset[1], offset[2]);
-       frag_shader += output_glsl_vec3("PREFIX(scale)", scale[0], scale[1], scale[2]);
 
        float cb_offset_x = compute_chroma_offset(
                ycbcr_format.cb_x_position, ycbcr_format.chroma_subsampling_x, widths[1]);

diff --git a/ycbcr_input.frag b/ycbcr_input.frag
index fbf20d165df616f15af98fde6f0b0714675f51d5..bd6ff766569730287af70152ef58dc679ef9d867 100644 (file)
--- a/ycbcr_input.frag
+++ b/ycbcr_input.frag
@@ -14,7 +14,6 @@ vec4 FUNCNAME(vec2 tc) {
        ycbcr.z = tex2D(PREFIX(tex_cr), tc + PREFIX(cr_offset)).x;
 
        ycbcr -= PREFIX(offset);
-       ycbcr *= PREFIX(scale);
 
        vec4 rgba;
        rgba.rgb = PREFIX(inv_ycbcr_matrix) * ycbcr;