Add an explanatory comment about dither with 16-bit output.

[movit] / ycbcr_input.cpp

diff --git a/ycbcr_input.cpp b/ycbcr_input.cpp
index b9cda5b776a49623bdedf10de820ba8e655377ef..e725750291b4e2ce8f7f71533175e83f8dfac469 100644 (file)
--- a/ycbcr_input.cpp
+++ b/ycbcr_input.cpp
@@ -139,7 +139,9 @@ void YCbCrInput::set_gl_state(GLuint glsl_program_num, const string& prefix, uns
 
        // Bind samplers.
        uniform_tex_y = *sampler_num + 0;
-       uniform_tex_cb = *sampler_num + 1;
+       if (ycbcr_input_splitting != YCBCR_INPUT_INTERLEAVED) {
+               uniform_tex_cb = *sampler_num + 1;
+       }
        if (ycbcr_input_splitting == YCBCR_INPUT_PLANAR) {
                uniform_tex_cr = *sampler_num + 2;
        }
@@ -151,20 +153,7 @@ string YCbCrInput::output_fragment_shader()
 {
        float offset[3];
        Matrix3d ycbcr_to_rgb;
-       compute_ycbcr_matrix(ycbcr_format, offset, &ycbcr_to_rgb);
-
-       if (type == GL_UNSIGNED_SHORT) {
-               // For 10-bit or 12-bit packed into 16-bit, we need to scale the values
-               // so that the max value goes from 1023 (or 4095) to 65535. We do this
-               // by folding the scaling into the conversion matrix, so it comes essentially
-               // for free. However, the offset is before the scaling (and thus assumes
-               // correctly scaled values), so we need to adjust that the other way.
-               double scale = 65535.0 / (ycbcr_format.num_levels - 1);
-               offset[0] /= scale;
-               offset[1] /= scale;
-               offset[2] /= scale;
-               ycbcr_to_rgb *= scale;
-       }
+       compute_ycbcr_matrix(ycbcr_format, offset, &ycbcr_to_rgb, type);
 
        string frag_shader;