Support 10-/12-bit Y'CbCr output packed in 16-bit.

[movit] / ycbcr.cpp

diff --git a/ycbcr.cpp b/ycbcr.cpp
index 8ae8d34328c1e05c61635515c9a177260cd28e07..8c4f7801d33c2efb1ad6c43dac73f3d5d87a30d0 100644 (file)
--- a/ycbcr.cpp
+++ b/ycbcr.cpp
@@ -59,7 +59,7 @@ float compute_chroma_offset(float pos, unsigned subsampling_factor, unsigned res
 // Given <ycbcr_format>, compute the values needed to turn Y'CbCr into R'G'B';
 // first subtract the returned offset, then left-multiply the returned matrix
 // (the scaling is already folded into it).
-void compute_ycbcr_matrix(YCbCrFormat ycbcr_format, float* offset, Matrix3d* ycbcr_to_rgb)
+void compute_ycbcr_matrix(YCbCrFormat ycbcr_format, float* offset, Matrix3d* ycbcr_to_rgb, GLenum type, double *scale_factor)
 {
        double coeff[3], scale[3];
 
@@ -136,6 +136,24 @@ void compute_ycbcr_matrix(YCbCrFormat ycbcr_format, float* offset, Matrix3d* ycb
 
        // Fold in the scaling.
        *ycbcr_to_rgb *= Map<const Vector3d>(scale).asDiagonal();
+
+       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;
+               if (scale_factor != NULL) {
+                       *scale_factor = scale;
+               }
+       } else if (scale_factor != NULL) {
+               *scale_factor = 1.0;
+       }
 }
 
 }  // namespace movit