Support 10- and 12-bit Y'CbCr output.

[movit] / ycbcr.h

diff --git a/ycbcr.h b/ycbcr.h
index 9179b1958a5cdcc73e1a5b74132a9b2bab45d3c8..e4ca43fa3259f04bd84f27d826dcf5db362a1b02 100644 (file)
--- a/ycbcr.h
+++ b/ycbcr.h
@@ -1,7 +1,8 @@
 #ifndef _MOVIT_YCBCR_H
 #define _MOVIT_YCBCR_H 1
 
-// Shared utility functions between YCbCrInput and YCbCr422InterleavedInput.
+// Shared utility functions between YCbCrInput, YCbCr422InterleavedInput
+// and YCbCrConversionEffect.
 //
 // Conversion from integer to floating-point representation in case of
 // Y'CbCr is seemingly tricky:
@@ -28,9 +29,10 @@
 // range, 10-bit goes out of range (white gets to 942), while if you select
 // 10-bit range, 8-bit gets only to 234, making true white impossible.
 //
-// We currently support the 8-bit ranges only, since all of our Y'CbCr
-// handling effects happen to support only 8-bit at the moment. We will need
-// to fix this eventually, though, with an added field to YCbCrFormat.
+// Thus, you will need to specify the actual precision of the Y'CbCr source
+// (or destination); the num_levels field is the right place. Most people
+// will want to simply set this to 256, as 8-bit Y'CbCr is the most common,
+// but the right value will naturally depend on your input.
 
 #include "image_format.h"
 
@@ -47,8 +49,8 @@ struct YCbCrFormat {
        // JPEG uses the Rec. 601 luma coefficients, but full range.
        bool full_range;
 
-       // Currently unused, but should be set to 256 for future expansion,
-       // indicating 8-bit interpretation (see file-level comment).
+       // Set to 2^n for n-bit Y'CbCr (e.g. 256 for 8-bit Y'CbCr).
+       // See file-level comment.
        int num_levels;
 
        // Sampling factors for chroma components. For no subsampling (4:4:4),