Commit ff8c2c41 authored by Vittorio Giovara's avatar Vittorio Giovara Committed by Michael Niedermayer

yuv2rgb: Document the color space coefficients

Based on the original documentation found in mpeg2dec (1995).
Signed-off-by: 's avatarVittorio Giovara <vittorio.giovara@gmail.com>
parent acd37069
......@@ -35,6 +35,17 @@
#include "swscale_internal.h"
#include "libavutil/pixdesc.h"
/* Color space conversion coefficients for YCbCr -> RGB mapping.
*
* Entries are {crv, cbu, cgu, cgv}
*
* crv = (255 / 224) * 65536 * (1 - cr) / 0.5
* cbu = (255 / 224) * 65536 * (1 - cb) / 0.5
* cgu = (255 / 224) * 65536 * (cb / cg) * (1 - cb) / 0.5
* cgv = (255 / 224) * 65536 * (cr / cg) * (1 - cr) / 0.5
*
* where Y = cr * R + cg * G + cb * B and cr + cg + cb = 1.
*/
const int32_t ff_yuv2rgb_coeffs[8][4] = {
{ 117504, 138453, 13954, 34903 }, /* no sequence_display_extension */
{ 117504, 138453, 13954, 34903 }, /* ITU-R Rec. 709 (1990) */
......
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