[FFmpeg-devel] [PATCH 1/2] swscale: fix bt709 yuv2rgb coefficients.

[Michael Niedermayer]

On Thu, Mar 31, 2016 at 04:01:16PM -0400, Ronald S. Bultje wrote:
> They were derived from incorrect values cr=0.2125 (should be cr=0.2126)
> and cb=0.0721 (should be cb=0.0722).
> ---
>  libswscale/yuv2rgb.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/libswscale/yuv2rgb.c b/libswscale/yuv2rgb.c
> index 62abb7d..a0242bf 100644
> --- a/libswscale/yuv2rgb.c
> +++ b/libswscale/yuv2rgb.c
> @@ -47,8 +47,8 @@
>   * 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) */
> +    { 117489, 138438, 13975, 34925 }, /* no sequence_display_extension */
> +    { 117489, 138438, 13975, 34925 }, /* ITU-R Rec. 709 (1990) */

it seems nothing in fate is using these
but if you checked the values and theye where wrong then this should
be ok

I do remember though that i was finetuning some SIMD yuv-rgb values
by +-1 to maximize PSNR for combinations of rgb-yuv and yuv-rgb
so keep that in mind if you find errors in them too :)



[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20160401/1ec53225/attachment.sig>