csputils: apply contrast equalizer in RGB

It's weird that this basically adjusts the contrast between luma and
chroma, and not blackness.

This is more in line with the behavior of libswscale, the vdpau
"procamp" (which mpv doesn't use), and Xv.

(cherry picked from commit 0600d378f9afb20d92e75d26c0df7d255e1df554)

1 files changed, 3 insertions, 8 deletions

diff --git a/video/csputils.c b/video/csputils.c
index a4d896f598..f42cfb398b 100644
--- a/video/csputils.c
+++ b/video/csputils.c
@@ -671,6 +671,9 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, struct mp_cmat *m)
         abort();
     }
 
+    rgblev.min = (rgblev.min + params->brightness) * params->contrast;
+    rgblev.max = (rgblev.max + params->brightness) * params->contrast;
+
     double ymul = (rgblev.max - rgblev.min) / (yuvlev.ymax - yuvlev.ymin);
     double cmul = (rgblev.max - rgblev.min) / (yuvlev.cmid - yuvlev.cmin) / 2;
     for (int i = 0; i < 3; i++) {
@@ -682,14 +685,6 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, struct mp_cmat *m)
                   -(m->m[i][1] + m->m[i][2]) * yuvlev.cmid;
     }
 
-    // Brightness adds a constant to output R,G,B.
-    // Contrast scales Y around 1/2 (not 0 in this implementation).
-    for (int i = 0; i < 3; i++) {
-        m->c[i] += params->brightness;
-        m->m[i][0] *= params->contrast;
-        m->c[i] += (rgblev.max-rgblev.min) * (1 - params->contrast)/2;
-    }
-
     int in_bits = FFMAX(params->int_bits_in, 1);
     int out_bits = FFMAX(params->int_bits_out, 1);
     double in_scale = (1 << in_bits) - 1.0;