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vo_gl: improve 10-bit YUV->RGB conversion accuracy slightly

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Modify the YUV->RGB conversion matrix to take into account the
difference between the same color value being x/255 in a 8-bit texture
and x*256/65535 in a 16-bit texture (actually things are stored as
x*4/65535 for 10-bit color, but that can be ignored here). This 0.4 %
difference in the shader float value could make shades of gray in
10-bit (or generally more than 8 bit) YUV produce RGB values with
green slightly higher than red/blue.
This commit is contained in:
Uoti Urpala 2012-03-08 05:25:33 +02:00
parent 2a2f867218
commit a816810266
4 changed files with 16 additions and 17 deletions
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24
libvo/csputils.c
View File

@ -143,10 +143,13 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float m[3][4])
int levels_in = params->colorspace.levels_in;
if (levels_in <= MP_CSP_LEVELS_AUTO || levels_in >= MP_CSP_LEVELS_COUNT)
levels_in = MP_CSP_LEVELS_TV;
assert(params->input_bits >= 8);
assert(params->texture_bits >= params->input_bits);
double s = (1 << params->input_bits-8) / ((1<<params->texture_bits)-1.);
// The values below are written in 0-255 scale
struct yuvlevels { double ymin, ymax, cmin, cmid; }
yuvlim = { 16, 235, 16, 128 },
yuvfull = { 0, 255, 1, 128 }, // '1' to make it symmetric around 128
yuvlim = { 16*s, 235*s, 16*s, 128*s },
yuvfull = { 0*s, 255*s, 1*s, 128*s }, // '1' for symmetry around 128
yuvlev;
switch (levels_in) {
case MP_CSP_LEVELS_TV: yuvlev = yuvlim; break;
@ -159,8 +162,8 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float m[3][4])
if (levels_out <= MP_CSP_LEVELS_AUTO || levels_out >= MP_CSP_LEVELS_COUNT)
levels_out = MP_CSP_LEVELS_PC;
struct rgblevels { double min, max; }
rgblim = { 16, 235 },
rgbfull = { 0, 255 },
rgblim = { 16/255., 235/255. },
rgbfull = { 0, 1 },
rgblev;
switch (levels_out) {
case MP_CSP_LEVELS_TV: rgblev = rgblim; break;
@ -176,8 +179,8 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float m[3][4])
m[i][COL_U] *= cmul;
m[i][COL_V] *= cmul;
// Set COL_C so that Y=umin,UV=cmid maps to RGB=min (black to black)
m[i][COL_C] = (rgblev.min - m[i][COL_Y] * yuvlev.ymin
-(m[i][COL_U] + m[i][COL_V]) * yuvlev.cmid) / 255;
m[i][COL_C] = rgblev.min - m[i][COL_Y] * yuvlev.ymin
-(m[i][COL_U] + m[i][COL_V]) * yuvlev.cmid;
}
// Brightness adds a constant to output R,G,B.
@ -185,15 +188,8 @@ void mp_get_yuv2rgb_coeffs(struct mp_csp_params *params, float m[3][4])
for (int i = 0; i < 3; i++) {
m[i][COL_C] += params->brightness;
m[i][COL_Y] *= params->contrast;
m[i][COL_C] += (rgblev.max-rgblev.min)/255 * (1 - params->contrast)/2;
m[i][COL_C] += (rgblev.max-rgblev.min) * (1 - params->contrast)/2;
}
float depth_multiplier = params->input_shift >= 0 ?
(1 << params->input_shift) :
(1.0 / (1 << -params->input_shift));
for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++)
m[i][j] *= depth_multiplier;
}
//! size of gamma map use to avoid slow exp function in gen_yuv2rgb_map

3
libvo/csputils.h
View File

@ -68,7 +68,8 @@ struct mp_csp_params {
float rgamma;
float ggamma;
float bgamma;
int input_shift;
int texture_bits;
int input_bits;
};
enum mp_csp_equalizer_param {

3
libvo/vo_gl.c
View File

@ -220,7 +220,8 @@ static void update_yuvconv(struct vo *vo)
mp_get_chroma_shift(p->image_format, &xs, &ys, &depth);
params.chrom_texw = params.texw >> xs;
params.chrom_texh = params.texh >> ys;
params.csp_params.input_shift = -depth & 7;
params.csp_params.input_bits = depth;
params.csp_params.texture_bits = depth+7 & ~7;
glSetupYUVConversion(gl, &params);
if (p->custom_prog) {
FILE *f = fopen(p->custom_prog, "rb");

3
libvo/vo_vdpau.c
View File

@ -599,7 +599,8 @@ static void update_csc_matrix(struct vo *vo)
// both are float[3][4]
VdpCSCMatrix matrix;
struct mp_csp_params cparams = { .colorspace = vc->colorspace };
struct mp_csp_params cparams = {
.colorspace = vc->colorspace, .input_bits = 8, .texture_bits = 8 };
mp_csp_copy_equalizer_values(&cparams, &vc->video_eq);
mp_get_yuv2rgb_coeffs(&cparams, matrix);