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authorwm4 <wm4@nowhere>2020-05-09 18:00:15 +0200
committerwm4 <wm4@nowhere>2020-05-09 18:02:57 +0200
commitbf19f34960ef1664ef8da614aa1b034003fcbc0f (patch)
treef5a7226c4ca5bd377917a30518eed19bf9617dea
parent56dbbc38479bd84905ac4478b1b853e907a583dd (diff)
downloadmpv-bf19f34960ef1664ef8da614aa1b034003fcbc0f.tar.bz2
mpv-bf19f34960ef1664ef8da614aa1b034003fcbc0f.tar.xz
csputils: add function for getting uint/float transformation
This provides a way to convert YUV in fixed point (or pseudo-fixed point; probably best to say "uint") to float, or rather coefficients to perform such a conversion. Things like colorspace conversion is out of scope, so this is simple and strictly per-component. This is somewhat similar to mp_get_csp_mul(), but includes proper color range expansion and correct chroma centering. The old function even seems to have a bug, and assumes something about shifted range for full range YCbCr, which is wrong. vo_gpu should probably use the new function eventually.
-rw-r--r--video/csputils.c43
-rw-r--r--video/csputils.h2
2 files changed, 44 insertions, 1 deletions
diff --git a/video/csputils.c b/video/csputils.c
index 8965b1324c..6833f583fb 100644
--- a/video/csputils.c
+++ b/video/csputils.c
@@ -637,7 +637,8 @@ static void mp_get_xyz2rgb_coeffs(struct mp_csp_params *params,
}
// Get multiplication factor required if image data is fit within the LSBs of a
-// higher smaller bit depth isfixed-point texture data.
+// higher smaller bit depth fixed-point texture data.
+// This is broken. Use mp_get_csp_uint_mul().
double mp_get_csp_mul(enum mp_csp csp, int input_bits, int texture_bits)
{
assert(texture_bits >= input_bits);
@@ -657,6 +658,46 @@ double mp_get_csp_mul(enum mp_csp csp, int input_bits, int texture_bits)
return (1LL << input_bits) / ((1LL << texture_bits) - 1.) * 255 / 256;
}
+// Return information about color fixed point representation.his is needed for
+// converting color from integer formats to or from float. Use as follows:
+// float_val = uint_val * m + o
+// uint_val = clamp(round((float_val - o) / m))
+// See H.264/5 Annex E.
+// csp: colorspace
+// levels: full range flag
+// component: ID of the channel, as in mp_regular_imgfmt:
+// 1 is red/luminance/gray, 2 is green/Cb, 3 is blue/Cr, 4 is alpha.
+// bits: number of significant bits, e.g. 10 for yuv420p10, 16 for p010
+// out_m: returns factor to multiply the uint number with
+// out_o: returns offset to add after multiplication
+void mp_get_csp_uint_mul(enum mp_csp csp, enum mp_csp_levels levels,
+ int bits, int component, double *out_m, double *out_o)
+{
+ uint16_t i_min = 0;
+ uint16_t i_max = (1u << bits) - 1;
+ double f_min = 0; // min. float value
+
+ if (csp != MP_CSP_RGB && component != 4) {
+ if (component == 2 || component == 3) {
+ f_min = (1u << (bits - 1)) / -(double)i_max; // force center => 0
+
+ if (levels != MP_CSP_LEVELS_PC && bits >= 8) {
+ i_min = 16 << (bits - 8); // => -0.5
+ i_max = 240 << (bits - 8); // => 0.5
+ f_min = -0.5;
+ }
+ } else {
+ if (levels != MP_CSP_LEVELS_PC && bits >= 8) {
+ i_min = 16 << (bits - 8); // => 0
+ i_max = 235 << (bits - 8); // => 1
+ }
+ }
+ }
+
+ *out_m = 1.0 / (i_max - i_min);
+ *out_o = (1 + f_min) - i_max * *out_m;
+}
+
/* Fill in the Y, U, V vectors of a yuv-to-rgb conversion matrix
* based on the given luma weights of the R, G and B components (lr, lg, lb).
* lr+lg+lb is assumed to equal 1.
diff --git a/video/csputils.h b/video/csputils.h
index dfc2a569cc..34e2894a28 100644
--- a/video/csputils.h
+++ b/video/csputils.h
@@ -288,6 +288,8 @@ void mp_get_cms_matrix(struct mp_csp_primaries src, struct mp_csp_primaries dest
enum mp_render_intent intent, float cms_matrix[3][3]);
double mp_get_csp_mul(enum mp_csp csp, int input_bits, int texture_bits);
+void mp_get_csp_uint_mul(enum mp_csp csp, enum mp_csp_levels levels,
+ int bits, int component, double *out_m, double *out_o);
void mp_get_csp_matrix(struct mp_csp_params *params, struct mp_cmat *out);
void mp_invert_matrix3x3(float m[3][3]);