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FFmpeg/libavutil/csp.c
Leo Izen 719a93f4e4 avutil/{color_utils, csp}: merge color_utils into csp and expose API 
libavutil/color_utils contains some avpriv_ symbols that map
enum AVTransferCharacteristic values to gamma-curve approximations and
to the actual transfer functions to invert them (i.e. -> linear).

There's two issues with this:
(1) avpriv is evil and should be avoided whenever possible
(2) libavutil/csp.h exposes a public API for handling color that
    already handles primaries and matricies

I don't see any reason this API has to be private, so this commit takes
the functionality from avutil/color_utils and merges it into avutil/csp
with an exposed av_ API rather than the previous avpriv_ API.

Every reference to the previous API has been updated to point to the
new one. color_utils.h has been deleted as well. This should not break
any applications as it only contained avpriv_ symbols in the first
place, so nothing in that header could be referenced by other
applications.

Signed-off-by: Leo Izen <leo.izen@gmail.com>
Signed-off-by: Anton Khirnov <anton@khirnov.net>
2023-02-09 15:35:14 +01:00

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/*
* Copyright (c) 2015 Kevin Wheatley <kevin.j.wheatley@gmail.com>
* Copyright (c) 2016 Ronald S. Bultje <rsbultje@gmail.com>
* Copyright (c) 2023 Leo Izen <leo.izen@gmail.com>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file Colorspace functions for libavutil
* @author Ronald S. Bultje <rsbultje@gmail.com>
* @author Leo Izen <leo.izen@gmail.com>
* @author Kevin Wheatley <kevin.j.wheatley@gmail.com>
*/
#include <stdlib.h>
#include <math.h>
#include "attributes.h"
#include "csp.h"
#include "pixfmt.h"
#include "rational.h"
#define AVR(d) { (int)(d * 100000 + 0.5), 100000 }
/*
* All constants explained in e.g. https://linuxtv.org/downloads/v4l-dvb-apis/ch02s06.html
* The older ones (bt470bg/m) are also explained in their respective ITU docs
* (e.g. https://www.itu.int/dms_pubrec/itu-r/rec/bt/R-REC-BT.470-5-199802-S!!PDF-E.pdf)
* whereas the newer ones can typically be copied directly from wikipedia :)
*/
static const struct AVLumaCoefficients luma_coefficients[AVCOL_SPC_NB] = {
[AVCOL_SPC_FCC] = { AVR(0.30), AVR(0.59), AVR(0.11) },
[AVCOL_SPC_BT470BG] = { AVR(0.299), AVR(0.587), AVR(0.114) },
[AVCOL_SPC_SMPTE170M] = { AVR(0.299), AVR(0.587), AVR(0.114) },
[AVCOL_SPC_BT709] = { AVR(0.2126), AVR(0.7152), AVR(0.0722) },
[AVCOL_SPC_SMPTE240M] = { AVR(0.212), AVR(0.701), AVR(0.087) },
[AVCOL_SPC_YCOCG] = { AVR(0.25), AVR(0.5), AVR(0.25) },
[AVCOL_SPC_RGB] = { AVR(1), AVR(1), AVR(1) },
[AVCOL_SPC_BT2020_NCL] = { AVR(0.2627), AVR(0.6780), AVR(0.0593) },
[AVCOL_SPC_BT2020_CL] = { AVR(0.2627), AVR(0.6780), AVR(0.0593) },
};
const struct AVLumaCoefficients *av_csp_luma_coeffs_from_avcsp(enum AVColorSpace csp)
{
const AVLumaCoefficients *coeffs;
if (csp >= AVCOL_SPC_NB)
return NULL;
coeffs = &luma_coefficients[csp];
if (!coeffs->cr.num)
return NULL;
return coeffs;
}
#define WP_D65 { AVR(0.3127), AVR(0.3290) }
#define WP_C { AVR(0.3100), AVR(0.3160) }
#define WP_DCI { AVR(0.3140), AVR(0.3510) }
#define WP_E { {1, 3}, {1, 3} }
static const AVColorPrimariesDesc color_primaries[AVCOL_PRI_NB] = {
[AVCOL_PRI_BT709] = { WP_D65, { { AVR(0.640), AVR(0.330) }, { AVR(0.300), AVR(0.600) }, { AVR(0.150), AVR(0.060) } } },
[AVCOL_PRI_BT470M] = { WP_C, { { AVR(0.670), AVR(0.330) }, { AVR(0.210), AVR(0.710) }, { AVR(0.140), AVR(0.080) } } },
[AVCOL_PRI_BT470BG] = { WP_D65, { { AVR(0.640), AVR(0.330) }, { AVR(0.290), AVR(0.600) }, { AVR(0.150), AVR(0.060) } } },
[AVCOL_PRI_SMPTE170M] = { WP_D65, { { AVR(0.630), AVR(0.340) }, { AVR(0.310), AVR(0.595) }, { AVR(0.155), AVR(0.070) } } },
[AVCOL_PRI_SMPTE240M] = { WP_D65, { { AVR(0.630), AVR(0.340) }, { AVR(0.310), AVR(0.595) }, { AVR(0.155), AVR(0.070) } } },
[AVCOL_PRI_SMPTE428] = { WP_E, { { AVR(0.735), AVR(0.265) }, { AVR(0.274), AVR(0.718) }, { AVR(0.167), AVR(0.009) } } },
[AVCOL_PRI_SMPTE431] = { WP_DCI, { { AVR(0.680), AVR(0.320) }, { AVR(0.265), AVR(0.690) }, { AVR(0.150), AVR(0.060) } } },
[AVCOL_PRI_SMPTE432] = { WP_D65, { { AVR(0.680), AVR(0.320) }, { AVR(0.265), AVR(0.690) }, { AVR(0.150), AVR(0.060) } } },
[AVCOL_PRI_FILM] = { WP_C, { { AVR(0.681), AVR(0.319) }, { AVR(0.243), AVR(0.692) }, { AVR(0.145), AVR(0.049) } } },
[AVCOL_PRI_BT2020] = { WP_D65, { { AVR(0.708), AVR(0.292) }, { AVR(0.170), AVR(0.797) }, { AVR(0.131), AVR(0.046) } } },
[AVCOL_PRI_JEDEC_P22] = { WP_D65, { { AVR(0.630), AVR(0.340) }, { AVR(0.295), AVR(0.605) }, { AVR(0.155), AVR(0.077) } } },
};
const AVColorPrimariesDesc *av_csp_primaries_desc_from_id(enum AVColorPrimaries prm)
{
const AVColorPrimariesDesc *p;
if (prm >= AVCOL_PRI_NB)
return NULL;
p = &color_primaries[prm];
if (!p->prim.r.x.num)
return NULL;
return p;
}
static av_always_inline AVRational abs_sub_q(AVRational r1, AVRational r2)
{
AVRational diff = av_sub_q(r1, r2);
/* denominator assumed to be positive */
return av_make_q(abs(diff.num), diff.den);
}
enum AVColorPrimaries av_csp_primaries_id_from_desc(const AVColorPrimariesDesc *prm)
{
AVRational delta;
for (enum AVColorPrimaries p = 0; p < AVCOL_PRI_NB; p++) {
const AVColorPrimariesDesc *ref = &color_primaries[p];
if (!ref->prim.r.x.num)
continue;
delta = abs_sub_q(prm->prim.r.x, ref->prim.r.x);
delta = av_add_q(delta, abs_sub_q(prm->prim.r.y, ref->prim.r.y));
delta = av_add_q(delta, abs_sub_q(prm->prim.g.x, ref->prim.g.x));
delta = av_add_q(delta, abs_sub_q(prm->prim.g.y, ref->prim.g.y));
delta = av_add_q(delta, abs_sub_q(prm->prim.b.x, ref->prim.b.x));
delta = av_add_q(delta, abs_sub_q(prm->prim.b.y, ref->prim.b.y));
delta = av_add_q(delta, abs_sub_q(prm->wp.x, ref->wp.x));
delta = av_add_q(delta, abs_sub_q(prm->wp.y, ref->wp.y));
if (av_cmp_q(delta, av_make_q(1, 1000)) < 0)
return p;
}
return AVCOL_PRI_UNSPECIFIED;
}
static const double approximate_gamma[AVCOL_TRC_NB] = {
[AVCOL_TRC_BT709] = 1.961,
[AVCOL_TRC_SMPTE170M] = 1.961,
[AVCOL_TRC_SMPTE240M] = 1.961,
[AVCOL_TRC_BT1361_ECG] = 1.961,
[AVCOL_TRC_BT2020_10] = 1.961,
[AVCOL_TRC_BT2020_12] = 1.961,
[AVCOL_TRC_GAMMA22] = 2.2,
[AVCOL_TRC_IEC61966_2_1] = 2.2,
[AVCOL_TRC_GAMMA28] = 2.8,
[AVCOL_TRC_LINEAR] = 1.0,
[AVCOL_TRC_SMPTE428] = 2.6,
};
double av_csp_approximate_trc_gamma(enum AVColorTransferCharacteristic trc)
{
double gamma;
if (trc >= AVCOL_TRC_NB)
return 0.0;
gamma = approximate_gamma[trc];
if (gamma > 0)
return gamma;
return 0.0;
}
#define BT709_alpha 1.099296826809442
#define BT709_beta 0.018053968510807
static double trc_bt709(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 4.500 * Lc
: a * pow(Lc, 0.45) - (a - 1.0);
}
static double trc_gamma22(double Lc)
{
return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.2);
}
static double trc_gamma28(double Lc)
{
return (0.0 > Lc) ? 0.0 : pow(Lc, 1.0/ 2.8);
}
static double trc_smpte240M(double Lc)
{
const double a = 1.1115;
const double b = 0.0228;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 4.000 * Lc
: a * pow(Lc, 0.45) - (a - 1.0);
}
static double trc_linear(double Lc)
{
return Lc;
}
static double trc_log(double Lc)
{
return (0.01 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.0;
}
static double trc_log_sqrt(double Lc)
{
// sqrt(10) / 1000
return (0.00316227766 > Lc) ? 0.0 : 1.0 + log10(Lc) / 2.5;
}
static double trc_iec61966_2_4(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (-b >= Lc) ? -a * pow(-Lc, 0.45) + (a - 1.0)
: ( b > Lc) ? 4.500 * Lc
: a * pow( Lc, 0.45) - (a - 1.0);
}
static double trc_bt1361(double Lc)
{
const double a = BT709_alpha;
const double b = BT709_beta;
return (-0.0045 >= Lc) ? -(a * pow(-4.0 * Lc, 0.45) + (a - 1.0)) / 4.0
: ( b > Lc) ? 4.500 * Lc
: a * pow( Lc, 0.45) - (a - 1.0);
}
static double trc_iec61966_2_1(double Lc)
{
const double a = 1.055;
const double b = 0.0031308;
return (0.0 > Lc) ? 0.0
: ( b > Lc) ? 12.92 * Lc
: a * pow(Lc, 1.0 / 2.4) - (a - 1.0);
}
static double trc_smpte_st2084(double Lc)
{
const double c1 = 3424.0 / 4096.0; // c3-c2 + 1
const double c2 = 32.0 * 2413.0 / 4096.0;
const double c3 = 32.0 * 2392.0 / 4096.0;
const double m = 128.0 * 2523.0 / 4096.0;
const double n = 0.25 * 2610.0 / 4096.0;
const double L = Lc / 10000.0;
const double Ln = pow(L, n);
return (0.0 > Lc) ? 0.0
: pow((c1 + c2 * Ln) / (1.0 + c3 * Ln), m);
}
static double trc_smpte_st428_1(double Lc)
{
return (0.0 > Lc) ? 0.0
: pow(48.0 * Lc / 52.37, 1.0 / 2.6);
}
static double trc_arib_std_b67(double Lc) {
// The function uses the definition from HEVC, which assumes that the peak
// white is input level = 1. (this is equivalent to scaling E = Lc * 12 and
// using the definition from the ARIB STD-B67 spec)
const double a = 0.17883277;
const double b = 0.28466892;
const double c = 0.55991073;
return (0.0 > Lc) ? 0.0 :
(Lc <= 1.0 / 12.0 ? sqrt(3.0 * Lc) : a * log(12.0 * Lc - b) + c);
}
static const av_csp_trc_function trc_funcs[AVCOL_TRC_NB] = {
[AVCOL_TRC_BT709] = trc_bt709,
[AVCOL_TRC_GAMMA22] = trc_gamma22,
[AVCOL_TRC_GAMMA28] = trc_gamma28,
[AVCOL_TRC_SMPTE170M] = trc_bt709,
[AVCOL_TRC_SMPTE240M] = trc_smpte240M,
[AVCOL_TRC_LINEAR] = trc_linear,
[AVCOL_TRC_LOG] = trc_log,
[AVCOL_TRC_LOG_SQRT] = trc_log_sqrt,
[AVCOL_TRC_IEC61966_2_4] = trc_iec61966_2_4,
[AVCOL_TRC_BT1361_ECG] = trc_bt1361,
[AVCOL_TRC_IEC61966_2_1] = trc_iec61966_2_1,
[AVCOL_TRC_BT2020_10] = trc_bt709,
[AVCOL_TRC_BT2020_12] = trc_bt709,
[AVCOL_TRC_SMPTE2084] = trc_smpte_st2084,
[AVCOL_TRC_SMPTE428] = trc_smpte_st428_1,
[AVCOL_TRC_ARIB_STD_B67] = trc_arib_std_b67,
};
av_csp_trc_function av_csp_trc_func_from_id(enum AVColorTransferCharacteristic trc)
{
av_csp_trc_function func;
if (trc >= AVCOL_TRC_NB)
return NULL;
func = trc_funcs[trc];
if (!func)
return NULL;
return func;
}
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