[FFmpeg-devel] [PATCH v7 1/1] avutil/csp: create public API for colorspace structs

Leo Izen leo.izen at gmail.com
Sat May 28 16:30:36 EEST 2022


This commit moves some of the functionality from avfilter/colorspace
into avutil/csp and exposes it as a public API so it can be used by
libavcodec and/or libavformat. It also converts those structs from
double values to AVRational to make regression testing easier and
more consistent.
---
 libavfilter/colorspace.c    | 143 ++++++++----------------------------
 libavfilter/colorspace.h    |  31 +-------
 libavfilter/fflcms2.c       |  33 +++++----
 libavfilter/fflcms2.h       |   4 +-
 libavfilter/vf_colorspace.c |  37 +++++-----
 libavfilter/vf_iccdetect.c  |   5 +-
 libavfilter/vf_tonemap.c    |  17 +----
 libavutil/Makefile          |   2 +
 libavutil/csp.c             | 128 ++++++++++++++++++++++++++++++++
 libavutil/csp.h             | 106 ++++++++++++++++++++++++++
 libavutil/version.h         |   2 +-
 11 files changed, 317 insertions(+), 191 deletions(-)
 create mode 100644 libavutil/csp.c
 create mode 100644 libavutil/csp.h

diff --git a/libavfilter/colorspace.c b/libavfilter/colorspace.c
index 8d7b882375..7f74fe5113 100644
--- a/libavfilter/colorspace.c
+++ b/libavfilter/colorspace.c
@@ -65,24 +65,28 @@ void ff_matrix_mul_3x3(double dst[3][3],
 /*
  * see e.g. http://www.brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
  */
-void ff_fill_rgb2xyz_table(const struct PrimaryCoefficients *coeffs,
-                           const struct WhitepointCoefficients *wp,
+void ff_fill_rgb2xyz_table(const AVPrimaryCoefficients *coeffs,
+                           const AVWhitepointCoefficients *wp,
                            double rgb2xyz[3][3])
 {
     double i[3][3], sr, sg, sb, zw;
-
-    rgb2xyz[0][0] = coeffs->xr / coeffs->yr;
-    rgb2xyz[0][1] = coeffs->xg / coeffs->yg;
-    rgb2xyz[0][2] = coeffs->xb / coeffs->yb;
+    double xr = av_q2d(coeffs->r.x), yr = av_q2d(coeffs->r.y);
+    double xg = av_q2d(coeffs->g.x), yg = av_q2d(coeffs->g.y);
+    double xb = av_q2d(coeffs->b.x), yb = av_q2d(coeffs->b.y);
+    double xw = av_q2d(wp->x), yw = av_q2d(wp->y);
+
+    rgb2xyz[0][0] = xr / yr;
+    rgb2xyz[0][1] = xg / yg;
+    rgb2xyz[0][2] = xb / yb;
     rgb2xyz[1][0] = rgb2xyz[1][1] = rgb2xyz[1][2] = 1.0;
-    rgb2xyz[2][0] = (1.0 - coeffs->xr - coeffs->yr) / coeffs->yr;
-    rgb2xyz[2][1] = (1.0 - coeffs->xg - coeffs->yg) / coeffs->yg;
-    rgb2xyz[2][2] = (1.0 - coeffs->xb - coeffs->yb) / coeffs->yb;
+    rgb2xyz[2][0] = (1.0 - xr - yr) / yr;
+    rgb2xyz[2][1] = (1.0 - xg - yg) / yg;
+    rgb2xyz[2][2] = (1.0 - xb - yb) / yb;
     ff_matrix_invert_3x3(rgb2xyz, i);
-    zw = 1.0 - wp->xw - wp->yw;
-    sr = i[0][0] * wp->xw + i[0][1] * wp->yw + i[0][2] * zw;
-    sg = i[1][0] * wp->xw + i[1][1] * wp->yw + i[1][2] * zw;
-    sb = i[2][0] * wp->xw + i[2][1] * wp->yw + i[2][2] * zw;
+    zw = 1.0 - xw - yw;
+    sr = i[0][0] * xw + i[0][1] * yw + i[0][2] * zw;
+    sg = i[1][0] * xw + i[1][1] * yw + i[1][2] * zw;
+    sb = i[2][0] * xw + i[2][1] * yw + i[2][2] * zw;
     rgb2xyz[0][0] *= sr;
     rgb2xyz[0][1] *= sg;
     rgb2xyz[0][2] *= sb;
@@ -107,119 +111,32 @@ static const double gbr_matrix[3][3] =
     { 0.5, -0.5, 0   },
 };
 
-/*
- * 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 LumaCoefficients luma_coefficients[AVCOL_SPC_NB] = {
-    [AVCOL_SPC_FCC]        = { 0.30,   0.59,   0.11   },
-    [AVCOL_SPC_BT470BG]    = { 0.299,  0.587,  0.114  },
-    [AVCOL_SPC_SMPTE170M]  = { 0.299,  0.587,  0.114  },
-    [AVCOL_SPC_BT709]      = { 0.2126, 0.7152, 0.0722 },
-    [AVCOL_SPC_SMPTE240M]  = { 0.212,  0.701,  0.087  },
-    [AVCOL_SPC_YCOCG]      = { 0.25,   0.5,    0.25   },
-    [AVCOL_SPC_RGB]        = { 1,      1,      1      },
-    [AVCOL_SPC_BT2020_NCL] = { 0.2627, 0.6780, 0.0593 },
-    [AVCOL_SPC_BT2020_CL]  = { 0.2627, 0.6780, 0.0593 },
-};
-
-const struct LumaCoefficients *ff_get_luma_coefficients(enum AVColorSpace csp)
-{
-    const struct LumaCoefficients *coeffs;
-
-    if (csp >= AVCOL_SPC_NB)
-        return NULL;
-    coeffs = &luma_coefficients[csp];
-    if (!coeffs->cr)
-        return NULL;
-
-    return coeffs;
-}
-
-#define WP_D65 { 0.3127, 0.3290 }
-#define WP_C   { 0.3100, 0.3160 }
-#define WP_DCI { 0.3140, 0.3510 }
-#define WP_E   { 1/3.0f, 1/3.0f }
-
-static const struct ColorPrimaries color_primaries[AVCOL_PRI_NB] = {
-    [AVCOL_PRI_BT709]     = { WP_D65, { 0.640, 0.330, 0.300, 0.600, 0.150, 0.060 } },
-    [AVCOL_PRI_BT470M]    = { WP_C,   { 0.670, 0.330, 0.210, 0.710, 0.140, 0.080 } },
-    [AVCOL_PRI_BT470BG]   = { WP_D65, { 0.640, 0.330, 0.290, 0.600, 0.150, 0.060 } },
-    [AVCOL_PRI_SMPTE170M] = { WP_D65, { 0.630, 0.340, 0.310, 0.595, 0.155, 0.070 } },
-    [AVCOL_PRI_SMPTE240M] = { WP_D65, { 0.630, 0.340, 0.310, 0.595, 0.155, 0.070 } },
-    [AVCOL_PRI_SMPTE428]  = { WP_E,   { 0.735, 0.265, 0.274, 0.718, 0.167, 0.009 } },
-    [AVCOL_PRI_SMPTE431]  = { WP_DCI, { 0.680, 0.320, 0.265, 0.690, 0.150, 0.060 } },
-    [AVCOL_PRI_SMPTE432]  = { WP_D65, { 0.680, 0.320, 0.265, 0.690, 0.150, 0.060 } },
-    [AVCOL_PRI_FILM]      = { WP_C,   { 0.681, 0.319, 0.243, 0.692, 0.145, 0.049 } },
-    [AVCOL_PRI_BT2020]    = { WP_D65, { 0.708, 0.292, 0.170, 0.797, 0.131, 0.046 } },
-    [AVCOL_PRI_JEDEC_P22] = { WP_D65, { 0.630, 0.340, 0.295, 0.605, 0.155, 0.077 } },
-};
-
-const struct ColorPrimaries *ff_get_color_primaries(enum AVColorPrimaries prm)
-{
-    const struct ColorPrimaries *p;
-
-    if (prm >= AVCOL_PRI_NB)
-        return NULL;
-    p = &color_primaries[prm];
-    if (!p->prim.xr)
-        return NULL;
-
-    return p;
-}
-
-enum AVColorPrimaries ff_detect_color_primaries(const struct ColorPrimaries *prm)
-{
-    double delta;
-
-    for (enum AVColorPrimaries p = 0; p < AVCOL_PRI_NB; p++) {
-        const struct ColorPrimaries *ref = &color_primaries[p];
-        if (!ref->prim.xr)
-            continue;
-
-        delta = fabs(prm->prim.xr - ref->prim.xr) +
-                fabs(prm->prim.yr - ref->prim.yr) +
-                fabs(prm->prim.yg - ref->prim.yg) +
-                fabs(prm->prim.yg - ref->prim.yg) +
-                fabs(prm->prim.yb - ref->prim.yb) +
-                fabs(prm->prim.yb - ref->prim.yb) +
-                fabs(prm->wp.xw - ref->wp.xw) +
-                fabs(prm->wp.yw - ref->wp.yw);
-
-        if (delta < 0.001)
-            return p;
-    }
-
-    return AVCOL_PRI_UNSPECIFIED;
-}
-
-void ff_fill_rgb2yuv_table(const struct LumaCoefficients *coeffs,
+void ff_fill_rgb2yuv_table(const AVLumaCoefficients *coeffs,
                            double rgb2yuv[3][3])
 {
     double bscale, rscale;
+    double cr = av_q2d(coeffs->cr), cg = av_q2d(coeffs->cg), cb = av_q2d(coeffs->cb);
 
     // special ycgco matrix
-    if (coeffs->cr == 0.25 && coeffs->cg == 0.5 && coeffs->cb == 0.25) {
+    if (cr == 0.25 && cg == 0.5 && cb == 0.25) {
         memcpy(rgb2yuv, ycgco_matrix, sizeof(double) * 9);
         return;
-    } else if (coeffs->cr == 1 && coeffs->cg == 1 && coeffs->cb == 1) {
+    } else if (cr == 1 && cg == 1 && cb == 1) {
         memcpy(rgb2yuv, gbr_matrix, sizeof(double) * 9);
         return;
     }
 
-    rgb2yuv[0][0] = coeffs->cr;
-    rgb2yuv[0][1] = coeffs->cg;
-    rgb2yuv[0][2] = coeffs->cb;
-    bscale = 0.5 / (coeffs->cb - 1.0);
-    rscale = 0.5 / (coeffs->cr - 1.0);
-    rgb2yuv[1][0] = bscale * coeffs->cr;
-    rgb2yuv[1][1] = bscale * coeffs->cg;
+    rgb2yuv[0][0] = cr;
+    rgb2yuv[0][1] = cg;
+    rgb2yuv[0][2] = cb;
+    bscale = 0.5 / (cb - 1.0);
+    rscale = 0.5 / (cr - 1.0);
+    rgb2yuv[1][0] = bscale * cr;
+    rgb2yuv[1][1] = bscale * cg;
     rgb2yuv[1][2] = 0.5;
     rgb2yuv[2][0] = 0.5;
-    rgb2yuv[2][1] = rscale * coeffs->cg;
-    rgb2yuv[2][2] = rscale * coeffs->cb;
+    rgb2yuv[2][1] = rscale * cg;
+    rgb2yuv[2][2] = rscale * cb;
 }
 
 double ff_determine_signal_peak(AVFrame *in)
diff --git a/libavfilter/colorspace.h b/libavfilter/colorspace.h
index 6959133a49..879518d242 100644
--- a/libavfilter/colorspace.h
+++ b/libavfilter/colorspace.h
@@ -20,43 +20,20 @@
 #ifndef AVFILTER_COLORSPACE_H
 #define AVFILTER_COLORSPACE_H
 
+#include "libavutil/csp.h"
 #include "libavutil/frame.h"
 #include "libavutil/pixfmt.h"
 
 #define REFERENCE_WHITE 100.0f
 
-struct LumaCoefficients {
-    double cr, cg, cb;
-};
-
-struct PrimaryCoefficients {
-    double xr, yr, xg, yg, xb, yb;
-};
-
-struct WhitepointCoefficients {
-    double xw, yw;
-};
-
-struct ColorPrimaries {
-    struct WhitepointCoefficients wp;
-    struct PrimaryCoefficients prim;
-};
-
 void ff_matrix_invert_3x3(const double in[3][3], double out[3][3]);
 void ff_matrix_mul_3x3(double dst[3][3],
                const double src1[3][3], const double src2[3][3]);
-void ff_fill_rgb2xyz_table(const struct PrimaryCoefficients *coeffs,
-                           const struct WhitepointCoefficients *wp,
+void ff_fill_rgb2xyz_table(const AVPrimaryCoefficients *coeffs,
+                           const AVWhitepointCoefficients *wp,
                            double rgb2xyz[3][3]);
-
-/* Returns AVCOL_PRI_UNSPECIFIED if no clear match can be identified */
-enum AVColorPrimaries ff_detect_color_primaries(const struct ColorPrimaries *prm);
-
-const struct ColorPrimaries *ff_get_color_primaries(enum AVColorPrimaries prm);
-const struct LumaCoefficients *ff_get_luma_coefficients(enum AVColorSpace csp);
-void ff_fill_rgb2yuv_table(const struct LumaCoefficients *coeffs,
+void ff_fill_rgb2yuv_table(const AVLumaCoefficients *coeffs,
                            double rgb2yuv[3][3]);
-
 double ff_determine_signal_peak(AVFrame *in);
 void ff_update_hdr_metadata(AVFrame *in, double peak);
 
diff --git a/libavfilter/fflcms2.c b/libavfilter/fflcms2.c
index efc7cb5189..fd370fb310 100644
--- a/libavfilter/fflcms2.c
+++ b/libavfilter/fflcms2.c
@@ -18,6 +18,7 @@
  */
 
 #include "libavutil/color_utils.h"
+#include "libavutil/csp.h"
 
 #include "fflcms2.h"
 
@@ -148,20 +149,20 @@ int ff_icc_profile_generate(FFIccContext *s,
                             cmsHPROFILE *out_profile)
 {
     cmsToneCurve *tonecurve;
-    const struct ColorPrimaries *prim;
+    const AVColorPrimariesDesc *prim;
     int ret;
 
-    if (!(prim = ff_get_color_primaries(color_prim)))
+    if (!(prim = av_csp_primaries_desc_from_id(color_prim)))
         return AVERROR_INVALIDDATA;
     if ((ret = get_curve(s, color_trc, &tonecurve)) < 0)
         return ret;
 
     *out_profile = cmsCreateRGBProfileTHR(s->ctx,
-        &(cmsCIExyY) { prim->wp.xw, prim->wp.yw, 1.0 },
+        &(cmsCIExyY) { av_q2d(prim->wp.x), av_q2d(prim->wp.y), 1.0 },
         &(cmsCIExyYTRIPLE) {
-            .Red    = { prim->prim.xr, prim->prim.yr, 1.0 },
-            .Green  = { prim->prim.xg, prim->prim.yg, 1.0 },
-            .Blue   = { prim->prim.xb, prim->prim.yb, 1.0 },
+            .Red    = { av_q2d(prim->prim.r.x), av_q2d(prim->prim.r.y), 1.0 },
+            .Green  = { av_q2d(prim->prim.g.x), av_q2d(prim->prim.g.y), 1.0 },
+            .Blue   = { av_q2d(prim->prim.b.x), av_q2d(prim->prim.b.y), 1.0 },
         },
         (cmsToneCurve *[3]) { tonecurve, tonecurve, tonecurve }
     );
@@ -194,15 +195,15 @@ int ff_icc_profile_attach(FFIccContext *s, cmsHPROFILE profile, AVFrame *frame)
     return 0;
 }
 
-static av_always_inline void XYZ_xy(cmsCIEXYZ XYZ, double *x, double *y)
+static av_always_inline void XYZ_xy(cmsCIEXYZ XYZ, AVCIExy *xy)
 {
     double k = 1.0 / (XYZ.X + XYZ.Y + XYZ.Z);
-    *x = k * XYZ.X;
-    *y = k * XYZ.Y;
+    xy->x = av_d2q(k * XYZ.X, 100000);
+    xy->y = av_d2q(k * XYZ.Y, 100000);
 }
 
 int ff_icc_profile_read_primaries(FFIccContext *s, cmsHPROFILE profile,
-                                  struct ColorPrimaries *out_primaries)
+                                  AVColorPrimariesDesc *out_primaries)
 {
     static const uint8_t testprimaries[4][3] = {
         { 0xFF,    0,    0 }, /* red */
@@ -211,8 +212,8 @@ int ff_icc_profile_read_primaries(FFIccContext *s, cmsHPROFILE profile,
         { 0xFF, 0xFF, 0xFF }, /* white */
     };
 
-    struct WhitepointCoefficients *wp = &out_primaries->wp;
-    struct PrimaryCoefficients *prim = &out_primaries->prim;
+    AVWhitepointCoefficients *wp = &out_primaries->wp;
+    AVPrimaryCoefficients *prim = &out_primaries->prim;
     cmsFloat64Number prev_adapt;
     cmsHPROFILE xyz;
     cmsHTRANSFORM tf;
@@ -241,10 +242,10 @@ int ff_icc_profile_read_primaries(FFIccContext *s, cmsHPROFILE profile,
 
     cmsDoTransform(tf, testprimaries, dst, 4);
     cmsDeleteTransform(tf);
-    XYZ_xy(dst[0], &prim->xr, &prim->yr);
-    XYZ_xy(dst[1], &prim->xg, &prim->yg);
-    XYZ_xy(dst[2], &prim->xb, &prim->yb);
-    XYZ_xy(dst[3], &wp->xw, &wp->yw);
+    XYZ_xy(dst[0], &prim->r);
+    XYZ_xy(dst[1], &prim->g);
+    XYZ_xy(dst[2], &prim->b);
+    XYZ_xy(dst[3], wp);
     return 0;
 }
 
diff --git a/libavfilter/fflcms2.h b/libavfilter/fflcms2.h
index ad6c8c47cf..0d238c679f 100644
--- a/libavfilter/fflcms2.h
+++ b/libavfilter/fflcms2.h
@@ -25,9 +25,9 @@
 #ifndef AVFILTER_FFLCMS2_H
 #define AVFILTER_FFLCMS2_H
 
+#include "libavutil/csp.h"
 #include "libavutil/frame.h"
 #include "libavutil/pixfmt.h"
-#include "colorspace.h"
 
 #include <lcms2.h>
 
@@ -72,7 +72,7 @@ int ff_icc_profile_attach(FFIccContext *s, cmsHPROFILE profile, AVFrame *frame);
  * Returns 0 on success, or a negative error code.
  */
 int ff_icc_profile_read_primaries(FFIccContext *s, cmsHPROFILE profile,
-                                  struct ColorPrimaries *out_primaries);
+                                  AVColorPrimariesDesc *out_primaries);
 
 /**
  * Attempt detecting the transfer characteristic that best approximates the
diff --git a/libavfilter/vf_colorspace.c b/libavfilter/vf_colorspace.c
index 3c8b3b20eb..21916b7b7a 100644
--- a/libavfilter/vf_colorspace.c
+++ b/libavfilter/vf_colorspace.c
@@ -24,6 +24,7 @@
  */
 
 #include "libavutil/avassert.h"
+#include "libavutil/csp.h"
 #include "libavutil/mem_internal.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
@@ -126,7 +127,7 @@ typedef struct ColorSpaceContext {
     unsigned rgb_sz;
     int *dither_scratch[3][2], *dither_scratch_base[3][2];
 
-    const struct ColorPrimaries *in_primaries, *out_primaries;
+    const AVColorPrimariesDesc *in_primaries, *out_primaries;
     int lrgb2lrgb_passthrough;
     DECLARE_ALIGNED(16, int16_t, lrgb2lrgb_coeffs)[3][3][8];
 
@@ -134,7 +135,7 @@ typedef struct ColorSpaceContext {
     int rgb2rgb_passthrough;
     int16_t *lin_lut, *delin_lut;
 
-    const struct LumaCoefficients *in_lumacoef, *out_lumacoef;
+    const AVLumaCoefficients *in_lumacoef, *out_lumacoef;
     int yuv2yuv_passthrough, yuv2yuv_fastmode;
     DECLARE_ALIGNED(16, int16_t, yuv2rgb_coeffs)[3][3][8];
     DECLARE_ALIGNED(16, int16_t, rgb2yuv_coeffs)[3][3][8];
@@ -233,8 +234,8 @@ static int fill_gamma_table(ColorSpaceContext *s)
  * This function uses the Bradford mechanism.
  */
 static void fill_whitepoint_conv_table(double out[3][3], enum WhitepointAdaptation wp_adapt,
-                                       const struct WhitepointCoefficients *wp_src,
-                                       const struct WhitepointCoefficients *wp_dst)
+                                       const AVWhitepointCoefficients *wp_src,
+                                       const AVWhitepointCoefficients *wp_dst)
 {
     static const double ma_tbl[NB_WP_ADAPT_NON_IDENTITY][3][3] = {
         [WP_ADAPT_BRADFORD] = {
@@ -248,18 +249,20 @@ static void fill_whitepoint_conv_table(double out[3][3], enum WhitepointAdaptati
         },
     };
     const double (*ma)[3] = ma_tbl[wp_adapt];
-    double zw_src = 1.0 - wp_src->xw - wp_src->yw;
-    double zw_dst = 1.0 - wp_dst->xw - wp_dst->yw;
+    double xw_src = av_q2d(wp_src->x), yw_src = av_q2d(wp_src->y);
+    double xw_dst = av_q2d(wp_dst->x), yw_dst = av_q2d(wp_dst->y);
+    double zw_src = 1.0 - xw_src - yw_src;
+    double zw_dst = 1.0 - xw_dst - yw_dst;
     double mai[3][3], fac[3][3], tmp[3][3];
     double rs, gs, bs, rd, gd, bd;
 
     ff_matrix_invert_3x3(ma, mai);
-    rs = ma[0][0] * wp_src->xw + ma[0][1] * wp_src->yw + ma[0][2] * zw_src;
-    gs = ma[1][0] * wp_src->xw + ma[1][1] * wp_src->yw + ma[1][2] * zw_src;
-    bs = ma[2][0] * wp_src->xw + ma[2][1] * wp_src->yw + ma[2][2] * zw_src;
-    rd = ma[0][0] * wp_dst->xw + ma[0][1] * wp_dst->yw + ma[0][2] * zw_dst;
-    gd = ma[1][0] * wp_dst->xw + ma[1][1] * wp_dst->yw + ma[1][2] * zw_dst;
-    bd = ma[2][0] * wp_dst->xw + ma[2][1] * wp_dst->yw + ma[2][2] * zw_dst;
+    rs = ma[0][0] * xw_src + ma[0][1] * yw_src + ma[0][2] * zw_src;
+    gs = ma[1][0] * xw_src + ma[1][1] * yw_src + ma[1][2] * zw_src;
+    bs = ma[2][0] * xw_src + ma[2][1] * yw_src + ma[2][2] * zw_src;
+    rd = ma[0][0] * xw_dst + ma[0][1] * yw_dst + ma[0][2] * zw_dst;
+    gd = ma[1][0] * xw_dst + ma[1][1] * yw_dst + ma[1][2] * zw_dst;
+    bd = ma[2][0] * xw_dst + ma[2][1] * yw_dst + ma[2][2] * zw_dst;
     fac[0][0] = rd / rs;
     fac[1][1] = gd / gs;
     fac[2][2] = bd / bs;
@@ -438,7 +441,7 @@ static int create_filtergraph(AVFilterContext *ctx,
             s->in_prm = default_prm[FFMIN(s->user_iall, CS_NB)];
         if (s->user_iprm != AVCOL_PRI_UNSPECIFIED)
             s->in_prm = s->user_iprm;
-        s->in_primaries = ff_get_color_primaries(s->in_prm);
+        s->in_primaries = av_csp_primaries_desc_from_id(s->in_prm);
         if (!s->in_primaries) {
             av_log(ctx, AV_LOG_ERROR,
                    "Unsupported input primaries %d (%s)\n",
@@ -446,7 +449,7 @@ static int create_filtergraph(AVFilterContext *ctx,
             return AVERROR(EINVAL);
         }
         s->out_prm = out->color_primaries;
-        s->out_primaries = ff_get_color_primaries(s->out_prm);
+        s->out_primaries = av_csp_primaries_desc_from_id(s->out_prm);
         if (!s->out_primaries) {
             if (s->out_prm == AVCOL_PRI_UNSPECIFIED) {
                 if (s->user_all == CS_UNSPECIFIED) {
@@ -466,7 +469,7 @@ static int create_filtergraph(AVFilterContext *ctx,
                                            sizeof(*s->in_primaries));
         if (!s->lrgb2lrgb_passthrough) {
             double rgb2xyz[3][3], xyz2rgb[3][3], rgb2rgb[3][3];
-            const struct WhitepointCoefficients *wp_out, *wp_in;
+            const AVWhitepointCoefficients *wp_out, *wp_in;
 
             wp_out = &s->out_primaries->wp;
             wp_in = &s->in_primaries->wp;
@@ -551,7 +554,7 @@ static int create_filtergraph(AVFilterContext *ctx,
         s->in_rng = in->color_range;
         if (s->user_irng != AVCOL_RANGE_UNSPECIFIED)
             s->in_rng = s->user_irng;
-        s->in_lumacoef = ff_get_luma_coefficients(s->in_csp);
+        s->in_lumacoef = av_csp_luma_coeffs_from_avcsp(s->in_csp);
         if (!s->in_lumacoef) {
             av_log(ctx, AV_LOG_ERROR,
                    "Unsupported input colorspace %d (%s)\n",
@@ -564,7 +567,7 @@ static int create_filtergraph(AVFilterContext *ctx,
     if (!s->out_lumacoef) {
         s->out_csp = out->colorspace;
         s->out_rng = out->color_range;
-        s->out_lumacoef = ff_get_luma_coefficients(s->out_csp);
+        s->out_lumacoef = av_csp_luma_coeffs_from_avcsp(s->out_csp);
         if (!s->out_lumacoef) {
             if (s->out_csp == AVCOL_SPC_UNSPECIFIED) {
                 if (s->user_all == CS_UNSPECIFIED) {
diff --git a/libavfilter/vf_iccdetect.c b/libavfilter/vf_iccdetect.c
index fb7871f035..7c08a2baaa 100644
--- a/libavfilter/vf_iccdetect.c
+++ b/libavfilter/vf_iccdetect.c
@@ -24,6 +24,7 @@
 
 #include <lcms2.h>
 
+#include "libavutil/csp.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 
@@ -69,7 +70,7 @@ static int iccdetect_filter_frame(AVFilterLink *inlink, AVFrame *frame)
     AVFilterContext *avctx = inlink->dst;
     IccDetectContext *s = avctx->priv;
     const AVFrameSideData *sd;
-    struct ColorPrimaries coeffs;
+    AVColorPrimariesDesc coeffs;
     cmsHPROFILE profile;
     int ret;
 
@@ -98,7 +99,7 @@ static int iccdetect_filter_frame(AVFilterLink *inlink, AVFrame *frame)
     if (ret < 0)
         return ret;
 
-    s->profile_prim = ff_detect_color_primaries(&coeffs);
+    s->profile_prim = av_csp_primaries_id_from_desc(&coeffs);
 
 done:
     if (s->profile_prim != AVCOL_PRI_UNSPECIFIED) {
diff --git a/libavfilter/vf_tonemap.c b/libavfilter/vf_tonemap.c
index 1285dbaa4d..d1087e6bd9 100644
--- a/libavfilter/vf_tonemap.c
+++ b/libavfilter/vf_tonemap.c
@@ -27,6 +27,7 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "libavutil/csp.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
 #include "libavutil/intreadwrite.h"
@@ -50,16 +51,6 @@ enum TonemapAlgorithm {
     TONEMAP_MAX,
 };
 
-static const struct LumaCoefficients luma_coefficients[AVCOL_SPC_NB] = {
-    [AVCOL_SPC_FCC]        = { 0.30,   0.59,   0.11   },
-    [AVCOL_SPC_BT470BG]    = { 0.299,  0.587,  0.114  },
-    [AVCOL_SPC_SMPTE170M]  = { 0.299,  0.587,  0.114  },
-    [AVCOL_SPC_BT709]      = { 0.2126, 0.7152, 0.0722 },
-    [AVCOL_SPC_SMPTE240M]  = { 0.212,  0.701,  0.087  },
-    [AVCOL_SPC_BT2020_NCL] = { 0.2627, 0.6780, 0.0593 },
-    [AVCOL_SPC_BT2020_CL]  = { 0.2627, 0.6780, 0.0593 },
-};
-
 typedef struct TonemapContext {
     const AVClass *class;
 
@@ -68,7 +59,7 @@ typedef struct TonemapContext {
     double desat;
     double peak;
 
-    const struct LumaCoefficients *coeffs;
+    const AVLumaCoefficients *coeffs;
 } TonemapContext;
 
 static av_cold int init(AVFilterContext *ctx)
@@ -135,7 +126,7 @@ static void tonemap(TonemapContext *s, AVFrame *out, const AVFrame *in,
 
     /* desaturate to prevent unnatural colors */
     if (s->desat > 0) {
-        float luma = s->coeffs->cr * *r_in + s->coeffs->cg * *g_in + s->coeffs->cb * *b_in;
+        float luma = av_q2d(s->coeffs->cr) * *r_in + av_q2d(s->coeffs->cg) * *g_in + av_q2d(s->coeffs->cb) * *b_in;
         float overbright = FFMAX(luma - s->desat, 1e-6) / FFMAX(luma, 1e-6);
         *r_out = MIX(*r_in, luma, overbright);
         *g_out = MIX(*g_in, luma, overbright);
@@ -249,7 +240,7 @@ static int filter_frame(AVFilterLink *link, AVFrame *in)
     }
 
     /* load original color space even if pixel format is RGB to compute overbrights */
-    s->coeffs = &luma_coefficients[in->colorspace];
+    s->coeffs = av_csp_luma_coeffs_from_avcsp(in->colorspace);
     if (s->desat > 0 && (in->colorspace == AVCOL_SPC_UNSPECIFIED || !s->coeffs)) {
         if (in->colorspace == AVCOL_SPC_UNSPECIFIED)
             av_log(s, AV_LOG_WARNING, "Missing color space information, ");
diff --git a/libavutil/Makefile b/libavutil/Makefile
index 234de62a4b..74d21a8103 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -20,6 +20,7 @@ HEADERS = adler32.h                                                     \
           common.h                                                      \
           cpu.h                                                         \
           crc.h                                                         \
+          csp.h                                                         \
           des.h                                                         \
           detection_bbox.h                                              \
           dict.h                                                        \
@@ -113,6 +114,7 @@ OBJS = adler32.o                                                        \
        color_utils.o                                                    \
        cpu.o                                                            \
        crc.o                                                            \
+       csp.o                                                            \
        des.o                                                            \
        detection_bbox.o                                                 \
        dict.o                                                           \
diff --git a/libavutil/csp.c b/libavutil/csp.c
new file mode 100644
index 0000000000..98fc83c1da
--- /dev/null
+++ b/libavutil/csp.c
@@ -0,0 +1,128 @@
+/*
+ * Copyright (c) 2016 Ronald S. Bultje <rsbultje at 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 at gmail.com>
+ * @author Leo Izen <leo.izen at gmail.com>
+ */
+
+#include <stdlib.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;
+}
diff --git a/libavutil/csp.h b/libavutil/csp.h
new file mode 100644
index 0000000000..37544449c6
--- /dev/null
+++ b/libavutil/csp.h
@@ -0,0 +1,106 @@
+/*
+ * Copyright (c) 2016 Ronald S. Bultje <rsbultje at 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
+ */
+
+#ifndef AVUTIL_CSP_H
+#define AVUTIL_CSP_H
+
+#include "pixfmt.h"
+#include "rational.h"
+
+/**
+ * @file Colorspace value utility functions for libavutil.
+ * @author Ronald S. Bultje <rsbultje at gmail.com>
+ * @author Leo Izen <leo.izen at gmail.com>
+ * @defgroup lavu_math_csp Colorspace Utility
+ * @ingroup lavu_math
+ * @{
+ */
+
+/**
+ * Struct containing luma coefficients to be used for RGB to YUV/YCoCg, or similar
+ * calculations.
+ */
+typedef struct AVLumaCoefficients {
+    AVRational cr, cg, cb;
+} AVLumaCoefficients;
+
+/**
+ * Struct containing chromaticity x and y values for the standard CIE 1931
+ * chromaticity definition.
+ */
+typedef struct AVCIExy {
+    AVRational x, y;
+} AVCIExy;
+
+/**
+ * Struct defining the red, green, and blue primary locations in terms of CIE
+ * 1931 chromaticity x and y.
+ */
+typedef struct AVPrimaryCoefficients {
+    AVCIExy r, g, b;
+} AVPrimaryCoefficients;
+
+/**
+ * Struct defining white point location in terms of CIE 1931 chromaticity x
+ * and y.
+ */
+typedef AVCIExy AVWhitepointCoefficients;
+
+/**
+ * Struct that contains both white point location and primaries location, providing
+ * the complete description of a color gamut.
+ */
+typedef struct AVColorPrimariesDesc {
+    AVWhitepointCoefficients wp;
+    AVPrimaryCoefficients prim;
+} AVColorPrimariesDesc;
+
+/**
+ * Retrieves the Luma coefficients necessary to construct a conversion matrix
+ * from an enum constant describing the colorspace.
+ * @param csp An enum constant indicating YUV or similar colorspace.
+ * @return The Luma coefficients associated with that colorspace, or NULL
+ *     if the constant is unknown to libavutil.
+ */
+const AVLumaCoefficients *av_csp_luma_coeffs_from_avcsp(enum AVColorSpace csp);
+
+/**
+ * Retrieves a complete gamut description from an enum constant describing the
+ * color primaries.
+ * @param prm An enum constant indicating primaries
+ * @return A description of the colorspace gamut associated with that enum
+ *     constant, or NULL if the constant is unknown to libavutil.
+ */
+const AVColorPrimariesDesc *av_csp_primaries_desc_from_id(enum AVColorPrimaries prm);
+
+/**
+ * Detects which enum AVColorPrimaries constant corresponds to the given complete
+ * gamut description.
+ * @see enum AVColorPrimaries
+ * @param prm A description of the colorspace gamut
+ * @return The enum constant associated with this gamut, or
+ *     AVCOL_PRI_UNSPECIFIED if no clear match can be idenitified.
+ */
+enum AVColorPrimaries av_csp_primaries_id_from_desc(const AVColorPrimariesDesc *prm);
+
+/**
+ * @}
+ */
+
+#endif /* AVUTIL_CSP_H */
diff --git a/libavutil/version.h b/libavutil/version.h
index 1b4b41d81f..2c7f4f6b37 100644
--- a/libavutil/version.h
+++ b/libavutil/version.h
@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  57
-#define LIBAVUTIL_VERSION_MINOR  25
+#define LIBAVUTIL_VERSION_MINOR  26
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
-- 
2.36.1



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