lavfi: generalize colorspace coefficent helpers

These are needed beyond just vf_colorspace, so give them a new home in
colorspace.h.

In addition to moving code around, also merge the white point and
primary coefficients into a single struct to slightly increase the
convenience and shrink the size of the new API by avoiding the need
to introduce an extra function just to look up the white point as well.
The only place the distinction matters is in a single enum comparison,
which can just as well be a single memcpy - the difference is
negligible.

Signed-off-by: Niklas Haas <git@haasn.dev>

1 files changed, 32 insertions, 0 deletions

diff --git a/libavfilter/colorspace.c b/libavfilter/colorspace.c
index 19616e4f12..25e99f4759 100644
--- a/libavfilter/colorspace.c
+++ b/libavfilter/colorspace.c
@@ -138,6 +138,38 @@ const struct LumaCoefficients *ff_get_luma_coefficients(enum AVColorSpace csp)
     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;
+}
+
 void ff_fill_rgb2yuv_table(const struct LumaCoefficients *coeffs,
                            double rgb2yuv[3][3])
 {