[FFmpeg-cvslog] avfilter/vf_lut3d: add spline 1D interpolation

[Paul B Mahol]

ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sat Nov 10 22:06:13 2018 +0100| [c47b48c0a629d65cd15e1d3869fbfbb9ee2ceafc] | committer: Paul B Mahol

avfilter/vf_lut3d: add spline 1D interpolation

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=c47b48c0a629d65cd15e1d3869fbfbb9ee2ceafc
---

 doc/filters.texi       |  4 ++++
 libavfilter/vf_lut3d.c | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/doc/filters.texi b/doc/filters.texi
index d16a8b8b1b..fb1dd8f353 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -11442,8 +11442,12 @@ Available values are:
 Use values from the nearest defined point.
 @item linear
 Interpolate values using the linear interpolation.
+ at item cosine
+Interpolate values using the cosine interpolation.
 @item cubic
 Interpolate values using the cubic interpolation.
+ at item spline
+Interpolate values using the spline interpolation.
 @end table
 @end table
 
diff --git a/libavfilter/vf_lut3d.c b/libavfilter/vf_lut3d.c
index 86a33ca4f3..1beaf5ac4e 100644
--- a/libavfilter/vf_lut3d.c
+++ b/libavfilter/vf_lut3d.c
@@ -986,6 +986,7 @@ enum interp_1d_mode {
     INTERPOLATE_1D_LINEAR,
     INTERPOLATE_1D_CUBIC,
     INTERPOLATE_1D_COSINE,
+    INTERPOLATE_1D_SPLINE,
     NB_INTERP_1D_MODE
 };
 
@@ -1077,6 +1078,7 @@ static const AVOption lut1d_options[] = {
         { "linear",  "use values from the linear interpolation",   0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATE_1D_LINEAR},    INT_MIN, INT_MAX, FLAGS, "interp_mode" },
         { "cosine",  "use values from the cosine interpolation",   0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATE_1D_COSINE},    INT_MIN, INT_MAX, FLAGS, "interp_mode" },
         { "cubic",   "use values from the cubic interpolation",    0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATE_1D_CUBIC},     INT_MIN, INT_MAX, FLAGS, "interp_mode" },
+        { "spline",  "use values from the spline interpolation",   0, AV_OPT_TYPE_CONST, {.i64=INTERPOLATE_1D_SPLINE},    INT_MIN, INT_MAX, FLAGS, "interp_mode" },
     { NULL }
 };
 
@@ -1138,6 +1140,27 @@ static inline float interp_1d_cubic(const LUT1DContext *lut1d,
     return a0 * mu * mu2 + a1 * mu2 + a2 * mu + a3;
 }
 
+static inline float interp_1d_spline(const LUT1DContext *lut1d,
+                                     int idx, const float s)
+{
+    const int prev = PREV(s);
+    const int next = NEXT1D(s);
+    const float x = s - prev;
+    float c0, c1, c2, c3;
+
+    float y0 = lut1d->lut[idx][FFMAX(prev - 1, 0)];
+    float y1 = lut1d->lut[idx][prev];
+    float y2 = lut1d->lut[idx][next];
+    float y3 = lut1d->lut[idx][FFMIN(next + 1, lut1d->lutsize - 1)];
+
+    c0 = y1;
+    c1 = .5f * (y2 - y0);
+    c2 = y0 - 2.5f * y1 + 2.f * y2 - .5f * y3;
+    c3 = .5f * (y3 - y0) + 1.5f * (y1 - y2);
+
+    return ((c3 * x + c2) * x + c1) * x + c0;
+}
+
 #define DEFINE_INTERP_FUNC_PLANAR_1D(name, nbits, depth)                     \
 static int interp_1d_##nbits##_##name##_p##depth(AVFilterContext *ctx,       \
                                                  void *arg, int jobnr,       \
@@ -1200,31 +1223,37 @@ DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     8, 8)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      8, 8)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      8, 8)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       8, 8)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      8, 8)
 
 DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     16, 9)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      16, 9)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      16, 9)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       16, 9)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      16, 9)
 
 DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     16, 10)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      16, 10)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      16, 10)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       16, 10)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      16, 10)
 
 DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     16, 12)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      16, 12)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      16, 12)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       16, 12)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      16, 12)
 
 DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     16, 14)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      16, 14)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      16, 14)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       16, 14)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      16, 14)
 
 DEFINE_INTERP_FUNC_PLANAR_1D(nearest,     16, 16)
 DEFINE_INTERP_FUNC_PLANAR_1D(linear,      16, 16)
 DEFINE_INTERP_FUNC_PLANAR_1D(cosine,      16, 16)
 DEFINE_INTERP_FUNC_PLANAR_1D(cubic,       16, 16)
+DEFINE_INTERP_FUNC_PLANAR_1D(spline,      16, 16)
 
 #define DEFINE_INTERP_FUNC_1D(name, nbits)                                   \
 static int interp_1d_##nbits##_##name(AVFilterContext *ctx, void *arg,       \
@@ -1274,11 +1303,13 @@ DEFINE_INTERP_FUNC_1D(nearest,     8)
 DEFINE_INTERP_FUNC_1D(linear,      8)
 DEFINE_INTERP_FUNC_1D(cosine,      8)
 DEFINE_INTERP_FUNC_1D(cubic,       8)
+DEFINE_INTERP_FUNC_1D(spline,      8)
 
 DEFINE_INTERP_FUNC_1D(nearest,     16)
 DEFINE_INTERP_FUNC_1D(linear,      16)
 DEFINE_INTERP_FUNC_1D(cosine,      16)
 DEFINE_INTERP_FUNC_1D(cubic,       16)
+DEFINE_INTERP_FUNC_1D(spline,      16)
 
 static int config_input_1d(AVFilterLink *inlink)
 {
@@ -1332,6 +1363,7 @@ static int config_input_1d(AVFilterLink *inlink)
     case INTERPOLATE_1D_LINEAR:      SET_FUNC_1D(linear);   break;
     case INTERPOLATE_1D_COSINE:      SET_FUNC_1D(cosine);   break;
     case INTERPOLATE_1D_CUBIC:       SET_FUNC_1D(cubic);    break;
+    case INTERPOLATE_1D_SPLINE:      SET_FUNC_1D(spline);   break;
     default:
         av_assert0(0);
     }