avfilter: add agate filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

1 files changed, 40 insertions, 0 deletions

diff --git a/libavfilter/hermite.h b/libavfilter/hermite.h
new file mode 100644
index 0000000000..6142391b2e
--- /dev/null
+++ b/libavfilter/hermite.h
@@ -0,0 +1,40 @@
+/*
+ * 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
+ */
+
+inline double hermite_interpolation(double x, double x0, double x1,
+                                    double p0, double p1,
+                                    double m0, double m1)
+{
+    double width = x1 - x0;
+    double t = (x - x0) / width;
+    double t2, t3;
+    double ct0, ct1, ct2, ct3;
+
+    m0 *= width;
+    m1 *= width;
+
+    t2 = t*t;
+    t3 = t2*t;
+    ct0 = p0;
+    ct1 = m0;
+
+    ct2 = -3 * p0 - 2 * m0 + 3 * p1 - m1;
+    ct3 = 2 * p0 + m0  - 2 * p1 + m1;
+
+    return ct3 * t3 + ct2 * t2 + ct1 * t + ct0;
+}