[FFmpeg-cvslog] avfilter/vf_v360: add mitchell interpolation
Paul B Mahol
git at videolan.org
Sun Oct 4 20:25:36 EEST 2020
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sun Oct 4 14:36:30 2020 +0200| [eaba6cecfb5e83ad7b37da5eda236aa5fc6f5f4c] | committer: Paul B Mahol
avfilter/vf_v360: add mitchell interpolation
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=eaba6cecfb5e83ad7b37da5eda236aa5fc6f5f4c
---
doc/filters.texi | 2 ++
libavfilter/v360.h | 1 +
libavfilter/vf_v360.c | 74 ++++++++++++++++++++++++++++++++++++++++++
libavfilter/x86/vf_v360_init.c | 3 +-
4 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index f072a84424..8404f4fb9a 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -19543,6 +19543,8 @@ Spline16 interpolation.
@item gauss
@item gaussian
Gaussian interpolation.
+ at item mitchell
+Mitchell interpolation.
@end table
Default value is @b{@samp{line}}.
diff --git a/libavfilter/v360.h b/libavfilter/v360.h
index 9b52827bd1..b64d4827f8 100644
--- a/libavfilter/v360.h
+++ b/libavfilter/v360.h
@@ -65,6 +65,7 @@ enum InterpMethod {
LANCZOS,
SPLINE16,
GAUSSIAN,
+ MITCHELL,
NB_INTERP_METHODS,
};
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index 1266ddc3b6..853a26da03 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -128,6 +128,7 @@ static const AVOption v360_options[] = {
{ "spline16", "spline16 interpolation", 0, AV_OPT_TYPE_CONST, {.i64=SPLINE16}, 0, 0, FLAGS, "interp" },
{ "gauss", "gaussian interpolation", 0, AV_OPT_TYPE_CONST, {.i64=GAUSSIAN}, 0, 0, FLAGS, "interp" },
{ "gaussian", "gaussian interpolation", 0, AV_OPT_TYPE_CONST, {.i64=GAUSSIAN}, 0, 0, FLAGS, "interp" },
+ { "mitchell", "mitchell interpolation", 0, AV_OPT_TYPE_CONST, {.i64=MITCHELL}, 0, 0, FLAGS, "interp" },
{ "w", "output width", OFFSET(width), AV_OPT_TYPE_INT, {.i64=0}, 0, INT16_MAX, FLAGS, "w"},
{ "h", "output height", OFFSET(height), AV_OPT_TYPE_INT, {.i64=0}, 0, INT16_MAX, FLAGS, "h"},
{ "in_stereo", "input stereo format", OFFSET(in_stereo), AV_OPT_TYPE_INT, {.i64=STEREO_2D}, 0, NB_STEREO_FMTS-1, FLAGS, "stereo" },
@@ -381,6 +382,7 @@ void ff_v360_init(V360Context *s, int depth)
case LANCZOS:
case SPLINE16:
case GAUSSIAN:
+ case MITCHELL:
s->remap_line = depth <= 8 ? remap4_8bit_line_c : remap4_16bit_line_c;
break;
}
@@ -669,6 +671,71 @@ static void gaussian_kernel(float du, float dv, const XYRemap *rmap,
}
}
+/**
+ * Calculate 1-dimensional cubic_bc_spline coefficients.
+ *
+ * @param t relative coordinate
+ * @param coeffs coefficients
+ */
+static void calculate_cubic_bc_coeffs(float t, float *coeffs,
+ float b, float c)
+{
+ float sum = 0.f;
+ float p0 = (6.f - 2.f * b) / 6.f,
+ p2 = (-18.f + 12.f * b + 6.f * c) / 6.f,
+ p3 = (12.f - 9.f * b - 6.f * c) / 6.f,
+ q0 = (8.f * b + 24.f * c) / 6.f,
+ q1 = (-12.f * b - 48.f * c) / 6.f,
+ q2 = (6.f * b + 30.f * c) / 6.f,
+ q3 = (-b - 6.f * c) / 6.f;
+
+ for (int i = 0; i < 4; i++) {
+ const float x = fabsf(t - i + 1.f);
+ if (x < 1.f) {
+ coeffs[i] = (p0 + x * x * (p2 + x * p3)) *
+ (p0 + x * x * (p2 + x * p3 / 2.f) / 4.f);
+ } else if (x < 2.f) {
+ coeffs[i] = (q0 + x * (q1 + x * (q2 + x * q3))) *
+ (q0 + x * (q1 + x * (q2 + x / 2.f * q3) / 2.f) / 2.f);
+ } else {
+ coeffs[i] = 0.f;
+ }
+ sum += coeffs[i];
+ }
+
+ for (int i = 0; i < 4; i++) {
+ coeffs[i] /= sum;
+ }
+}
+
+/**
+ * Calculate kernel for mitchell interpolation.
+ *
+ * @param du horizontal relative coordinate
+ * @param dv vertical relative coordinate
+ * @param rmap calculated 4x4 window
+ * @param u u remap data
+ * @param v v remap data
+ * @param ker ker remap data
+ */
+static void mitchell_kernel(float du, float dv, const XYRemap *rmap,
+ int16_t *u, int16_t *v, int16_t *ker)
+{
+ float du_coeffs[4];
+ float dv_coeffs[4];
+
+ calculate_cubic_bc_coeffs(du, du_coeffs, 1.f / 3.f, 1.f / 3.f);
+ calculate_cubic_bc_coeffs(dv, dv_coeffs, 1.f / 3.f, 1.f / 3.f);
+
+ for (int i = 0; i < 4; i++) {
+ for (int j = 0; j < 4; j++) {
+ u[i * 4 + j] = rmap->u[i][j];
+ v[i * 4 + j] = rmap->v[i][j];
+ ker[i * 4 + j] = lrintf(du_coeffs[j] * dv_coeffs[i] * 16385.f);
+ }
+ }
+}
+
/**
* Modulo operation with only positive remainders.
*
@@ -4138,6 +4205,13 @@ static int config_output(AVFilterLink *outlink)
sizeof_uv = sizeof(int16_t) * s->elements;
sizeof_ker = sizeof(int16_t) * s->elements;
break;
+ case MITCHELL:
+ s->calculate_kernel = mitchell_kernel;
+ s->remap_slice = depth <= 8 ? remap4_8bit_slice : remap4_16bit_slice;
+ s->elements = 4 * 4;
+ sizeof_uv = sizeof(int16_t) * s->elements;
+ sizeof_ker = sizeof(int16_t) * s->elements;
+ break;
default:
av_assert0(0);
}
diff --git a/libavfilter/x86/vf_v360_init.c b/libavfilter/x86/vf_v360_init.c
index 7d001a6948..2b2b06dd40 100644
--- a/libavfilter/x86/vf_v360_init.c
+++ b/libavfilter/x86/vf_v360_init.c
@@ -64,7 +64,8 @@ av_cold void ff_v360_init_x86(V360Context *s, int depth)
if (EXTERNAL_AVX2_FAST(cpu_flags) && (s->interp == BICUBIC ||
s->interp == LANCZOS ||
s->interp == SPLINE16 ||
- s->interp == GAUSSIAN) && depth <= 8)
+ s->interp == GAUSSIAN ||
+ s->interp == MITCHELL) && depth <= 8)
s->remap_line = ff_remap4_8bit_line_avx2;
#endif
}
More information about the ffmpeg-cvslog
mailing list