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avfilter/vf_v360: add gaussian interpolation

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This commit is contained in:
Paul B Mahol 2020-01-18 13:43:33 +01:00
parent 3972ec28e7
commit 62a0d22621
3 changed files with 67 additions and 0 deletions
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3
doc/filters.texi
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@ -19027,6 +19027,9 @@ Lanczos interpolation.
@item sp16
@item spline16
Spline16 interpolation.
@item gauss
@item gaussian
Gaussian interpolation.
@end table
Default value is @b{@samp{line}}.

1
libavfilter/v360.h
View File

@ -55,6 +55,7 @@ enum InterpMethod {
BICUBIC,
LANCZOS,
SPLINE16,
GAUSSIAN,
NB_INTERP_METHODS,
};

63
libavfilter/vf_v360.c
View File

@ -101,6 +101,8 @@ static const AVOption v360_options[] = {
{ "lanczos", "lanczos interpolation", 0, AV_OPT_TYPE_CONST, {.i64=LANCZOS}, 0, 0, FLAGS, "interp" },
{ "sp16", "spline16 interpolation", 0, AV_OPT_TYPE_CONST, {.i64=SPLINE16}, 0, 0, FLAGS, "interp" },
{ "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" },
{ "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" },
@ -317,6 +319,7 @@ void ff_v360_init(V360Context *s, int depth)
case BICUBIC:
case LANCZOS:
case SPLINE16:
case GAUSSIAN:
s->remap_line = depth <= 8 ? remap4_8bit_line_c : remap4_16bit_line_c;
break;
}
@ -511,6 +514,59 @@ static void spline16_kernel(float du, float dv, const XYRemap *rmap,
}
}
/**
* Calculate 1-dimensional gaussian coefficients.
*
* @param t relative coordinate
* @param coeffs coefficients
*/
static void calculate_gaussian_coeffs(float t, float *coeffs)
{
float sum = 0.f;
for (int i = 0; i < 4; i++) {
const float x = t - (i - 1);
if (x == 0.f) {
coeffs[i] = 1.f;
} else {
coeffs[i] = expf(-2.f * x * x) * expf(-x * x / 2.f);
}
sum += coeffs[i];
}
for (int i = 0; i < 4; i++) {
coeffs[i] /= sum;
}
}
/**
* Calculate kernel for gaussian 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 gaussian_kernel(float du, float dv, const XYRemap *rmap,
uint16_t *u, uint16_t *v, int16_t *ker)
{
float du_coeffs[4];
float dv_coeffs[4];
calculate_gaussian_coeffs(du, du_coeffs);
calculate_gaussian_coeffs(dv, dv_coeffs);
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.
*
@ -2733,6 +2789,13 @@ static int config_output(AVFilterLink *outlink)
sizeof_uv = sizeof(uint16_t) * s->elements;
sizeof_ker = sizeof(uint16_t) * s->elements;
break;
case GAUSSIAN:
s->calculate_kernel = gaussian_kernel;
s->remap_slice = depth <= 8 ? remap4_8bit_slice : remap4_16bit_slice;
s->elements = 4 * 4;
sizeof_uv = sizeof(uint16_t) * s->elements;
sizeof_ker = sizeof(uint16_t) * s->elements;
break;
default:
av_assert0(0);
}