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avfilter/vf_v360: add octahedron format

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This commit is contained in:
Paul B Mahol 2020-09-27 22:33:05 +02:00
parent a6e72fb46d
commit 6db1b1af4c
3 changed files with 103 additions and 0 deletions
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3
doc/filters.texi
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@ -19511,6 +19511,9 @@ Set input horizontal/vertical/diagonal field of view. Values in degrees.
If diagonal field of view is set it overrides horizontal and vertical field of view.
@end table
@item octahedron
Octahedron projection.
@end table
@item interp

1
libavfilter/v360.h
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@ -53,6 +53,7 @@ enum Projections {
HEQUIRECTANGULAR,
EQUISOLID,
ORTHOGRAPHIC,
OCTAHEDRON,
NB_PROJECTIONS,
};

99
libavfilter/vf_v360.c
View File

@ -83,6 +83,7 @@ static const AVOption v360_options[] = {
{ "he", "half equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=HEQUIRECTANGULAR},0, 0, FLAGS, "in" },
{ "equisolid", "equisolid", 0, AV_OPT_TYPE_CONST, {.i64=EQUISOLID}, 0, 0, FLAGS, "in" },
{ "og", "orthographic", 0, AV_OPT_TYPE_CONST, {.i64=ORTHOGRAPHIC}, 0, 0, FLAGS, "in" },
{"octahedron", "octahedron", 0, AV_OPT_TYPE_CONST, {.i64=OCTAHEDRON}, 0, 0, FLAGS, "in" },
{ "output", "set output projection", OFFSET(out), AV_OPT_TYPE_INT, {.i64=CUBEMAP_3_2}, 0, NB_PROJECTIONS-1, FLAGS, "out" },
{ "e", "equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=EQUIRECTANGULAR}, 0, 0, FLAGS, "out" },
{ "equirect", "equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=EQUIRECTANGULAR}, 0, 0, FLAGS, "out" },
@ -112,6 +113,7 @@ static const AVOption v360_options[] = {
{ "he", "half equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=HEQUIRECTANGULAR},0, 0, FLAGS, "out" },
{ "equisolid", "equisolid", 0, AV_OPT_TYPE_CONST, {.i64=EQUISOLID}, 0, 0, FLAGS, "out" },
{ "og", "orthographic", 0, AV_OPT_TYPE_CONST, {.i64=ORTHOGRAPHIC}, 0, 0, FLAGS, "out" },
{"octahedron", "octahedron", 0, AV_OPT_TYPE_CONST, {.i64=OCTAHEDRON}, 0, 0, FLAGS, "out" },
{ "interp", "set interpolation method", OFFSET(interp), AV_OPT_TYPE_INT, {.i64=BILINEAR}, 0, NB_INTERP_METHODS-1, FLAGS, "interp" },
{ "near", "nearest neighbour", 0, AV_OPT_TYPE_CONST, {.i64=NEAREST}, 0, 0, FLAGS, "interp" },
{ "nearest", "nearest neighbour", 0, AV_OPT_TYPE_CONST, {.i64=NEAREST}, 0, 0, FLAGS, "interp" },
@ -3747,6 +3749,91 @@ static int xyz_to_tspyramid(const V360Context *s,
return 1;
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in octahedron format.
*
* @param s filter private context
* @param i horizontal position on frame [0, width)
* @param j vertical position on frame [0, height)
* @param width frame width
* @param height frame height
* @param vec coordinates on sphere
*/
static int octahedron_to_xyz(const V360Context *s,
int i, int j, int width, int height,
float *vec)
{
float x = ((i + 0.5f) / width) * 2.f - 1.f;
float y = ((j + 0.5f) / height) * 2.f - 1.f;
float ax = fabsf(x);
float ay = fabsf(y);
vec[2] = 1.f - (ax + ay);
if (ax + ay > 1.f) {
vec[0] = (1.f - ay) * FFSIGN(x);
vec[1] = (1.f - ax) * FFSIGN(y);
} else {
vec[0] = x;
vec[1] = y;
}
normalize_vector(vec);
return 1;
}
/**
* Calculate frame position in octahedron format for corresponding 3D coordinates on sphere.
*
* @param s filter private context
* @param vec coordinates on sphere
* @param width frame width
* @param height frame height
* @param us horizontal coordinates for interpolation window
* @param vs vertical coordinates for interpolation window
* @param du horizontal relative coordinate
* @param dv vertical relative coordinate
*/
static int xyz_to_octahedron(const V360Context *s,
const float *vec, int width, int height,
int16_t us[4][4], int16_t vs[4][4], float *du, float *dv)
{
float uf, vf, zf;
int ui, vi;
float div = fabsf(vec[0]) + fabsf(vec[1]) + fabsf(vec[2]);
uf = vec[0] / div;
vf = vec[1] / div;
zf = vec[2];
if (zf < 0.f) {
zf = vf;
vf = (1.f - fabsf(uf)) * FFSIGN(zf);
uf = (1.f - fabsf(zf)) * FFSIGN(uf);
}
uf = uf * 0.5f + 0.5f;
vf = vf * 0.5f + 0.5f;
uf *= width;
vf *= height;
ui = floorf(uf);
vi = floorf(vf);
*du = uf - ui;
*dv = vf - vi;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
us[i][j] = av_clip(uf + j - 1, 0, width - 1);
vs[i][j] = av_clip(vf + i - 1, 0, height - 1);
}
}
return 1;
}
static void multiply_matrix(float c[3][3], const float a[3][3], const float b[3][3])
{
for (int i = 0; i < 3; i++) {
@ -4264,6 +4351,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h / 2.f;
break;
case OCTAHEDRON:
s->in_transform = xyz_to_octahedron;
err = 0;
wf = w;
hf = h / 2.f;
break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified input format is not handled.\n");
return AVERROR_BUG;
@ -4412,6 +4505,12 @@ static int config_output(AVFilterLink *outlink)
w = lrintf(wf);
h = lrintf(hf * 2.f);
break;
case OCTAHEDRON:
s->out_transform = octahedron_to_xyz;
prepare_out = NULL;
w = lrintf(wf);
h = lrintf(hf * 2.f);
break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified output format is not handled.\n");
return AVERROR_BUG;