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avfilter/vf_v360: add tetrahedron format

This commit is contained in:
Paul B Mahol 2020-01-22 22:21:32 +01:00
parent 5f7727e1c9
commit ec4f764249
3 changed files with 99 additions and 0 deletions
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2
doc/filters.texi
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@ -19043,6 +19043,8 @@ Format specific options:
Set perspective parameter.
@end table
@item tetrahedron
Tetrahedron projection.
@end table
@item interp

1
libavfilter/v360.h
View File

@ -47,6 +47,7 @@ enum Projections {
PANNINI,
CYLINDRICAL,
PERSPECTIVE,
TETRAHEDRON,
NB_PROJECTIONS,
};

96
libavfilter/vf_v360.c
View File

@ -74,6 +74,7 @@ static const AVOption v360_options[] = {
{"sinusoidal", "sinusoidal", 0, AV_OPT_TYPE_CONST, {.i64=SINUSOIDAL}, 0, 0, FLAGS, "in" },
{ "fisheye", "fisheye", 0, AV_OPT_TYPE_CONST, {.i64=FISHEYE}, 0, 0, FLAGS, "in" },
{"cylindrical", "cylindrical", 0, AV_OPT_TYPE_CONST, {.i64=CYLINDRICAL}, 0, 0, FLAGS, "in" },
{"tetrahedron", "tetrahedron", 0, AV_OPT_TYPE_CONST, {.i64=TETRAHEDRON}, 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" },
@ -96,6 +97,7 @@ static const AVOption v360_options[] = {
{ "pannini", "pannini", 0, AV_OPT_TYPE_CONST, {.i64=PANNINI}, 0, 0, FLAGS, "out" },
{"cylindrical", "cylindrical", 0, AV_OPT_TYPE_CONST, {.i64=CYLINDRICAL}, 0, 0, FLAGS, "out" },
{"perspective", "perspective", 0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE}, 0, 0, FLAGS, "out" },
{"tetrahedron", "tetrahedron", 0, AV_OPT_TYPE_CONST, {.i64=TETRAHEDRON}, 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" },
@ -2589,6 +2591,88 @@ static void perspective_to_xyz(const V360Context *s,
normalize_vector(vec);
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in tetrahedron 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 void tetrahedron_to_xyz(const V360Context *s,
int i, int j, int width, int height,
float *vec)
{
const float uf = (float)i / width;
const float vf = (float)j / height;
vec[0] = uf < 0.5f ? uf * 4.f - 1.f : 3.f - uf * 4.f;
vec[1] = 1.f - vf * 2.f;
vec[2] = 2.f * fabsf(1.f - fabsf(1.f - uf * 2.f + vf)) - 1.f;
normalize_vector(vec);
}
/**
* Calculate frame position in tetrahedron 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 void xyz_to_tetrahedron(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 d = 0.5f * (vec[0] * vec[0] + vec[1] * vec[1] + vec[2] * vec[2]);
const float d0 = (vec[0] * 0.5f + vec[1] * 0.5f + vec[2] *-0.5f) / d;
const float d1 = (vec[0] *-0.5f + vec[1] *-0.5f + vec[2] *-0.5f) / d;
const float d2 = (vec[0] * 0.5f + vec[1] *-0.5f + vec[2] * 0.5f) / d;
const float d3 = (vec[0] *-0.5f + vec[1] * 0.5f + vec[2] * 0.5f) / d;
float uf, vf, x, y, z;
int ui, vi;
d = FFMAX(d0, FFMAX3(d1, d2, d3));
x = vec[0] / d;
y = vec[1] / d;
z = -vec[2] / d;
vf = 0.5f - y * 0.5f;
if ((x + y >= 0.f && y + z >= 0.f && -z - x <= 0.f) ||
(x + y <= 0.f && -y + z >= 0.f && z - x >= 0.f)) {
uf = 0.25f * x + 0.25f;
} else {
uf = 0.75f - 0.25f * x;
}
uf *= width - 1;
vf *= height - 1;
ui = floorf(uf);
vi = floorf(vf);
*du = uf - ui;
*dv = vf - vi;
for (int i = -1; i < 3; i++) {
for (int j = -1; j < 3; j++) {
us[i + 1][j + 1] = av_clip(ui + j, 0, width - 1);
vs[i + 1][j + 1] = av_clip(vi + i, 0, height - 1);
}
}
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in dual fisheye format.
*
@ -3206,6 +3290,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h * 2.f;
break;
case TETRAHEDRON:
s->in_transform = xyz_to_tetrahedron;
err = 0;
wf = w;
hf = h;
break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified input format is not handled.\n");
return AVERROR_BUG;
@ -3318,6 +3408,12 @@ static int config_output(AVFilterLink *outlink)
w = lrintf(wf / 2.f);
h = lrintf(hf);
break;
case TETRAHEDRON:
s->out_transform = tetrahedron_to_xyz;
prepare_out = NULL;
w = lrintf(wf);
h = lrintf(hf);
break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified output format is not handled.\n");
return AVERROR_BUG;