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avfilter/vf_v360: add cylindrical equal area format

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This commit is contained in:
Paul B Mahol 2021-06-30 00:12:41 +02:00
parent cea05864e6
commit e11fd47f8d
3 changed files with 129 additions and 0 deletions
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4
doc/filters.texi
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@ -20977,6 +20977,10 @@ If diagonal field of view is set it overrides horizontal and vertical field of v
Octahedron projection.
@end table
@item cylindricalea
Cylindrical Equal Area projection.
@end table
@item interp
Set interpolation method.@*
@i{Note: more complex interpolation methods require much more memory to run.}

1
libavfilter/v360.h
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@ -54,6 +54,7 @@ enum Projections {
EQUISOLID,
ORTHOGRAPHIC,
OCTAHEDRON,
CYLINDRICALEA,
NB_PROJECTIONS,
};

124
libavfilter/vf_v360.c
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@ -84,6 +84,7 @@ static const AVOption v360_options[] = {
{ "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" },
{"cylindricalea", "cylindrical equal area", 0, AV_OPT_TYPE_CONST, {.i64=CYLINDRICALEA}, 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" },
@ -114,6 +115,7 @@ static const AVOption v360_options[] = {
{ "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" },
{"cylindricalea", "cylindrical equal area", 0, AV_OPT_TYPE_CONST, {.i64=CYLINDRICALEA}, 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" },
@ -3136,6 +3138,116 @@ static int xyz_to_cylindrical(const V360Context *s,
return visible;
}
/**
* Prepare data for processing cylindrical equal area output format.
*
* @param ctx filter context
*
* @return error code
*/
static int prepare_cylindricalea_out(AVFilterContext *ctx)
{
V360Context *s = ctx->priv;
s->flat_range[0] = s->h_fov * M_PI / 360.f;
s->flat_range[1] = s->v_fov / 180.f;
return 0;
}
/**
* Prepare data for processing cylindrical equal area input format.
*
* @param ctx filter context
*
* @return error code
*/
static int prepare_cylindricalea_in(AVFilterContext *ctx)
{
V360Context *s = ctx->priv;
s->iflat_range[0] = M_PI * s->ih_fov / 360.f;
s->iflat_range[1] = s->iv_fov / 180.f;
return 0;
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in cylindrical equal area 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 cylindricalea_to_xyz(const V360Context *s,
int i, int j, int width, int height,
float *vec)
{
const float uf = s->flat_range[0] * ((2.f * i + 1.f) / width - 1.f);
const float vf = s->flat_range[1] * ((2.f * j + 1.f) / height - 1.f);
const float phi = uf;
const float theta = asinf(vf);
const float sin_phi = sinf(phi);
const float cos_phi = cosf(phi);
const float sin_theta = sinf(theta);
const float cos_theta = cosf(theta);
vec[0] = cos_theta * sin_phi;
vec[1] = sin_theta;
vec[2] = cos_theta * cos_phi;
normalize_vector(vec);
return 1;
}
/**
* Calculate frame position in cylindrical equal area 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_cylindricalea(const V360Context *s,
const float *vec, int width, int height,
int16_t us[4][4], int16_t vs[4][4], float *du, float *dv)
{
const float phi = atan2f(vec[0], vec[2]) / s->iflat_range[0];
const float theta = asinf(vec[1]);
const float uf = (phi + 1.f) * (width - 1) / 2.f;
const float vf = (sinf(theta) / s->iflat_range[1] + 1.f) * height / 2.f;
const int ui = floorf(uf);
const int vi = floorf(vf);
const int visible = vi >= 0 && vi < height && ui >= 0 && ui < width &&
theta <= M_PI * s->iv_fov / 180.f &&
theta >= -M_PI * s->iv_fov / 180.f;
*du = uf - ui;
*dv = vf - vi;
for (int i = 0; i < 4; i++) {
for (int j = 0; j < 4; j++) {
us[i][j] = visible ? av_clip(ui + j - 1, 0, width - 1) : 0;
vs[i][j] = visible ? av_clip(vi + i - 1, 0, height - 1) : 0;
}
}
return visible;
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in perspective format.
*
@ -4448,6 +4560,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h * 2.f;
break;
case CYLINDRICALEA:
s->in_transform = xyz_to_cylindricalea;
err = prepare_cylindricalea_in(ctx);
wf = w;
hf = h;
break;
case TETRAHEDRON:
s->in_transform = xyz_to_tetrahedron;
err = 0;
@ -4596,6 +4714,12 @@ static int config_output(AVFilterLink *outlink)
w = lrintf(wf);
h = lrintf(hf * 0.5f);
break;
case CYLINDRICALEA:
s->out_transform = cylindricalea_to_xyz;
prepare_out = prepare_cylindricalea_out;
w = lrintf(wf);
h = lrintf(hf);
break;
case PERSPECTIVE:
s->out_transform = perspective_to_xyz;
prepare_out = NULL;