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avfilter/vf_v360: add perspective output projection

This commit is contained in:
Paul B Mahol 2020-01-18 16:26:59 +01:00
parent 6ae84e7b03
commit fdddc0d678
3 changed files with 63 additions and 0 deletions
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9
doc/filters.texi
View File

@ -19003,6 +19003,15 @@ Set 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 perspective
Perspective projection. @i{(output only)}
Format specific options:
@table @option
@item v_fov
Set perspective parameter.
@end table
@end table
@item interp

1
libavfilter/v360.h
View File

@ -46,6 +46,7 @@ enum Projections {
FISHEYE,
PANNINI,
CYLINDRICAL,
PERSPECTIVE,
NB_PROJECTIONS,
};

53
libavfilter/vf_v360.c
View File

@ -90,6 +90,7 @@ static const AVOption v360_options[] = {
{ "fisheye", "fisheye", 0, AV_OPT_TYPE_CONST, {.i64=FISHEYE}, 0, 0, FLAGS, "out" },
{ "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" },
{ "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" },
@ -2334,6 +2335,51 @@ static void cylindrical_to_xyz(const V360Context *s,
normalize_vector(vec);
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in perspective 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 perspective_to_xyz(const V360Context *s,
int i, int j, int width, int height,
float *vec)
{
const float uf = ((2.f * i) / width - 1.f);
const float vf = ((2.f * j) / height - 1.f);
const float rh = hypotf(uf, vf);
const float sinzz = 1.f - rh * rh;
const float h = 1.f + s->v_fov;
const float sinz = (h - sqrtf(sinzz)) / (h / rh + rh / h);
const float sinz2 = sinz * sinz;
if (sinz2 <= 1.f) {
const float cosz = sqrtf(1.f - sinz2);
const float theta = asinf(cosz);
const float phi = atan2f(uf, 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;
} else {
vec[0] = 0.f;
vec[1] = -1.f;
vec[2] = 0.f;
}
normalize_vector(vec);
}
/**
* Calculate 3D coordinates on sphere for corresponding frame position in dual fisheye format.
*
@ -2884,6 +2930,7 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h / 9.f * 8.f;
break;
case PERSPECTIVE:
case CYLINDRICAL:
case PANNINI:
case FISHEYE:
@ -3038,6 +3085,12 @@ static int config_output(AVFilterLink *outlink)
w = roundf(wf);
h = roundf(hf * 0.5f);
break;
case PERSPECTIVE:
s->out_transform = perspective_to_xyz;
prepare_out = NULL;
w = roundf(wf / 2.f);
h = roundf(hf);
break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified output format is not handled.\n");
return AVERROR_BUG;