[FFmpeg-cvslog] avfilter/vf_v360: add tetrahedron format
Paul B Mahol
git at videolan.org
Thu Jan 23 00:50:58 EET 2020
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Wed Jan 22 22:21:32 2020 +0100| [ec4f764249817a93787d76990dc4618d59e70f5d] | committer: Paul B Mahol
avfilter/vf_v360: add tetrahedron format
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ec4f764249817a93787d76990dc4618d59e70f5d
---
doc/filters.texi | 2 ++
libavfilter/v360.h | 1 +
libavfilter/vf_v360.c | 96 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 99 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index 40db2e5c54..a9ae75f0c0 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -19043,6 +19043,8 @@ Format specific options:
Set perspective parameter.
@end table
+ at item tetrahedron
+Tetrahedron projection.
@end table
@item interp
diff --git a/libavfilter/v360.h b/libavfilter/v360.h
index ba3d0da60f..8e080f0b6c 100644
--- a/libavfilter/v360.h
+++ b/libavfilter/v360.h
@@ -47,6 +47,7 @@ enum Projections {
PANNINI,
CYLINDRICAL,
PERSPECTIVE,
+ TETRAHEDRON,
NB_PROJECTIONS,
};
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index 2ed0acb5a7..1173b33ae1 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -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;
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