[FFmpeg-cvslog] avfilter/vf_v360: add octahedron format
Paul B Mahol
git at videolan.org
Sun Sep 27 23:42:11 EEST 2020
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sun Sep 27 22:33:05 2020 +0200| [6db1b1af4c93c98c31e8f2dc546647d77c0bdb5f] | committer: Paul B Mahol
avfilter/vf_v360: add octahedron format
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=6db1b1af4c93c98c31e8f2dc546647d77c0bdb5f
---
doc/filters.texi | 3 ++
libavfilter/v360.h | 1 +
libavfilter/vf_v360.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 103 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index 06572218b8..f072a84424 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -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
+
+ at item octahedron
+Octahedron projection.
@end table
@item interp
diff --git a/libavfilter/v360.h b/libavfilter/v360.h
index 7fbbecf691..851bbcb8d8 100644
--- a/libavfilter/v360.h
+++ b/libavfilter/v360.h
@@ -53,6 +53,7 @@ enum Projections {
HEQUIRECTANGULAR,
EQUISOLID,
ORTHOGRAPHIC,
+ OCTAHEDRON,
NB_PROJECTIONS,
};
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index c021724fa3..f3d269ecde 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -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;
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