[FFmpeg-cvslog] avfilter/vf_v360: add half equirectangular input format
Paul B Mahol
git at videolan.org
Tue Mar 3 13:43:42 EET 2020
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Tue Mar 3 12:21:16 2020 +0100| [580d68f90e4cd363ad75d187a7b42f7951733f79] | committer: Paul B Mahol
avfilter/vf_v360: add half equirectangular input format
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=580d68f90e4cd363ad75d187a7b42f7951733f79
---
doc/filters.texi | 3 +++
libavfilter/vf_v360.c | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 51 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index b4f3e1ab42..433abe296d 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -19031,6 +19031,9 @@ Tetrahedron projection.
@item tsp
Truncated square pyramid projection.
+ at item he
+ at item hequirect
+Half equirectangular projection.
@end table
@item interp
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index 3d4ee25216..05c558d97d 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -78,6 +78,8 @@ static const AVOption v360_options[] = {
{"tetrahedron", "tetrahedron", 0, AV_OPT_TYPE_CONST, {.i64=TETRAHEDRON}, 0, 0, FLAGS, "in" },
{"barrelsplit", "barrel split facebook's 360 format", 0, AV_OPT_TYPE_CONST, {.i64=BARREL_SPLIT}, 0, 0, FLAGS, "in" },
{ "tsp", "truncated square pyramid", 0, AV_OPT_TYPE_CONST, {.i64=TSPYRAMID}, 0, 0, FLAGS, "in" },
+ { "hequirect", "half equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=HEQUIRECTANGULAR},0, 0, FLAGS, "in" },
+ { "he", "half equirectangular", 0, AV_OPT_TYPE_CONST, {.i64=HEQUIRECTANGULAR},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" },
@@ -1800,6 +1802,46 @@ static int xyz_to_equirect(const V360Context *s,
return 1;
}
+/**
+ * Calculate frame position in half equirectangular 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_hequirect(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->input_mirror_modifier[0];
+ const float theta = asinf(-vec[1]) * s->input_mirror_modifier[1];
+
+ const float uf = (phi / M_PI_2 + 1.f) * width / 2.f;
+ const float vf = (theta / M_PI_2 + 1.f) * height / 2.f;
+
+ const int ui = floorf(uf);
+ const int vi = floorf(vf);
+
+ const int visible = phi >= -M_PI_2 && phi <= M_PI_2;
+
+ *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(ui + j - 1, 0, width - 1);
+ vs[i][j] = av_clip(vi + i - 1, 0, height - 1);
+ }
+ }
+
+ return visible;
+}
+
/**
* Prepare data for processing flat input format.
*
@@ -3835,6 +3877,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h;
break;
+ case HEQUIRECTANGULAR:
+ s->in_transform = xyz_to_hequirect;
+ err = 0;
+ wf = w * 2.f;
+ hf = h;
+ break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified input format is not handled.\n");
return AVERROR_BUG;
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