[FFmpeg-cvslog] avfilter/vf_v360: add mercator projection
Paul B Mahol
git at videolan.org
Tue Sep 17 23:23:58 EEST 2019
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Tue Sep 17 22:15:07 2019 +0200| [251284e44aa568f344e973d4d0b8f03d2b3734aa] | committer: Paul B Mahol
avfilter/vf_v360: add mercator projection
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=251284e44aa568f344e973d4d0b8f03d2b3734aa
---
doc/filters.texi | 3 ++
libavfilter/v360.h | 1 +
libavfilter/vf_v360.c | 78 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 82 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index bbfdad4d4d..4888869473 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -18057,6 +18057,9 @@ 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
+ at item mercator
+Mercator format.
+
@end table
@item interp
diff --git a/libavfilter/v360.h b/libavfilter/v360.h
index a15ff7dbc4..cb968dab46 100644
--- a/libavfilter/v360.h
+++ b/libavfilter/v360.h
@@ -39,6 +39,7 @@ enum Projections {
BARREL,
CUBEMAP_1_6,
STEREOGRAPHIC,
+ MERCATOR,
NB_PROJECTIONS,
};
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index d5b94cf747..f8d3be80a5 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -65,6 +65,7 @@ static const AVOption v360_options[] = {
{ "fb", "barrel facebook's 360 format", 0, AV_OPT_TYPE_CONST, {.i64=BARREL}, 0, 0, FLAGS, "in" },
{ "c1x6", "cubemap 1x6", 0, AV_OPT_TYPE_CONST, {.i64=CUBEMAP_1_6}, 0, 0, FLAGS, "in" },
{ "sg", "stereographic", 0, AV_OPT_TYPE_CONST, {.i64=STEREOGRAPHIC}, 0, 0, FLAGS, "in" },
+ { "mercator", "mercator", 0, AV_OPT_TYPE_CONST, {.i64=MERCATOR}, 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" },
@@ -79,6 +80,7 @@ static const AVOption v360_options[] = {
{ "fb", "barrel facebook's 360 format", 0, AV_OPT_TYPE_CONST, {.i64=BARREL}, 0, 0, FLAGS, "out" },
{ "c1x6", "cubemap 1x6", 0, AV_OPT_TYPE_CONST, {.i64=CUBEMAP_1_6}, 0, 0, FLAGS, "out" },
{ "sg", "stereographic", 0, AV_OPT_TYPE_CONST, {.i64=STEREOGRAPHIC}, 0, 0, FLAGS, "out" },
+ { "mercator", "mercator", 0, AV_OPT_TYPE_CONST, {.i64=MERCATOR}, 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" },
@@ -1517,6 +1519,70 @@ static void xyz_to_equirect(const V360Context *s,
}
/**
+ * Calculate frame position in mercator format for corresponding 3D coordinates on sphere.
+ *
+ * @param s filter 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_mercator(const V360Context *s,
+ const float *vec, int width, int height,
+ uint16_t us[4][4], uint16_t vs[4][4], float *du, float *dv)
+{
+ const float phi = atan2f(vec[0], -vec[2]) * s->input_mirror_modifier[0];
+ const float theta = 0.5f * asinhf(vec[1] / sqrtf(1.f - vec[1] * vec[1])) * s->input_mirror_modifier[1];
+ float uf, vf;
+ int ui, vi;
+
+ uf = (phi / M_PI + 1.f) * width / 2.f;
+ vf = (theta / M_PI + 1.f) * height / 2.f;
+ 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] = mod(ui + j, width);
+ vs[i + 1][j + 1] = av_clip(vi + i, 0, height - 1);
+ }
+ }
+}
+
+/**
+ * Calculate 3D coordinates on sphere for corresponding frame position in mercator format.
+ *
+ * @param s filter 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 mercator_to_xyz(const V360Context *s,
+ int i, int j, int width, int height,
+ float *vec)
+{
+ const float phi = ((2.f * i) / width - 1.f) * M_PI;
+ const float theta = atanf(sinhf(((2.f * j) / height - 1.f) * 2.f * M_PI));
+
+ 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;
+}
+
+/**
* Prepare data for processing equi-angular cubemap input format.
*
* @param ctx filter context
@@ -2357,6 +2423,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h / 2.f;
break;
+ case MERCATOR:
+ s->in_transform = xyz_to_mercator;
+ err = 0;
+ wf = w;
+ hf = h;
+ break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified input format is not handled.\n");
return AVERROR_BUG;
@@ -2421,6 +2493,12 @@ static int config_output(AVFilterLink *outlink)
w = roundf(wf);
h = roundf(hf * 2.f);
break;
+ case MERCATOR:
+ s->out_transform = mercator_to_xyz;
+ prepare_out = NULL;
+ w = roundf(wf);
+ h = roundf(hf);
+ break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified output format is not handled.\n");
return AVERROR_BUG;
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