[FFmpeg-cvslog] avfilter/vf_v360: add hammer projection
Paul B Mahol
git at videolan.org
Sat Sep 21 17:36:49 EEST 2019
ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Sat Sep 21 15:29:18 2019 +0200| [b8dfc108a22501fc7b07cf1c1835d3d9e576398a] | committer: Paul B Mahol
avfilter/vf_v360: add hammer projection
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b8dfc108a22501fc7b07cf1c1835d3d9e576398a
---
doc/filters.texi | 3 ++
libavfilter/v360.h | 1 +
libavfilter/vf_v360.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 95 insertions(+)
diff --git a/doc/filters.texi b/doc/filters.texi
index 1f65b097d6..2cc0d9dfc5 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -18063,6 +18063,9 @@ Mercator format.
@item ball
Ball format, gives significant distortion toward the back.
+ at item hammer
+Hammer-Aitoff map projection format.
+
@end table
@item interp
diff --git a/libavfilter/v360.h b/libavfilter/v360.h
index 70b30264a0..aa0bb948d5 100644
--- a/libavfilter/v360.h
+++ b/libavfilter/v360.h
@@ -41,6 +41,7 @@ enum Projections {
STEREOGRAPHIC,
MERCATOR,
BALL,
+ HAMMER,
NB_PROJECTIONS,
};
diff --git a/libavfilter/vf_v360.c b/libavfilter/vf_v360.c
index 4f7d22f11e..d966723770 100644
--- a/libavfilter/vf_v360.c
+++ b/libavfilter/vf_v360.c
@@ -67,6 +67,7 @@ static const AVOption v360_options[] = {
{ "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" },
{ "ball", "ball", 0, AV_OPT_TYPE_CONST, {.i64=BALL}, 0, 0, FLAGS, "in" },
+ { "hammer", "hammer", 0, AV_OPT_TYPE_CONST, {.i64=HAMMER}, 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" },
@@ -83,6 +84,7 @@ static const AVOption v360_options[] = {
{ "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" },
{ "ball", "ball", 0, AV_OPT_TYPE_CONST, {.i64=BALL}, 0, 0, FLAGS, "out" },
+ { "hammer", "hammer", 0, AV_OPT_TYPE_CONST, {.i64=HAMMER}, 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" },
@@ -1659,6 +1661,83 @@ static void ball_to_xyz(const V360Context *s,
}
/**
+ * Calculate 3D coordinates on sphere for corresponding frame position in hammer 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 hammer_to_xyz(const V360Context *s,
+ int i, int j, int width, int height,
+ float *vec)
+{
+ const float x = ((2.f * i) / width - 1.f);
+ const float y = ((2.f * j) / height - 1.f);
+
+ const float xx = x * x;
+ const float yy = y * y;
+
+ const float z = sqrtf(1.f - xx * 0.5f - yy * 0.5f);
+
+ const float a = M_SQRT2 * x * z;
+ const float b = 2.f * z * z - 1.f;
+
+ const float aa = a * a;
+ const float bb = b * b;
+
+ const float w = sqrtf(1.f - 2.f * yy * z * z);
+
+ vec[0] = w * 2.f * a * b / (aa + bb);
+ vec[1] = -M_SQRT2 * y * z;
+ vec[2] = -w * (bb - aa) / (aa + bb);
+
+ normalize_vector(vec);
+}
+
+/**
+ * Calculate frame position in hammer 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_hammer(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 theta = atan2f(vec[0], -vec[2]) * s->input_mirror_modifier[0];
+
+ const float z = sqrtf(1.f + sqrtf(1.f - vec[1] * vec[1]) * cosf(theta * 0.5f));
+ const float x = sqrtf(1.f - vec[1] * vec[1]) * sinf(theta * 0.5f) / z;
+ const float y = -vec[1] / z * s->input_mirror_modifier[1];
+ float uf, vf;
+ int ui, vi;
+
+ uf = (x + 1.f) * width / 2.f;
+ vf = (y + 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);
+ }
+ }
+}
+
+/**
* Prepare data for processing equi-angular cubemap input format.
*
* @param ctx filter context
@@ -2512,6 +2591,12 @@ static int config_output(AVFilterLink *outlink)
wf = w;
hf = h / 2.f;
break;
+ case HAMMER:
+ s->in_transform = xyz_to_hammer;
+ err = 0;
+ wf = w;
+ hf = h;
+ break;
default:
av_log(ctx, AV_LOG_ERROR, "Specified input format is not handled.\n");
return AVERROR_BUG;
@@ -2588,6 +2673,12 @@ static int config_output(AVFilterLink *outlink)
w = roundf(wf);
h = roundf(hf * 2.f);
break;
+ case HAMMER:
+ s->out_transform = hammer_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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