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ffmpeg.wasm-core
Commit 22cfa1f7 authored by Nicholas Robbins's avatar Nicholas Robbins Committed by Michael Niedermayer
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libavfi: added option to vf_perspective to specify transformation by giving... 

libavfi: added option to vf_perspective to specify transformation by giving destinations of corners of source.
Signed-off-by: 's avatarNicholas Robbins <nickrobbins@yahoo.com>
Signed-off-by: 's avatarMichael Niedermayer <michaelni@gmx.at>
parent 9d51bad6
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Showing with 86 additions and 20 deletions
doc/filters.texi
View file @ 22cfa1f7
......@@ -6718,6 +6718,9 @@ A description of the accepted parameters follows.
@item y3
Set coordinates expression for top left, top right, bottom left and bottom right corners.
Default values are @code{0:0:W:0:0:H:W:H} with which perspective will remain unchanged.
If the @code{sense} option is set to @code{source}, then the specified points will be sent
to the corners of the destination. If the @code{sense} option is set to @code{destination},
then the corners of the source will be sent to the specified coordinates.
The expressions can use the following variables:
......@@ -6737,6 +6740,24 @@ It accepts the following values:
@end table
Default value is @samp{linear}.
@item sense
Set interpretation of coordinate options.
It accepts the following values:
@table @samp
@item 0, source
Send point in the source specified by the given coordinates to
the corners of the destination.
@item 1, destination
Send the corners of the source to the point in the destination specified
by the given coordinates.
Default value is @samp{source}.
@end table
@end table
@section phase
......
libavfilter/vf_perspective.c
View file @ 22cfa1f7
......@@ -46,6 +46,7 @@ typedef struct PerspectiveContext {
int height[4];
int hsub, vsub;
int nb_planes;
int sense;
int (*perspective)(AVFilterContext *ctx,
void *arg, int job, int nb_jobs);
......@@ -54,6 +55,11 @@ typedef struct PerspectiveContext {
#define OFFSET(x) offsetof(PerspectiveContext, x)
#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
enum PERSPECTIVESense {
PERSPECTIVE_SENSE_SOURCE = 0, ///< coordinates give locations in source of corners of destination.
PERSPECTIVE_SENSE_DESTINATION = 1, ///< coordinates give locations in destination of corners of source.
};
static const AVOption perspective_options[] = {
{ "x0", "set top left x coordinate", OFFSET(expr_str[0][0]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
{ "y0", "set top left y coordinate", OFFSET(expr_str[0][1]), AV_OPT_TYPE_STRING, {.str="0"}, 0, 0, FLAGS },
......@@ -66,6 +72,12 @@ static const AVOption perspective_options[] = {
{ "interpolation", "set interpolation", OFFSET(interpolation), AV_OPT_TYPE_INT, {.i64=LINEAR}, 0, 1, FLAGS, "interpolation" },
{ "linear", "", 0, AV_OPT_TYPE_CONST, {.i64=LINEAR}, 0, 0, FLAGS, "interpolation" },
{ "cubic", "", 0, AV_OPT_TYPE_CONST, {.i64=CUBIC}, 0, 0, FLAGS, "interpolation" },
{ "sense", "specify the sense of the coordinates", OFFSET(sense), AV_OPT_TYPE_INT, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 1, FLAGS, "sense"},
{ "source", "specify locations in source to send to corners in destination",
0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_SOURCE}, 0, 0, FLAGS, "sense"},
{ "destination", "specify locations in destination to send corners of source",
0, AV_OPT_TYPE_CONST, {.i64=PERSPECTIVE_SENSE_DESTINATION}, 0, 0, FLAGS, "sense"},
{ NULL }
};
......@@ -105,7 +117,8 @@ enum { VAR_W, VAR_H, VAR_VARS_NB };
static int config_input(AVFilterLink *inlink)
{
double x0, x1, x2, x3, x4, x5, x6, x7, q;
double x0, x1, x2, x3, x4, x5, x6, x7, x8, q;
double t0, t1, t2, t3;
AVFilterContext *ctx = inlink->dst;
PerspectiveContext *s = ctx->priv;
double (*ref)[2] = s->ref;
......@@ -141,32 +154,64 @@ static int config_input(AVFilterLink *inlink)
if (!s->pv)
return AVERROR(ENOMEM);
x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
(ref[2][1] - ref[3][1]) -
( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
(ref[2][0] - ref[3][0])) * h;
x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
(ref[1][0] - ref[3][0]) -
( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
(ref[1][1] - ref[3][1])) * w;
q = ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -
( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);
x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];
x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];
x2 = q * ref[0][0] * w * h;
x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];
x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];
x5 = q * ref[0][1] * w * h;
switch (s->sense) {
case PERSPECTIVE_SENSE_SOURCE:
x6 = ((ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
(ref[2][1] - ref[3][1]) -
( ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
(ref[2][0] - ref[3][0])) * h;
x7 = ((ref[0][1] - ref[1][1] - ref[2][1] + ref[3][1]) *
(ref[1][0] - ref[3][0]) -
( ref[0][0] - ref[1][0] - ref[2][0] + ref[3][0]) *
(ref[1][1] - ref[3][1])) * w;
q = ( ref[1][0] - ref[3][0]) * (ref[2][1] - ref[3][1]) -
( ref[2][0] - ref[3][0]) * (ref[1][1] - ref[3][1]);
x0 = q * (ref[1][0] - ref[0][0]) * h + x6 * ref[1][0];
x1 = q * (ref[2][0] - ref[0][0]) * w + x7 * ref[2][0];
x2 = q * ref[0][0] * w * h;
x3 = q * (ref[1][1] - ref[0][1]) * h + x6 * ref[1][1];
x4 = q * (ref[2][1] - ref[0][1]) * w + x7 * ref[2][1];
x5 = q * ref[0][1] * w * h;
x8 = q * w * h;
break;
case PERSPECTIVE_SENSE_DESTINATION:
t0 = ref[0][0] * (ref[3][1] - ref[1][1]) +
ref[1][0] * (ref[0][1] - ref[3][1]) +
ref[3][0] * (ref[1][1] - ref[0][1]);
t1 = ref[1][0] * (ref[2][1] - ref[3][1]) +
ref[2][0] * (ref[3][1] - ref[1][1]) +
ref[3][0] * (ref[1][1] - ref[2][1]);
t2 = ref[0][0] * (ref[3][1] - ref[2][1]) +
ref[2][0] * (ref[0][1] - ref[3][1]) +
ref[3][0] * (ref[2][1] - ref[0][1]);
t3 = ref[0][0] * (ref[1][1] - ref[2][1]) +
ref[1][0] * (ref[2][1] - ref[0][1]) +
ref[2][0] * (ref[0][1] - ref[1][1]);
x0 = t0 * t1 * w * (ref[2][1] - ref[0][1]);
x1 = t0 * t1 * w * (ref[0][0] - ref[2][0]);
x2 = t0 * t1 * w * (ref[0][1] * ref[2][0] - ref[0][0] * ref[2][1]);
x3 = t1 * t2 * h * (ref[1][1] - ref[0][1]);
x4 = t1 * t2 * h * (ref[0][0] - ref[1][0]);
x5 = t1 * t2 * h * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]);
x6 = t1 * t2 * (ref[1][1] - ref[0][1]) +
t0 * t3 * (ref[2][1] - ref[3][1]);
x7 = t1 * t2 * (ref[0][0] - ref[1][0]) +
t0 * t3 * (ref[3][0] - ref[2][0]);
x8 = t1 * t2 * (ref[0][1] * ref[1][0] - ref[0][0] * ref[1][1]) +
t0 * t3 * (ref[2][0] * ref[3][1] - ref[2][1] * ref[3][0]);
break;
}
for (y = 0; y < h; y++){
for (x = 0; x < w; x++){
int u, v;
u = (int)floor(SUB_PIXELS * (x0 * x + x1 * y + x2) /
(x6 * x + x7 * y + q * w * h) + 0.5);
(x6 * x + x7 * y + x8) + 0.5);
v = (int)floor(SUB_PIXELS * (x3 * x + x4 * y + x5) /
(x6 * x + x7 * y + q * w * h) + 0.5);
(x6 * x + x7 * y + x8) + 0.5);
s->pv[x + y * w][0] = u;
s->pv[x + y * w][1] = v;
......
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