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drawbox: Respect thickness parameter

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The drawbox video filter is drawing lines one pixel thinner than
requested. The default thickness is 4 pixel but in fact the lines
drawn by default are only 3 pixel wide.

Change the comparisons in the code to fix this off-by-one bug. Also
change the default thickness from 4 to 3 to minimize the unexpected
changes from the user's perspective.

As I was already touching these lines, I also removed the "maximum" in
the thickness parameter description, as I don't think it was adding
any value and I even found it confusing.

Reviewed-by: Andrey Utkin <andrey.krieger.utkin@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Jean Delvare 2013-06-12 10:48:57 +02:00 committed by Michael Niedermayer
parent e850a064ce
commit cef42ded8d
2 changed files with 7 additions and 7 deletions
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2
doc/filters.texi
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@ -2900,7 +2900,7 @@ value @code{invert} is used, the box edge color is the same as the
video with inverted luma.
@item thickness, t
Set the thickness of the box edge. Default value is @code{4}.
Set the thickness of the box edge. Default value is @code{3}.
@end table
@subsection Examples

12
libavfilter/vf_drawbox.c
View File

@ -114,15 +114,15 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
if (s->invert_color) {
for (x = FFMAX(xb, 0); x < xb + s->w && x < frame->width; x++)
if ((y - yb < s->thickness-1) || (yb + s->h - y < s->thickness) ||
(x - xb < s->thickness-1) || (xb + s->w - x < s->thickness))
if ((y - yb < s->thickness) || (yb + s->h - 1 - y < s->thickness) ||
(x - xb < s->thickness) || (xb + s->w - 1 - x < s->thickness))
row[0][x] = 0xff - row[0][x];
} else {
for (x = FFMAX(xb, 0); x < xb + s->w && x < frame->width; x++) {
double alpha = (double)s->yuv_color[A] / 255;
if ((y - yb < s->thickness-1) || (yb + s->h - y < s->thickness) ||
(x - xb < s->thickness-1) || (xb + s->w - x < s->thickness)) {
if ((y - yb < s->thickness) || (yb + s->h - 1 - y < s->thickness) ||
(x - xb < s->thickness) || (xb + s->w - 1 - x < s->thickness)) {
row[0][x ] = (1 - alpha) * row[0][x ] + alpha * s->yuv_color[Y];
row[1][x >> s->hsub] = (1 - alpha) * row[1][x >> s->hsub] + alpha * s->yuv_color[U];
row[2][x >> s->hsub] = (1 - alpha) * row[2][x >> s->hsub] + alpha * s->yuv_color[V];
@ -148,8 +148,8 @@ static const AVOption drawbox_options[] = {
{ "h", "set height of the box", OFFSET(h_opt), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
{ "color", "set color of the box", OFFSET(color_str), AV_OPT_TYPE_STRING, { .str = "black" }, CHAR_MIN, CHAR_MAX, FLAGS },
{ "c", "set color of the box", OFFSET(color_str), AV_OPT_TYPE_STRING, { .str = "black" }, CHAR_MIN, CHAR_MAX, FLAGS },
{ "thickness", "set the box maximum thickness", OFFSET(thickness), AV_OPT_TYPE_INT, {.i64=4}, 0, INT_MAX, FLAGS },
{ "t", "set the box maximum thickness", OFFSET(thickness), AV_OPT_TYPE_INT, {.i64=4}, 0, INT_MAX, FLAGS },
{ "thickness", "set the box thickness", OFFSET(thickness), AV_OPT_TYPE_INT, { .i64 = 3 }, 0, INT_MAX, FLAGS },
{ "t", "set the box thickness", OFFSET(thickness), AV_OPT_TYPE_INT, { .i64 = 3 }, 0, INT_MAX, FLAGS },
{ NULL }
};