On Tue, Sep 02, 2014 at 02:20:40PM -0700, hjiodjf 97xgw46 wrote: > The cropdetect filter is prone to reporting negative-sized rectangles, > particularly for dark images. This patch adjusts the limits of the > filter loops, preventing the left/right and top/bottom offsets from > crossing each other, so that such a zero-sized rectangle is reported > instead of a negative one. This improves the reliability of using > cropdetect to find a maximum bounding rectangle.
> vf_cropdetect.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
> 07877d20186041d6ad44359d10c2c079ba954d06
> 0001-Prevent-vf_cropdetect-from-returning-negative-rectan.patch
> From 971e0ec056e6200064598dbca49c18b8653e08d4 Mon Sep 17 00:00:00 2001
> From: tue46wsdgxfjrt <jfb...@gmail.com>
> Date: Tue, 2 Sep 2014 13:57:45 -0700
> Subject: [PATCH] Prevent vf_cropdetect from returning negative rectangle
> sizes.
>
> ---
> libavfilter/vf_cropdetect.c | 12 ++++++------
> 1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/libavfilter/vf_cropdetect.c b/libavfilter/vf_cropdetect.c
> index f85a0bb..f554ff8 100644
> --- a/libavfilter/vf_cropdetect.c
> +++ b/libavfilter/vf_cropdetect.c
> @@ -106,8 +106,8 @@ static int config_input(AVFilterLink *inlink)
>
> s->x1 = inlink->w - 1;
> s->y1 = inlink->h - 1;
> - s->x2 = 0;
> - s->y2 = 0;
> + s->x2 = inlink->w - 1;
> + s->y2 = inlink->h - 1;
>
> return 0;
> }
> @@ -131,8 +131,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *frame)
> if (s->reset_count > 0 && s->frame_nb > s->reset_count) {
> s->x1 = frame->width - 1;
> s->y1 = frame->height - 1;
> - s->x2 = 0;
> - s->y2 = 0;
> + s->x2 = frame->width - 1;
> + s->y2 = frame->height - 1;
> s->frame_nb = 1;
> }
>
> @@ -143,7 +143,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *frame)
> }
> }
>
> - for (y = frame->height - 1; y > s->y2; y--) {
> + for (y = frame->height - 1; y >= s->y1; y--) {
> if (checkline(ctx, frame->data[0] + frame->linesize[0] * y, bpp,
> frame->width, bpp) > s->limit) {
> s->y2 = y;
> break;
this isnt correct
nor is the change below
both will result in incorrect combination of croping rectangles over
multiple frames
> @@ -157,7 +157,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
> *frame)
> }
> }
>
> - for (y = frame->width - 1; y > s->x2; y--) {
> + for (y = frame->width - 1; y >= s->x1; y--) {
> if (checkline(ctx, frame->data[0] + bpp*y, frame->linesize[0],
> frame->height, bpp) > s->limit) {
> s->x2 = y;
> break;
> --
> 1.8.5.2 (Apple Git-48)
>
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--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
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