The cropdetect filter, at present, skips the first two frames. This
behaviour is hardcoded.
New option 'skip' allows users to change this. Convenient for when
input is a single image or a trimmed video stream.
Default is kept at 2 to preserve current behaviour.
---
doc/filters.texi | 4 ++++
libavfilter/vf_cropdetect.c | 10 ++++++----
2 files changed, 10 insertions(+), 4 deletions(-)
diff --git a/doc/filters.texi b/doc/filters.texi
index 62d6e26a02..d9f606604e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -8899,6 +8899,10 @@ The value which the width/height should be
divisible by. It defaults to
get only even dimensions (needed for 4:2:2 video). 16 is best when
encoding to most video codecs.
+@item skip
+Set the number of initial frames for which evaluation is skipped.
+Default is 2. Range is 0 to INT_MAX.
+
@item reset_count, reset
Set the counter that determines after how many frames cropdetect will
reset the previously detected largest video area and start over to
diff --git a/libavfilter/vf_cropdetect.c b/libavfilter/vf_cropdetect.c
index 7c7d0b953a..5ae87cad2d 100644
--- a/libavfilter/vf_cropdetect.c
+++ b/libavfilter/vf_cropdetect.c
@@ -37,6 +37,7 @@ typedef struct CropDetectContext {
int x1, y1, x2, y2;
float limit;
int round;
+ int skip;
int reset_count;
int frame_nb;
int max_pixsteps[4];
@@ -127,10 +128,10 @@ static av_cold int init(AVFilterContext *ctx)
{
CropDetectContext *s = ctx->priv;
- s->frame_nb = -2;
+ s->frame_nb = -1 * s->skip;
- av_log(ctx, AV_LOG_VERBOSE, "limit:%f round:%d reset_count:%d\n",
- s->limit, s->round, s->reset_count);
+ av_log(ctx, AV_LOG_VERBOSE, "limit:%f round:%d skip:%d
reset_count:%d\n",
+ s->limit, s->round, s->skip, s->reset_count);
return 0;
}
@@ -167,7 +168,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame
*frame)
int outliers, last_y;
int limit = lrint(s->limit);
- // ignore first 2 frames - they may be empty
+ // ignore first s->skip frames
if (++s->frame_nb > 0) {
metadata = &frame->metadata;
@@ -247,6 +248,7 @@ static const AVOption cropdetect_options[] = {
{ "limit", "Threshold below which the pixel is considered black",
OFFSET(limit), AV_OPT_TYPE_FLOAT, { .dbl = 24.0/255 }, 0, 65535,
FLAGS },
{ "round", "Value by which the width/height should be divisible",
OFFSET(round), AV_OPT_TYPE_INT, { .i64 = 16 }, 0, INT_MAX, FLAGS },
{ "reset", "Recalculate the crop area after this many frames",
OFFSET(reset_count), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
+ { "skip", "Number of initial frames to skip",
OFFSET(skip), AV_OPT_TYPE_INT, { .i64 = 2 }, 0, INT_MAX, FLAGS },
{ "reset_count", "Recalculate the crop area after this many
frames",OFFSET(reset_count),AV_OPT_TYPE_INT,{ .i64 = 0 }, 0, INT_MAX,
FLAGS },
{ "max_outliers", "Threshold count of outliers",
OFFSET(max_outliers),AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, FLAGS },
{ NULL }
--
2.27.0
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