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vf_fps: add 'start_time' option 

This allows for dropping or duplication to match a particular start time.
This commit is contained in:
Justin Ruggles 2013-08-15 16:14:57 -04:00 committed by Justin Ruggles
parent 2a61592573
commit 545a0b807c
2 changed files with 23 additions and 1 deletions
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8
doc/filters.texi
View File

@ -1241,6 +1241,14 @@ This filter accepts the following named parameters:
@item fps
Desired output framerate.
@item start_time
Assume the first PTS should be the given value, in seconds. This allows for
padding/trimming at the start of stream. By default, no assumption is made
about the first frame's expected PTS, so no padding or trimming is done.
For example, this could be set to 0 to pad the beginning with duplicates of
the first frame if a video stream starts after the audio stream or to trim any
frames with a negative PTS.
@end table
@anchor{frei0r}

14
libavfilter/vf_fps.c
View File

@ -40,6 +40,8 @@ typedef struct FPSContext {
int64_t first_pts; ///< pts of the first frame that arrived on this filter
int64_t pts; ///< pts of the first frame currently in the fifo
double start_time; ///< pts, in seconds, of the expected first frame
AVRational framerate; ///< target framerate
char *fps; ///< a string describing target framerate
@ -54,6 +56,7 @@ typedef struct FPSContext {
#define V AV_OPT_FLAG_VIDEO_PARAM
static const AVOption options[] = {
{ "fps", "A string describing desired output framerate", OFFSET(fps), AV_OPT_TYPE_STRING, { .str = "25" }, .flags = V },
{ "start_time", "Assume the first PTS should be this value.", OFFSET(start_time), AV_OPT_TYPE_DOUBLE, { .dbl = AV_NOPTS_VALUE}, INT64_MIN, INT64_MAX, V },
{ NULL },
};
@ -78,6 +81,7 @@ static av_cold int init(AVFilterContext *ctx)
return AVERROR(ENOMEM);
s->pts = AV_NOPTS_VALUE;
s->first_pts = AV_NOPTS_VALUE;
av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num, s->framerate.den);
return 0;
@ -177,7 +181,17 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *buf)
if (ret < 0)
return ret;
if (s->start_time != AV_NOPTS_VALUE) {
double first_pts = s->start_time * AV_TIME_BASE;
first_pts = FFMIN(FFMAX(first_pts, INT64_MIN), INT64_MAX);
s->first_pts = s->pts = av_rescale_q(first_pts, AV_TIME_BASE_Q,
inlink->time_base);
av_log(ctx, AV_LOG_VERBOSE, "Set first pts to (in:%"PRId64" out:%"PRId64")\n",
s->first_pts, av_rescale_q(first_pts, AV_TIME_BASE_Q,
outlink->time_base));
} else {
s->first_pts = s->pts = buf->pts;
}
} else {
av_log(ctx, AV_LOG_WARNING, "Discarding initial frame(s) with no "
"timestamp.\n");