diff options
Diffstat (limited to 'libavdevice/timefilter.c')
-rw-r--r-- | libavdevice/timefilter.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/libavdevice/timefilter.c b/libavdevice/timefilter.c index e225ed11a9..4b8a10cb40 100644 --- a/libavdevice/timefilter.c +++ b/libavdevice/timefilter.c @@ -36,14 +36,21 @@ struct TimeFilter { int count; }; -TimeFilter *ff_timefilter_new(double clock_period, - double feedback2_factor, - double feedback3_factor) +/* 1 - exp(-x) using a 3-order power series */ +static double qexpneg(double x) +{ + return 1 - 1 / (1 + x * (1 + x / 2 * (1 + x / 3))); +} + +TimeFilter *ff_timefilter_new(double time_base, + double period, + double bandwidth) { TimeFilter *self = av_mallocz(sizeof(TimeFilter)); - self->clock_period = clock_period; - self->feedback2_factor = feedback2_factor; - self->feedback3_factor = feedback3_factor; + double o = 2 * M_PI * bandwidth * period * time_base; + self->clock_period = time_base; + self->feedback2_factor = qexpneg(M_SQRT2 * o); + self->feedback3_factor = qexpneg(o * o); return self; } |