diff options
Diffstat (limited to 'libavdevice/timefilter.c')
-rw-r--r-- | libavdevice/timefilter.c | 36 |
1 files changed, 24 insertions, 12 deletions
diff --git a/libavdevice/timefilter.c b/libavdevice/timefilter.c index 4e0d5006d7..ad6485d5e7 100644 --- a/libavdevice/timefilter.c +++ b/libavdevice/timefilter.c @@ -5,20 +5,20 @@ * Author: Olivier Guilyardi <olivier samalyse com> * Michael Niedermayer <michaelni gmx at> * - * This file is part of Libav. + * This file is part of FFmpeg. * - * Libav is free software; you can redistribute it and/or + * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * - * Libav is distributed in the hope that it will be useful, + * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public - * License along with Libav; if not, write to the Free Software + * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ @@ -37,18 +37,25 @@ 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) { - TimeFilter *self = av_mallocz(sizeof(TimeFilter)); + 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)); + double o = 2 * M_PI * bandwidth * period * time_base; if (!self) return NULL; - self->clock_period = clock_period; - self->feedback2_factor = feedback2_factor; - self->feedback3_factor = feedback3_factor; + self->clock_period = time_base; + self->feedback2_factor = qexpneg(M_SQRT2 * o); + self->feedback3_factor = qexpneg(o * o) / period; return self; } @@ -73,7 +80,12 @@ double ff_timefilter_update(TimeFilter *self, double system_time, double period) loop_error = system_time - self->cycle_time; self->cycle_time += FFMAX(self->feedback2_factor, 1.0 / self->count) * loop_error; - self->clock_period += self->feedback3_factor * loop_error / period; + self->clock_period += self->feedback3_factor * loop_error; } return self->cycle_time; } + +double ff_timefilter_eval(TimeFilter *self, double delta) +{ + return self->cycle_time + self->clock_period * delta; +} |