/* * Delay Locked Loop based time filter * Copyright (c) 2009 Samalyse * Author: Olivier Guilyardi * * This file is part of FFmpeg. * * 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. * * 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 FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "config.h" #include "avformat.h" #include "timefilter.h" struct TimeFilter { /// Delay Locked Loop data. These variables refer to mathematical /// concepts described in: http://www.kokkinizita.net/papers/usingdll.pdf double cycle_time; double feedback2_factor; double feedback3_factor; double integrator2_state; }; TimeFilter * ff_timefilter_new(double period, double feedback2_factor, double feedback3_factor) { TimeFilter *self = av_mallocz(sizeof(TimeFilter)); self->integrator2_state = period; self->feedback2_factor = feedback2_factor; self->feedback3_factor = feedback3_factor; return self; } void ff_timefilter_destroy(TimeFilter *self) { av_freep(&self); } void ff_timefilter_reset(TimeFilter *self) { self->cycle_time = 0; } void ff_timefilter_update(TimeFilter *self, double system_time) { if (!self->cycle_time) { /// init loop self->cycle_time = system_time; } else { double loop_error; self->cycle_time+= self->integrator2_state; /// calculate loop error loop_error = system_time - self->cycle_time; /// update loop self->cycle_time += self->feedback2_factor * loop_error; self->integrator2_state += self->feedback3_factor * loop_error; } } double ff_timefilter_read(TimeFilter *self) { return self->cycle_time; }