| /* |
| * Delay Locked Loop based time filter |
| * Copyright (c) 2009 Samalyse |
| * Copyright (c) 2009 Michael Niedermayer |
| * Author: Olivier Guilyardi <olivier samalyse com> |
| * Michael Niedermayer <michaelni gmx at> |
| * |
| * 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 clock_period; |
| int count; |
| }; |
| |
| TimeFilter * ff_timefilter_new(double clock_period, double feedback2_factor, double feedback3_factor) |
| { |
| TimeFilter *self = av_mallocz(sizeof(TimeFilter)); |
| self->clock_period = clock_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->count = 0; |
| } |
| |
| double ff_timefilter_update(TimeFilter *self, double system_time, double period) |
| { |
| self->count++; |
| if (self->count==1) { |
| /// init loop |
| self->cycle_time = system_time; |
| } else { |
| double loop_error; |
| self->cycle_time += self->clock_period * period; |
| /// calculate loop error |
| loop_error = system_time - self->cycle_time; |
| |
| /// update loop |
| self->cycle_time += FFMAX(self->feedback2_factor, 1.0/(self->count)) * loop_error; |
| self->clock_period += self->feedback3_factor * loop_error / period; |
| } |
| return self->cycle_time; |
| } |
| |
| #ifdef TEST |
| #include "libavutil/lfg.h" |
| #define LFG_MAX ((1LL << 32) - 1) |
| |
| #undef printf |
| |
| int main(void) |
| { |
| AVLFG prng; |
| double n0,n1; |
| #define SAMPLES 1000 |
| double ideal[SAMPLES]; |
| double samples[SAMPLES]; |
| #if 1 |
| for(n0= 0; n0<40; n0=2*n0+1){ |
| for(n1= 0; n1<10; n1=2*n1+1){ |
| #else |
| {{ |
| n0=7; |
| n1=1; |
| #endif |
| double best_error= 1000000000; |
| double bestpar0=1; |
| double bestpar1=0.001; |
| int better, i; |
| |
| av_lfg_init(&prng, 123); |
| for(i=0; i<SAMPLES; i++){ |
| ideal[i] = 10 + i + n1*i/(1000); |
| samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) |
| / (LFG_MAX * 10LL); |
| } |
| |
| do{ |
| double par0, par1; |
| better=0; |
| for(par0= bestpar0*0.8; par0<=bestpar0*1.21; par0+=bestpar0*0.05){ |
| for(par1= bestpar1*0.8; par1<=bestpar1*1.21; par1+=bestpar1*0.05){ |
| double error=0; |
| TimeFilter *tf= ff_timefilter_new(1, par0, par1); |
| for(i=0; i<SAMPLES; i++){ |
| double filtered; |
| filtered= ff_timefilter_update(tf, samples[i], 1); |
| error += (filtered - ideal[i]) * (filtered - ideal[i]); |
| } |
| ff_timefilter_destroy(tf); |
| if(error < best_error){ |
| best_error= error; |
| bestpar0= par0; |
| bestpar1= par1; |
| better=1; |
| } |
| } |
| } |
| }while(better); |
| #if 0 |
| double lastfil=9; |
| TimeFilter *tf= ff_timefilter_new(1, bestpar0, bestpar1); |
| for(i=0; i<SAMPLES; i++){ |
| double filtered; |
| filtered= ff_timefilter_update(tf, samples[i], 1); |
| printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i], samples[FFMAX(i, 1)] - samples[FFMAX(i-1, 0)], filtered - lastfil); |
| lastfil= filtered; |
| } |
| ff_timefilter_destroy(tf); |
| #else |
| printf(" [%f %f %9f]", bestpar0, bestpar1, best_error); |
| #endif |
| } |
| printf("\n"); |
| } |
| return 0; |
| } |
| #endif |