/*
* 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.
*
double cycle_time;
double feedback2_factor;
double feedback3_factor;
- double integrator2_state;
+ double clock_period;
+ int count;
};
-TimeFilter * ff_timefilter_new(double feedback2_factor, double feedback3_factor)
+TimeFilter * ff_timefilter_new(double clock_period, double feedback2_factor, double feedback3_factor)
{
TimeFilter *self = av_mallocz(sizeof(TimeFilter));
- self->integrator2_state = 1.0;
+ self->clock_period = clock_period;
self->feedback2_factor = feedback2_factor;
self->feedback3_factor = feedback3_factor;
return self;
void ff_timefilter_reset(TimeFilter *self)
{
- self->cycle_time = 0;
+ self->count = 0;
}
-void ff_timefilter_update(TimeFilter *self, double system_time, double period)
+double ff_timefilter_update(TimeFilter *self, double system_time, double period)
{
- if (!self->cycle_time) {
+ self->count++;
+ if (self->count==1) {
/// init loop
- self->cycle_time = system_time;
+ self->cycle_time = system_time;
} else {
double loop_error;
- self->cycle_time+= self->integrator2_state * period;
+ self->cycle_time += self->clock_period * period;
/// calculate loop error
- loop_error = system_time - self->cycle_time;
+ 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 / period;
+ 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;
}
-double ff_timefilter_read(TimeFilter *self)
+#ifdef TEST
+#include "libavutil/lfg.h"
+#define LFG_MAX ((1LL << 32) - 1)
+
+int main(void)
{
- return self->cycle_time;
+ 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