* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
-
+#include "libavutil/mem.h"
#include "config.h"
#include "timefilter.h"
-#include "libavutil/mem.h"
struct TimeFilter {
/// Delay Locked Loop data. These variables refer to mathematical
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));
- self->clock_period = clock_period;
- self->feedback2_factor = feedback2_factor;
- self->feedback3_factor = feedback3_factor;
+ 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;
+ self->clock_period = time_base;
+ self->feedback2_factor = qexpneg(M_SQRT2 * o);
+ self->feedback3_factor = qexpneg(o * o) / period;
return self;
}
void ff_timefilter_reset(TimeFilter *self)
{
- self->count = 0;
+ self->count = 0;
}
double ff_timefilter_update(TimeFilter *self, double system_time, double period)
{
self->count++;
- if (self->count==1) {
+ if (self->count == 1) {
/// init loop
- self->cycle_time = system_time;
+ self->cycle_time = system_time;
} else {
double loop_error;
- self->cycle_time += self->clock_period * 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 += 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;
+}
+
#ifdef TEST
#include "libavutil/lfg.h"
#define LFG_MAX ((1LL << 32) - 1)
int main(void)
{
AVLFG prng;
- double n0,n1;
+ double n0, n1;
#define SAMPLES 1000
double ideal[SAMPLES];
double samples[SAMPLES];
+ double samplet[SAMPLES];
#if 1
- for(n0= 0; n0<40; n0=2*n0+1){
- for(n1= 0; n1<10; n1=2*n1+1){
+ for (n0 = 0; n0 < 40; n0 = 2 * n0 + 1) {
+ for (n1 = 0; n1 < 10; n1 = 2 * n1 + 1) {
#else
- {{
- n0=7;
- n1=1;
+ {
+ {
+ n0 = 7;
+ n1 = 1;
#endif
- double best_error= 1000000000;
- double bestpar0=1;
- double bestpar1=0.001;
+ double best_error = 1000000000;
+ double bestpar0 = 1;
+ double bestpar1 = 1;
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);
+ for (i = 0; i < SAMPLES; i++) {
+ samplet[i] = 10 + i + (av_lfg_get(&prng) < LFG_MAX/2 ? 0 : 0.999);
+ ideal[i] = samplet[i] + n1 * i / (1000);
+ samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2) / (LFG_MAX * 10LL);
+ if(i && samples[i]<samples[i-1])
+ samples[i]=samples[i-1]+0.001;
}
- do{
+ 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++){
+ 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]);
+ filtered = ff_timefilter_update(tf, samples[i], i ? (samplet[i] - samplet[i-1]) : 1);
+ if(filtered < 0 || filtered > 1000000000)
+ printf("filter is unstable\n");
+ error += (filtered - ideal[i]) * (filtered - ideal[i]);
}
ff_timefilter_destroy(tf);
- if(error < best_error){
- best_error= error;
- bestpar0= par0;
- bestpar1= par1;
- better=1;
+ if (error < best_error) {
+ best_error = error;
+ bestpar0 = par0;
+ bestpar1 = par1;
+ better = 1;
}
}
}
- }while(better);
+ } while (better);
#if 0
- double lastfil=9;
- TimeFilter *tf= ff_timefilter_new(1, bestpar0, bestpar1);
- for(i=0; i<SAMPLES; i++){
+ 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;
+ 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
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