/*
  * 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 "timefilter.h"

 #include "libavutil/mem.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