/*
To resample audio frame by frame of 1.5 sec duration to frequency 5512 Hz
*/
void resampling(AVFrame *frame){ //decoded frame from avcodec_decode_audio4()
  //refer to article https://www.ffmpeg.org/doxygen/2.3/group__lswr.html
  int ret,in_count,out_count,i,src_nb_channels=0,dst_nb_channels=0;
  int src_linesize=0,dst_linesize;
  int src_nb_samples = 1024, dst_nb_samples;
  enum AVSampleFormat src_sample_fmt;
  src_sample_fmt = dec_ctx->sample_fmt;

  uint8_t *out=NULL,**in=NULL;
  char err[128];
  in = frame->data;
  in_count = frame->nb_samples;
  printf("Sample rate:%d\tNumber of samples:%d\n",frame->sample_rate,frame->nb_samples);

  if(fmt_ctx == NULL){
    printf("No format context present(null)\n");
    return;
  }
  swr = swr_alloc();
if(swr == NULL){
    printf("SWR context not allocted\n");
    return;
  }
  av_opt_set_channel_layout(swr, "in_channel_layout", frame->channel_layout, 0);
  av_opt_set_channel_layout(swr, "out_channel_layout", AV_CH_LAYOUT_MONO, 0);
  av_opt_set_int(swr, "in_sample_rate",frame->sample_rate, 0);
  av_opt_set_int(swr, "out_sample_rate", 5512, 0);
  av_opt_set_sample_fmt(swr, "in_sample_fmt", src_sample_fmt, 0);
  av_opt_set_sample_fmt(swr, "out_sample_fmt", AV_SAMPLE_FMT_S16P, 0);
  ret = swr_init(swr);
  if(ret < 0){
    printf("SWR not initialised\n");
    return;
  }

  out_count = av_rescale_rnd(swr_get_delay(swr, frame->sample_rate) + frame->nb_samples, 5512, frame->sample_rate, AV_ROUND_UP);
  printf("Number of samples of output:%d\n",out_count);
  av_samples_alloc(&out, NULL, 2, out_count, AV_SAMPLE_FMT_S16, 0);
  ret = swr_convert(swr, &out, out_count,(const uint8_t **) in, in_count);
  if( ret < 0){
    printf("Not successfull swr_convert returned: %d\n",ret);
    return;
  }
  for(i = 0; i < out_count; i++)
    printf("in:%d\nout:%d\n",in[i],out[i]);
  swr_free(&swr);
  free(out);
  exit(0);
}