int quick_sort_partition(int a[], int start, int end) {
int p = random_selector(a, start, end);
int temp;
temp = a[p];
a[p] = a[end];
a[end] = temp;
p = end;
int j = start; // all elements whose index < j are < a[p]
while(a[j] < a[p] && j <= end)
j++;
int i;
for(i = end - 1; i >= j; i--) {
if(a[i] < a[p]) {
// put a[i] at a[j]
temp = a[j];
a[j] = a[i];
a[i] = temp;
j++;
while(a[j] < a[p] && j <= i)
j++;
}
}
temp = a[j];
a[j] = a[end];
a[end] = temp;
return j;
}
int main (int argc, const char * argv[])
{
// choose which zero of autocorrelation should be set as delay parameter
int delay_choice =2;
int embed_dimension =3;
int num_neighbours = 15;
long num_of_points_retained=500;
int percentile =70;
long output_len=2*(((float)percentile)/100)*num_of_points_retained;
printf("%ld output_len =",output_len);
float *output = malloc(output_len* sizeof(float));
printf("Density based subsampling running \n");
if (argc != 2) {
fprintf(stderr, "Expecting wav file as argument\n");
return 1;
}
// Open sound file that comes in as a command line argument
SF_INFO sndInfo;
SNDFILE *sndFile = sf_open(argv[1], SFM_READ, &sndInfo);
if (sndFile == NULL) {
fprintf(stderr, "Error reading source file '%s': %s\n", argv[1], sf_strerror(sndFile));
return 1;
}
// Check format - 16bit PCM
if (sndInfo.format != (SF_FORMAT_WAV | SF_FORMAT_PCM_16)) {
fprintf(stderr, "Input should be 16bit Wav\n");
sf_close(sndFile);
return 1;
}
// Now we know the length of the wav file, we can create a buffer for it, in this case, we are creating a double array.
// Allocate memory
float *buffer = malloc(sndInfo.frames * sizeof(float)* sndInfo.channels);
if (buffer == NULL)
{
fprintf(stderr, "Could not allocate memory for data\n");
sf_close(sndFile);
return 1;
}
// This next step, actually reads in the wav file data. This function automatically converts the whichever format the audio file data is in to doubles. The library can convert to a number of different formats.
// Load data
long numFrames = sf_readf_float(sndFile, buffer, sndInfo.frames);
// Check correct number of samples loaded
if (numFrames != sndInfo.frames) {
fprintf(stderr, "Did not read enough samples for source\n");
sf_close(sndFile);
free(buffer);
return 1;
}
// Now just output some info about the wav file
printf("Read %ld samples from %s, Sample rate: %d, Length: %fs\n",
numFrames, argv[1], sndInfo.samplerate, (float)numFrames/sndInfo.samplerate);
// extract a single channel out
float *buffer_singlechannel = malloc(sndInfo.frames * sizeof(float));
long i=0;
for (long f=0 ; f<numFrames ; f++) {
buffer_singlechannel[f]= buffer[i]; // Channel 1
i+=sndInfo.channels;
}
// free the buffer with multiple channel input
free(buffer);
// array to store the autocorrelation function
double *buffer_autocorrelation = malloc((2*sndInfo.frames +1)* sizeof(double));
// calculate autocorrelation
xcorr( buffer_singlechannel, buffer_singlechannel, buffer_autocorrelation, sndInfo.frames, 0,sndInfo.frames, 1, 1, sndInfo.frames,sndInfo.frames, sndInfo.frames, sndInfo.frames);
// choose delay to be second zero of auto correlation
long long delay = zeroCrossing(buffer_autocorrelation, 2*sndInfo.frames +1, delay_choice);
printf("Delay chosen = %lld\n",delay);
long long delay_embd_length= (sndInfo.frames -(delay*embed_dimension)+2)* embed_dimension;
//create delay embedding and store in a linear array in row major form
float *buffer_delayembedding =malloc(delay_embd_length*sizeof(float));
long long k1=0;
for (long long l=(delay*embed_dimension)-2; l<sndInfo.frames; l=l+1) {
buffer_delayembedding[k1]=buffer_singlechannel[l];
buffer_delayembedding[k1+1]=buffer_singlechannel[l-delay];
buffer_delayembedding[k1+2]=buffer_singlechannel[l-2*delay];
// printf("%f %f %f\n", buffer_delayembedding[k1],buffer_delayembedding[k1+1],buffer_delayembedding[k1+2]);
k1=k1+embed_dimension;
}
int *array =malloc(num_of_points_retained *sizeof(int));
random_selector( delay_embd_length/ embed_dimension ,num_of_points_retained , array);
for (int i=0; i<num_of_points_retained; i++) {
// printf("%d\n",array[i]);
}
float *buffer_delayembedding_selec =malloc(num_of_points_retained*embed_dimension*sizeof(float));
float * density_vals =malloc(num_of_points_retained* sizeof(float));
printf("total len = %lld\n ", delay_embd_length/3 );
printf("buffer len = %ld\n", num_of_points_retained*embed_dimension);
printf("num_of_points_retained = %ld\n", num_of_points_retained);
for (int i=0; i<num_of_points_retained; i=i+1)
{
int loc=(array[i]-1)*embed_dimension;
// printf("i :%d loc=%d array[i]: %d \n",i, loc, array[i]);
buffer_delayembedding_selec[3*i]=buffer_delayembedding[loc];
buffer_delayembedding_selec[3*i+1]=buffer_delayembedding[loc+1];
buffer_delayembedding_selec[3*i+2]=buffer_delayembedding[loc+2];
// printf("buffer selec [%d] = %f ", 3*i, buffer_delayembedding_selec[3*i]);
// printf("[%d] = %f ", 3*i+1, buffer_delayembedding_selec[3*i+1]);
// printf("[%d] = %f \n", 3*i+2, buffer_delayembedding_selec[3*i+2]);
}
// for (int i=0; i<delay_embd_length/ embed_dimension ; i++)
// {
// printf("% d th original :%f %f %f\n",i, buffer_delayembedding [3*i],buffer_delayembedding [3*i+1],buffer_delayembedding [3*i+2]);
// }
knn (buffer_delayembedding_selec, density_vals , (num_of_points_retained), num_neighbours);
// free all arrays used till now except the single channel wave file and close the sndFile object
sf_close(sndFile);
//desnity based subsampling
float * density_vals_temp =malloc(num_of_points_retained* sizeof(float));
memcpy(density_vals_temp,density_vals,num_of_points_retained* sizeof(float));
qsort(density_vals_temp, num_of_points_retained, sizeof(float), cmpfunc);
float key=findNumber(100-percentile,density_vals_temp,500);
// Function call and the print statement
// printf(" \n %d percentile: %.4lf \n", percentile, key);
printf(" \n the linear array output contains the subsampled point cloud \n");
//for (int kk=0; kk<num_of_points_retained; kk++) {
// printf("%d index %f \n", kk,density_vals_temp[kk]);
//}
free(density_vals_temp);
int counter2=0;
for( int counter = 0 ; counter < num_of_points_retained; counter++)
{
if (density_vals[counter]>=key && counter2<output_len/2)
{
output[2*counter2]=buffer_delayembedding_selec[3*counter];
output[2*counter2+1]=buffer_delayembedding_selec[3*counter+1];
//printf("%d output %.4lf , %.4lf\n", counter2,output[2*counter2],output[2*counter2+1]);
//printf("%d output %.4lf , %.4lf\n", counter,buffer_delayembedding_selec[3*counter],buffer_delayembedding_selec[3*counter+1]);
counter2++;
}
}
free(buffer_singlechannel);
free(buffer_autocorrelation);
free(buffer_delayembedding);
free(array);
free(buffer_delayembedding_selec);
free(density_vals);
printf("Density based subsampling End\n");
free(output);
return 0;
}
