/*
 * Silence Removal in Speech Signal
 *
 *  Created on: Sep 7, 2016
 *      Author: Agustín J. González
 * It assumes mono audio file of 16-bit PCM samples, little-endian format, sampled at 8 KHz 
 */

#include <stdlib.h>
#include <fstream>  // ifstream , ofstream

using namespace std;

int main (int argc, char * argv[]) {
	float threshold;
	ifstream audioInFile;
	ofstream audioOutFile;
	int packetSize;
	short *buff, *zeroBuff;
  
	if (argc < 5) {
		printf("Usage: %s <threshold> <packet size > <input file> <output file>\n", argv[0]);
		exit(-1); 
	}
	threshold = atof(argv[1]);  // First argument is a threshold for sensibility
	packetSize = atoi(argv[2]); 
	audioInFile.open (argv[3], ios::in | ios::binary);  // input audio file
	audioOutFile.open (argv[4], ios::out | ios::binary); //output audio file
	buff = new short[packetSize];
	zeroBuff = new short[packetSize];
   
	while (!audioInFile.eof()) {
		float energy=0;
		int sampleRead;
      
		audioInFile.read((char *)buff, sizeof(short)*packetSize);
		sampleRead= audioInFile.gcount()/sizeof(short); 
		for (int i=0; i <sampleRead; i++) 
			energy += buff[i]*buff[i];
		energy /= sampleRead;
		if (energy > threshold) 
			audioOutFile.write((char*)buff, sizeof(short)*sampleRead);
		else
			audioOutFile.write((char*)zeroBuff, sizeof(short)*sampleRead);
	}
	audioInFile.close();
	audioOutFile.close();
}