/* clap.c
	a Simple demo to detect claps from the sound card turned 
	in to a PC clapper switch that executes a given command 

 	1/27/05 eric buehl; eric@thebuehls.com 
 	10/8/08 FLD@r00t3d.com 
*/

#include <fcntl.h>
#include <sys/soundcard.h>
#include <sys/ioctl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

/*#define DEBUG		/* uncomment to get some info about claps received */

/* in order to configure, uncomment the debug line.  commands
will not be executed in debug mode */

/* these values will very greatly depending on your setup, microphone used, etc */

/* Values for detecting claps in the buffer */
#define BUF_SIZE 2048		/* amount of audio samples to record at a time */
#define PEAK 160			/* what values are considered a peak */
#define BOTTOM  96			/* what values are considered a min */
#define FREQ_GAP 30			/* the maximum space between a peak */
#define MIN_GAP 150			/* the minumum number of peaks that make a clap */
#define MAX_GAP 800			/* the max length of a clap */
#define MIN_FREQ 0.35		/* the minimum freq that we consider to be a clap */
#define MAX_FREQ 0.50		/* the maximum freq that we consider to be a clap */

/* How many buffers between the two claps ( 1 buffer is about 47ms ) */
#define MIN_CLAP_GAP 5		/* the minumum amount of silent samples between claps */
#define MAX_CLAP_GAP 10		/* the maximum amount of silent samples between claps */

/* Sound Settings */
int format = AFMT_U8;		/* Standard Unsigned 8 bit */
int sample_rate = 44100;	/* 44.1kHz */
int chn = 1;				/* Mono */

int audio_fd;	/* The audio device */
unsigned char recBuffer[BUF_SIZE]; /* Samples */
int peaks[BUF_SIZE]; /* Samples that are above Peak value */
int numPeaks=0; /* How many Peaked */
int capSilent = 0; /* Do we need to count silent buffers */
int silence = 0; /* How many silent buffers */
int bufnum = 0; /* Used in Debug mode to count Buffers */

int main(int argc, char *argv[])
{
	int i,j;
	int len;
	float freq;
	int vol;
	char DEVICE_NAME[50];
	char COMMAND[200]={0};
	int start,finish;

	if(argc<3){
		printf("Usage: %s device_name command\nEXAMPLE: %s /dev/dsp echo clap received\\n\n\n",argv[0],argv[0]);
		return -1;
	}
	
	/* Parse Commandline Arguments */
	strcpy(DEVICE_NAME,argv[1]);
	for(i=2;i<argc;i++){
		strcat(COMMAND,argv[i]);
		strcat(COMMAND," ");
	}
	strcat(COMMAND," &");
	printf("Listening to device: %s\n",DEVICE_NAME);

	/* Open Audio Device */
	if ((audio_fd = open(DEVICE_NAME, /*O_RDWR*/ O_RDONLY, 0)) == -1)
	{
		perror(DEVICE_NAME);
		exit(-1);
	}
	
	/* Set Sample Format */
  	if (ioctl (audio_fd, SNDCTL_DSP_SETFMT, &format) == -1)
    {
      perror ("SNDCTL_DSP_SETFMT");
      exit (-1);
    }
  	if (format != AFMT_U8)
    {
      fprintf (stderr,
	       "The device doesn't support the 8 bit sample format...\n");
      exit (-1);
    }
    
    /* Set amount of Channels*/
 	if (ioctl (audio_fd, SNDCTL_DSP_CHANNELS, &chn) == -1)
    {
      perror ("SNDCTL_DSP_CHANNELS");
      exit (-1);
    }
  	if (chn != 1)
    {
      fprintf (stderr, "The device doesn't support mono mode...\n");
      exit (-1);
    }
    
    /* Set Sample Rate */
  	if (ioctl (audio_fd, SNDCTL_DSP_SPEED, &sample_rate) == -1)
    {
      perror ("SNDCTL_DSP_SPEED");
      exit (-1);
    }
	
    /* - The Main Loop - */
	while(1)
	{
		/* Get the Sample Data and store the Values to recBuffer[n] */
		if ((len = read(audio_fd, recBuffer, BUF_SIZE)) == -1)
		{
			perror("audio read");
			exit(-2);
		}
		
		/* Look for samples that go over the Peak Limit*/
		for(i=0;i<BUF_SIZE;i++)
		{
			if((recBuffer[i]<=BOTTOM)||(recBuffer[i]>=PEAK))
			{
				peaks[numPeaks++]=i;
				/*printf("recBuffer: %d\n",recBuffer[i]); */
			}
		}
		
		/* Stop counting silent Buffers if there are too many */
		if (silence > MAX_CLAP_GAP)
		{
			silence = 0;
			capSilent = 0;
		}

		/* Go through every Sample that is over the Peak Limit */
		for(i=0;i<numPeaks;i++)
		{
			start=peaks[i]; /* First Peak Sample */
			/* Check the Gap between the Peaks */
			while((i < numPeaks-1) && ((peaks[i]+FREQ_GAP) > (peaks[++i])));
			
			finish=peaks[i]; /* Last Peak Sample */
			/* Check that there are enough of Peaks */
			if(finish-start < MIN_GAP || finish-start > MAX_GAP) 
				continue;
			
			/* compute avergae frequency of clap */
			/* if we find the number of samples over a certain value
			   per constant time, we get an abstract frequency */
			j=start;
			freq=0;
			vol=0;
			while(j<=finish)
			{
				if(recBuffer[j]>128) vol+=recBuffer[j];
				if(recBuffer[j++] > 128 /* PEAK */) freq++;
			}
			freq /= (finish-start);
			vol /= j;
			if(freq<MIN_FREQ || freq>MAX_FREQ)
			{ 
				continue;
			}
			
			/* Not enough Silence after the first clap 
			   so we zero the Silence counter */
			if (silence < MIN_CLAP_GAP)
				silence = 0;
			capSilent = 1;
			
			#ifdef DEBUG
				printf("start:  %d\n",start);
				printf("finish: %d\n",finish);
				printf("diff:   %d\n",finish-start);
				printf("vol:    %d\n",vol);
				printf("freq:   %f\n",freq);
				printf("silence: %d\n",silence);
				if (silence >= MIN_CLAP_GAP && silence <= MAX_CLAP_GAP) 
					printf("run: Yes\n\n");
				else
					printf("run: No\n\n");
			#else
				if (silence >= MIN_CLAP_GAP && silence <= MAX_CLAP_GAP) 
				{
					system(COMMAND);
					capSilent = 0;
					silence = 0;
				}
			#endif
		}
		
		/* Start counting Silent Buffers after the first Clap is detected */
		if (capSilent == 1) 
			silence++;
		numPeaks = 0;
		
		#ifdef DEBUG
			if (bufnum > 127) 
				bufnum = 0;
			bufnum++;
			printf("--new buffer #%d--\n",bufnum);
		#endif
		
	} /* End of the Main Loop */
	
	close(audio_fd); /* <-- This will happen when (1 != 1)? */
	return 0;
}