/*
* _______ _____ _____ _____
* |__ __| | __ \ / ____| __ \
* | | __ _ _ __ ___ ___ ___| | | | (___ | |__) |
* | |/ _` | '__/ __|/ _ \/ __| | | |\___ \| ___/
* | | (_| | | \__ \ (_) \__ \ |__| |____) | |
* |_|\__,_|_| |___/\___/|___/_____/|_____/|_|
*
* -------------------------------------------------------------
*
* TarsosDSP is developed by Joren Six at IPEM, University Ghent
*
* -------------------------------------------------------------
*
* Info: http://0110.be/tag/TarsosDSP
* Github: https://github.com/JorenSix/TarsosDSP
* Releases: http://0110.be/releases/TarsosDSP/
*
* TarsosDSP includes modified source code by various authors,
* for credits and info, see README.
*
*/
package be.tarsos.dsp.pitch;
/**
* Utility class to generate Dual-tone multi-frequency (DTMF) signaling tones.
* This class also contains a list of valid DTMF frequencies and characters.
*
* See the <a href="http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling"
* >WikiPedia article on DTMF</a>.
*
* @author Joren Six
*/
public class DTMF {
/**
* The list of valid DTMF frequencies. See the <a
* href="http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling"
* >WikiPedia article on DTMF</a>.
*/
public static final double[] DTMF_FREQUENCIES = { 697, 770, 852, 941, 1209,
1336, 1477, 1633 };
/**
* The list of valid DTMF characters. See the <a
* href="http://en.wikipedia.org/wiki/Dual-tone_multi-frequency_signaling"
* >WikiPedia article on DTMF</a> for the relation between the characters
* and frequencies.
*/
public static final char[][] DTMF_CHARACTERS = { { '1', '2', '3', 'A' },
{ '4', '5', '6', 'B' }, { '7', '8', '9', 'C' },
{ '*', '0', '#', 'D' } };
/**
* Generate a DTMF - tone for a valid DTMF character.
* @param character a valid DTMF character (present in DTMF_CHARACTERS}
* @return a float buffer of predefined length (7168 samples) with the correct DTMF tone representing the character.
*/
public static float[] generateDTMFTone(char character){
double firstFrequency = -1;
double secondFrequency = -1;
for(int row = 0 ; row < DTMF_CHARACTERS.length ; row++){
for(int col = 0 ; col < DTMF_CHARACTERS[row].length ; col++){
if(DTMF_CHARACTERS[row][col] == character){
firstFrequency = DTMF_FREQUENCIES[row];
secondFrequency = DTMF_FREQUENCIES[col + 4];
}
}
}
return DTMF.audioBufferDTMF(firstFrequency,secondFrequency,512*2*10);
}
/**
* Checks if the given character is present in DTMF_CHARACTERS.
*
* @param character
* the character to check.
* @return True if the given character is present in
* DTMF_CHARACTERS, false otherwise.
*/
public static boolean isDTMFCharacter(char character){
double firstFrequency = -1;
double secondFrequency = -1;
for(int row = 0 ; row < DTMF_CHARACTERS.length ; row++){
for(int col = 0 ; col < DTMF_CHARACTERS[row].length ; col++){
if(DTMF_CHARACTERS[row][col] == character){
firstFrequency = DTMF_FREQUENCIES[row];
secondFrequency = DTMF_FREQUENCIES[col + 4];
}
}
}
return (firstFrequency!=-1 && secondFrequency!=-1);
}
/**
* Creates an audio buffer in a float array of the defined size. The sample
* rate is 44100Hz by default. It mixes the two given frequencies with an
* amplitude of 0.5.
*
* @param f0
* The first fundamental frequency.
* @param f1
* The second fundamental frequency.
* @param size
* The size of the float array (sample rate is 44.1kHz).
* @return An array of the defined size.
*/
public static float[] audioBufferDTMF(final double f0, final double f1,
int size) {
final double sampleRate = 44100.0;
final double amplitudeF0 = 0.4;
final double amplitudeF1 = 0.4;
final double twoPiF0 = 2 * Math.PI * f0;
final double twoPiF1 = 2 * Math.PI * f1;
final float[] buffer = new float[size];
for (int sample = 0; sample < buffer.length; sample++) {
final double time = sample / sampleRate;
double f0Component = amplitudeF0 * Math.sin(twoPiF0 * time);
double f1Component = amplitudeF1 * Math.sin(twoPiF1 * time);
buffer[sample] = (float) (f0Component + f1Component);
}
return buffer;
}
}