Detecting DTMF digits from a 3GP file

Question

I was wondering is there any way to detect DTMF digits from a 3GP file using java.

Answer 1

You can use TarsosDSP to decode DTMF in Java. An example implementation of this is availabie in this blogpost.

How to decode the audio from the 3GP depends on the audio codec used within it.

Answer 2

Is it possible to use such library "TarsosDSP" on the code I'm going to post below this sentense?

If yes, how?

Please forgive me if this question is daft, I'm genuinely curious and I want to understand!

 import java.io.IOException;

 import org.JMathStudio.DataStructure.Complex;
 import org.JMathStudio.DataStructure.Cell.Cell;
 import org.JMathStudio.DataStructure.Cell.CellTools;
 import org.JMathStudio.DataStructure.Vector.CVector;
 import org.JMathStudio.DataStructure.Vector.Vector;
 import org.JMathStudio.DataStructure.Vector.VectorStack;
 import org.JMathStudio.Exceptions.DimensionMismatchException;
 import org.JMathStudio.Exceptions.IllegalArgumentException;
 import org.JMathStudio.Exceptions.UnSupportedImageFormatException;
 import org.JMathStudio.SignalToolkit.GeneralTools.SignalUtilities;
 import org.JMathStudio.SignalToolkit.TransformTools.FourierSet.FFT1D;
 import org.JMathStudio.SignalToolkit.Utilities.SignalGenerator;


 public class DTMF_Demo {
static int [] freqTableRow = {
        697, 770, 852, 941  
} ;

static int [] freqTableCol = {
        1209, 1336, 1477
} ;

static char [][] dialKey = {
    {'1', '2', '3'},
    {'4', '5', '6'},
    {'7', '8', '9'},
    {'*', '0', '#'}
} ;

static int fs = 4000 ;              // Sampling Rate
static float noiseLevel = 0.2f ;    // Amplitude of the noise signal before normalization

private String dialKeyString ;      // The dial key sequence generated

// This is the method that generate the dial key sequence signal
public float [] dtmfDial() throws IllegalArgumentException 
{

    VectorStack numberStack = new VectorStack() ;   // A temporary storage for a list of signal vectors
    int totalLength = 0 ;   // Total length of the dial key sequence signal generated
    int row ;               // Row index into the frequency table
    int col ;               // Column index into the frequency table
    int length ;            // Length of a dial key signal
    int numDigit ;          // Number of keys to generate for a dial key sequence
    int pauseLength ;       // Length of pause signal
    int i, j, k ;           // Looping variables
    float normFactor ;      // Normalization factor for dial key sequence

    normFactor = 2.0f + noiseLevel ;
    dialKeyString = new String("") ;



    numDigit = Math.round((float) (5.0f + Math.random() * 11.0f)) ;


    for(i = 0; i < numDigit; i++) 
    {
        row = Math.round((float) (Math.random() * 3.99 - 0.49)) ;


        col = Math.round((float) (Math.random() * 2.99 - 0.49)) ;


        length = Math.round((float) (fs/2 + Math.random() * 1.5 * fs)) ;


        pauseLength = Math.round((float) (fs/4 + Math.random() * 0.75 * fs)) ;



        Vector tone = SignalGenerator.cosine(freqTableRow[row], fs, 0.0f, length+pauseLength) ;



        Vector tone2 = SignalGenerator.cosine(freqTableCol[col], fs, 0.0f, length+pauseLength) ;



        Vector noise = SignalGenerator.random(length+pauseLength) ;





        dialKeyString += dialKey[row][col] ;    // Look up actual key dialed



        totalLength += (length+pauseLength) ;





        // Sum the two sinusoids with addition of noise
        for(j = 0; j < length; j++) 
        {
            tone.accessVectorBuffer()[j] += tone2.accessVectorBuffer()[j] ;
            tone.accessVectorBuffer()[j] += ((2.0f * noiseLevel) * noise.accessVectorBuffer()[j] - noiseLevel);
            tone.accessVectorBuffer()[j] /= normFactor ;

        }


        // Inject pause and noise signals
        for(j = length; j < length + pauseLength; j++) 
        {
            tone.accessVectorBuffer()[j] = ((2.0f * noiseLevel) * noise.accessVectorBuffer()[j] - noiseLevel) ;
            tone.accessVectorBuffer()[j] /= normFactor ;

        }



        numberStack.addVector(tone) ;   // Add the dial key signal into the stack of signal vectors



    }



    float [] dtmfSignal = new float[totalLength] ;  // Array of floats to serve as the output dial key sequence signal
    Vector [] numberVectorArray = numberStack.accessVectorArray();

    // Concatenate the dial key signals to form the output dial key sequence signal
    k = 0 ;
    for(i = 0; i < numberStack.size(); i++) 
    {
        for(j = 0; j < numberVectorArray[i].length(); j++) 
        {
            dtmfSignal[k] = numberVectorArray[i].accessVectorBuffer()[j] ;



            k++ ;
        }
    }


    return dtmfSignal ;
}



public Boolean dialKeyStringMatch(String decodedKeyString) 
{
    return dialKeyString.equals(decodedKeyString) ;
}



public String getDialString() 
{
    return dialKeyString ;
}




public static void main(String[] args) throws IOException, UnSupportedImageFormatException, DimensionMismatchException 
{
    // TODO Auto-generated method stub
    DTMF_Demo demo = new DTMF_Demo() ;
    DTMF_Decode decoder = new DTMF_Decode() ;


    try 
    {
        int correct = 0 ;
        int totalCount = 1 ;

        for(int i = 0; i < totalCount; i++) 
        {
            // Generate Dial Key Sequence Signal
            float [] dtmfSignal = demo.dtmfDial() ;

            // Call your implemented dtmfAnalyse method and obtain decoded key string
            String decodedKeyString = decoder.dtmfAnalyse(dtmfSignal, fs) ;

            // Compare your decoded key sequence with the ground truth
            if(demo.dialKeyStringMatch(decodedKeyString)) 
            {
                correct++ ;
            }
            else 
            {
                // Print out incorrectly decoded dial key sequence
                System.out.println(demo.getDialString() + " (original) != " + decodedKeyString + " (decoded)") ;
            }







        }

        System.out.println(correct + " out of " + totalCount + " are correct.") ;

    } 
    catch (Exception e) 
    {
        e.printStackTrace() ;
    }

}

}