How to get PCM data from a wav file?

Question

I have a .wav file. I want to get the PCM data from that sound file, so that I can get the individual data chunks from the sound and process it.

But I don't know how to do it. Can anyone tell me how to do it? I have done this so far:

public class test
{

    static int frameSample;
    static int timeofFrame;
    static int N;
    static int runTimes;
    static int bps;
    static int channels;
    static double times;
    static int bufSize;
    static int frameSize;
    static int frameRate;
    static long length;

    public static void main(String[] args)
    {
        try
        {
            AudioInputStream ais = AudioSystem.getAudioInputStream(new File("music/audio.wav"));
            AudioInputStream a;
            int numBytes = ais.available();
            System.out.println("numbytes: "+numBytes);
            byte[] buffer = new byte[numBytes];
            byte[] buffer1=new byte[numBytes] ;
            int k=0;
            int count=0;
            while(count!=-1){
                count=ais.read(buffer, 0, numBytes);
            }
            long value = 0;

            for (int i = 0; i < buffer.length; i++)
            {
               value = ((long) buffer[i] & 0xffL) << (8 * i);
               System.out.println("value: "+value);
            }
        } catch(Exception e) {

        }
    }
}

Barrada

Do you want to do this using Java or J? I head never heard of 'J' before your question, and suspect you mean Java. – Pericles

sorry. i did not mean j. i want to do it in java. sorry again. – Barrada

Answer 1

This can be done with the Java Sound API.

• Use the AudioSystem to get an AudioInputStream from the file.
• Query the stream for the AudioFormat.
• Create a byte[] to suit the format. E.G. 8 bit mono is a byte[1]. 16 bit stereo is byte[4].
• Read the stream in chunks of the byte[] and it will contain the sound, frame by frame.
• Proceed with further processing..

Pericles

i have done this so far. is this correct? i want to collect the integer values from the bytes. the code is with the question. – Barrada

Please use a consistent and logical indent for code blocks. Note that the frames are 'individual data chunks' so your question has been answered. You should ask a separate question as to how to turn the frames into an int (mono) or a pair of ints (stereo). – Pericles

would you please tell me how can i seperate the header from the wav? please let me know. – Barrada

The bytes read from an AudioInputStream are pure sound data, there is no need to ignore any of them. But why should I keep trying to help, when you ignore advice about code formatting etc.? – Pericles

Answer 2

Here is a fully working example using the javax.sound.sampled package. If you need details on the audio format you can get them via audioInputStream.getFormat() which will return a AudioFormat object.

public static byte[] getPcmByteArray(String filename) throws UnsupportedAudioFileException, IOException {

    ByteArrayOutputStream baos = new ByteArrayOutputStream(65536);
    File inputFile = new File(filename);
    AudioInputStream audioInputStream = AudioSystem.getAudioInputStream(inputFile);

    byte[] buffer = new byte[4096];
    int bytesRead;
    while ((bytesRead = audioInputStream.read(buffer)) != -1) {
        baos.write(buffer, 0, bytesRead);
    }

    return baos.toByteArray();
}

Italian