Question

How can you convert a Wav file into a PNG waveform image file using Java?

java MyProgram.class [path to wav file] [path where to write png file]

Expected results:

Png saved in path specified is a waveform of the wav file passed in.

Answer 1

Below is a java class that will do this very thing. There are certain parameters that I’m hard coding here like width of image, height of image, background color of image, and some more stuff. If you want to pull those out, you could.

import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.font.FontRenderContext;
import java.awt.font.LineBreakMeasurer;
import java.awt.font.TextAttribute;
import java.awt.font.TextLayout;
import java.awt.geom.Line2D;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
import java.text.AttributedCharacterIterator;
import java.text.AttributedString;
import java.util.Vector;

import javax.imageio.ImageIO;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.LineUnavailableException;
import javax.sound.sampled.TargetDataLine;
import javax.sound.sampled.UnsupportedAudioFileException;


public class AudioWaveformCreator {
    AudioInputStream audioInputStream;
    Vector<Line2D.Double> lines = new Vector<Line2D.Double>();
    String errStr;
    Capture capture = new Capture();
    double duration, seconds;
    File file;
    String fileName;
    SamplingGraph samplingGraph;
    String waveformFilename;
    Color imageBackgroundColor = new Color(20,20,20);

    public AudioWaveformCreator(String fileName, String waveformFilename) throws UnsupportedAudioFileException, IOException {
        file = new File(fileName);
        this.waveformFilename = waveformFilename;
    }

    public void createAudioInputStream() throws Exception {
        if (file != null && file.isFile()) {
            try {
                errStr = null;
                audioInputStream = AudioSystem.getAudioInputStream(file);
                fileName = file.getName();
                long milliseconds = (long)((audioInputStream.getFrameLength() * 1000) / audioInputStream.getFormat().getFrameRate());
                duration = milliseconds / 1000.0;
                samplingGraph = new SamplingGraph();
                samplingGraph.createWaveForm(null);                
            } catch (Exception ex) { 
                reportStatus(ex.toString());
                throw ex;
            }
        } else {
            reportStatus("Audio file required.");
        }
    }
    /**
     * Render a WaveForm.
     */
    class SamplingGraph implements Runnable {

        private Thread thread;
        private Font font10 = new Font("serif", Font.PLAIN, 10);
        private Font font12 = new Font("serif", Font.PLAIN, 12);
        Color jfcBlue = new Color(000, 000, 255);
        Color pink = new Color(255, 175, 175);


        public SamplingGraph() {
        }


        public void createWaveForm(byte[] audioBytes) {

            lines.removeAllElements();  // clear the old vector

            AudioFormat format = audioInputStream.getFormat();
            if (audioBytes == null) {
                try {
                    audioBytes = new byte[
                        (int) (audioInputStream.getFrameLength() 
                        * format.getFrameSize())];
                    audioInputStream.read(audioBytes);
                } catch (Exception ex) { 
                    reportStatus(ex.getMessage());
                    return; 
                }
            }
            int w = 500;
            int h = 200;
            int[] audioData = null;
            if (format.getSampleSizeInBits() == 16) {
                 int nlengthInSamples = audioBytes.length / 2;
                 audioData = new int[nlengthInSamples];
                 if (format.isBigEndian()) {
                    for (int i = 0; i < nlengthInSamples; i++) {
                         /* First byte is MSB (high order) */
                         int MSB = (int) audioBytes[2*i];
                         /* Second byte is LSB (low order) */
                         int LSB = (int) audioBytes[2*i+1];
                         audioData[i] = MSB << 8 | (255 & LSB);
                     }
                 } else {
                     for (int i = 0; i < nlengthInSamples; i++) {
                         /* First byte is LSB (low order) */
                         int LSB = (int) audioBytes[2*i];
                         /* Second byte is MSB (high order) */
                         int MSB = (int) audioBytes[2*i+1];
                         audioData[i] = MSB << 8 | (255 & LSB);
                     }
                 }
             } else if (format.getSampleSizeInBits() == 8) {
                 int nlengthInSamples = audioBytes.length;
                 audioData = new int[nlengthInSamples];
                 if (format.getEncoding().toString().startsWith("PCM_SIGN")) {
                     for (int i = 0; i < audioBytes.length; i++) {
                         audioData[i] = audioBytes[i];
                     }
                 } else {
                     for (int i = 0; i < audioBytes.length; i++) {
                         audioData[i] = audioBytes[i] - 128;
                     }
                 }
            }

            int frames_per_pixel = audioBytes.length / format.getFrameSize()/w;
            byte my_byte = 0;
            double y_last = 0;
            int numChannels = format.getChannels();
            for (double x = 0; x < w && audioData != null; x++) {
                int idx = (int) (frames_per_pixel * numChannels * x);
                if (format.getSampleSizeInBits() == 8) {
                     my_byte = (byte) audioData[idx];
                } else {
                     my_byte = (byte) (128 * audioData[idx] / 32768 );
                }
                double y_new = (double) (h * (128 - my_byte) / 256);
                lines.add(new Line2D.Double(x, y_last, x, y_new));
                y_last = y_new;
            }
            saveToFile(waveformFilename);
        }


        public void saveToFile(String filename) {            
            int w = 500;
            int h = 200;
            int INFOPAD = 15;

            BufferedImage bufferedImage = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
            Graphics2D g2 = bufferedImage.createGraphics();

            createSampleOnGraphicsContext(w, h, INFOPAD, g2);            
            g2.dispose();
            // Write generated image to a file
            try {
                // Save as PNG
                File file = new File(filename);
                ImageIO.write(bufferedImage, "png", file);
            } catch (IOException e) {
            }
        }


        private void createSampleOnGraphicsContext(int w, int h, int INFOPAD, Graphics2D g2) {            
            g2.setBackground(imageBackgroundColor);
            g2.clearRect(0, 0, w, h);
            g2.setColor(Color.white);
            g2.fillRect(0, h-INFOPAD, w, INFOPAD);

            if (errStr != null) {
                g2.setColor(jfcBlue);
                g2.setFont(new Font("serif", Font.BOLD, 18));
                g2.drawString("ERROR", 5, 20);
                AttributedString as = new AttributedString(errStr);
                as.addAttribute(TextAttribute.FONT, font12, 0, errStr.length());
                AttributedCharacterIterator aci = as.getIterator();
                FontRenderContext frc = g2.getFontRenderContext();
                LineBreakMeasurer lbm = new LineBreakMeasurer(aci, frc);
                float x = 5, y = 25;
                lbm.setPosition(0);
                while (lbm.getPosition() < errStr.length()) {
                    TextLayout tl = lbm.nextLayout(w-x-5);
                    if (!tl.isLeftToRight()) {
                        x = w - tl.getAdvance();
                    }
                    tl.draw(g2, x, y += tl.getAscent());
                    y += tl.getDescent() + tl.getLeading();
                }
            } else if (capture.thread != null) {
                g2.setColor(Color.black);
                g2.setFont(font12);
                //g2.drawString("Length: " + String.valueOf(seconds), 3, h-4);
            } else {
                g2.setColor(Color.black);
                g2.setFont(font12);
                //g2.drawString("File: " + fileName + "  Length: " + String.valueOf(duration) + "  Position: " + String.valueOf(seconds), 3, h-4);

                if (audioInputStream != null) {
                    // .. render sampling graph ..
                    g2.setColor(jfcBlue);
                    for (int i = 1; i < lines.size(); i++) {
                        g2.draw((Line2D) lines.get(i));
                    }

                    // .. draw current position ..
                    if (seconds != 0) {
                        double loc = seconds/duration*w;
                        g2.setColor(pink);
                        g2.setStroke(new BasicStroke(3));
                        g2.draw(new Line2D.Double(loc, 0, loc, h-INFOPAD-2));
                    }
                }
            }
        }

        public void start() {
            thread = new Thread(this);
            thread.setName("SamplingGraph");
            thread.start();
            seconds = 0;
        }

        public void stop() {
            if (thread != null) {
                thread.interrupt();
            }
            thread = null;
        }

        public void run() {
            seconds = 0;
            while (thread != null) {
                if ( (capture.line != null) && (capture.line.isActive()) ) {
                    long milliseconds = (long)(capture.line.getMicrosecondPosition() / 1000);
                    seconds =  milliseconds / 1000.0;
                }
                try { thread.sleep(100); } catch (Exception e) { break; }                              
                while ((capture.line != null && !capture.line.isActive())) 
                {
                    try { thread.sleep(10); } catch (Exception e) { break; }
                }
            }
            seconds = 0;
        }
    } // End class SamplingGraph

    /** 
     * Reads data from the input channel and writes to the output stream
     */
    class Capture implements Runnable {

        TargetDataLine line;
        Thread thread;

        public void start() {
            errStr = null;
            thread = new Thread(this);
            thread.setName("Capture");
            thread.start();
        }

        public void stop() {
            thread = null;
        }

        private void shutDown(String message) {
            if ((errStr = message) != null && thread != null) {
                thread = null;
                samplingGraph.stop();                
                System.err.println(errStr);
            }
        }

        public void run() {

            duration = 0;
            audioInputStream = null;

            // define the required attributes for our line, 
            // and make sure a compatible line is supported.

            AudioFormat format = audioInputStream.getFormat();
            DataLine.Info info = new DataLine.Info(TargetDataLine.class, 
                format);

            if (!AudioSystem.isLineSupported(info)) {
                shutDown("Line matching " + info + " not supported.");
                return;
            }

            // get and open the target data line for capture.

            try {
                line = (TargetDataLine) AudioSystem.getLine(info);
                line.open(format, line.getBufferSize());
            } catch (LineUnavailableException ex) { 
                shutDown("Unable to open the line: " + ex);
                return;
            } catch (SecurityException ex) { 
                shutDown(ex.toString());
                JavaSound.showInfoDialog();
                return;
            } catch (Exception ex) { 
                shutDown(ex.toString());
                return;
            }

            // play back the captured audio data
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            int frameSizeInBytes = format.getFrameSize();
            int bufferLengthInFrames = line.getBufferSize() / 8;
            int bufferLengthInBytes = bufferLengthInFrames * frameSizeInBytes;
            byte[] data = new byte[bufferLengthInBytes];
            int numBytesRead;

            line.start();

            while (thread != null) {
                if((numBytesRead = line.read(data, 0, bufferLengthInBytes)) == -1) {
                    break;
                }
                out.write(data, 0, numBytesRead);
            }

            // we reached the end of the stream.  stop and close the line.
            line.stop();
            line.close();
            line = null;

            // stop and close the output stream
            try {
                out.flush();
                out.close();
            } catch (IOException ex) {
                ex.printStackTrace();
            }

            // load bytes into the audio input stream for playback

            byte audioBytes[] = out.toByteArray();
            ByteArrayInputStream bais = new ByteArrayInputStream(audioBytes);
            audioInputStream = new AudioInputStream(bais, format, audioBytes.length / frameSizeInBytes);

            long milliseconds = (long)((audioInputStream.getFrameLength() * 1000) / format.getFrameRate());
            duration = milliseconds / 1000.0;

            try {
                audioInputStream.reset();
            } catch (Exception ex) { 
                ex.printStackTrace(); 
                return;
            }

            samplingGraph.createWaveForm(audioBytes);
        }
    } // End class Capture    

    public static void main(String [] args) throws Exception {
        if (args.length != 2) {
            printUsage();
            System.exit(1);
        }                
        AudioWaveformCreator awc = new AudioWaveformCreator(args[0], args[1]);
        awc.createAudioInputStream();
    }

    private void reportStatus(String msg) {
        if ((errStr = msg) != null) {
            System.out.println(errStr);            
        }
    }

    private static void printUsage() {
        System.out.println("AudioWaveformCreator usage: java AudioWaveformCreator.class [path to audio file for generating the image] [path to save waveform image to]");
    }
}