I found this topic while working with minim and looking for how to save an array of floats as an audio file. The solution has been found, of course, but this may be of interest:
/**
* Saves audio data to 16-bit integer PCM format, which Processing can also open.
*
* @param samples an array of floats in the audio range (-1.0f, 1.0f)
* @param sampleRate audio sample rate for the file
* @param fileName name of the file to save to
* @throws IOException an Exception you'll need to handle to call this method
* @throws UnsupportedAudioFileException another Exception
*/
public static void saveAudioToFile(float[] samples, float sampleRate, String fileName)
throws IOException, UnsupportedAudioFileException {
// Convert samples from float to 16-bit PCM
byte[] audioBytes = new byte[samples.length * 2];
int index = 0;
for (float sample : samples) {
// Scale sample to 16-bit signed integer
int intSample = (int) (sample * 32767);
// Convert to bytes
audioBytes[index++] = (byte) (intSample & 0xFF);
audioBytes[index++] = (byte) ((intSample >> 8) & 0xFF);
}
// Create an AudioInputStream
ByteArrayInputStream byteStream = new ByteArrayInputStream(audioBytes);
AudioFormat format = new AudioFormat(sampleRate, 16, 1, true, false);
AudioInputStream audioInputStream = new AudioInputStream(byteStream, format, samples.length);
// Save the AudioInputStream to a WAV file
File outFile = new File(fileName);
AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, outFile);
}
/**
* Saves audio data to a 32-bit floating point format that has higher resolution than 16-bit integer PCM.
* The format can't be opened by Processing but can be opened by audio applications.
*
* @param samples an array of floats in the audio range (-1.0f, 1.0f)
* @param sampleRate the sample rate for the file
* @param fileName name of the file
* @throws IOException an Exception you'll need to catch to call this method (see keyPressed entry for 's')
*/
public static void saveAudioTo32BitPCMFile(float[] samples, float sampleRate, String fileName) throws IOException {
// convert samples to 32-bit PCM float
byte[] audioBytes = new byte[samples.length * 4];
int index = 0;
// convert to IEEE 754 floating-point "single format" bit layout
for (float sample : samples) {
int intBits = Float.floatToIntBits(sample);
audioBytes[index++] = (byte) (intBits & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 8) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 16) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 24) & 0xFF);
}
ByteArrayInputStream byteStream = new ByteArrayInputStream(audioBytes);
AudioFormat format = new AudioFormat(sampleRate, 32, 1, true, false);
AudioInputStream audioInputStream = new AudioInputStream(byteStream, format, samples.length);
File outFile = new File(fileName);
AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, outFile);
}
/**
* Saves stereo audio data to 16-bit integer PCM format, which Processing can also open.
*
* @param leftChannel an array of floats in the audio range (-1.0f, 1.0f)
* @param rightChannel an array of floats in the audio range (-1.0f, 1.0f)
* @param sampleRate audio sample rate for the file
* @param fileName name of the file to save to
* @throws IOException an Exception you'll need to handle to call this method (see keyPressed entry for 's')
* @throws UnsupportedAudioFileException another Exception (see keyPressed entry for 's')
*/
public static void saveStereoAudioToFile(float[] leftChannel, float[] rightChannel, float sampleRate, String fileName)
throws IOException, UnsupportedAudioFileException {
int numSamples = leftChannel.length;
// Convert samples from float to 16-bit PCM
byte[] audioBytes = new byte[leftChannel.length * 2 * 2];
int index = 0;
for (int i = 0; i < numSamples; i++) {
// Scale leftChannel sample to 16-bit signed integer
int intSample = (int) (leftChannel[i] * 32767);
// Convert to bytes
audioBytes[index++] = (byte) (intSample & 0xFF);
audioBytes[index++] = (byte) ((intSample >> 8) & 0xFF);
// Scale rightChannel sample to 16-bit signed integer
intSample = (int) (rightChannel[i] * 32767);
// Convert to bytes
audioBytes[index++] = (byte) (intSample & 0xFF);
audioBytes[index++] = (byte) ((intSample >> 8) & 0xFF);
}
// Create an AudioInputStream
ByteArrayInputStream byteStream = new ByteArrayInputStream(audioBytes);
AudioFormat format = new AudioFormat(sampleRate, 16, 1, true, false);
AudioInputStream audioInputStream = new AudioInputStream(byteStream, format, numSamples);
// Save the AudioInputStream to a WAV file
File outFile = new File(fileName);
AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, outFile);
}
/**
* Saves stereo audio data to a 32-bit floating point format that has higher resolution than 16-bit integer PCM.
* The format can't be opened by Processing but can be opened by audio applications.
*
* @param leftChannel an array of floats in the audio range (-1.0f, 1.0f)
* @param rightChannel an array of floats in the audio range (-1.0f, 1.0f)
* @param sampleRate the sample rate for the file
* @param fileName name of the file
* @throws IOException an Exception you'll need to handle when calling this method
*/
public static void saveStereoAudioTo32BitPCMFile(float[] leftChannel, float[] rightChannel, float sampleRate, String fileName) throws IOException {
int numSamples = leftChannel.length;
// convert leftChannel to 32-bit PCM float
byte[] audioBytes = new byte[numSamples * 2 * 4];
int index = 0;
// convert to IEEE 754 floating-point "single format" bit layout
for (int i = 0; i < numSamples; i++) {
// Left channel sample
int intBits = Float.floatToIntBits(leftChannel[i]);
audioBytes[index++] = (byte) (intBits & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 8) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 16) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 24) & 0xFF);
// Right channel sample
intBits = Float.floatToIntBits(rightChannel[i]);
audioBytes[index++] = (byte) (intBits & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 8) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 16) & 0xFF);
audioBytes[index++] = (byte) ((intBits >> 24) & 0xFF);
}
// create an AudioInputStream
ByteArrayInputStream byteStream = new ByteArrayInputStream(audioBytes);
AudioFormat format = new AudioFormat(sampleRate, 32, 2, true, false);
AudioInputStream audioInputStream = new AudioInputStream(byteStream, format, numSamples);
// write the file
File outFile = new File(fileName);
AudioSystem.write(audioInputStream, AudioFileFormat.Type.WAVE, outFile);
}
I’ve incorporated this into a library I am developing in Eclipse – that’s the reason for the static keyword and the ‘f’ after floating point numbers. A typical way to call it from a keyPressed event switch statement would be like this:
case 's':
try {
saveAudioToFile(audioSignal, sampleRate, sketchPath("") + "/wavesynth.wav");
println("Saved file to sketch path: "+ sketchPath(""));
}
catch (IOException e) {
println("--->> There was an error outputting the audio file wavesynth.wav."+ e.getMessage());
}
catch (UnsupportedAudioFileException e) {
println("--->> The file format is unsupported."+ e.getMessage());
}
And don’t forget:
import java.io.*;
import javax.sound.*;