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Old 10-15-2007, 11:15 AM   #1
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Location: Costa Rica
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Java sound: line.write() returns 0

I'm trying to play a sine wave.

I have a SourceDataLine, but when I try to write to it, the write method return 0, meaning that it coulen't write anything to the mixer's output stream, right? I also don't get to hear a thing, by the way.

Here's the code I'm using:
byte [] sample = new byte[4];
int written = 0;
while (true) {
	int valor = (int) ((2 << 15 -1) * wave.height());
	sample[0] = sample[2] = (byte) (valor & 0xff);
	sample[1] = sample[3] = (byte) (valor >> 8);
	written = line.write(sample, 0, 4);
	if (written != 4) {
		System.err.println("Couldn't write all the bytes!");
wave.height() returns the height of the wave (-1 to 1) for that moment in time.

The Audio Format is PCM_SIGNED, at 44.1 KHtz, 16 bits per sample, Stereo, little endian.

Any ideas?

Last edited by eantoranz; 10-15-2007 at 11:16 AM.
Old 10-15-2007, 09:13 PM   #2
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Registered: Apr 2003
Location: Costa Rica
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I will refrase the problem:

How can I get a SourceDataLine I could use to hear a wave? Im doing this, but I don't get a single line that works:

AudioFormat format = new AudioFormat(44100f, 16, 2, true, false);
DataLine.Info info = new DataLine.Info(SourceDataLine.class, format);

SourceDataLine line = null;
Mixer.Info [] mixerInfo = AudioSystem.getMixerInfo();
Mixer mixer;
for (int i = 0; line == null && i < mixerInfo.length; i++) {
	mixer = AudioSystem.getMixer(mixerInfo[i]);
	try {
		line = (SourceDataLine) mixer.getLine(info);
		if (!line.getLineInfo().matches(info)) {
			line = null;
	} catch (LineUnavailableException e) {
		line = null;
	} catch (IllegalArgumentException e) {
		line = null;
if (line == null) {
	System.out.println("No line was found");
The funny thing is that sometimes mixer.getLine(info) does return a mixer, but then the matches(info) fails. How can I get that done?


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