Trying to get AudioFormat details from Mixer

问题

This is my first try with Java Sound and what I'm trying to achieve is getting the source and target lines format so I can then listen to the data and record it to a file by creating the correct AudioFormat object with the details obtained, but when trying to print all the details through the Java console, nothing is printed out. As I said this is my very first steps with Java Sound and I don't really know if there's a simpler approach.

This is the test code I have so far...

import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.DataLine.Info;
import javax.sound.sampled.Line;
import javax.sound.sampled.Mixer;

    public class SoundTest {

    public static void main(String[] args) {

        for (javax.sound.sampled.Mixer.Info info : AudioSystem.getMixerInfo()) {
            System.out.println(info.getName() + " " + 
                               info.getDescription() + " " + 
                               info.getVendor() + "\n");
        }

        Mixer mixer = (Mixer) AudioSystem.getMixer(AudioSystem.getMixerInfo()[4]);
        System.out.println("Mixer: " + mixer.getMixerInfo().getName());

        Line[] target = mixer.getTargetLines();
        Line[] source = mixer.getSourceLines();

        DataLine.Info objTarget, objSource;

        for (Line t : target) {
            objTarget = (Info) t.getLineInfo();
            for (AudioFormat format : objTarget.getFormats()) {
                formatInfo(format); // prints nothing.
            }
        }

        for (Line t : source) {
            objSource = (Info) t.getLineInfo();
            for (AudioFormat format : objSource.getFormats()) {
                formatInfo(format); // prints nothing.
            }
        }
    }

    private static void formatInfo(AudioFormat format) {
        System.out.println("Number of channels: " + format.getChannels() + "\n" + "Sample rate: "
                + format.getSampleRate() + "\n" + "Frame rate: " + format.getFrameRate() + "\n" + "Frame size: "
                + format.getFrameSize() + "\n" + "Sample size bits: " + format.getSampleSizeInBits() + "\n"
                + "Encoding: " + format.getEncoding() + "\n");
    }

}

回答1:

The Mixer getSourceLines and getTargetLines methods only return open lines - there probably aren't any open when you run your code. Use getSourceLineInfo and getTargetLineInfo instead.

This is the test code I usually use:

public static void displayMixerInfo()
{
  Mixer.Info [] mixersInfo = AudioSystem.getMixerInfo();

  for (Mixer.Info mixerInfo : mixersInfo)
   {
     System.out.println("Mixer: " + mixerInfo.getName());

     Mixer mixer = AudioSystem.getMixer(mixerInfo);

     Line.Info [] sourceLineInfo = mixer.getSourceLineInfo();
     for (Line.Info info : sourceLineInfo)
       showLineInfo(info);

     Line.Info [] targetLineInfo = mixer.getTargetLineInfo();
     for (Line.Info info : targetLineInfo)
       showLineInfo(info);
   }
}


private static void showLineInfo(final Line.Info lineInfo)
{
  System.out.println("  " + lineInfo.toString());

  if (lineInfo instanceof DataLine.Info)
   {
     DataLine.Info dataLineInfo = (DataLine.Info)lineInfo;

     AudioFormat [] formats = dataLineInfo.getFormats();
     for (final AudioFormat format : formats)
       System.out.println("    " + format.toString());
   }
}

来源：https://stackoverflow.com/questions/39509597/trying-to-get-audioformat-details-from-mixer

标签

java

javasound