Question

我正在编写一个记录屏幕和音频的应用程序。虽然屏幕录制效果很好，但我很难使用JDK库获取原始音频。这是代码：

try {
            // Now, we're going to loop
            long startTime = System.nanoTime();

            System.out.println("Encoding Image.....");
            while (!Thread.currentThread().isInterrupted()) {
                // take the screen shot
                BufferedImage screen = robot.createScreenCapture(screenBounds);


                // convert to the right image type
                BufferedImage bgrScreen = convertToType(screen,
                        BufferedImage.TYPE_3BYTE_BGR);

                // encode the image
                writer.encodeVideo(0, bgrScreen, System.nanoTime()
                        - startTime, TimeUnit.NANOSECONDS);

                /* Need to get audio here and then encode using xuggler. Something like 

                    WaveData wd = new WaveData();

                    TargetDataLine line;
                    AudioInputStream aus = new AudioInputStream(line);

                    short[] samples = getSourceSamples();
                       writer.encodeAudio(0, samples); */


                if (timeCreation < 10) {
                    timeCreation = getGMTTime();
                }
                // sleep for framerate milliseconds
                try {
                    Thread.sleep((long) (1000 / FRAME_RATE.getDouble()));
                } catch (Exception ex) {
                    System.err.println("stopping....");
                    break;
                }

            }
            // Finally we tell the writer to close and write the trailer if
            // needed
        } finally {
            writer.close();
        }

此page有一些伪代码，如

while(haveMoreAudio())
 {
   short[] samples = getSourceSamples();
   writer.encodeAudio(0, samples);
 }

但我应该为getSourceSamples()做些什么？

另外，一个额外的问题 - 在这种方法中可以从多个麦克风中进行选择吗？

另见： Xuggler encoding and muxing

Answer 1

试试这个：

// Pick a format. Need 16 bits, the rest can be set to anything
// It is better to enumerate the formats that the system supports, because getLine() can error out with any particular format
AudioFormat audioFormat = new AudioFormat(44100.0F, 16, 2, true, false); 

// Get default TargetDataLine with that format
DataLine.Info dataLineInfo = new DataLine.Info( TargetDataLine.class, audioFormat );
TargetDataLine line = (TargetDataLine) AudioSystem.getLine(dataLineInfo);

// Open and start capturing audio    
line.open(audioFormat, line.getBufferSize());
line.start();

while (true) {
    // read as raw bytes
    byte[] audioBytes = new byte[ line.getBufferSize() / 2 ]; // best size?
    int numBytesRead = 0;
    numBytesRead =  line.read(audioBytes, 0, audioBytes.length);

    // convert to signed shorts representing samples
    int numSamplesRead = numBytesRead / 2;
    short[] audioSamples = new short[ numSamplesRead ];
    if (format.isBigEndian()) {
        for (int i = 0; i < numSamplesRead; i++) {
            audioSamples[i] = (short)((audioBytes[2*i] << 8) | audioBytes[2*i + 1]);
        }
    }
    else {
        for (int i = 0; i < numSamplesRead; i++) {
            audioSamples[i] = (short)((audioBytes[2*i + 1] << 8) | audioBytes[2*i]);
        }
    }

    // use audioSamples in Xuggler etc
}

要选择麦克风，您可能必须这样做：

Mixer.Info[] mixerInfo = AudioSystem.getMixerInfo();
// Look through and select a mixer here, different mixers should be different inputs
int selectedMixerIndex = 0;
Mixer mixer = AudioSystem.getMixer(mixerInfo[ selectedMixerIndex ]);
TargetDataLine line = (TargetDataLine) mixer.getLine(dataLineInfo);

我认为多个麦克风可能会在一个调音台中显示为不同的源数据线。在这种情况下，您必须打开它们并致电dataLine.getControl(FloatControl.Type.MASTER_GAIN).setValue( volume );以打开和关闭它们。

请参阅： WaveData.java

Sound wave from TargetDataLine

How to set volume of a SourceDataLine in Java

如何使用Xuggler获取用于编码的音频

1 个答案: