Question

我正在使用Visualizer来绘制我正在播放的声音文件的可视化。声波正在显示，但是我想让它不那么详细，因为它对我的帧速率有影响。这方面的文件非常有限。所以我试图做到以下几点：

mVisualizer.setCaptureSize(2);

将捕获率设置为非常低的值。但是，似乎正在绘制具有相同数量细节的线条。我在文档中读到：

Sets the capture size, i.e. the number of bytes returned by getWaveForm(byte[]) and getFft(byte[]) methods.

我的另一个问题是，我想在我正在播放的声音文件中检测到具有高能量级别的声音，因此我可以在屏幕上直观地表示它们。例如：屏幕随基线闪烁。以下是我到目前为止的情况：

public static void setupVisualizer() {
    mVisualizer = new Visualizer(mpSong.getAudioSessionId());
    mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);
    mVisualizer.setDataCaptureListener(
            new Visualizer.OnDataCaptureListener() {
                public void onWaveFormDataCapture(Visualizer visualizer,
                        byte[] bytes, int samplingRate) {
                    Game.updateVisualizer(bytes);
                }

                public void onFftDataCapture(Visualizer visualizer,
                        byte[] bytes, int samplingRate) {
                }
            }, Visualizer.getMaxCaptureRate() / 2, true, false);
}

是否有可能在侦听器中检测到某些声音？或者有哪些替代方案？对不起，我的英语不好。非常感谢你的朋友们。

Answer 1

好几个小时的测试和研究后我找到了解决方案。它可能不是很准确，但它是我能想到的唯一选择。我创建了一个名为BeatDetector的类：

public class BeatDetectorByFrequency {
private static final String TAG = "TEST";

private Visualizer mVisualizer = null;

private double mRunningSoundAvg[];
private double mCurrentAvgEnergyOneSec[];
private int mNumberOfSamplesInOneSec;
private long mSystemTimeStartSec;
// FREQS
private static final int LOW_FREQUENCY = 300;
private static final int MID_FREQUENCY = 2500;
private static final int HIGH_FREQUENCY = 10000;
private OnBeatDetectedListener onBeatDetectedListener = null;

public BeatDetectorByFrequency() {
    init();
}

private void init() {
    mRunningSoundAvg = new double[3];
    mCurrentAvgEnergyOneSec = new double[3];
    mCurrentAvgEnergyOneSec[0] = -1;
    mCurrentAvgEnergyOneSec[1] = -1;
    mCurrentAvgEnergyOneSec[2] = -1;
}

public void link(MediaPlayer player) {
    if (player == null) {
        throw new NullPointerException("Cannot link to null MediaPlayer");
    }
    mVisualizer = new Visualizer(player.getAudioSessionId());
    mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);

    Visualizer.OnDataCaptureListener captureListener = new Visualizer.OnDataCaptureListener() {
        @Override
        public void onWaveFormDataCapture(Visualizer visualizer,
                byte[] bytes, int samplingRate) {
            // DO NOTHING
        }

        @Override
        public void onFftDataCapture(Visualizer visualizer, byte[] bytes,
                int samplingRate) {
            updateVisualizerFFT(bytes);
        }
    };

    mVisualizer.setDataCaptureListener(captureListener,
            Visualizer.getMaxCaptureRate() / 2, false, true);
    mVisualizer.setEnabled(true);
    player.setOnCompletionListener(new MediaPlayer.OnCompletionListener() {
        @Override
        public void onCompletion(MediaPlayer mediaPlayer) {
            mVisualizer.setEnabled(false);
        }
    });
    mSystemTimeStartSec = System.currentTimeMillis();
}

public void release() {
    if (mVisualizer != null) {
        mVisualizer.setEnabled(false);
        mVisualizer.release();
    }
}

public void pause() {
    if (mVisualizer != null) {
        mVisualizer.setEnabled(false);
    }
}

public void resume() {
    if (mVisualizer != null) {
        mVisualizer.setEnabled(true);
    }
}

public void updateVisualizerFFT(byte[] audioBytes) {
    int energySum = 0;
    energySum += Math.abs(audioBytes[0]);
    int k = 2;
    double captureSize = mVisualizer.getCaptureSize() / 2;
    int sampleRate = mVisualizer.getSamplingRate() / 2000;
    double nextFrequency = ((k / 2) * sampleRate) / (captureSize);
    while (nextFrequency < LOW_FREQUENCY) {
        energySum += Math.sqrt((audioBytes[k] * audioBytes[k])
                * (audioBytes[k + 1] * audioBytes[k + 1]));
        k += 2;
        nextFrequency = ((k / 2) * sampleRate) / (captureSize);
    }
    double sampleAvgAudioEnergy = (double) energySum
            / (double) ((k * 1.0) / 2.0);

    mRunningSoundAvg[0] += sampleAvgAudioEnergy;
    if ((sampleAvgAudioEnergy > mCurrentAvgEnergyOneSec[0])
            && (mCurrentAvgEnergyOneSec[0] > 0)) {
        fireBeatDetectedLowEvent(sampleAvgAudioEnergy);
    }
    energySum = 0;
    while (nextFrequency < MID_FREQUENCY) {
        energySum += Math.sqrt((audioBytes[k] * audioBytes[k])
                * (audioBytes[k + 1] * audioBytes[k + 1]));
        k += 2;
        nextFrequency = ((k / 2) * sampleRate) / (captureSize);
    }

    sampleAvgAudioEnergy = (double) energySum / (double) ((k * 1.0) / 2.0);
    mRunningSoundAvg[1] += sampleAvgAudioEnergy;
    if ((sampleAvgAudioEnergy > mCurrentAvgEnergyOneSec[1])
            && (mCurrentAvgEnergyOneSec[1] > 0)) {
        fireBeatDetectedMidEvent(sampleAvgAudioEnergy);
    }
    energySum = Math.abs(audioBytes[1]);

    while ((nextFrequency < HIGH_FREQUENCY) && (k < audioBytes.length)) {
        energySum += Math.sqrt((audioBytes[k] * audioBytes[k])
                * (audioBytes[k + 1] * audioBytes[k + 1]));
        k += 2;
        nextFrequency = ((k / 2) * sampleRate) / (captureSize);
    }

    sampleAvgAudioEnergy = (double) energySum / (double) ((k * 1.0) / 2.0);
    mRunningSoundAvg[2] += sampleAvgAudioEnergy;
    if ((sampleAvgAudioEnergy > mCurrentAvgEnergyOneSec[2])
            && (mCurrentAvgEnergyOneSec[2] > 0)) {
        fireBeatDetectedHighEvent(sampleAvgAudioEnergy);
    }

    mNumberOfSamplesInOneSec++;
    if ((System.currentTimeMillis() - mSystemTimeStartSec) > 1000) {
        mCurrentAvgEnergyOneSec[0] = mRunningSoundAvg[0]
                / mNumberOfSamplesInOneSec;
        mCurrentAvgEnergyOneSec[1] = mRunningSoundAvg[1]
                / mNumberOfSamplesInOneSec;
        mCurrentAvgEnergyOneSec[2] = mRunningSoundAvg[2]
                / mNumberOfSamplesInOneSec;
        mNumberOfSamplesInOneSec = 0;
        mRunningSoundAvg[0] = 0.0;
        mRunningSoundAvg[1] = 0.0;
        mRunningSoundAvg[2] = 0.0;
        mSystemTimeStartSec = System.currentTimeMillis();
    }
}

// USE INTERFACES IN NEXT UPDATE:
private void fireBeatDetectedLowEvent(double power) {
    // Utility.log("LOW BEAT DETECTED!");
    Game.lowBeat(power);
    if (onBeatDetectedListener != null) {
        onBeatDetectedListener.onBeatDetectedLow();
    }
}

private void fireBeatDetectedMidEvent(double power) {
    // Utility.log("MEDIUM BEAT DETECTED!");
    Game.mediumBeat(power);
    if (onBeatDetectedListener != null) {
        onBeatDetectedListener.onBeatDetectedMid();
    }
}

private void fireBeatDetectedHighEvent(double power) {
    // Utility.log("HIGH BEAT DETECTED!");
    Game.highBeat(power);
    if (onBeatDetectedListener != null) {
        onBeatDetectedListener.onBeatDetectedHigh();
    }
}

public void setOnBeatDetectedListener(OnBeatDetectedListener listener) {
    onBeatDetectedListener = listener;
}

public interface OnBeatDetectedListener {
    public abstract void onBeatDetectedLow();

    public abstract void onBeatDetectedMid();

    public abstract void onBeatDetectedHigh();
}
}

它将MediaPlayer对象作为参数，然后根据字节数据的EnergySum计算三个不同的频率。可以根据需要多次分割频率。我正在考虑创建一个频率数组，每个人都有一个监听器。然后我使用以下绘制矩形：

public static void highBeat(double power) {
    HIGH_FREQUENCY += (power * 1000); // ORIGINAL: * 1000
    if (HIGH_FREQUENCY > GameValues.FREQ_MAX) {
        HIGH_FREQUENCY = GameValues.FREQ_MAX;
    }
    updateHighFreq();
}

public static void updateHighFreq() {
    prcnt = HIGH_FREQUENCY * 100 / GameValues.FREQ_MAX;
    if (prcnt < 0)
        prcnt = 0;
    HIGH_F_HEIGHT = (int) (GameValues.FREQ_MAX_HEIGHT * (prcnt / 100));
}

通过计算基于条的最大功率和最大高度的百分比来计算矩形的高度。它不是很准确，但这是我能想到的最好的东西。同样，这可以根据您的需要为多个频率完成。以下是一些帮助我的链接：

https://android.googlesource.com/platform/cts/+/master/tests/tests/media/src/android/media/cts/VisualizerTest.java

https://www.codota.com/android/scenarios/518916b8da0af8330dfa9398/android.media.audiofx.Visualizer?tag=out_2013_05_05_07_19_34

希望我能帮助其他人解决这些问题。

Android Visualizer检测节拍？和Visualizer.setCaptureSize（）不工作？备择方案？

1 个答案: