Android Mediaplayer播放時設定頻譜
阿新 • • 發佈:2019-02-15
仿網易雲音樂播放時跳躍的頻譜狀態,此案例是根據聲音的大小動態的設定跳動頻率和高度,而網易雲音樂是固定的。
//建立一個展示音波柱的自定義View
VisualizerView mVisualizerView = new VisualizerView();
給MediaPlay設定Visualizer監聽聲音訊率
private void setupVisualizer() {
if (mVisualizer == null) {
mVisualizer = new Visualizer(mediaPlayer.getAudioSessionId());
//設定需要轉換的音樂內容長度,專業的說這就是取樣,該取樣值一般為2的指數倍,如64,128,256,512,1024。這裡我設定了128,原因是長度越長,FFT演算法執行時間更長。
mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[0]);
//rate, 表示取樣的週期,即隔多久取樣一次,聯絡前文就是隔多久取樣128個數據,本文設定為512mHz更新一次(Visualizer.getMaxCaptureRate()/2)
//iswave,是波形訊號
//isfft,是FFT訊號,表示是獲取波形訊號還是頻域訊號
mVisualizer.setDataCaptureListener(new Visualizer.OnDataCaptureListener() {
@Override
public void onWaveFormDataCapture(Visualizer visualizer, byte[] waveform,
int samplingRate) {
}
@Override
public void onFftDataCapture(Visualizer visualizer, byte[] fft,
int samplingRate) {
//將頻譜設定到自定義View上顯示
mVisualizerView.updateVisualizer(fft);
},Visualizer.getMaxCaptureRate()/2 ,false,true);
mVisualizer.setEnabled(true);
}
}
}
展示音波的自定義View,我的需求是像網易雲音樂類似的三個跳躍的柱形,可根據需求自行更改
package com.xui.music.view;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.View;
public class VisualizerView extends View {
private byte[] mBytes;
private float[] mPoints;
private Rect mRect = new Rect();
private Paint mForePaint = new Paint();
private int mSpectrumNum;
public VisualizerView(Context context) {
super(context);
init();
}
public VisualizerView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public VisualizerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
private void init() {
mBytes = null;
mForePaint.setStrokeWidth(4.5f);
mForePaint.setAntiAlias(true);
mForePaint.setColor(Color.WHITE);
}
public void updateVisualizer(byte[] fft) {
mSpectrumNum = fft.length / 2;
byte[] model = new byte[fft.length / 2];
for (int i = 0, j = 0; j < mSpectrumNum; j++) {
model[j] = (byte) Math.hypot(fft[i], fft[i + 1]);
i += 2;
}
mBytes = model;
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
if (mBytes == null) {
return;
}
if (mPoints == null || mPoints.length < mBytes.length * 4) {
mPoints = new float[mBytes.length * 4];
}
mRect.set(0, 0, getWidth(), getHeight());
//繪製柱形頻譜
final int baseX = mRect.width() / mSpectrumNum;
final int height = mRect.height();
for (int i = 0; i < mSpectrumNum; i++) {
if (mBytes[i] < 0) {
mBytes[i] = 127;
}
final int xi = baseX * i + baseX / 2;
mPoints[i * 4] = xi;
mPoints[i * 4 + 1] = height;
mPoints[i * 4 + 2] = xi;
mPoints[i * 4 + 3] = height - mBytes[i];
}
canvas.drawLines(mPoints, mForePaint);
}
}