android > Android 音频均衡器，可通过拖动调节音频EQ

AudioFxActionty.java

package com.terry.AudioFx;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnCompletionListener;
import android.media.audiofx.Equalizer;
import android.media.audiofx.Visualizer;
import android.media.audiofx.Visualizer.OnDataCaptureListener;
import android.os.Bundle;
import android.view.Gravity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.LinearLayout;
import android.widget.SeekBar;
import android.widget.TextView;
import android.widget.SeekBar.OnSeekBarChangeListener;

@SuppressLint("NewApi")
public class AudioFxActivity extends Activity {
	private static final float VISUALIZER_HEIGHT_DIP = 50f;

	private MediaPlayer mMediaPlayer;
	private Visualizer mVisualizer;
	private Equalizer mEqualizer; // 均衡器

	private LinearLayout mLayout;
	VisualizerView mVisualizerView;
	private TextView mStatusTextView;

	/** Called when the activity is first created. */
	@SuppressLint("NewApi")
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setVolumeControlStream(AudioManager.STREAM_MUSIC);

		mStatusTextView = new TextView(this);
		mLayout = new LinearLayout(this);
		mLayout.setOrientation(LinearLayout.VERTICAL);  
		mLayout.addView(mStatusTextView);  
		setContentView(mLayout);

		mMediaPlayer = MediaPlayer.create(this, R.raw.eason);

		setupVisualizerFxAndUi();
		setupEqualizeFxAndUi();

		mVisualizer.setEnabled(true);
		mMediaPlayer.setOnCompletionListener(new OnCompletionListener() {

			@Override
			public void onCompletion(MediaPlayer mp) {
				// TODO Auto-generated method stub
				mVisualizer.setEnabled(false);
			}
		});

		mMediaPlayer.start();
		mStatusTextView.setText("播放中。。。");
	}

	/**
	 * 通过mMediaPlayer返回的AudioSessionId创建一个优先级为0均衡器对象 并且通过频谱生成相应的UI和对应的事件
	 */
	@SuppressLint("NewApi")
	private void setupEqualizeFxAndUi() {
		mEqualizer = new Equalizer(0, mMediaPlayer.getAudioSessionId());
		mEqualizer.setEnabled(true);// 启用均衡器
		TextView eqTextView = new TextView(this);
		eqTextView.setText("均衡器：");
		mLayout.addView(eqTextView);

		// 通过均衡器得到其支持的频谱引擎
		short bands = mEqualizer.getNumberOfBands();

		// getBandLevelRange 是一个数组，返回一组频谱等级数组，
		// 第一个下标为最低的限度范围
		// 第二个下标为最大的上限,依次取出
		final short minEqualizer = mEqualizer.getBandLevelRange()[0];
		final short maxEqualizer = mEqualizer.getBandLevelRange()[1];

		for (short i = 0; i < bands; i++) {
			final short band = i;

			TextView freqTextView = new TextView(this);
			freqTextView.setLayoutParams(new ViewGroup.LayoutParams(
					ViewGroup.LayoutParams.FILL_PARENT,
					ViewGroup.LayoutParams.WRAP_CONTENT));

			freqTextView.setGravity(Gravity.CENTER_HORIZONTAL);

			// 取出中心频率
			freqTextView
					.setText((mEqualizer.getCenterFreq(band) / 1000) + "HZ");
			mLayout.addView(freqTextView);

			LinearLayout row = new LinearLayout(this);
			row.setOrientation(LinearLayout.HORIZONTAL);

			TextView minDbTextView = new TextView(this);
			minDbTextView.setLayoutParams(new ViewGroup.LayoutParams(
					ViewGroup.LayoutParams.WRAP_CONTENT,
					ViewGroup.LayoutParams.WRAP_CONTENT));

			minDbTextView.setText((minEqualizer / 100) + " dB");

			TextView maxDbTextView = new TextView(this);
			maxDbTextView.setLayoutParams(new ViewGroup.LayoutParams(
					ViewGroup.LayoutParams.WRAP_CONTENT,
					ViewGroup.LayoutParams.WRAP_CONTENT));
			maxDbTextView.setText((maxEqualizer / 100) + " dB");

			LinearLayout.LayoutParams layoutParams = new LinearLayout.LayoutParams(
					ViewGroup.LayoutParams.FILL_PARENT,
					ViewGroup.LayoutParams.WRAP_CONTENT);

			layoutParams.weight = 1; 

			SeekBar seekbar = new SeekBar(this);  
			seekbar.setLayoutParams(layoutParams); 
			seekbar.setMax(maxEqualizer - minEqualizer);
			seekbar.setProgress(mEqualizer.getBandLevel(band));

			seekbar.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {

				@Override
				public void onStopTrackingTouch(SeekBar seekBar) {
				}

				@Override
				public void onStartTrackingTouch(SeekBar seekBar) {
				}

				@Override
				public void onProgressChanged(SeekBar seekBar, int progress,
						boolean fromUser) {
					// TODO Auto-generated method stub
					mEqualizer.setBandLevel(band,
							(short) (progress + minEqualizer));
				}
			});
			row.addView(minDbTextView);
			row.addView(seekbar);
			row.addView(maxDbTextView);

			mLayout.addView(row);
		}

	}

	/**
	 * 生成一个VisualizerView对象，使音频频谱的波段能够反映到 VisualizerView上
	 */
	@SuppressLint("NewApi")
	private void setupVisualizerFxAndUi() {
		mVisualizerView = new VisualizerView(this);
		mVisualizerView.setLayoutParams(new ViewGroup.LayoutParams(
				ViewGroup.LayoutParams.FILL_PARENT,
				(int) (VISUALIZER_HEIGHT_DIP * getResources()
						.getDisplayMetrics().density)));
		mLayout.addView(mVisualizerView);

		mVisualizer = new Visualizer(mMediaPlayer.getAudioSessionId());
		// 参数内必须是2的位数
		mVisualizer.setCaptureSize(Visualizer.getCaptureSizeRange()[1]);

		// 设置允许波形表示，并且捕获它
		mVisualizer.setDataCaptureListener(new OnDataCaptureListener() {

			@Override
			public void onWaveFormDataCapture(Visualizer visualizer,
					byte[] waveform, int samplingRate) {
				// TODO Auto-generated method stub
				mVisualizerView.updateVisualizer(waveform);
			}

			@Override
			public void onFftDataCapture(Visualizer visualizer, byte[] fft,
					int samplingRate) {
				// TODO Auto-generated method stub

			}
		}, Visualizer.getMaxCaptureRate() / 2, true, false);

	}

	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		if (isFinishing() && mMediaPlayer != null) {
			mVisualizer.release();
			mMediaPlayer.release();
			mEqualizer.release();
			mMediaPlayer = null;
		}
	}

	class VisualizerView extends View {

		@SuppressLint("NewApi")
		private byte[] mBytes;
		private float[] mPoints;
		// 矩形区域
		private Rect mRect = new Rect();
		// 画笔
		private Paint mPaint = new Paint();

		// 初始化画笔
		private void init() {
			mBytes = null;
			mPaint.setStrokeWidth(1f);
			mPaint.setAntiAlias(true);
			mPaint.setColor(Color.BLUE);
		}

		public VisualizerView(Context context) {
			super(context);
			init();
		}

		public void updateVisualizer(byte[] mbyte) {
			mBytes = mbyte;
			invalidate();
		}

		@Override
		protected void onDraw(Canvas canvas) {
			// TODO Auto-generated method stub
			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());

			for (int i = 0; i < mBytes.length - 1; i++) {
				mPoints[i * 4] = mRect.width() * i / (mBytes.length - 1);
				mPoints[i * 4 + 1] = mRect.height() / 2
						+ ((byte) (mBytes[i] + 128)) * (mRect.height() / 2)
						/ 128;
				mPoints[i * 4 + 2] = mRect.width() * (i + 1)
						/ (mBytes.length - 1);
				mPoints[i * 4 + 3] = mRect.height() / 2
						+ ((byte) (mBytes[i + 1] + 128)) * (mRect.height() / 2)
						/ 128;
			}

			canvas.drawLines(mPoints, mPaint);
		}
	}
}