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android音乐柱状频谱实现

摘要：
我做了些修改，使稍微好看了些，继续分享。

原文地址：http://blog.csdn.net/caryee89/article/details/6935237

注意android2.3以后才可用，主要用到这个类Visualizer，这个源码其实是apiDemos中一个例子，但例子中实现的是两种中的波形显示，而不是频谱显示，

原文博主实现了另一种频谱显示，并分享出来，精神可嘉。我做了些修改，使稍微好看了些，继续分享。

官方文档解释：

public intgetFft(byte[] fft)

Returns a frequency capture of currently playing audio content.

This method must be called when the Visualizer is enabled.

The capture is an 8-bit magnitude FFT, the frequency range covered being 0 (DC) to half of the sampling rate returned bygetSamplingRate(). The capture returns the real and imaginary parts of a number of frequency points equal to half of the capture size plus one.

Note: only the real part is returned for the first point (DC) and the last point (sampling frequency / 2).

The layout in the returned byte array is as follows:

  • n is the capture size returned by getCaptureSize()
  • Rfk, Ifk are respectively the real and imaginary parts of the kth frequency component
  • If Fs is the sampling frequency retuned by getSamplingRate() the kth frequency is: (k*Fs)/(n/2)
Index

0

1

2

3

4

5

...

n - 2

n - 1

Data

Rf0

Rf(n/2)

Rf1

If1

Rf2

If2

...

Rf(n-1)/2

If(n-1)/2

Parameters
fftarray of bytes where the FFT should be returned
Returns

实部和虚部的平方和就是振幅的平方，因为是byte类型，所以最大值是127。

对原文的代码做了一些修改，使更好看一些，代码中用到的歌曲谁要用到，自己重新放一首就行，代码如下：

  1. /*
  2. *Copyright(C)2010TheAndroidOpenSourceProject
  3. *
  4. *LicensedundertheApacheLicense,Version2.0(the"License");
  5. *youmaynotusethisfileexceptincompliancewiththeLicense.
  6. *YoumayobtainacopyoftheLicenseat
  7. *
  8. *http://www.apache.org/licenses/LICENSE-2.0
  9. *
  10. *Unlessrequiredbyapplicablelaworagreedtoinwriting,software
  11. *distributedundertheLicenseisdistributedonan"ASIS"BASIS,
  12. *WITHOUTWARRANTIESORCONDITIONSOFANYKIND,eitherexpressorimplied.
  13. *SeetheLicenseforthespecificlanguagegoverningpermissionsand
  14. *limitationsundertheLicense.
  15. */
  17. packagecom.AudioFx;
  19. importandroid.app.Activity;
  20. importandroid.content.Context;
  21. importandroid.graphics.Canvas;
  22. importandroid.graphics.Color;
  23. importandroid.graphics.Paint;
  24. importandroid.graphics.Rect;
  25. importandroid.media.AudioManager;
  26. importandroid.media.MediaPlayer;
  27. importandroid.media.audiofx.Equalizer;
  28. importandroid.media.audiofx.Visualizer;
  29. importandroid.os.Bundle;
  30. importandroid.util.Log;
  31. importandroid.view.Gravity;
  32. importandroid.view.View;
  33. importandroid.view.ViewGroup;
  34. importandroid.view.WindowManager;
  35. importandroid.widget.LinearLayout;
  36. importandroid.widget.SeekBar;
  37. importandroid.widget.TextView;
  39. publicclassAudioFxActivityextendsActivity
  40. {
  41. privatestaticfinalStringTAG="AudioFxActivity";
  43. privatestaticfinalfloatVISUALIZER_HEIGHT_DIP=160f;
  45. privateMediaPlayermMediaPlayer;
  46. privateVisualizermVisualizer;
  47. privateEqualizermEqualizer;
  49. privateLinearLayoutmLinearLayout;
  50. privateVisualizerViewmVisualizerView;
  51. privateTextViewmStatusTextView;
  52. privateTextViewmInfoView;
  54. @Override
  55. publicvoidonCreate(Bundleicicle)
  56. {
  57. super.onCreate(icicle);
  59. mStatusTextView=newTextView(this);
  61. mLinearLayout=newLinearLayout(this);
  62. mLinearLayout.setOrientation(LinearLayout.VERTICAL);
  63. mLinearLayout.addView(mStatusTextView);
  65. setContentView(mLinearLayout);
  67. //CreatetheMediaPlayer
  68. mMediaPlayer=MediaPlayer.create(this,R.raw.my_life);
  69. Log.d(TAG,
  70. "MediaPlayeraudiosessionID:"
  71. +mMediaPlayer.getAudioSessionId());
  73. setupVisualizerFxAndUI();
  74. setupEqualizerFxAndUI();
  76. //Makesurethevisualizerisenabledonlywhenyouactuallywantto
  77. //receivedata,and
  78. //whenitmakessensetoreceivedata.
  79. mVisualizer.setEnabled(true);
  81. //Whenthestreamends,wedon'tneedtocollectanymoredata.We
  82. //don'tdothisin
  83. //setupVisualizerFxAndUIbecausewelikelywanttohavemore,
  84. //non-Visualizerrelatedcode
  85. //inthiscallback.
  86. mMediaPlayer.setOnCompletionListener(newMediaPlayer.OnCompletionListener()
  87. {
  88. publicvoidonCompletion(MediaPlayermediaPlayer)
  89. {
  90. mVisualizer.setEnabled(false);
  91. getWindow().clearFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
  92. setVolumeControlStream(AudioManager.STREAM_SYSTEM);
  93. mStatusTextView.setText("音乐播放完毕");
  94. }
  95. });
  97. getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
  98. setVolumeControlStream(AudioManager.STREAM_MUSIC);
  99. mMediaPlayer.start();
  100. mStatusTextView.setText("播放音乐中....");
  101. }
  103. privatevoidsetupEqualizerFxAndUI()
  104. {
  105. //CreatetheEqualizerobject(anAudioEffectsubclass)andattachit
  106. //toourmediaplayer,
  107. //withadefaultpriority(0).
  108. mEqualizer=newEqualizer(0,mMediaPlayer.getAudioSessionId());
  109. mEqualizer.setEnabled(true);
  111. TextVieweqTextView=newTextView(this);
  112. eqTextView.setText("均衡器:");
  113. mLinearLayout.addView(eqTextView);
  115. shortbands=mEqualizer.getNumberOfBands();
  117. finalshortminEQLevel=mEqualizer.getBandLevelRange()[0];
  118. finalshortmaxEQLevel=mEqualizer.getBandLevelRange()[1];
  120. for(shorti=0;i<bands;i++)
  121. {
  122. finalshortband=i;
  124. TextViewfreqTextView=newTextView(this);
  125. freqTextView.setLayoutParams(newViewGroup.LayoutParams(
  126. ViewGroup.LayoutParams.FILL_PARENT,
  127. ViewGroup.LayoutParams.WRAP_CONTENT));
  128. freqTextView.setGravity(Gravity.CENTER_HORIZONTAL);
  129. freqTextView.setText((mEqualizer.getCenterFreq(band)/1000)
  130. +"Hz");
  131. mLinearLayout.addView(freqTextView);
  133. LinearLayoutrow=newLinearLayout(this);
  134. row.setOrientation(LinearLayout.HORIZONTAL);
  136. TextViewminDbTextView=newTextView(this);
  137. minDbTextView.setLayoutParams(newViewGroup.LayoutParams(
  138. ViewGroup.LayoutParams.WRAP_CONTENT,
  139. ViewGroup.LayoutParams.WRAP_CONTENT));
  140. minDbTextView.setText((minEQLevel/100)+"dB");
  142. TextViewmaxDbTextView=newTextView(this);
  143. maxDbTextView.setLayoutParams(newViewGroup.LayoutParams(
  144. ViewGroup.LayoutParams.WRAP_CONTENT,
  145. ViewGroup.LayoutParams.WRAP_CONTENT));
  146. maxDbTextView.setText((maxEQLevel/100)+"dB");
  148. LinearLayout.LayoutParamslayoutParams=newLinearLayout.LayoutParams(
  149. ViewGroup.LayoutParams.FILL_PARENT,
  150. ViewGroup.LayoutParams.WRAP_CONTENT);
  151. layoutParams.weight=1;
  152. SeekBarbar=newSeekBar(this);
  153. bar.setLayoutParams(layoutParams);
  154. bar.setMax(maxEQLevel-minEQLevel);
  155. bar.setProgress(mEqualizer.getBandLevel(band));
  157. bar.setOnSeekBarChangeListener(newSeekBar.OnSeekBarChangeListener()
  158. {
  159. publicvoidonProgressChanged(SeekBarseekBar,intprogress,
  160. booleanfromUser)
  161. {
  162. mEqualizer.setBandLevel(band,(short)(progress+minEQLevel));
  163. }
  165. publicvoidonStartTrackingTouch(SeekBarseekBar)
  166. {
  167. }
  169. publicvoidonStopTrackingTouch(SeekBarseekBar)
  170. {
  171. }
  172. });
  174. row.addView(minDbTextView);
  175. row.addView(bar);
  176. row.addView(maxDbTextView);
  178. mLinearLayout.addView(row);
  179. }
  180. }
  182. privatevoidsetupVisualizerFxAndUI()
  183. {
  184. mVisualizerView=newVisualizerView(this);
  185. mVisualizerView.setLayoutParams(newViewGroup.LayoutParams(
  186. ViewGroup.LayoutParams.FILL_PARENT,
  187. (int)(VISUALIZER_HEIGHT_DIP*getResources()
  188. .getDisplayMetrics().density)));
  189. mLinearLayout.addView(mVisualizerView);
  191. mInfoView=newTextView(this);
  192. StringinfoStr="";
  194. int[]csr=Visualizer.getCaptureSizeRange();
  195. if(csr!=null)
  196. {
  197. StringcsrStr="CaptureSizeRange:";
  198. for(inti=0;i<csr.length;i++)
  199. {
  200. csrStr+=csr[i];
  201. csrStr+="";
  202. }
  203. infoStr+=csrStr;
  204. }
  206. finalintmaxCR=Visualizer.getMaxCaptureRate();
  208. infoStr=infoStr+" MaxCaptureRate:"+maxCR;
  210. mInfoView.setText(infoStr);
  211. mLinearLayout.addView(mInfoView);
  213. mVisualizer=newVisualizer(mMediaPlayer.getAudioSessionId());
  214. mVisualizer.setCaptureSize(256);
  215. mVisualizer.setDataCaptureListener(
  216. newVisualizer.OnDataCaptureListener()
  217. {
  218. publicvoidonWaveFormDataCapture(Visualizervisualizer,
  219. byte[]bytes,intsamplingRate)
  220. {
  221. mVisualizerView.updateVisualizer(bytes);
  222. }
  224. publicvoidonFftDataCapture(Visualizervisualizer,
  225. byte[]fft,intsamplingRate)
  226. {
  227. mVisualizerView.updateVisualizer(fft);
  228. }
  229. },maxCR/2,false,true);
  230. }
  232. @Override
  233. protectedvoidonPause()
  234. {
  235. super.onPause();
  237. if(isFinishing()&&mMediaPlayer!=null)
  238. {
  239. mVisualizer.release();
  240. mEqualizer.release();
  241. mMediaPlayer.release();
  242. mMediaPlayer=null;
  243. }
  244. }
  246. /**
  247. *Asimpleclassthatdrawswaveformdatareceivedfroma
  248. *{@linkVisualizer.OnDataCaptureListener#onWaveFormDataCapture}
  249. */
  250. classVisualizerViewextendsView
  251. {
  252. privatebyte[]mBytes;
  253. privatefloat[]mPoints;
  254. privateRectmRect=newRect();
  256. privatePaintmForePaint=newPaint();
  257. privateintmSpectrumNum=48;
  258. privatebooleanmFirst=true;
  260. publicVisualizerView(Contextcontext)
  261. {
  262. super(context);
  263. init();
  264. }
  266. privatevoidinit()
  267. {
  268. mBytes=null;
  270. mForePaint.setStrokeWidth(8f);
  271. mForePaint.setAntiAlias(true);
  272. mForePaint.setColor(Color.rgb(0,128,255));
  273. }
  275. publicvoidupdateVisualizer(byte[]fft)
  276. {
  277. if(mFirst)
  278. {
  279. mInfoView.setText(mInfoView.getText().toString()+" CaptureSize:"+fft.length);
  280. mFirst=false;
  281. }
  284. byte[]model=newbyte[fft.length/2+1];
  286. model[0]=(byte)Math.abs(fft[0]);
  287. for(inti=2,j=1;j<mSpectrumNum;)
  288. {
  289. model[j]=(byte)Math.hypot(fft[i],fft[i+1]);
  290. i+=2;
  291. j++;
  292. }
  293. mBytes=model;
  294. invalidate();
  295. }
  297. @Override
  298. protectedvoidonDraw(Canvascanvas)
  299. {
  300. super.onDraw(canvas);
  302. if(mBytes==null)
  303. {
  304. return;
  305. }
  307. if(mPoints==null||mPoints.length<mBytes.length*4)
  308. {
  309. mPoints=newfloat[mBytes.length*4];
  310. }
  312. mRect.set(0,0,getWidth(),getHeight());
  314. //绘制波形
  315. //for(inti=0;i<mBytes.length-1;i++){
  316. //mPoints[i*4]=mRect.width()*i/(mBytes.length-1);
  317. //mPoints[i*4+1]=mRect.height()/2
  318. //+((byte)(mBytes[i]+128))*(mRect.height()/2)/128;
  319. //mPoints[i*4+2]=mRect.width()*(i+1)/(mBytes.length-1);
  320. //mPoints[i*4+3]=mRect.height()/2
  321. //+((byte)(mBytes[i+1]+128))*(mRect.height()/2)/128;
  322. //}
  324. //绘制频谱
  325. finalintbaseX=mRect.width()/mSpectrumNum;
  326. finalintheight=mRect.height();
  328. for(inti=0;i<mSpectrumNum;i++)
  329. {
  330. if(mBytes[i]<0)
  331. {
  332. mBytes[i]=127;
  333. }
  335. finalintxi=baseX*i+baseX/2;
  337. mPoints[i*4]=xi;
  338. mPoints[i*4+1]=height;
  340. mPoints[i*4+2]=xi;
  341. mPoints[i*4+3]=height-mBytes[i];
  342. }
  344. canvas.drawLines(mPoints,mForePaint);
  345. }
  346. }
  347. }

运行效果如下：

android音乐柱状频谱实现第1张

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