Android audio Visualization

Related links:

Android calls built-in recording audioProgram
Http://www.eoeandroid.com/thread-78949-1-1.html

Mediarecoder enables audio recording and playing
Http://www.eoeandroid.com/thread-237311-1-1.html

Android audio Introduction
Http://www.eoeandroid.com/thread-68377-1-1.html

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Let's take a look at it first:

 Public   Class Fftactivity Extends Activity Implements  Onclicklistener {  Private  Button button;  Private Imageview;  Private   Int Frequency = 8000 ;  Private   Int Channelconfiguration = Audioformat. channel_configuration_mono;  Private   Int Audioencoding = Audioformat. encoding_pcm_16bit;  Private  Realdoublefft transformer;  Private  Int Blocksize = 256 ;  Private   Boolean Started = False  ;  Private  Canvas canvas;  Private  Paint paint;  Private  Bitmap bitmap; @ override  Protected   Void Oncreate (bundle savedinstancestate ){  Super  . Oncreate (savedinstancestate); setcontentview (R. layout. FFT); button = (Button) findviewbyid (R. Id. fft_button); button. setonclicklistener (  This  ); Imageview = (Imageview) findviewbyid (R. Id. fft_imageview); Transformer = New  Realdoublefft (blocksize); bitmap = Bitmap. createbitmap (256,100, Bitmap. config. argb_8888); canvas = New  Canvas (Bitmap); Paint = New  Paint (); paint. setcolor (color. Green); imageview. setimagebitmap (Bitmap );}  Private   Class Recordaudio Extends Asynctask <void, Double [], Void> {@ Override  Protected Void doinbackground (void... Params ){  Int Buffersize = Audiorecord. getminbuffersize (frequency, channelconfiguration, audioencoding); audiorecord = New  Audiorecord (mediarecorder. audiosource. Mic, frequency, channelconfiguration, audioencoding, buffersize );  Short [] Buffer = New   Short [Blocksize];  Double [] Totransform = New   Double  [Blocksize]; audiorecord. startrecording ();  While  (Started ){  //  Read the record data to the buffer, but I think it may be more appropriate to write the data.                                  Int Bufferresult = audiorecord. Read (buffer, 0 , Blocksize );  For (Int I = 0; I <bufferresult; I ++ ) {Totransform <I> = ( Double ) Buffer <I>/ Short. max_value;} transformer. ft (totransform); publishprogress (totransform);} audiorecord. Stop ();  Return   Null  ;} @ Override  Protected   Void Onprogressupdate ( Double  []... Values ){  Super  . Onprogressupdate (values); canvas. drawcolor (color. Black );  For ( Int I = 0; I <values [0]. length; I ++ ){  Int X = I;  Int Downy = ( Int ) (100-(Values [0] <I>) * 10);  Int Upy = 100. ; Canvas. drawline (x, downy, X, upy, paint);} imageview. invalidate () ;}@ override  Public   Void  Onclick (view v) {started = True  ;  New  Recordaudio(.exe cute ();}} 

Android audio visualization uses discrete Fourier transform, but do not worry about poor mathematics. There are open-source Java Discrete Fourier TransformCode!! Go to www.netlib.org/fftpack/jfftpack.tgzand drag the internal ourcedirectory to the src directory !!