问预先计算的Web音频API时域和谱图可视化

EN

   var off = new OfflineAudioContext(2 /* stereo */,
                                     44100 /* length in frames */,
                                     44100 /* samplerate */);
   /* do your thing: setup your graph as usual */
   off.createOscillator(...);
   ...
   ...

   /* This is called when the graph has rendered one
    * second of audio, here: 44100 frames at 44100 frames per second */

   off.oncomplete = function(e) {
     e.renderedBuffer; /* is an AudioBuffer that contains the PCM data */
   };
   /* kick off the rendering */
   off.startRendering();