title: pyaudio change the number of samples of calling the callback function
body: <p>I want to do a simple realtime processing to audio every 4096 samples. But this code calls the callback function every 1024 samples. I just want to change the frame_count to 4096.</p>
  
  <pre><code>import pyaudio
  import time
  
  WIDTH = 2
  CHANNELS = 1
  RATE = 44100
  
  p = pyaudio.PyAudio()
  
  def callback(in_data, frame_count, time_info, status):
      out=do_something(in_data)
      print(frame_count)#1024
      return (out, pyaudio.paContinue)
  
  stream = p.open(format=p.get_format_from_width(WIDTH),
                  channels=CHANNELS,
                  rate=RATE,
                  input=True,
                  output=True,
                  stream_callback=callback)
  
  stream.start_stream()
  
  while stream.is_active():
      time.sleep(0.1)
  
  stream.stop_stream()
  stream.close()
  
  p.terminate()
  </code></pre>