Real Time Audio Display
=======================


Reading a wav file has been done before in these notes. But this time
we don't read the entire file into a numpy array. Instead we will only
open the wav file and determine the sound signal parameters. For this
we use the standard Python Wave package.

.. code:: python

   import wave

   wf = wave.open('testwave.wav', 'rb')
   nchannels = wd.getnchannels() # 1: mono, 2: stereo
   nbytesframe = wf.getsamplewidth() # 1: unsigned byte, 2: signed int
   framerate = wf.getframerate() # no of samples per second


Given this initialization we can use the method `readframes` to read a
specific number of frames from the stream. This method returns the raw
stream of bytes as a string. It is up to the programmer to make this
into useful numerical data.

.. code:: python

   if nbytesframe == 1:
	  tp = dtype.uint8
   else:
	  tp = dtype.int16
	  
   x = np.fromstring(wf.readframes(N), tp)

   if nchannels == 1:
	  xleft = x
	  xright = x
   else:
	  xleft = x[::2]
	  xright = x[1::2]

In the above code we always return a stereo signal. In case the
original signal was mono, the left and right signal are the same.