#!/usr/bin/env python
# coding: utf-8

# # Reading and Writing Audio Files with ewave
# 
# [back to overview page](index.ipynb)
# 
# https://github.com/melizalab/py-ewave
# 
# Advantages:
# 
# * "pure Python" (plus NumPy!)
# * floating-point files can be used
# * WAVEX is supported
# * files can be read partially
# * uses [numpy.memmap](http://docs.scipy.org/doc/numpy/reference/generated/numpy.memmap.html)
# 
# Disadvantages:
# 
# * no 24-bit PCM
# * function for rescaling has to be invoked separately (but at least it's available)
# 
# Installation:
# 
#     python3 -m pip install ewave

# ## Reading

# In[ ]:


import ewave


# In[ ]:


with ewave.open('data/test_wav_pcm16.wav') as w:
    print("samplerate = {0.sampling_rate} Hz, length = {0.nframes} samples, "
          "channels = {0.nchannels}, dtype = {0.dtype!r}".format(w))
    data = w.read()


# In[ ]:


data


# In[ ]:


get_ipython().run_line_magic('matplotlib', 'inline')
import matplotlib.pyplot as plt
import numpy as np


# In[ ]:


plt.plot(data);


# Obviously, the returned samples have the `dtype` `'int16'` (as stored in the file).
# To be able to do something useful, we'll have to convert it to floating point and normalize it to a range from -1 to 1.
# Luckily, there is a function especially made for this:

# In[ ]:


np.set_printoptions(precision=4)
ewave.rescale(data, 'float32')


# Note: until version 1.0.4 this was broken, but now it works (see https://github.com/melizalab/py-ewave/issues/4).
# 
# Files with floating point data can be used, WAVEX is supported:

# In[ ]:


with ewave.open('data/test_wav_float32.wav') as w:
    data = w.read()
    
plt.plot(data);


# Looking good!

# In[ ]:


with ewave.open('data/test_wavex_pcm16.wav') as w:
    data = w.read()
    
plt.plot(data);


# In[ ]:


with ewave.open('data/test_wavex_float32.wav') as w:
    data = w.read()
    
plt.plot(data);


# Opening a 24-bit PCM file fails with a not very verbose error message:

# In[ ]:


import traceback
try:
    ewave.open('data/test_wav_pcm24.wav')
except:
    traceback.print_exc()
else:
    print("It works (unexpectedly)!")


# ## Writing

# In[ ]:


# TODO!


# ## Version Info

# In[ ]:


print("ewave:", ewave.__version__)

import numpy, IPython, sys
print("NumPy: {}; IPython: {}".format(numpy.__version__, IPython.__version__))

print("Python interpreter:")
print(sys.version)


# <p xmlns:dct="http://purl.org/dc/terms/">
#   <a rel="license"
#      href="http://creativecommons.org/publicdomain/zero/1.0/">
#     <img src="http://i.creativecommons.org/p/zero/1.0/88x31.png" style="border-style: none;" alt="CC0" />
#   </a>
#   <br />
#   To the extent possible under law,
#   <span rel="dct:publisher" resource="[_:publisher]">the person who associated CC0</span>
#   with this work has waived all copyright and related or neighboring
#   rights to this work.
# </p>