分享python分析wave, pcm音频文件

最近研究的，我用的是python3.3, 用matplotlib画图，

下面代码演示分析pcm文件，如果是wave文件，把wave的文件头(前44字节)去掉就是pcm文件了。

代码如下

 # -*- coding:utf-8 -*-

 import array
 import os
 from matplotlib import pyplot

 fileName = 'e:/music/qianqian.pcm' # 2 channel, 16 bit per sample
 file = open(fileName, 'rb')
 base = 1 / (1<<15)

 shortArray = array.array('h') # int16
 size = int(os.path.getsize(fileName) / shortArray.itemsize)
 count = int(size / 2)
 shortArray.fromfile(file, size) # faster than struct.unpack
 file.close()
 leftChannel = shortArray[::2]
 rightChannel = shortArray[1::2]

 def showPCM(leftChannel, rightChannel, start = 0, end = 5000):
     fig = pyplot.figure(1)

     pyplot.subplot(211)
     pyplot.title('pcm left channel [{0}-{1}] max[{2}]'.format(start, end, count))
     pyplot.plot(range(start, end), leftChannel[start:end])

     pyplot.subplot(212)
     pyplot.title('pcm right channel [{0}-{1}] max[{2}]'.format(start, end, count))
     pyplot.plot(range(start, end), rightChannel[start:end])

     pyplot.show()
     # fig.savefig('pcm.pdf') # save figure to pdf file

 showPCM(leftChannel, rightChannel, 0, count)

另一种分析方法，用struct.unpack，但读取要比上一种慢很多

 # -*- coding:utf-8 -*-

 import struct
 from matplotlib import pyplot

 file = open('e:/music/qianqian.pcm', 'rb') # if file is too large, pyplot may overflow
 count = 0
 total = 0
 base = 1 / (1<<15)
 maxl = 0
 minl = 0
 maxr = 0
 minr = 0
 larray = []
 rarray = []
 # file has two channels, 16 bit per sample
 while True:
     lr = file.read(4)
     if len(lr) < 4:
         break
     count += 1
     lvalue = struct.unpack('h', lr[:2])[0] * base
     larray.append(lvalue)
     if lvalue > maxl:
         maxl = lvalue
     if lvalue < minl:
         minl = lvalue
     total += lvalue
     rvalue = struct.unpack('h', lr[2:])[0] * base
     rarray.append(rvalue)
     if rvalue > maxr:
         maxr = rvalue
     if rvalue < minr:
         minr = rvalue

 file.close()
 avarage = total / count
 print(count, total, avarage)
 print('max = {0} min = {1}'.format(maxl, minl))

 fig = pyplot.figure(1)
 pyplot.subplot(211)
 pyplot.title('pcm left channel')
 pyplot.plot(range(count), larray)
 pyplot.subplot(212)
 pyplot.title('pcm right channel')
 pyplot.plot(range(count), rarray)
 pyplot.show()
 # fig.savefig('pcm.pdf')

代码及pcm下载：

链接：https://pan.baidu.com/s/1lTn7o2kpwKzd1tFiIDfIdQ
提取码：oqgz

下面这个地址也有一个例子：http://stackoverflow.com/questions/18625085/how-to-plot-a-wav-file可以看看。