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的文件头去掉就是pcm文件了。
代码如下
1 # -*- coding:utf-8 -*-
2
3 import array
4 import os
5 from matplotlib import pyplot
6
7 fileName = ‘e:/music/qianqian.pcm‘ # 2 channel, 16 bit per sample
8 file = open(fileName, ‘rb‘)
9 base = 1 / (1<<15)
10
11 shortArray = array.array(‘h‘) # int16
12 size = int(os.path.getsize(fileName) / shortArray.itemsize)
13 count = int(size / 2)
14 shortArray.fromfile(file, size) # faster than struct.unpack
15 file.close()
16 leftChannel = shortArray[::2]
17 rightChannel = shortArray[1::2]
18
19 def showPCM(leftChannel, rightChannel, start = 0, end = 5000):
20 fig = pyplot.figure(1)
21
22 pyplot.subplot(211)
23 pyplot.title(‘pcm left channel [{0}-{1}] max[{2}]‘.format(start, end, count))
24 pyplot.plot(range(start, end), leftChannel[start:end])
25
26 pyplot.subplot(212)
27 pyplot.title(‘pcm right channel [{0}-{1}] max[{2}]‘.format(start, end, count))
28 pyplot.plot(range(start, end), rightChannel[start:end])
29
30 pyplot.show()
31 # fig.savefig(‘pcm.pdf‘) # save figure to pdf file
32
33 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
1 # -*- coding:utf-8 -*-
2
3 import struct
4 from matplotlib import pyplot
5
6 file = open(‘e:/music/qianqian.pcm‘, ‘rb‘) # if file is too large, pyplot may overflow
7 count = 0
8 total = 0
9 base = 1 / (1<<15)
10 maxl = 0
11 minl = 0
12 maxr = 0
13 minr = 0
14 larray = []
15 rarray = []
16 # file has two channels, 16 bit per sample
17 while True:
18 lr = file.read(4)
19 if len(lr) < 4:
20 break
21 count += 1
22 lvalue = struct.unpack(‘h‘, lr[:2])[0] * base
23 larray.append(lvalue)
24 if lvalue > maxl:
25 maxl = lvalue
26 if lvalue < minl:
27 minl = lvalue
28 total += lvalue
29 rvalue = struct.unpack(‘h‘, lr[2:])[0] * base
30 rarray.append(rvalue)
31 if rvalue > maxr:
32 maxr = rvalue
33 if rvalue < minr:
34 minr = rvalue
35
36 file.close()
37 avarage = total / count
38 print(count, total, avarage)
39 print(‘max = {0} min = {1}‘.format(maxl, minl))
40
41 fig = pyplot.figure(1)
42 pyplot.subplot(211)
43 pyplot.title(‘pcm left channel‘)
44 pyplot.plot(range(count), larray)
45 pyplot.subplot(212)
46 pyplot.title(‘pcm right channel‘)
47 pyplot.plot(range(count), rarray)
48 pyplot.show()
49 # fig.savefig(‘pcm.pdf‘)
代码及pcm下载：http://yun.baidu.com/s/1gdf3e3D
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。
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时间： 2024-10-13 03:35:55