scipy.io:无法编写wavfile

Question

我有一个问题,写一个2d numpy数组作为波形文件(音频)

根据文档我应该写一个2d int16 numpy数组

https://docs.scipy.org/doc/scipy-0.18.1/reference/generated/scipy.io.wavfile.write.html

16-bit PCM  -32768  +32767  int16

作为我在float32格式的范围(-1,1)中的numpy数组,我首先将其转换为16位int

stereoAudio = ((stereoAudio * bits16max)).astype('int16')

print "argmax : " + str(np.amax(stereoAudio))
print "argmin : " + str(np.amin(stereoAudio))

outWaveFileName = "out/file.wav"
print "writing " + outWaveFileName
wavfile.write(outWaveFileName,44100,stereoAudio)

我得到以下输出:

argmax : 4389
argmin : -4381
writing out/file.wav
Traceback (most recent call last):
  File "/Users/me/file.py", line 132, in <module>
wavfile.write(outWaveFileName,44100,stereoAudio)
  File "//anaconda/lib/python2.7/site-packages/scipy/io/wavfile.py", line 353, in write
    bytes_per_second, block_align, bit_depth)
error: ushort format requires 0 <= number <= USHRT_MAX

因为我的值在1639格式之间介于-4391和4389之间,所以应该没问题.但我的数据看起来像是短暂的

Answer 1

的write在功能scipy.io.wavfile预计输入数组具有形状(num_samples, num_channels).我怀疑你的阵列有形状(num_channels, num_samples).然后write尝试num_samples在写入WAV文件的结构中放入一个16位字段,但是num_samples对于16位值,该值太大.(请注意,如果num_samples足够小,则不会出现错误,但文件格式不正确.)

快速解决方法是编写数组的转置:

wavfile.write(outWaveFileName, 44100, stereoAudio.T)

例如,以下是一些演示错误的代码; x并y有形状(2,40000):

In [12]: x = (2*np.random.rand(2, 40000) - 1).astype(np.float32)

In [13]: y = (x*32767).astype('int16')

In [14]: from scipy.io import wavfile

In [15]: wavfile.write('foo.wav', 44100, y)
---------------------------------------------------------------------------
error                                     Traceback (most recent call last)
<ipython-input-15-36b8cd0e729c> in <module>()
----> 1 wavfile.write('foo.wav', 44100, y)

/Users/warren/anaconda/lib/python2.7/site-packages/scipy/io/wavfile.pyc in write(filename, rate, data)
    351 
    352         fmt_chunk_data = struct.pack('<HHIIHH', format_tag, channels, fs,
--> 353                                      bytes_per_second, block_align, bit_depth)
    354         if not (dkind == 'i' or dkind == 'u'):
    355             # add cbSize field for non-PCM files

error: ushort format requires 0 <= number <= USHRT_MAX

转置数组使输入wavfile.write具有预期的形状:

In [16]: wavfile.write('foo.wav', 44100, y.T)

回读数据以验证它是否按预期工作:

In [22]: fs, z = wavfile.read('foo.wav')

In [23]: np.allclose(z, y.T)
Out[23]: True