scipy.io : 不能写 wavfile [英] scipy.io : can't write wavfile
问题描述
我在将 2d numpy 数组写入波形文件(音频)时遇到问题
I have an issue writing a 2d numpy array as a wave file (audio)
根据文档,我应该编写一个 2d int16 numpy 数组
According to the doc I should write a 2d int16 numpy array
https://docs.scipy.org/doc/scipy-0.18.1/reference/generated/scipy.io.wavfile.write.html
16-bit PCM -32768 +32767 int16
作为 float32 格式的范围 (-1,1) 中的 numpy 数组,我首先将其转换为 16 位 int
As my numpy array in range (-1,1) in float32 format I first convert it to 16 bits 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 16 位格式的 -4391 和 4389 之间,所以应该没问题.但我的数据看起来被解释为 ushort
as my values are between -4391 and 4389 in 16bits format it should be ok. but my data looks interpreted as ushort
推荐答案
write
scipy.io.wavfile
函数期望输入数组具有 (num_samples, num_channels)代码>.我怀疑您的数组具有
(num_channels, num_samples)
形状.然后 write
尝试将 num_samples
放在写入 WAV 文件的结构中的 16 位字段中,但是 num_samples
的值太高了对于 16 位值来说很大.(请注意,如果 num_samples
足够小,则不会出现错误,但文件的格式将不正确.)
The write
function in scipy.io.wavfile
expects the input array to have the shape (num_samples, num_channels)
. I suspect your array has shape (num_channels, num_samples)
. Then write
tries to put num_samples
in a 16 bit field in a structure that gets written to the WAV file, but the value of num_samples
is too big for a 16 bit value. (Note that if num_samples
were small enough, you would not get an error, but the file would not have the correct format.)
快速解决方法是编写数组的转置:
A quick fix is to write the transpose of your array:
wavfile.write(outWaveFileName, 44100, stereoAudio.T)
例如,这里是一些演示错误的代码;x
和 y
的形状为 (2, 40000):
For example, here is some code that demonstrates the error; x
and y
have shape (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 wavfile.write
的输入具有预期的形状:
Transpose the array so the input to wavfile.write
has the expected shape:
In [16]: wavfile.write('foo.wav', 44100, y.T)
回读数据以验证它是否按预期工作:
Read back the data to verify that it worked as expected:
In [22]: fs, z = wavfile.read('foo.wav')
In [23]: np.allclose(z, y.T)
Out[23]: True
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