將3個字節的立體聲WAV文件轉換爲numpy陣列

Question

我已經給出了一個連續水下錄製的大型WAV文件，我想將其轉換爲用於分析的numpy數組。我正在努力做到這一點。

到目前爲止，我有：

import numpy as np 
import scipy as sp 
import wave as wv 
import struct 

wavefile = wv.open(filename,'r') 
(nchannels,sampwidth,framerate,nframes,comptype,compname) = wavefile.getparams() 

// read a sample as example 

wavedata =wavefile.readframes(1) 

第一幀看起來是這樣的： '\ XCD \命苦\ XFF @ \ X01 \ X00'。我試圖使用結構解壓縮它，但解壓縮任何我做我會得到以下錯誤：「字符大小不匹配格式」。我想這與Python結構無法處理24位數據的事實有關。

波文件的參數看起來如下：

• nchannels = 2
• sampwidth = 3
• 幀率= 48000
• 將爲nframes = 283516532L
• comptype = 'NONE'
• compname ='not compressed'

有人知道如何將24位立體聲WAV文件讀入numpy數組中嗎？

Answer 1

對於那些有類似問題我張貼我的解決方案。請注意，這會將24位波形文件轉換爲有符號浮點numpy數組。僅當轉換爲整數時，將/ int2float部分留出。

frames = wavfile.readframes(nsamples) 

ch1 = np.zeros(nsamples) 
ch2 = np.zeros(nsamples) 
int2float = (2**23)-1 

for x in np.arange(int(nsamples)): 
    ch1_24bit_sample = frames[x*6:x*6+3] 
    ch2_24bit_sample = frames[x*6+3:x*6+6] 
    ch1_32bit_sample = bit24_2_32(ch1_24bit_sample) 
    ch2_32bit_sample = bit24_2_32(ch2_24bit_sample) 
    ch1[x]=struct.unpack('i',ch_32bit_sample)[0] 
    ch2[x]=struct.unpack('i',ch_32bit_sample)[0] 
    ch1[x]=ch1[x]/int2float 
    ch2[x]=ch2[x]/int2float 

def bit24_2_32(strbytes): 
    if strbytes[2] < '\x80': 
     return strbytes+'\x00' 
    else: 
     return strbytes+'\xff' 

Answer 2

這裏的一個循環，處理2，圖3，以及與信道的任意數4字節WAV文件：

def dataFromWave(fname): 
""" return list with interleaved samples """ 
    f = wave.open(fname, 'rb') 
    chans = f.getnchannels() 
    samps = f.getnframes() 
    sampwidth = f.getsampwidth() 
    if sampwidth == 3: #have to read this one sample at a time 
     s = '' 
     for k in xrange(samps): 
      fr = f.readframes(1) 
      for c in xrange(0,3*chans,3):     
       s += '\0'+fr[c:(c+3)] # put TRAILING 0 to make 32-bit (file is little-endian) 
    else: 
     s = f.readframes(samps) 
    f.close() 
    unpstr = '<{0}{1}'.format(samps*chans, {1:'b',2:'h',3:'i',4:'i',8:'q'}[sampwidth]) 
    x = list(struct.unpack(unpstr, s)) 
    if sampwidth == 3: 
     x = [k >> 8 for k in x] #downshift to get +/- 2^24 with sign extension 
    return x