Creating .wav file from bytes

Question

I am reading bytes from wav audio downloaded from a URL. I would like to "reconstruct" these bytes into a .wav file. I have attempted the code below, but the resulting file is pretty much static. For example, when I download audio of myself speaking, the .wav file produced is static only, but I can hear slight alterations/distortions when I know the audio should be playing my voice. What am I doing wrong?

from pprint import pprint
import scipy.io.wavfile
import numpy

#download a wav audio recording from a url
>>>response = client.get_recording(r"someurl.com")
>>>pprint(response)
(b'RIFFv\xfc\x03\x00WAVEfmt \x10\x00\x00\x00\x01\x00\x01\x00\x80>\x00\x00'
 ...
 b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'
...
 b'\xea\xff\xfd\xff\x10\x00\x0c\x00\xf0\xff\x06\x00\x10\x00\x06\x00'
 ...)

>>>a=bytearray(response)
>>>pprint(a)
bytearray(b'RIFFv\xfc\x03\x00WAVEfmt \x10\x00\x00\x00\x01\x00\x01\x00'       
      b'\x80>\x00\x00\x00}\x00\x00\x02\x00\x10\x00LISTJ\x00\x00\x00INFOINAM'
      b'0\x00\x00\x00Conference d95ac842-08b7-4380-83ec-85ac6428cc41\x00'
      b'IART\x06\x00\x00\x00Nexmo\x00data\x00\xfc\x03\x00\xff\xff'
      b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff'
      ...
      b'\x12\x00\xf6\xff\t\x00\xed\xff\xf6\xff\xfc\xff\xea\xff\xfd\xff'
      ...)

>>>b = numpy.array(a, dtype=numpy.int16)
>>>pprint(b)
array([ 82,  73,  70, ..., 255, 248, 255], dtype=int16)

>>>scipy.io.wavfile.write(r"C:\Users\somefolder\newwavfile.wav", 
16000, b)

Solution 1

You can simply write the data in response to a file:

with open('myfile.wav', mode='bx') as f:
    f.write(response)

If you want to access the audio data as a NumPy array without writing it to a file first, you can do this with the soundfile module like this:

import io
import soundfile as sf

data, samplerate = sf.read(io.BytesIO(response))

See also this example: https://pysoundfile.readthedocs.io/en/0.9.0/#virtual-io

Solution 2

AudioSegment.from_raw() also will work while you have a continues stream of bytes:

import io
from pydub import AudioSegment

current_data is defined as the stream of bytes that you receive

s = io.BytesIO(current_data)
audio = AudioSegment.from_raw(s, sample_width, frame_rate, channels).export(filename, format='wav')

Solution 3

To add wave file header to raw audio bytes (extracted from wave library):

import struct

def write_header(_bytes, _nchannels, _sampwidth, _framerate):
    WAVE_FORMAT_PCM = 0x0001
    initlength = len(_bytes)
    bytes_to_add = b'RIFF'
    
    _nframes = initlength // (_nchannels * _sampwidth)
    _datalength = _nframes * _nchannels * _sampwidth

    bytes_to_add += struct.pack('<L4s4sLHHLLHH4s',
        36 + _datalength, b'WAVE', b'fmt ', 16,
        WAVE_FORMAT_PCM, _nchannels, _framerate,
        _nchannels * _framerate * _sampwidth,
        _nchannels * _sampwidth,
        _sampwidth * 8, b'data')

    bytes_to_add += struct.pack('<L', _datalength)

    return bytes_to_add + _bytes

Comments

[Jose Ramon]

I am trying to do a similar task. Therefore, I tried the perform solution and I am receiving the following: RuntimeError: Error opening <_io.BytesIO object at 0x000001E251444410>: File contains data in an unknown format.

[Matthias]

Does the data have a known format? Does it work if you write it to a file? Is it probably raw data?

[Jose Ramon]

Yes they are raw data. Is there a way to handle them as in the case of the .wav file?

[Matthias]

Yes, you simply have to specify format (= 'RAW'), subtype, channels and samplerate explicitly. See pysoundfile.readthedocs.io/en/0.9.0/#raw-files.