Skip to main content
`Ctrl`+`K`

# scipy.io.wavfile.read

scipy.io.wavfile.read(filename, mmap=False)

  Open a WAV file.

  Return the sample rate (in samples/sec) and data from an LPCM WAV file.

  Parameters:
    filename string or open file handle

      Input WAV file.

    mmap bool, optional

      Whether to read data as memory-mapped (default: False). Not compatible with some bit depths; see Notes. Only to be used on real files.

      New in version 0.12.0.

  Returns:
    rate int

      Sample rate of WAV file.

    data numpy array

      Data read from WAV file. Data-type is determined from the file; see Notes. Data is 1-D for 1-channel WAV, or 2-D of shape (Nsamples, Nchannels) otherwise. If a file-like input without a C-like file descriptor (e.g., `io.BytesIO`) is passed, this will not be writeable.

  Notes

  Common data types: [1]

  WAV format | Min | Max | NumPy dtype
  --- | --- | --- | ---
  32-bit floating-point | -1.0 | +1.0 | float32
  32-bit integer PCM | -2147483648 | +2147483647 | int32
  24-bit integer PCM | -2147483648 | +2147483392 | int32
  16-bit integer PCM | -32768 | +32767 | int16
  8-bit integer PCM | 0 | 255 | uint8

  WAV files can specify arbitrary bit depth, and this function supports reading any integer PCM depth from 1 to 64 bits. Data is returned in the smallest compatible numpy int type, in left-justified format. 8-bit and lower is unsigned, while 9-bit and higher is signed.

  For example, 24-bit data will be stored as int32, with the MSB of the 24-bit data stored at the MSB of the int32, and typically the least significant byte is 0x00. (However, if a file actually contains data past its specified bit depth, those bits will be read and output, too. [2])

  This bit justification and sign matches WAV’s native internal format, which allows memory mapping of WAV files that use 1, 2, 4, or 8 bytes per sample (so 24-bit files cannot be memory-mapped, but 32-bit can).

  IEEE float PCM in 32- or 64-bit format is supported, with or without mmap. Values exceeding [-1, +1] are not clipped.

  Non-linear PCM (mu-law, A-law) is not supported.

  References

  [1]

  IBM Corporation and Microsoft Corporation, “Multimedia Programming Interface and Data Specifications 1.0”, section “Data Format of the Samples”, August 1991 http://www.tactilemedia.com/info/MCI_Control_Info.html

  [2]

  Adobe Systems Incorporated, “Adobe Audition 3 User Guide”, section “Audio file formats: 24-bit Packed Int (type 1, 20-bit)”, 2007

  Examples

      >>> from os.path import dirname, join as pjoin
      >>> from scipy.io import wavfile
      >>> import scipy.io

  Get the filename for an example .wav file from the tests/data directory.

      >>> data_dir = pjoin(dirname(scipy.io.__file__), 'tests', 'data')
      >>> wav_fname = pjoin(data_dir, 'test-44100Hz-2ch-32bit-float-be.wav')

  Load the .wav file contents.

      >>> samplerate, data = wavfile.read(wav_fname)
      >>> print(f"number of channels = {data.shape[1]}")
      number of channels = 2
      >>> length = data.shape[0] / samplerate
      >>> print(f"length = {length}s")
      length = 0.01s

  Plot the waveform.

      >>> import matplotlib.pyplot as plt
      >>> import numpy as np
      >>> time = np.linspace(0., length, data.shape[0])
      >>> plt.plot(time, data[:, 0], label="Left channel")
      >>> plt.plot(time, data[:, 1], label="Right channel")
      >>> plt.legend()
      >>> plt.xlabel("Time [s]")
      >>> plt.ylabel("Amplitude")
      >>> plt.show()