read#
- scipy.io.wavfile.read(filename, mmap=False)[source]#
- Open a WAV file. - Return the sample rate (in samples/sec) and data from an LPCM WAV file. - Parameters:
- filenamestring or open file handle
- Input WAV file. 
- mmapbool, 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. - Added in version 0.12.0. 
 
- Returns:
- rateint
- Sample rate of WAV file. 
- datanumpy 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() 