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wavread

Read WAVE (.wav) sound file

    Note:   wavread will be removed in a future release. Use audioread instead.

Syntax

y = wavread(filename)
[y, Fs] = wavread(filename)
[y, Fs, nbits] = wavread(filename)
[y, Fs, nbits, opts] = wavread(filename)
[___] = wavread(filename, N)
[___] = wavread(filename, [N1 N2])
[___] = wavread(___, fmt)
siz = wavread(filename,'size')

Description

y = wavread(filename) loads a WAVE file specified by the string filename, returning the sampled data in y. If filename does not include an extension, wavread appends .wav.

[y, Fs] = wavread(filename) returns the sample rate (Fs) in Hertz used to encode the data in the file.

[y, Fs, nbits] = wavread(filename) returns the number of bits per sample (nbits).

[y, Fs, nbits, opts] = wavread(filename) returns a structure opts of additional information contained in the WAV file. The content of this structure differs from file to file. Typical structure fields include opts.fmt (audio format information) and opts.info (text that describes the title, author, etc.).

[___] = wavread(filename, N) returns only the first N samples from each channel in the file.

[___] = wavread(filename, [N1 N2]) returns only samples N1 through N2 from each channel in the file.

[___] = wavread(___, fmt) specifies the data format of y used to represent samples read from the file. fmt can be either of the following values, or a partial match (case-insensitive):

'double'Double-precision normalized samples (default).
'native'Samples in the native data type found in the file.

siz = wavread(filename,'size') returns the size of the audio data contained in filename instead of the actual audio data, returning the vector siz = [samples channels].

Output Scaling

The range of values in y depends on the data format fmt specified. Some examples of output scaling based on typical bit-widths found in a WAV file are given below for both 'double' and 'native' formats.

Native Formats

Number of BitsMATLAB Data TypeData Range
8uint8 (unsigned integer) 0 <= y <= 255
16int16 (signed integer) -32768 <= y <= +32767
24int32 (signed integer) -2^23 <= y <= 2^23-1
32single (floating point) -1.0 <= y < +1.0

Double Formats

Number of BitsMATLAB Data TypeData Range
N<32double-1.0 <= y < +1.0
N=32double-1.0 <= y <= +1.0
Note: Values in y might exceed -1.0 or +1.0 for the case of N=32 bit data samples stored in the WAV file.

wavread supports multi-channel data, with up to 32 bits per sample.

wavread supports Pulse-code Modulation (PCM) data format only.

Examples

Create a WAV file from the example file handel.mat, and read portions of the file back into MATLAB®.

% Create WAV file in current folder.
load handel.mat
 
hfile = 'handel.wav';
wavwrite(y, Fs, hfile)
clear y Fs
 
% Read the data back into MATLAB, and listen to audio.
[y, Fs, nbits, readinfo] = wavread(hfile);
sound(y, Fs);

% Pause before next read and playback operation.
duration = numel(y) / Fs;
pause(duration + 2)
 
% Read and play only the first 2 seconds.
nsamples = 2 * Fs;
[y2, Fs] = wavread(hfile, nsamples);
sound(y2, Fs);
pause(4)
 
% Read and play the middle third of the file.
sizeinfo = wavread(hfile, 'size');
 
tot_samples = sizeinfo(1);
startpos = tot_samples / 3;
endpos = 2 * startpos;
 
[y3, Fs] = wavread(hfile, [startpos endpos]);
sound(y3, Fs);

See Also

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