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audioread

Read audio file

Syntax

  • [y,Fs] = audioread(filename) example
  • [y,Fs] = audioread(filename,samples) example
  • [y,Fs] = audioread(___,dataType) example

Description

example

[y,Fs] = audioread(filename) reads data from the file named filename, and returns sampled data,y, and a sample rate for that data, Fs.

example

[y,Fs] = audioread(filename,samples) reads the selected range of audio samples in the file, where samples is a vector of the form [start,finish].

example

[y,Fs] = audioread(___,dataType) returns sampled data in the data range corresponding to the dataType of 'native' or 'double', and can include any of the input arguments in previous syntaxes.

Examples

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Read Complete Audio File

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

Create a WAVE (.wav) file in the current folder.

load handel.mat

filename = 'handel.wav';
audiowrite(filename,y,Fs);
clear y Fs

Read the data back into MATLAB using audioread.

[y,Fs] = audioread('handel.wav');

Play the audio.

sound(y,Fs);

Read Portion of Audio File

Create a FLAC file from the example file handel.mat, and then read only the first 2 seconds.

Create a FLAC (.flac) file in the current folder.

load handel.mat

filename = 'handel.flac';
audiowrite(filename,y,Fs);

Read only the first 2 seconds.

samples = [1,2*Fs];
clear y Fs
[y,Fs] = audioread(filename,samples);

Play the samples.

sound(y,Fs);

Return Audio in Native Integer Format

Create a FLAC file and read the first 2 seconds according to the previous Example. Then, view the data type of the sampled data y.

whos y
  Name          Size             Bytes  Class     Attributes

  y         16384x1             131072  double   

The data type of y is double.

Request audio data in the native format of the file, and then view the data type of the sampled data y.

[y,Fs] = audioread(filename,'native');
whos y
  Name          Size            Bytes  Class    Attributes

  y         16384x1             32768  int16              

The data type of y is now int16.

Input Arguments

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filename — Name of file to readstring

Name of file to read, specified as a string that includes the file extension. If a path is specified, it can be absolute, relative or partial.

Example: 'myFile.mp3'

Example: '../myFile.mp3'

Example: 'C:\temp\myFile.mp3'

audioread supports the following file formats.

Platform SupportFile Format
All platformsWAVE (.wav)
OGG (.ogg)
FLAC (.flac)
AU (.au)
Windows® 7 (or later), Macintosh, and Linux®MP3 (.mp3)
MPEG-4 AAC (.m4a, .mp4)

On Windows platforms prior to Windows 7, audioread does not read WAVE files with MP3 encoded data.

On Windows 7 (or later) platforms, audioread might also read any files supported by Windows Media® Foundation.

On Linux platforms, audioread might also read any files supported by GStreamer.

audioread can extract audio from MPEG-4 (.mp4, .m4v) video files on Windows 7 or later, Macintosh, and Linux, and from Windows Media Video (.wmv) and AVI (.avi) files on Windows 7 (or later) and Linux platforms.

samples — Audio samples to read[1,inf] (default) | two-element vector of positive scalar integers

Audio samples to read, specified as a two-element vector of the form [start,finish], where start and finish are the first and last samples to read, and are positive scalar integers.

  • start must be less than or equal to finish.

  • start and finish must be less than the number of audio samples in the file,

  • You can use inf to indicate the last sample in the file.

    Note:   When reading a portion of some MP3 files on Windows 7 platforms, audioread might read a shifted range of samples. This is due to a limitation in the underlying Windows Media Foundation framework.

    When reading a portion of MP3 and M4A files on Linux platforms, audioread might read a shifted range of samples. This is due to a limitation in the underlying GStreamer framework.

Example: [1,100]

Data Types: double

dataType — Data format of audio data, y'double' (default) | 'native'

Data format of audio data,y, specified as one of the following strings:

'double'Double-precision normalized samples.
'native'Samples in the native format found in the file.

For compressed audio formats, such as MP3 and MPEG-4 AAC that do not store data in integer form, 'native' defaults to 'single'.

Output Arguments

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y — Audio datamatrix

Audio data in the file, returned as an m-by-n matrix, where m is the number of audio samples read and n is the number of audio channels in the file.

  • If you do not specify dataType, or dataType is 'double', then y is of type double, and matrix elements are normalized values between −1.0 and 1.0.

  • If dataType is 'native', then y can be one of several MATLAB data types, depending on the file format and the BitsPerSample value of the input file. Call audioinfo to determine the BitsPerSample value of the file.

    File FormatBitsPerSample Data Type of yData Range of y
    WAVE (.wav)8uint80 ≤ y ≤ 255
    16int16-32768 ≤ y ≤ +32767
    24int32-2^32 ≤ y ≤ 2^32–1
    32int32-2^32 ≤ y ≤ 2^32–1
    32single-1.0 ≤ y ≤ +1.0
    64double-1.0 ≤ y ≤ +1.0
    FLAC (.flac)8uint80 ≤ y ≤ 255
    16int16-32768 ≤ y ≤ +32767
    24int32-2^32 ≤ y ≤ 2^32–1
    MP3 (.mp3), MPEG-4 AAC (.m4a, .mp4), OGG (.ogg), and certain compressed WAVE filesN/Asingle-1.0 ≤ y ≤ +1.0

    Note:   Where y is single or double and the BitsPerSample is 32 or 64, values in y might exceed −1.0 or +1.0.

Fs — Sample ratepositive scalar

Sample rate, in hertz, of audio data y, returned as a positive scalar.

Limitations

  • For MP3 and MPEG-4 AAC audio files on Windows 7 or later and Linux platforms, audioread might read fewer samples than expected. On Windows 7 platforms, this is due to a limitation in the underlying Media Foundation framework. On Linux platforms, this is due to a limitation in the underlying GStreamer framework. If you require sample-accurate reading, work with WAV or FLAC files.

  • On Linux platforms, audioread reads MPEG-4 AAC files that contain single-channel data as stereo data.

See Also

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