audioread

Read audio file

Syntax

[y,Fs] = audioread(filename)

[y,Fs] = audioread(filename,samples)

[y,Fs] = audioread(___,dataType)

Description

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

[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].

[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

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, read the first 2 seconds of the file and then return audio in the native integer format.

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 and specify the data and view the datatype of the sampled data y. The data type of y is double.

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

  Name          Size             Bytes  Class     Attributes

  y         16384x1             131072  double              

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

[y,Fs] = audioread(filename,'native');
whos y

  Name          Size             Bytes  Class    Attributes

  y         73113x1             146226  int16              

Input Arguments

filename — Name of file to read

character vector | string scalar

Name of file to read, specified as a character vector or string scalar that includes the file extension.

Depending on the location of your file, filename can take on one of these forms.

Current folder	Specify the name of the file in filename. Example: 'sample_audio.wav'
Other folders	If the file is not in the current folder or in a folder on the MATLAB® path, then specify the full or relative path name in filename. Example: 'C:\myFolder\myFile.sample_audio.wav' Example: 'myFolder\sample_audio.mp3'
Internet URL	If the file is specified as an internet uniform resource locator (URL), then filename must contain the protocol type 'http://' or 'https://'. Example: 'http://hostname/path_to_file/sample_audio.mp3'
Remote Location	If the file is stored at a remote location, then filename must contain the full path of the file specified with the form: scheme_name://path_to_file/my_file.ext Based on the remote location, scheme_name can be one of the values in this table. Remote Location scheme_name Amazon S3™ s3 Windows Azure® Blob Storage wasb, wasbs HDFS™ hdfs For more information, see Work with Remote Data. Example: 's3://bucketname/path_to_file/sample_audio.mp3'

Example: 'myFile.mp3'

Example: '../myFile.mp3'

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

audioread supports the following file formats.

Platform Support	File Format
All platforms	WAVE (.wav)
	OGG (.ogg)
	FLAC (.flac)
	AU (.au)
	AIFF (.aiff, .aif)
	AIFC (.aifc)
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.

Data Types: char | string

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:

'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'.

Data Types: char | string

Output Arguments

y — Audio data

matrix

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 Format	BitsPerSample	Data Type of y	Data Range of y
  WAVE (.wav)	8	uint8	0 ≤ y ≤ 255
  	16	int16	-32768 ≤ y ≤ +32767
  	24	int32	-2^31 ≤ y ≤ 2^31–1
  	32	int32	-2^31 ≤ y ≤ 2^31–1
  	32	single	-1.0 ≤ y ≤ +1.0
  	64	double	-1.0 ≤ y ≤ +1.0
  WAVE (.wav) (u-law)	8	int16	-32124 ≤ y ≤ +32124
  WAVE (.wav) (A-law)	8	int16	-32256 ≤ y ≤ +32256
  FLAC (.flac)	8	uint8	0 ≤ y ≤ 255
  	16	int16	-32768 ≤ y ≤ +32767
  	24	int32	-2^31 ≤ y ≤ 2^31–1
  MP3 (.mp3), MPEG-4 AAC (.m4a, .mp4), OGG (.ogg), and certain compressed WAVE files	N/A	single	-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 rate

positive scalar

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

Limitations

• For MP3, MPEG-4 AAC, and AVI 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.