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Audio File Read

Read audio frames from an audio file

  • Library:
  • Simulink Support Package for Raspberry Pi Hardware / Audio and Video

Description

The Audio File Read block copies an audio source file and outputs the audio data into your model. The audio data can be played on a loop multiple times, as specified by the Number of times to play file parameter. The audio data can consist of one or more channels, C. A mono audio source file has only one channel, and a stereo audio source file has two channels. The audio data is output from the block as N consecutive samples of audio data.

Algorithm

The Audio File Read block determines the sample time (Ts) from the samples per audio channel (N) and sampling frequency (Fs) of the selected audio file.

Ts = N / Fs

For example, if N is 4410 samples and Fs is 44,100 Hz, the block sample time is 4410/44,100 = 0.1 seconds.

N is the value that you specify in the Samples per audio channel (N) parameter. Fs of the selected audio file is automatically displayed on the block when you browse the file using the File name parameter.

Ports

Output

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The block outputs the audio data as N-by-C matrix, where N is the samples per channel, and C is the number of channels supported by the audio.

For example, for a stereo audio source file with the Samples per audio channel (N) parameter set to 3, the block organizes the audio data into a 3-by-2 matrix, which represents a 2-channel signal containing three samples per channel.

Specify N with the Samples per audio channel (N) parameter. The number of channels, C, supported by the selected audio file is displayed in the block when you browse for the audio file using the File name parameter.

When the number of times the audio is played exceeds the value specified in the Number of times to play file parameter, the Port_1 port outputs 0 every sample time. For example, if you set the Number of times to play file parameter to 3, the Port_1 port outputs zeroes after the audio file is played three times.

Data Types: int16

The port outputs 1 when the last audio sample is output from the block. Otherwise, the port outputs 0.

Dependencies

To enable the port, select the Output end of audio indicator parameter.

Data Types: Boolean

Parameters

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If the location of the file does not appear on your MATLAB® path, click Browse to specify the full path. If the location of this file does appear on your MATLAB path, enter only the file name.

Enter inf to play the file until you stop the simulation.

The EOF port outputs 1 when the last audio sample is output from the block. Otherwise, the port outputs 0.

This parameter specifies the number of rows of the output matrix that the block outputs. The output matrix has dimensions N-by-C, where N is the number of samples per channel, and C is the number of channels.

See Also

Introduced in R2017b