listAudioDevices

List available ALSA audio devices

Add-On Required: This feature requires the Simulink Support Package for Raspberry Pi Hardware add-on.

Syntax

devices = listAudioDevices(audioType)

Description

devices = listAudioDevices(audioType) returns a list of Advanced Linux Sound Architecture (ALSA) audio devices connected to your Raspberry Pi^® hardware. The type of listed audio devices (capture or playback) depends on the audioType specified in the function.

Note

Simulink^® Online™ does not support the listAudioDevices function currently.

Examples

List Available ALSA Audio Input Devices

To list all connected ALSA audio input devices:

Create a connection to the Raspberry Pi hardware.

raspPiObj = raspberrypi('192.168.1.5','pi','raspberrypi')

rasPiObj = 

  raspberrypi with properties:

    DeviceAddress: '192.168.1.5'
             Port: 22

For more information on raspberrypi, see raspberrypi.

Use the listAudioDevices function. In the function, specify audioType as 'capture'. The function returns a structured array with field names that correspond to the properties of ALSA audio input devices connected to raspPiObj.

devices = raspPiObj.listAudioDevices('capture')

devices = 

  1×2 struct array with fields:

    Name
    Device
    Channels
    BitDepth
    SamplingRate

In this example, the function returns a 1-by-2 array, indicating that two audio input devices are connected to raspPiObj.

View the properties of the first ALSA audio input device.

devices(1)

ans = 

  struct with fields:

          Name: ' bcm2835 - bcm2835 ALSA↵'
        Device: '0,0'
      Channels: {'CHANNELS: [1 2]'}
      BitDepth: {'8-bit integer'  '16-bit integer'}
  SamplingRate: {'8000 48000'} 

List Available ALSA Audio Output Devices

To list all connected ALSA audio output devices:

Create a connection to the Raspberry Pi hardware.

raspPiObj = raspberrypi('192.168.1.5','pi','raspberrypi')

Use the listAudioDevices function. In the function, specify audioType as 'playback'. The function returns a structured array with field names that correspond to the properties of ALSA audio output devices connected to raspPiObj.

devices = raspPiObj.listAudioDevices('playback')

devices = 

  1×3 struct array with fields:

    Name
    Device
    Channels
    BitDepth
    SamplingRate

In this example, the function returns a 1-by-3 array, indicating that three audio output devices are connected to raspPiObj.

View the properties of the second ALSA audio output device.

devices(2)

ans = 

  struct with fields:

          Name: ' bcm2835 - bcm2835 ALSA↵'
        Device: '0,1'
      Channels: {'CHANNELS: 2'}
      BitDepth: {'8-bit integer'  '16-bit integer'}
  SamplingRate: {'44100 48000'} 

Input Arguments

audioType — Type of audio device

'capture' | 'playback'

Specify the type of audio to be listed:

• 'capture' — All ALSA audio input devices connected to Raspberry Pi.

• 'playback' — All ALSA audio output devices connected to Raspberry Pi.

Example: 'playback'

Data Types: char

Output Arguments

devices — List of connected ALSA audio devices

array

The type of listed audio devices depends on the audioType specified in the function. The resulting structured array contains these details:

• Name: The name of the audio device.

• Device: The device number of the audio device.

• Channels: The number of channels supported by the audio device. For example, in List Available ALSA Audio Output Devices, the audio device supports audio from two channels only.

• BitDepth: The data type in which the audio device reads or sends data.

• SamplingRate: The sample rates supported by the audio device.

Data Types: cell

Version History

Introduced in R2018a