Audio Device Writer

Play to sound card

• Library:

• Audio Toolbox / Sinks

  DSP System Toolbox / Sinks

• 

Description

The Audio Device Writer block writes audio samples to an audio output device.

Parameters of the Audio Device Writer block specify the driver, the device, and device attributes such as sample rate and bit depth.

Ports

Input

Port_1 — Input signal

scalar | vector | matrix

If input to the Audio Device Writer block is of data type double or single, the block clips values outside the range [–1, 1]. For other data types, the allowed input range is [min, max] of the specified data type.

Data Types: single | double | int16 | int32 | uint8

Output

Port_1 — Number of samples underrun

scalar

This port outputs the number of samples underrun while writing a frame of data (one input matrix).

Dependencies

To enable this port, select the Output number of samples underrun parameter.

Data Types: uint32

Parameters

Main Tab

Driver — Driver used to access your audio device

DirectSound (default) | ASIO | WASAPI

• ASIO drivers do not come pre-installed on Windows machines. To use the ASIO driver option, install an ASIO driver outside of MATLAB^®.

  Note

  If Driver is set to ASIO, open the ASIO UI outside of MATLAB to set the sound card buffer size to the frame size (number of rows) input to the Audio Device Writer block. See the documentation of your ASIO driver for more information.

• WASAPI drivers are supported for exclusive-mode only.

ASIO and WASAPI drivers do not provide sample rate conversion. For ASIO and WASAPI drivers, supply an audio stream with a sample rate supported by your audio device.

This parameter applies only on Windows machines. Linux machines always use the ALSA driver. Mac machines always use the CoreAudio driver.

To specify nondefault Driver values, you must install Audio Toolbox™. If the toolbox is not installed, specifying nondefault Driver values returns an error.

Device — Device used to play audio samples

default audio device (default)

The device list is populated with devices available on your computer.

Info — View information about your audio output configuration

button

This button opens a dialog box that lists your selected audio driver, the full name of your audio device, and the maximum output channels for your configuration. For example:

Inherit sample rate from input — Specify source of input sample rate

on (default) | off

When you select this parameter, the block inherits its sample rate from the input signal. When you clear this parameter, you specify the sample rate in Sample rate (Hz).

Sample rate (Hz) — Sample rate used by device to play audio data

44100 (default) | positive scalar

The possible range of Sample rate (Hz) depends on your audio hardware.

Dependencies

To enable this parameter, clear the Inherit sample rate from input parameter.

Advanced Tab

Device bit depth — Data type used by device to perform digital-to-analog conversion

16-bit integer (default) | 8-bit integer | 24-bit integer | 32-bit float

Before performing digital-to-analog conversion, the input data is cast to a data type specified by this parameter.

Note

To specify a nondefault Device bit depth, you must install Audio Toolbox. If the toolbox is not installed, specifying a nondefault Device bit depth returns an error.

Use default channel mapping — Toggle channel mapping source

on (default) | off

When you select this parameter, the block uses the default mapping between columns of the matrix input to this block and the channels of your device. When you clear this parameter, you specify the mapping in Device output channels.

Device output channels — Specify nondefault channel mapping

[1:MaximumOutputChannels] (default) | scalar | vector

Nondefault mapping between columns of matrix input to the Audio Device Writer block and channels of output device, specified as a scalar or vector. For example:

If Device output channels is specified as 1:3, then:

• The first column of the input matrix maps to channel 1.

• The second column of the input matrix maps to channel 2.

• The third column of the input matrix maps to channel 3.

If Device output channels is specified as [3,1,2], then:

• The first column of the input matrix maps to channel 3.

• The second column of the input matrix maps to channel 1.

• The third column of the input matrix maps to channel 2.

Note

To selectively map between columns of the input matrix and your sound card's output channels, you must install Audio Toolbox. If the toolbox is not installed, specifying nondefault values for Device output channels returns an error.

Dependencies

To enable this parameter, clear the Use default mapping between columns of input of this block and sound card’s output channels parameter.

Output number of samples underrun — Specify output port for number of samples underrun

off (default) | on

When you select this parameter, an output port is added to the block. The port outputs the number of samples underrun while writing a frame of data (one input matrix).

Model Examples

Decrease Underrun

Examine the Audio Device Writer block in a Simulink® model, determine underrun, and decrease underrun.

Channel Mapping

Examine the Audio Device Writer block in a Simulink® model and specify a nondefault channel mapping.

Block Characteristics

Data Types	double | integer[a] | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	yes
Zero-Crossing Detection	no
[a] Supports 16- and 32-bit signed and 8-bit unsigned integers.

Extended Capabilities

C/C++ Code Generation

Generate C and C++ code using Simulink® Coder™.

The following code generation limitations apply:

• Host computer only. Excludes Simulink^® Desktop Real-Time™ code generation.

• The executable generated from this block relies on prebuilt dynamic library files (.dll files) included with MATLAB. Use the packNGo function to package the code generated from this block and all the relevant files in a compressed zip file. Using this zip file, you can relocate, unpack, and rebuild your project in another development environment where MATLAB is not installed. For more details, see Run Audio I/O Features Outside MATLAB and Simulink.