Audio Device Reader

Record from sound card

• 

Libraries:
Audio Toolbox / Sources

Description

The Audio Device Reader block reads audio samples using your computer's audio device. The Audio Device Reader block specifies the driver, the device and its attributes, and the data type and size output from your Audio Device Reader block.

Examples

Read from Microphone and Write to Speaker

Examine the Audio Device Reader block in a Simulink® model, modify parameters, and explore overrun.

• Open Model

Ports

Output

A — Output signal

scalar | vector | matrix

The output of the Audio Device Reader block is determined by the block’s parameters. If the block output is a matrix, the columns correspond to independent channels.

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

O — Number of samples overrun

scalar

This port outputs the number of samples overrun while acquiring a frame of data (one output matrix).

Dependencies

To enable this port, select the Output number of samples overrun 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 value specified by the Samples per frame parameter. 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, set Sample rate (Hz) to 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.

Device — Device used to acquire audio samples

default audio device (default)

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

Info — View information about your audio input configuration

button

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

Sample rate (Hz) — Sample rate your device uses to acquire audio data

44100 (default) | integer

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

Number of channels — Number of channels acquired by your audio device

1 (default) | integer

The number of input channels is also the number of channels (matrix columns) output by the Audio Device Reader block.

Dependencies

To specify which input channels your audio device acquires, on the Advanced tab, select the Use default channel mapping parameter.

Samples per frame — Frame size read from audio device

1024 (default) | integer

Samples per frame is also the device buffer size, and the frame size (number of matrix rows) output by the Audio Device Reader block.

Advanced Tab

Device bit depth — Data type used by device to acquire audio data

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

Data type used by device to acquire audio data, specified as a character vector or string.

Use default channel mapping — Toggle channel mapping source

on (default) | off

When you select this parameter, the block uses the default mapping between the sound card’s input channels and the matrix columns output by this block. When you clear this parameter, you specify the mapping in Device input channels.

Device input channels — Specify nondefault channel mapping

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

Nondefault map of device channels and matrix output by the Audio Device Reader block, specified as a scalar or vector. For example:

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

• Channel 1 maps to the first column of the output matrix.

• Channel 2 maps to the second column of the output matrix.

• Channel 3 maps to the third column of the output matrix.

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

• Channel 3 maps to the first column of the output matrix.

• Channel 1 maps to the second column of the output matrix.

• Channel 2 maps to the third column of the output matrix.

Dependencies

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

Output number of samples overrun — Specify additional output port for number of samples overrun

off (default) | on

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

Output data type — Data type output from block

double (default) | single | int32 | int16 | uint8

Data type of the output.

Note

If this parameter is specified as double or single, the block outputs data in the range [–1, 1]. For other data types, the range is [min, max] of the specified data type.

Block Characteristics

Data Types	double | integera | single
Direct Feedthrough	no
Multidimensional Signals	no
Variable-Size Signals	no
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 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 object 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.

Version History

Introduced in R2016a