WASAPI support

SONAR provides support for WASAPI (Windows Audio Session API), which is the new standard for audio in Windows 7 and future Windows operating systems.

The primary advantages of WASAPI are:

Better compatibility with consumer audio devices:

Supports a wide variety of audio devices, including newer WaveRT devices and legacy Windows audio devices.

Lets you use consumer audio devices that don’t have ASIO drivers or drivers that don’t work well under WDM.

Provides low latency access to audio devices.

Using WASAPI

WASAPI has four different modes of operation. SONAR supports WASAPI Exclusive mode and WASAPI Shared mode.

Exclusive mode provides low latency audio and direct access to the audio driver, bypassing the Windows audio engine. The disadvantage is that only one application can access the driver in Exclusive mode.

Shared mode allows multiple applications to access the audio driver. When Shared mode is selected, Windows will mix the audio output from SONAR along with audio from other apps such as YouTube. One advantage of Windows 10 is that WASAPI Shared mode supports low latency playback and recording at buffer sizes down to 2 milliseconds. In Windows 7, WASAPI Shared mode is less efficient and requires higher latency since it uses polling to access the driver.

In order to use WASAPI in SONAR, your audio device must have WDM drivers that Windows can successfully communicate with. In order to use WASAPI Exclusive mode, the audio device must be enabled to work in Exclusive mode.

Exclusive mode is the default in Windows 7 and can be configured from your audio device’s taskbar or Properties dialog box in Device Manager. Consult your audio device’s manual if you need further information.

Exclusive mode requires exclusive access to the audio device. Another program will not be able to use the audio device simultaneously with SONAR.

Tip: If you select Suspend Audio Engine When SONAR Is Not in Focus in Edit > Preferences > Audio - Playback and Recording, SONAR will relinquish control of the audio device when the program loses Windows focus.

To enable WASAPI mode in SONAR

1.	Go to Edit > Preferences > Audio - Playback and Recording.

2.	In the Driver Mode list, select WASAPI Exclusive or WASAPI Shared.

3.	Select the Audio - Devices page tab (Edit > Preferences > Audio - Devices).

4.	In the Input Drivers and Output Drivers lists, select the desired input and output ports.

5.	Click OK to close the Preferences dialog box.

To enable/disable built-in DSP

In Windows 10, WASAPI Shared mode has support for configuring built-in signal processing for inputs and output independently. Many onboard audio devices have built in DSP, such as Dolby audio enhancement of audio outputs and noise reduction for audio inputs. While these effects may be desirable for better quality audio from laptops (for example, for noise gating of microphone inputs), the DSP processing of these effects can cause latency.

SONAR allows you to enable or disable DSP effects on inputs and output devices in WASAPI Shared mode. This is done via the EnableWasapiDSP variable in Aud.ini. By default, SONAR enables endpoint DSP effects for input devices (for noise removal).

To configure the built-in signal processing for inputs and outputs:

1.	Go to Edit > Preferences > Audio - Configuration File.

2.	Under Configuration Settings, click Edit Config File.

The Aud.ini file opens in the default Windows text editor.

3.	In Aud.ini, add a new entry called EnableWasapiDSP in the [Wave] section, and set its value to the minimum desired buffer sample value. For example:

[Wave]

EnableWasapiDSP=0

Valid values are as follows:

0 = Disable all signal processing for inputs and outputs (RAW mode)

1 = Enable signal processing for inputs (default)

2 = Enable signal processing for outputs

3 = Enable signal processing for inputs and outputs

4.	Save Aud.ini and close the Windows text editor.

5.	Click Reload Config Settings to reload the current audio configuration settings from Aud.ini.

 

Note: Setting the EnableWasapiDSP variable to 2 or 3 will result in a minimum latency of 5 milliseconds in SONAR when using WASAPI Shared mode.

 

See also:

WaveRT updates