COM Objects > ASIO object > Methods > ASIO.DeviceMasterVolumeSet method

Remarks

Sets the master volume for input or output ASIO channels of a specific ASIO device.

When changing the master volume, original volume level for single channels will be maintained and multiplied by the master volume. If for example you have set the volume level for channel 0 to "50" and the volume level for channel 1 to "75", by applying an amplified master volume of "200" you will obtain that channel 0 will have a volume level of "100" and channel 1 a volume level of "150".

For further details about the use of ASIO drivers see the ASIO object section and the How to manage ASIO drivers tutorial.

Syntax

[Visual Basic]

control.ASIO.DeviceMasterVolumeSet (

nDeviceIndex as Integer,

bInputChannel as enumBoolean,

fVolume as Single,

nScaleType as enumVolumeScales

) as enumErrorCodes

[C++]

short control.ASIO.DeviceMasterVolumeSet (

short nDeviceIndex,

short bInputChannel,

float fVolume,

short nScaleType

);

Parameter

Description

nDeviceIndex

Number representing the zero-based index of the ASIO device.

This index is related to available ASIO devices so it must be the related to the enumeration performed through the ASIO.DeviceGetCount and ASIO.DeviceGetDesc methods: it must not be confused with indexes related to generic input devices enumerated through the GetInputDevicesCount and GetInputDeviceDesc methods which may contain both DirectSound and ASIO devices.

bInputChannel

Boolean value that specifies if we need to modify the master volume for input or output channels.

Supported values are the following:

Mnemonic constant	Value	Meaning
BOOL_FALSE	0	Output channel
BOOL_TRUE	1	Input channel

fVolume

New volume expressed in the unit specified by the nScaleType parameter below.

nScaleType

The volume scaling type.

Supported values are the following:

Mnemonic constant

Value

Meaning

SCALE_LINEAR

Volume, expressed in percentage, is based upon a linear scale:

- value 0.0 means that channel is muted

- values higher than 0.0 and smaller than 100.0 attenuate the channel volume

- value 100.0 keeps original sound level unchanged

- values higher than 100.0 amplify the sound level

SCALE_LOG

Volume, expressed in dB, is based upon a logarithmic scale:

- value -100.0 means that channel is muted

- values higher than -100.0 and smaller than 0.0 attenuate the channel volume

- value 0.0 keeps original sound level unchanged

- values higher than 0.0 amplify the sound level

The actual applied formula for converting a linear volume into a logarithmic volume is the following:

VolumeInDB = 20 * log10 (VolumeLinear/100)

The C syntax for converting a logarithmic volume into a linear volume is the following:

VolumeLinear = 100 * pow (10, VolumeInDB/20);

Return value

Value	Meaning

Negative value	An error occurred (see the LastError property for further error details)
enumErrorCodes.ERR_NOERROR (0)	The volume has been changed correctly