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

Remarks

Obtains the volume for a specific input or output ASIO channel. This volume can be modified through the ASIO.DeviceChannelVolumeSet method.

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.DeviceChannelVolumeGet (

nDeviceIndex as Integer,

nChannelIndex as Integer,

bInputChannel as enumBoolean,

nScaleType as enumVolumeScales

) as Single

[C++]

float control.ASIO.DeviceChannelVolumeGet (

short nDeviceIndex,

short nChannelIndex,

short bInputChannel,

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 output devices enumerated through the GetOutputDevicesCount and GetOutputDeviceDesc methods which may contain both DirectSound and ASIO devices.

nChannelIndex

Number representing the zero-based index of the ASIO channel of interest

bInputChannel

Boolean value that specifies if the nChannelIndex parameter is related to an input or output channel.

Supported values are the following:

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

nScaleType

The volume scaling type.

Supported values are the following:

Mnemonic constant

Value

Meaning

SCALE_LINEAR

Returned 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

Returned 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)
>= 0	The current channel volume