AudioParam

The AudioParam interface represents audio-related parameter (such as gain property of GainNode`). It can be set to specific value or schedule value change to happen at specific time, and following specific pattern.

a-rate vs k-rate

• a-rate - takes the current audio parameter value for each sample frame of the audio signal.
• k-rate - uses the same initial audio parameter value for the whole block processed.

Properties

Name	Type	Description
defaultValue	number	Initial value of the parameter.	Read only
minValue	number	Minimum possible value of the parameter.	Read only
maxValue	number	Maximum possible value of the parameter.	Read only
value	number	Current value of the parameter. Initially set to defaultValue.

Methods

setValueAtTime

Schedules an instant change to the value at given startTime.

caution

If you need to call this function many times (especially more than 31 times), it is recommended to use the methods described below (such as linearRampToValueAtTime or exponentialRampToValueAtTime), as they are more efficient for continuous changes. For more specific use cases, you can schedule multiple value changes using setValueCurveAtTime.

Parameter	Type	Description
value	number	A float representing the value the AudioParam will be set at given time
startTime	number	The time, in seconds, at which the change in value is going to happen. If it's smaller than currentTime, it will be clamped to currentTime.

Errors:

Error type	Description
RangeError	startTime is negative number.
NotSupportedError	startTime falls within the interval $[T, T+D)$ where $T$ is the time of previously scheduled setValueCurveAtTime event and $D$ is its duration.

Returns AudioParam.

linearRampToValueAtTime

Schedules a gradual linear change to the new value. The change begins at the time designated for the previous event. It follows a linear ramp to the value, achieving it by the specified endTime.

Parameter	Type	Description
value	number	A float representing the value, the AudioParam will ramp to by given time.
endTime	number	The time, in seconds, at which the value ramp will end. If it's smaller than currentTime, it will be clamped to currentTime.

Errors

Error type	Description
RangeError	endTime is negative number.
NotSupportedError	endTime falls within the interval $[T, T+D)$ where $T$ is the time of previously scheduled setValueCurveAtTime event and $D$ is its duration.

Returns AudioParam.

exponentialRampToValueAtTime

Schedules a gradual exponential change to the new value. The change begins at the time designated for the previous event. It follows an exponential ramp to the value, achieving it by the specified endTime.

Parameter	Type	Description
value	number	A float representing the value the AudioParam will ramp to by given time.
endTime	number	The time, in seconds, at which the value ramp will end. If it's smaller than currentTime, it will be clamped to currentTime.

Errors

Error type	Description
RangeError	endTime is negative number.
NotSupportedError	endTime falls within the interval $[T, T+D)$ where $T$ is the time of previously scheduled setValueCurveAtTime event and $D$ is its duration.

Returns AudioParam.

setTargetAtTime

Schedules a gradual change to the new value at the start time. This method is useful for decay or release portions of ADSR envelopes.

Parameter	Type	Description
target	number	A float representing the value to which the AudioParam will start transitioning.
startTime	number	The time, in seconds, at which exponential transition will begin. If it's smaller than currentTime, it will be clamped to currentTime.
timeConstant	number	A double representing the time-constant value of an exponential approach to the target.

Errors

Error type	Description
RangeError	startTime is negative number.
RangeError	timeConstant is negative number.
NotSupportedError	startTime falls within the interval $[T, T+D)$ where $T$ is the time of previously scheduled setValueCurveAtTime event and $D$ is its duration.

Returns AudioParam.

setValueCurveAtTime

Schedules the parameters's value change following a curve defined by given array.

Parameter	Type	Description
values	Float32Array	The array of values defining a curve, which change will follow.
startTime	number	The time, in seconds, at which change will begin. If it's smaller than currentTime, it will be clamped to currentTime.
duration	number	A double representing total time over which the change will happen.

Errors

Error type	Description
RangeError	startTime is negative number.
NotSupportedError	there are already scheduled events that fall within the interval $(T, T+D)$ where $T$ is the startTime and $D$ is the duration.

Returns AudioParam.

cancelScheduledValues

Cancels all scheduled changes after given cancel time.

Parameter	Type	Description
cancelTime	number	The time, in seconds, after which all scheduled changes will be cancelled. If it's smaller than currentTime, it will be clamped to currentTime.

Errors

Error type	Description
RangeError	cancelTime is negative number.

Returns AudioParam.

cancelAndHoldAtTime

Cancels all scheduled changes after given cancel time, but holds its value at given cancel time until further changes appear.

Parameter	Type	Description
cancelTime	number	The time, in seconds, after which all scheduled changes will be cancelled. If it's smaller than currentTime, it will be clamped to currentTime.

Errors

Error type	Description
RangeError	cancelTime is negative number.

Returns AudioParam.

Remarks

All time parameters should be in the same time coordinate system as BaseAudioContext.currentTime.