The read-only offset
property of the ConstantSourceNode
interface returns a AudioParam
object indicating the numeric a-rate value which is always returned by the source when asked for the next sample.
While the AudioParam
named offset
is read-only, the value
property within is not. So you can change the value of offset
by setting the value of ConstantSourceNode.offset.value
:
myConstantSourceNode.offset.value = newValue;
Syntax
let offsetParameter = ConstantAudioNode.offset; let offset = ConstantSourceNode.offset.value; ConstantSourceNode.offset.value = newValue;
Value
An AudioParam
object indicating the a-rate value returned for every sample by this node. The default value is 1.0, and its nominal range is -∞ to +∞. To access the value of the parameter, access the parameter's value
property, as shown below in the synta box above.
Example
This example shows how to set up a ConstantSourceNode
so its offset
is used as the input to a pair of GainNode
s; this snippet is derived from the complete example you can find in Controlling multiple parameters with ConstantSourcenode.
gainNode2 = context.createGain(); gainNode3 = context.createGain(); gainNode2.gain.value = gainNode3.gain.value = 0.5; volumeSliderControl.value = gainNode2.gain.value; constantNode = context.createConstantSource(); constantSource.connect(gainNode2.gain); constantSource.connect(gainNode3.gain);
First, the gain nodes are created and configured, and a slider control's value is set to match the gain on the two nodes. Then we create a new ConstantSourceNode
and make it the source for the two gain nodes' GainNode.gain
values. Each of those values is also an AudioParam
.
Let's say we have an event handler (for click
events, in this case) which needs to respond by altering the value of the two gain nodes. With the linkage above in place, that can be done using this simple event handler:
function handleClickEvent(event) { volumeSliderControl.value = constantSource.offset.value; }
All this function has to do is fetch the current value of the slider control we're using to control the paired nodes' gains, then store that value into the ConstantSourceNode
's offset
parameter. That's done by simply changing the contents of its AudioParam.value
property. The two gain nodes quickly adopt the new volume level.
Specifications
Specification | Status | Comment |
---|---|---|
Web Audio API The definition of 'offset' in that specification. |
Working Draft |
Browser compatibility
Feature | Chrome | Edge | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) |
---|---|---|---|---|---|---|
Basic support | 56 | ? | 52 (52) | No support | 43 | ? |
Feature | Android | Edge | Firefox Mobile (Gecko) | Firefox OS (Gecko) | IE Phone | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|---|---|
Basic support | 56 | ? | 52.0 (52) | ? | ? | 43 | ? |