The read-only port
property of the AudioWorkletNode
interface returns the associated MessagePort
. It can be used to communicate between the node and its associated AudioWorkletProcessor
.
Note: The port at the other end of the channel is available under the port
property of the processor.
The MessagePort
object that is connecting the AudioWorkletNode
and its associated AudioWorkletProcessor
.
To demonstrate bidirectional communication capabilities, we'll create an AudioWorkletProcessor
, which will output silence and respond to ping requests from its AudioWorkletNode
.
First, we need to define a custom AudioWorkletProcessor
, and register it. Note that this should be done in a separate file.
class PingPongProcessor extends AudioWorkletProcessor {
constructor(...args) {
super(...args);
this.port.onmessage = (e) => {
console.log(e.data);
this.port.postMessage("pong");
};
}
process(inputs, outputs, parameters) {
return true;
}
}
registerProcessor("ping-pong-processor", PingPongProcessor);
Now in our main scripts file we'll load the processor, create an instance of AudioWorkletNode
passing the name of the processor, and connect the node to an audio graph.
const audioContext = new AudioContext();
await audioContext.audioWorklet.addModule("ping-pong-processor.js");
const pingPongNode = new AudioWorkletNode(audioContext, "ping-pong-processor");
setInterval(() => pingPongNode.port.postMessage("ping"), 1000);
pingPongNode.port.onmessage = (e) => console.log(e.data);
pingPongNode.connect(audioContext.destination);
This will output "ping"
and "pong"
strings to the console every second.