Ensure that Amazon Voice Focus only receives downmixed mono input. (#…

…1458)

When the SDK requests an audio input, it specifies _ideal_
single-channel input. The browser is not guaranteed to return a mono
stream, and indeed builders can supply a stereo stream from their own
audio sources.

This change ensures that the Web Audio graph will provide a
single-channel mixed input to the node, and thus the processor will
receive only a single array of samples.

Co-authored-by: Trung Le <58827450+ltrung@users.noreply.github.com>

CHANGELOG.md

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Improve the meeting event guide.
 - Fixed Project Board guide with correct community template link.
 - Updated Amazon Voice Focus integration guide to reflect recent Safari versions.
+- Import current Amazon Voice Focus code, which ensures that stereo inputs are downmixed to mono.
 
 ## [2.13.0] - 2021-06-29
 

libs/voicefocus/worklet-inline-node.js

@@ -14,6 +14,8 @@ const types_js_1 = require("./types.js");
 class VoiceFocusInlineNode extends types_js_1.VoiceFocusAudioWorkletNode {
     constructor(context, options) {
         super(context, options.processor, options);
+        this.channelCountMode = 'explicit';
+        this.channelCount = 1;
         const { modelURL, worker, fetchBehavior, logger, } = options;
         this.logger = logger;
         this.port.onmessage = this.onProcessorMessage.bind(this);

libs/voicefocus/worklet-worker-postMessage-node.js

@@ -14,6 +14,8 @@ const types_js_1 = require("./types.js");
 class VoiceFocusWorkerPostMessageNode extends types_js_1.VoiceFocusAudioWorkletNode {
     constructor(context, options) {
         super(context, options.processor, options);
+        this.channelCountMode = 'explicit';
+        this.channelCount = 1;
         const { modelURL, audioBufferURL, worker, fetchBehavior, delegate, } = options;
         this.delegate = delegate;
         this.worker = worker;

libs/voicefocus/worklet-worker-sab-node.js

@@ -23,6 +23,8 @@ const STATES = {
 class VoiceFocusWorkerBufferNode extends types_js_1.VoiceFocusAudioWorkletNode {
     constructor(context, options) {
         super(context, options.processor, options);
+        this.channelCountMode = 'explicit';
+        this.channelCount = 1;
         const { modelURL, resamplerURL, worker, fetchBehavior, delegate, } = options;
         this.delegate = delegate;
         this.worker = worker;