doc: add warning about buffer.slice

.changeset/four-schools-report.md

@@ -0,0 +1,5 @@
+---
+"@livekit/rtc-node": patch
+---
+
+doc: add warning about buffer.slice

packages/livekit-rtc/README.md

@@ -65,9 +65,12 @@ const track = LocalAudioTrack.createAudioTrack('audio', source);
 const options = new TrackPublishOptions();
 options.source = TrackSource.SOURCE_MICROPHONE;
 
-// read file into Uint16Array
+// note: if converting from Uint8Array to Int16Array, *do not* use buffer.slice!
+// it is marked unstable by Node and can cause undefined behaviour, such as massive chunks of
+// noise being added to the end.
+// it is recommended to use buffer.subarray instead.
 const sample = readFileSync(pathToFile);
-var buffer = new Uint16Array(sample.buffer);
+var buffer = new Int16Array(sample.buffer);
 
 await room.localParticipant.publishTrack(track, options);
 await source.captureFrame(new AudioFrame(buffer, 16000, 1, buffer.byteLength / 2));

packages/livekit-rtc/src/audio_frame.ts

@@ -11,6 +11,11 @@ export class AudioFrame {
   channels: number;
   samplesPerChannel: number;
 
+  // note: if converting from Uint8Array to Int16Array, *do not* use buffer.slice!
+  // it is marked unstable by Node and can cause undefined behaviour, such as massive chunks of
+  // noise being added to the end.
+  // it is recommended to use buffer.subarray instead.
+  // XXX(nbsp): add this when writing proper docs
   constructor(data: Int16Array, sampleRate: number, channels: number, samplesPerChannel: number) {
     this.data = data;
     this.sampleRate = sampleRate;