VoiceRecordings: add higher-quality audio recording

When recording non-voice audio (e.g. music, FX), a different Opus encoder
application should be specified. It is also recommended to increase the
bitrate to 64-96 kb/s for musical use.

Note: the HQ mode is currently activated when noise suppression is
turned off. This is a very arbitrary condition.

Signed-off-by: László Várady <[email protected]>

src/audio/VoiceRecording.ts

@@ -32,12 +32,26 @@ import mxRecorderWorkletPath from "./RecorderWorklet";
 
 const CHANNELS = 1; // stereo isn't important
 export const SAMPLE_RATE = 48000; // 48khz is what WebRTC uses. 12khz is where we lose quality.
-const BITRATE = 24000; // 24kbps is pretty high quality for our use case in opus.
 const TARGET_MAX_LENGTH = 900; // 15 minutes in seconds. Somewhat arbitrary, though longer == larger files.
 const TARGET_WARN_TIME_LEFT = 10; // 10 seconds, also somewhat arbitrary.
 
 export const RECORDING_PLAYBACK_SAMPLES = 44;
 
+interface RecorderOptions {
+    bitrate: number;
+    encoderApplication: number;
+}
+
+const voiceRecorderOptions: RecorderOptions = {
+    bitrate: 24000,
+    encoderApplication: 2048,
+};
+
+const higQualityRecorderOptions: RecorderOptions = {
+    bitrate: 96000,
+    encoderApplication: 2049,
+};
+
 export interface IRecordingUpdate {
     waveform: number[]; // floating points between 0 (low) and 1 (high).
     timeSeconds: number; // float
@@ -88,6 +102,10 @@ export class VoiceRecording extends EventEmitter implements IDestroyable {
         this.targetMaxLength = null;
     }
 
+    private shouldRecordInHighQuality(): boolean {
+        return !MediaDeviceHandler.getAudioNoiseSuppression();
+    }
+
     private async makeRecorder() {
         try {
             this.recorderStream = await navigator.mediaDevices.getUserMedia({
@@ -137,15 +155,17 @@ export class VoiceRecording extends EventEmitter implements IDestroyable {
                 this.recorderProcessor.addEventListener("audioprocess", this.onAudioProcess);
             }
 
+            const hqRecording = this.shouldRecordInHighQuality();
             this.recorder = new Recorder({
                 encoderPath, // magic from webpack
                 encoderSampleRate: SAMPLE_RATE,
-                encoderApplication: 2048, // voice (default is "audio")
+                encoderApplication: hqRecording ? higQualityRecorderOptions.encoderApplication
+                    : voiceRecorderOptions.encoderApplication,
                 streamPages: true, // this speeds up the encoding process by using CPU over time
                 encoderFrameSize: 20, // ms, arbitrary frame size we send to the encoder
                 numberOfChannels: CHANNELS,
                 sourceNode: this.recorderSource,
-                encoderBitRate: BITRATE,
+                encoderBitRate: hqRecording ? higQualityRecorderOptions.bitrate : voiceRecorderOptions.bitrate,
 
                 // We use low values for the following to ease CPU usage - the resulting waveform
                 // is indistinguishable for a voice message. Note that the underlying library will