blap/apps/web/src/audio/VoiceRecording.ts

/*
Copyright 2024 New Vector Ltd.
Copyright 2021 The Matrix.org Foundation C.I.C.

SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
Please see LICENSE files in the repository root for full details.
*/

import Recorder from "opus-recorder/dist/recorder.min.js";
import encoderPath from "opus-recorder/dist/encoderWorker.min.js";
import { SimpleObservable } from "matrix-widget-api";
import EventEmitter from "events";
import { logger } from "matrix-js-sdk/src/logger";
import { clamp } from "@element-hq/web-shared-components";

import MediaDeviceHandler from "../MediaDeviceHandler";
import { type IDestroyable } from "../utils/IDestroyable";
import { Singleflight } from "../utils/Singleflight";
import { PayloadEvent, WORKLET_NAME } from "./consts";
import { UPDATE_EVENT } from "../stores/AsyncStore";
import { createAudioContext } from "./compat";
import { FixedRollingArray } from "../utils/FixedRollingArray";
import recorderWorkletFactory from "./recorderWorkletFactory";

const CHANNELS = 1; // stereo isn't important
export const SAMPLE_RATE = 48000; // 48khz is what WebRTC uses. 12khz is where we lose quality.
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;
}

export const voiceRecorderOptions: RecorderOptions = {
    bitrate: 24000, // recommended Opus bitrate for high-quality VoIP
    encoderApplication: 2048, // voice
};

export const highQualityRecorderOptions: RecorderOptions = {
    bitrate: 96000, // recommended Opus bitrate for high-quality music/audio streaming
    encoderApplication: 2049, // full band audio
};

export interface IRecordingUpdate {
    waveform: number[]; // floating points between 0 (low) and 1 (high).
    timeSeconds: number; // float
}

export enum RecordingState {
    Started = "started",
    EndingSoon = "ending_soon", // emits an object with a single numerical value: secondsLeft
    Ended = "ended",
    Uploading = "uploading",
    Uploaded = "uploaded",
}

export class VoiceRecording extends EventEmitter implements IDestroyable {
    private recorder?: Recorder;
    private recorderContext?: AudioContext;
    private recorderSource?: MediaStreamAudioSourceNode;
    private recorderStream?: MediaStream;
    private recorderWorklet?: AudioWorkletNode;
    private recorderProcessor?: ScriptProcessorNode;
    private recording = false;
    private observable?: SimpleObservable<IRecordingUpdate>;
    private targetMaxLength: number | null = TARGET_MAX_LENGTH;
    public amplitudes: number[] = []; // at each second mark, generated
    private liveWaveform = new FixedRollingArray(RECORDING_PLAYBACK_SAMPLES, 0);
    public onDataAvailable?: (data: ArrayBuffer) => void;

    public get contentType(): string {
        return "audio/ogg";
    }

    public get durationSeconds(): number {
        if (!this.recorder || !this.recorderContext) throw new Error("Duration not available without a recording");
        return this.recorderContext.currentTime;
    }

    public get isRecording(): boolean {
        return this.recording;
    }

    public emit(event: string, ...args: any[]): boolean {
        super.emit(event, ...args);
        super.emit(UPDATE_EVENT, event, ...args);
        return true; // we don't ever care if the event had listeners, so just return "yes"
    }

    public disableMaxLength(): void {
        this.targetMaxLength = null;
    }

    private shouldRecordInHighQuality(): boolean {
        // Non-voice use case is suspected when noise suppression is disabled by the user.
        // When recording complex audio, higher quality is required to avoid audio artifacts.
        // This is a really arbitrary decision, but it can be refined/replaced at any time.
        return !MediaDeviceHandler.getAudioNoiseSuppression();
    }

    private async makeRecorder(): Promise<void> {
        try {
            const requestedDeviceId = MediaDeviceHandler.getAudioInput();
            const deviceIdConstraint =
                requestedDeviceId && requestedDeviceId !== "default" ? { deviceId: { exact: requestedDeviceId } } : {};

            this.recorderStream = await navigator.mediaDevices.getUserMedia({
                audio: {
                    channelCount: CHANNELS,
                    ...deviceIdConstraint,
                    autoGainControl: { ideal: MediaDeviceHandler.getAudioAutoGainControl() },
                    echoCancellation: { ideal: MediaDeviceHandler.getAudioEchoCancellation() },
                    noiseSuppression: { ideal: MediaDeviceHandler.getAudioNoiseSuppression() },
                },
            });
            this.recorderContext = createAudioContext({
                // latencyHint: "interactive", // we don't want a latency hint (this causes data smoothing)
            });
            this.recorderSource = this.recorderContext.createMediaStreamSource(this.recorderStream);

            // Connect our inputs and outputs
            if (this.recorderContext.audioWorklet) {
                // Set up our worklet. We use this for timing information and waveform analysis: the
                // web audio API prefers this be done async to avoid holding the main thread with math.
                await recorderWorkletFactory(this.recorderContext);

                this.recorderWorklet = new AudioWorkletNode(this.recorderContext, WORKLET_NAME);
                this.recorderSource.connect(this.recorderWorklet);
                this.recorderWorklet.connect(this.recorderContext.destination);

                // Dev note: we can't use `addEventListener` for some reason. It just doesn't work.
                this.recorderWorklet.port.onmessage = (ev) => {
                    switch (ev.data["ev"]) {
                        case PayloadEvent.Timekeep:
                            this.processAudioUpdate(ev.data["timeSeconds"]);
                            break;
                        case PayloadEvent.AmplitudeMark:
                            // Sanity check to make sure we're adding about one sample per second
                            if (ev.data["forIndex"] === this.amplitudes.length) {
                                this.amplitudes.push(ev.data["amplitude"]);
                                this.liveWaveform.pushValue(ev.data["amplitude"]);
                            }
                            break;
                    }
                };
            } else {
                // Safari fallback: use a processor node instead, buffered to 1024 bytes of data
                // like the worklet is.
                this.recorderProcessor = this.recorderContext.createScriptProcessor(1024, CHANNELS, CHANNELS);
                this.recorderSource.connect(this.recorderProcessor);
                this.recorderProcessor.connect(this.recorderContext.destination);
                this.recorderProcessor.addEventListener("audioprocess", this.onAudioProcess);
            }

            const recorderOptions = this.shouldRecordInHighQuality()
                ? highQualityRecorderOptions
                : voiceRecorderOptions;
            const { encoderApplication, bitrate } = recorderOptions;

            this.recorder = new Recorder({
                encoderPath, // magic from webpack
                encoderSampleRate: SAMPLE_RATE,
                encoderApplication: 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,

                // 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
                // pick defaults which prefer the highest possible quality, CPU be damned.
                encoderComplexity: 3, // 0-10, 10 is slow and high quality.
                resampleQuality: 3, // 0-10, 10 is slow and high quality
            });

            // not using EventEmitter here because it leads to detached bufferes
            this.recorder.ondataavailable = (data: ArrayBuffer) => this.onDataAvailable?.(data);
        } catch (e) {
            logger.error("Error starting recording: ", e);
            if (e instanceof DOMException) {
                // Unhelpful DOMExceptions are common - parse them sanely
                logger.error(`${e.name} (${e.code}): ${e.message}`);
            }

            // Clean up as best as possible
            if (this.recorderStream) this.recorderStream.getTracks().forEach((t) => t.stop());
            if (this.recorderSource) this.recorderSource.disconnect();
            if (this.recorder) this.recorder.close();
            if (this.recorderContext) {
                // noinspection ES6MissingAwait - not important that we wait
                this.recorderContext.close();
            }

            throw e; // rethrow so upstream can handle it
        }
    }

    public get liveData(): SimpleObservable<IRecordingUpdate> {
        if (!this.recording || !this.observable) throw new Error("No observable when not recording");
        return this.observable;
    }

    public get isSupported(): boolean {
        return !!Recorder.isRecordingSupported();
    }

    private onAudioProcess = (ev: AudioProcessingEvent): void => {
        this.processAudioUpdate(ev.playbackTime);

        // We skip the functionality of the worklet regarding waveform calculations: we
        // should get that information pretty quick during the playback info.
    };

    private processAudioUpdate = (timeSeconds: number): void => {
        if (!this.recording) return;

        this.observable!.update({
            waveform: this.liveWaveform.value.map((v) => clamp(v, 0, 1)),
            timeSeconds: timeSeconds,
        });

        // Now that we've updated the data/waveform, let's do a time check. We don't want to
        // go horribly over the limit. We also emit a warning state if needed.
        //
        // We use the recorder's perspective of time to make sure we don't cut off the last
        // frame of audio, otherwise we end up with a 14:59 clip (899.68 seconds). This extra
        // safety can allow us to overshoot the target a bit, but at least when we say 15min
        // maximum we actually mean it.
        //
        // In testing, recorder time and worker time lag by about 400ms, which is roughly the
        // time needed to encode a sample/frame.
        //

        if (!this.targetMaxLength) {
            // skip time checks if max length has been disabled
            return;
        }

        const secondsLeft = TARGET_MAX_LENGTH - this.recorderSeconds!;
        if (secondsLeft < 0) {
            // go over to make sure we definitely capture that last frame
            // noinspection JSIgnoredPromiseFromCall - we aren't concerned with it overlapping
            this.stop();
        } else if (secondsLeft <= TARGET_WARN_TIME_LEFT) {
            Singleflight.for(this, "ending_soon").do(() => {
                this.emit(RecordingState.EndingSoon, { secondsLeft });
                return Singleflight.Void;
            });
        }
    };

    /**
     * {@link https://github.com/chris-rudmin/opus-recorder#instance-fields ref for recorderSeconds}
     */
    public get recorderSeconds(): number | undefined {
        if (!this.recorder) return undefined;
        return this.recorder.encodedSamplePosition / 48000;
    }

    public async start(): Promise<void> {
        if (this.recording) {
            throw new Error("Recording already in progress");
        }
        if (this.observable) {
            this.observable.close();
        }
        this.observable = new SimpleObservable<IRecordingUpdate>();
        await this.makeRecorder();
        await this.recorder?.start();
        this.recording = true;
        this.emit(RecordingState.Started);
    }

    public async stop(): Promise<void> {
        return Singleflight.for(this, "stop").do(async (): Promise<void> => {
            if (!this.recording) {
                throw new Error("No recording to stop");
            }

            // Disconnect the source early to start shutting down resources
            await this.recorder!.stop(); // stop first to flush the last frame
            this.recorderSource!.disconnect();
            if (this.recorderWorklet) this.recorderWorklet.disconnect();
            if (this.recorderProcessor) {
                this.recorderProcessor.disconnect();
                this.recorderProcessor.removeEventListener("audioprocess", this.onAudioProcess);
            }

            // close the context after the recorder so the recorder doesn't try to
            // connect anything to the context (this would generate a warning)
            await this.recorderContext!.close();

            // Now stop all the media tracks so we can release them back to the user/OS
            this.recorderStream!.getTracks().forEach((t) => t.stop());

            // Finally do our post-processing and clean up
            this.recording = false;
            await this.recorder!.close();
            this.emit(RecordingState.Ended);
        });
    }

    public destroy(): void {
        // noinspection JSIgnoredPromiseFromCall - not concerned about stop() being called async here
        this.stop();
        this.removeAllListeners();
        this.onDataAvailable = undefined;
        Singleflight.forgetAllFor(this);
        // noinspection JSIgnoredPromiseFromCall - not concerned about being called async here
        this.observable?.close();
    }
}