/
Track.ts
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Track.ts
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import {
VideoQuality as ProtoQuality,
StreamState as ProtoStreamState,
TrackSource,
TrackType,
} from '@livekit/protocol';
import { EventEmitter } from 'events';
import type TypedEventEmitter from 'typed-emitter';
import type { SignalClient } from '../../api/SignalClient';
import log, { LoggerNames, StructuredLogger, getLogger } from '../../logger';
import { TrackEvent } from '../events';
import type { LoggerOptions } from '../types';
import { isFireFox, isSafari, isWeb } from '../utils';
import type { TrackProcessor } from './processor/types';
import { getLogContextFromTrack } from './utils';
const BACKGROUND_REACTION_DELAY = 5000;
// keep old audio elements when detached, we would re-use them since on iOS
// Safari tracks which audio elements have been "blessed" by the user.
const recycledElements: Array<HTMLAudioElement> = [];
export enum VideoQuality {
LOW = ProtoQuality.LOW,
MEDIUM = ProtoQuality.MEDIUM,
HIGH = ProtoQuality.HIGH,
}
export abstract class Track<
TrackKind extends Track.Kind = Track.Kind,
> extends (EventEmitter as new () => TypedEventEmitter<TrackEventCallbacks>) {
readonly kind: TrackKind;
attachedElements: HTMLMediaElement[] = [];
isMuted: boolean = false;
source: Track.Source;
/**
* sid is set after track is published to server, or if it's a remote track
*/
sid?: Track.SID;
/**
* @internal
*/
mediaStream?: MediaStream;
/**
* indicates current state of stream, it'll indicate `paused` if the track
* has been paused by congestion controller
*/
streamState: Track.StreamState = Track.StreamState.Active;
protected _mediaStreamTrack: MediaStreamTrack;
protected _mediaStreamID: string;
protected isInBackground: boolean = false;
private backgroundTimeout: ReturnType<typeof setTimeout> | undefined;
private loggerContextCb: LoggerOptions['loggerContextCb'];
protected _currentBitrate: number = 0;
protected monitorInterval?: ReturnType<typeof setInterval>;
protected log: StructuredLogger = log;
protected constructor(
mediaTrack: MediaStreamTrack,
kind: TrackKind,
loggerOptions: LoggerOptions = {},
) {
super();
this.log = getLogger(loggerOptions.loggerName ?? LoggerNames.Track);
this.loggerContextCb = loggerOptions.loggerContextCb;
this.setMaxListeners(100);
this.kind = kind;
this._mediaStreamTrack = mediaTrack;
this._mediaStreamID = mediaTrack.id;
this.source = Track.Source.Unknown;
}
protected get logContext() {
return {
...this.loggerContextCb?.(),
...getLogContextFromTrack(this),
};
}
/** current receive bits per second */
get currentBitrate(): number {
return this._currentBitrate;
}
get mediaStreamTrack() {
return this._mediaStreamTrack;
}
/**
* @internal
* used for keep mediaStream's first id, since it's id might change
* if we disable/enable a track
*/
get mediaStreamID(): string {
return this._mediaStreamID;
}
/**
* creates a new HTMLAudioElement or HTMLVideoElement, attaches to it, and returns it
*/
attach(): HTMLMediaElement;
/**
* attaches track to an existing HTMLAudioElement or HTMLVideoElement
*/
attach(element: HTMLMediaElement): HTMLMediaElement;
attach(element?: HTMLMediaElement): HTMLMediaElement {
let elementType = 'audio';
if (this.kind === Track.Kind.Video) {
elementType = 'video';
}
if (this.attachedElements.length === 0 && Track.Kind.Video) {
this.addAppVisibilityListener();
}
if (!element) {
if (elementType === 'audio') {
recycledElements.forEach((e) => {
if (e.parentElement === null && !element) {
element = e;
}
});
if (element) {
// remove it from pool
recycledElements.splice(recycledElements.indexOf(element), 1);
}
}
if (!element) {
element = <HTMLMediaElement>document.createElement(elementType);
}
}
if (!this.attachedElements.includes(element)) {
this.attachedElements.push(element);
}
// even if we believe it's already attached to the element, it's possible
// the element's srcObject was set to something else out of band.
// we'll want to re-attach it in that case
attachToElement(this.mediaStreamTrack, element);
// handle auto playback failures
const allMediaStreamTracks = (element.srcObject as MediaStream).getTracks();
const hasAudio = allMediaStreamTracks.some((tr) => tr.kind === 'audio');
// manually play media to detect auto playback status
element
.play()
.then(() => {
this.emit(hasAudio ? TrackEvent.AudioPlaybackStarted : TrackEvent.VideoPlaybackStarted);
})
.catch((e) => {
if (e.name === 'NotAllowedError') {
this.emit(hasAudio ? TrackEvent.AudioPlaybackFailed : TrackEvent.VideoPlaybackFailed, e);
} else if (e.name === 'AbortError') {
// commonly triggered by another `play` request, only log for debugging purposes
log.debug(
`${hasAudio ? 'audio' : 'video'} playback aborted, likely due to new play request`,
);
} else {
log.warn(`could not playback ${hasAudio ? 'audio' : 'video'}`, e);
}
// If audio playback isn't allowed make sure we still play back the video
if (
hasAudio &&
element &&
allMediaStreamTracks.some((tr) => tr.kind === 'video') &&
e.name === 'NotAllowedError'
) {
element.muted = true;
element.play().catch(() => {
// catch for Safari, exceeded options at this point to automatically play the media element
});
}
});
this.emit(TrackEvent.ElementAttached, element);
return element;
}
/**
* Detaches from all attached elements
*/
detach(): HTMLMediaElement[];
/**
* Detach from a single element
* @param element
*/
detach(element: HTMLMediaElement): HTMLMediaElement;
detach(element?: HTMLMediaElement): HTMLMediaElement | HTMLMediaElement[] {
try {
// detach from a single element
if (element) {
detachTrack(this.mediaStreamTrack, element);
const idx = this.attachedElements.indexOf(element);
if (idx >= 0) {
this.attachedElements.splice(idx, 1);
this.recycleElement(element);
this.emit(TrackEvent.ElementDetached, element);
}
return element;
}
const detached: HTMLMediaElement[] = [];
this.attachedElements.forEach((elm) => {
detachTrack(this.mediaStreamTrack, elm);
detached.push(elm);
this.recycleElement(elm);
this.emit(TrackEvent.ElementDetached, elm);
});
// remove all tracks
this.attachedElements = [];
return detached;
} finally {
if (this.attachedElements.length === 0) {
this.removeAppVisibilityListener();
}
}
}
stop() {
this.stopMonitor();
this._mediaStreamTrack.stop();
}
protected enable() {
this._mediaStreamTrack.enabled = true;
}
protected disable() {
this._mediaStreamTrack.enabled = false;
}
/* @internal */
abstract startMonitor(signalClient?: SignalClient): void;
/* @internal */
stopMonitor() {
if (this.monitorInterval) {
clearInterval(this.monitorInterval);
}
}
/** @internal */
updateLoggerOptions(loggerOptions: LoggerOptions) {
if (loggerOptions.loggerName) {
this.log = getLogger(loggerOptions.loggerName);
}
if (loggerOptions.loggerContextCb) {
this.loggerContextCb = loggerOptions.loggerContextCb;
}
}
private recycleElement(element: HTMLMediaElement) {
if (element instanceof HTMLAudioElement) {
// we only need to re-use a single element
let shouldCache = true;
element.pause();
recycledElements.forEach((e) => {
if (!e.parentElement) {
shouldCache = false;
}
});
if (shouldCache) {
recycledElements.push(element);
}
}
}
protected appVisibilityChangedListener = () => {
if (this.backgroundTimeout) {
clearTimeout(this.backgroundTimeout);
}
// delay app visibility update if it goes to hidden
// update immediately if it comes back to focus
if (document.visibilityState === 'hidden') {
this.backgroundTimeout = setTimeout(
() => this.handleAppVisibilityChanged(),
BACKGROUND_REACTION_DELAY,
);
} else {
this.handleAppVisibilityChanged();
}
};
protected async handleAppVisibilityChanged() {
this.isInBackground = document.visibilityState === 'hidden';
}
protected addAppVisibilityListener() {
if (isWeb()) {
this.isInBackground = document.visibilityState === 'hidden';
document.addEventListener('visibilitychange', this.appVisibilityChangedListener);
} else {
this.isInBackground = false;
}
}
protected removeAppVisibilityListener() {
if (isWeb()) {
document.removeEventListener('visibilitychange', this.appVisibilityChangedListener);
}
}
}
export function attachToElement(track: MediaStreamTrack, element: HTMLMediaElement) {
let mediaStream: MediaStream;
if (element.srcObject instanceof MediaStream) {
mediaStream = element.srcObject;
} else {
mediaStream = new MediaStream();
}
// check if track matches existing track
let existingTracks: MediaStreamTrack[];
if (track.kind === 'audio') {
existingTracks = mediaStream.getAudioTracks();
} else {
existingTracks = mediaStream.getVideoTracks();
}
if (!existingTracks.includes(track)) {
existingTracks.forEach((et) => {
mediaStream.removeTrack(et);
});
mediaStream.addTrack(track);
}
if (!isSafari() || !(element instanceof HTMLVideoElement)) {
// when in low power mode (applies to both macOS and iOS), Safari will show a play/pause overlay
// when a video starts that has the `autoplay` attribute is set.
// we work around this by _not_ setting the autoplay attribute on safari and instead call `setTimeout(() => el.play(),0)` further down
element.autoplay = true;
}
// In case there are no audio tracks present on the mediastream, we set the element as muted to ensure autoplay works
element.muted = mediaStream.getAudioTracks().length === 0;
if (element instanceof HTMLVideoElement) {
element.playsInline = true;
}
// avoid flicker
if (element.srcObject !== mediaStream) {
element.srcObject = mediaStream;
if ((isSafari() || isFireFox()) && element instanceof HTMLVideoElement) {
// Firefox also has a timing issue where video doesn't actually get attached unless
// performed out-of-band
// Safari 15 has a bug where in certain layouts, video element renders
// black until the page is resized or other changes take place.
// Resetting the src triggers it to render.
// https://developer.apple.com/forums/thread/690523
setTimeout(() => {
element.srcObject = mediaStream;
// Safari 15 sometimes fails to start a video
// when the window is backgrounded before the first frame is drawn
// manually calling play here seems to fix that
element.play().catch(() => {
/** do nothing */
});
}, 0);
}
}
}
/** @internal */
export function detachTrack(track: MediaStreamTrack, element: HTMLMediaElement) {
if (element.srcObject instanceof MediaStream) {
const mediaStream = element.srcObject;
mediaStream.removeTrack(track);
if (mediaStream.getTracks().length > 0) {
element.srcObject = mediaStream;
} else {
element.srcObject = null;
}
}
}
export namespace Track {
export enum Kind {
Audio = 'audio',
Video = 'video',
Unknown = 'unknown',
}
export type SID = string;
export enum Source {
Camera = 'camera',
Microphone = 'microphone',
ScreenShare = 'screen_share',
ScreenShareAudio = 'screen_share_audio',
Unknown = 'unknown',
}
export enum StreamState {
Active = 'active',
Paused = 'paused',
Unknown = 'unknown',
}
export interface Dimensions {
width: number;
height: number;
}
/** @internal */
export function kindToProto(k: Kind): TrackType {
switch (k) {
case Kind.Audio:
return TrackType.AUDIO;
case Kind.Video:
return TrackType.VIDEO;
default:
// FIXME this was UNRECOGNIZED before
return TrackType.DATA;
}
}
/** @internal */
export function kindFromProto(t: TrackType): Kind | undefined {
switch (t) {
case TrackType.AUDIO:
return Kind.Audio;
case TrackType.VIDEO:
return Kind.Video;
default:
return Kind.Unknown;
}
}
/** @internal */
export function sourceToProto(s: Source): TrackSource {
switch (s) {
case Source.Camera:
return TrackSource.CAMERA;
case Source.Microphone:
return TrackSource.MICROPHONE;
case Source.ScreenShare:
return TrackSource.SCREEN_SHARE;
case Source.ScreenShareAudio:
return TrackSource.SCREEN_SHARE_AUDIO;
default:
return TrackSource.UNKNOWN;
}
}
/** @internal */
export function sourceFromProto(s: TrackSource): Source {
switch (s) {
case TrackSource.CAMERA:
return Source.Camera;
case TrackSource.MICROPHONE:
return Source.Microphone;
case TrackSource.SCREEN_SHARE:
return Source.ScreenShare;
case TrackSource.SCREEN_SHARE_AUDIO:
return Source.ScreenShareAudio;
default:
return Source.Unknown;
}
}
/** @internal */
export function streamStateFromProto(s: ProtoStreamState): StreamState {
switch (s) {
case ProtoStreamState.ACTIVE:
return StreamState.Active;
case ProtoStreamState.PAUSED:
return StreamState.Paused;
default:
return StreamState.Unknown;
}
}
}
export type TrackEventCallbacks = {
message: () => void;
muted: (track?: any) => void;
unmuted: (track?: any) => void;
restarted: (track?: any) => void;
ended: (track?: any) => void;
updateSettings: () => void;
updateSubscription: () => void;
audioPlaybackStarted: () => void;
audioPlaybackFailed: (error?: Error) => void;
audioSilenceDetected: () => void;
visibilityChanged: (visible: boolean, track?: any) => void;
videoDimensionsChanged: (dimensions: Track.Dimensions, track?: any) => void;
videoPlaybackStarted: () => void;
videoPlaybackFailed: (error?: Error) => void;
elementAttached: (element: HTMLMediaElement) => void;
elementDetached: (element: HTMLMediaElement) => void;
upstreamPaused: (track: any) => void;
upstreamResumed: (track: any) => void;
trackProcessorUpdate: (processor?: TrackProcessor<Track.Kind, any>) => void;
};