@100mslive/hms-video-store/src/media/tracks/HMSTrack.ts

@100mslive Core SDK which abstracts the complexities of webRTC while providing a reactive store for data management with a unidirectional data flow

import { HMSTrackType } from './HMSTrackType';
import AnalyticsEventFactory from '../../analytics/AnalyticsEventFactory';
import { stringifyMediaStreamTrack } from '../../utils/json';
import HMSLogger from '../../utils/logger';
import { HMSMediaStream } from '../streams';

export type HMSTrackSource = 'regular' | 'screen' | 'plugin' | 'audioplaylist' | 'videoplaylist' | string;

export abstract class HMSTrack {
  /**
   * @internal
   */
  readonly stream: HMSMediaStream;
  source?: HMSTrackSource;
  peerId?: string;
  transceiver?: RTCRtpTransceiver;

  /**
   * @internal to print as a helpful identifier alongside logs
   */
  logIdentifier = '';

  /** The native mediastream track, for local, this changes on mute/unmute(for video),
   * and on device change.
   * @internal */
  nativeTrack: MediaStreamTrack;

  /**
   * Firefox doesn't respect the track id as sent from the backend when calling peerconnection.ontrack callback. This
   * breaks correlation of future track updates from backend. So we're storing the sdp track id as present in the
   * original offer along with the track as well and will let this override the native track id for any correlation
   * purpose.
   * This applies for remote tracks only.
   * @internal */
  private sdpTrackId?: string;

  /**
   * @internal
   * The local track id is changed on mute/unmute or when device id changes, this is abstracted as an internal
   * detail of HMSTrack and the variable is used for this enacapsulation where the first track id is remembered
   * and treated as the fixed track id for this HMSTrack. This simplifies things for the user of the sdk who
   * do not have to worry about changing track IDs.
   * This applies for local tracks only.
   */
  private firstTrackId?: string;

  abstract readonly type: HMSTrackType;

  public get enabled(): boolean {
    return this.nativeTrack.enabled;
  }

  /**
   * firstTrackId => encapsulates change in local track ids
   * sdpTrackId => fixes remote track updates correlation on firefox
   */
  public get trackId(): string {
    return this.firstTrackId || this.sdpTrackId || this.nativeTrack.id;
  }

  getMediaTrackSettings(): MediaTrackSettings {
    return this.nativeTrack.getSettings();
  }

  /**
   * Get performance metrics from attached plugins (e.g., effects SDK).
   * Override in subclasses that support plugins.
   * @returns Object with plugin names as keys and their metrics as values, or undefined
   */
  getPluginsMetrics(): Record<string, Record<string, unknown> | undefined> | undefined {
    return undefined;
  }

  async setEnabled(value: boolean): Promise<void> {
    this.nativeTrack.enabled = value;
  }

  protected constructor(stream: HMSMediaStream, track: MediaStreamTrack, source?: HMSTrackSource) {
    this.stream = stream;
    this.nativeTrack = track;
    this.source = source;
  }

  /**
   * @internal
   */
  setSdpTrackId(sdpTrackId: string) {
    this.sdpTrackId = sdpTrackId;
  }

  /**
   * @internal
   */
  protected setFirstTrackId(trackId: string) {
    this.firstTrackId = trackId;
  }

  isTrackNotPublishing = () => {
    return this.nativeTrack.readyState === 'ended' || this.nativeTrack.muted;
  };

  /**
   * @internal
   * It will send event to analytics when interruption start/stop
   */
  sendInterruptionEvent({ started, reason }: { started: boolean; reason: string }) {
    const track = this.nativeTrack;
    return AnalyticsEventFactory.interruption({
      started,
      type: this.type,
      reason,
      deviceInfo: {
        deviceId: track.getSettings().deviceId,
        groupId: track.getSettings().groupId,
      },
      trackInfo: {
        label: track.label,
        enabled: track.enabled,
        muted: track.muted,
        readyState: track.readyState,
        settings: track.getSettings(),
      },
    });
  }
  /**
   * @internal
   * take care of -
   * 1. https://bugs.chromium.org/p/chromium/issues/detail?id=1232649
   * 2. stopping any tracks
   * 3. plugins related cleanups and stopping
   */
  cleanup() {
    HMSLogger.d('[HMSTrack]', 'Stopping track', this.toString());
    this.nativeTrack?.stop();
  }

  toString() {
    return `{
      streamId: ${this.stream.id};
      peerId: ${this.peerId};
      trackId: ${this.trackId};
      mid: ${this.transceiver?.mid || '-'};
      logIdentifier: ${this.logIdentifier};
      source: ${this.source};
      enabled: ${this.enabled};
      nativeTrack: ${stringifyMediaStreamTrack(this.nativeTrack)};
    }`;
  }
}