Add degradationPreference option for LocalVideoTrack (#1138)

* Add degradationPreference option for LocalVideoTrack

* Create dull-buckets-chew.md

* remove redundant check

.changeset/dull-buckets-chew.md

@@ -0,0 +1,5 @@
+---
+"livekit-client": patch
+---
+
+Add degradationPreference option for LocalVideoTrack

src/room/participant/LocalParticipant.ts

@@ -54,6 +54,7 @@ import { trackPermissionToProto } from './ParticipantTrackPermission';
 import {
   computeTrackBackupEncodings,
   computeVideoEncodings,
+  getDefaultDegradationPreference,
   mediaTrackToLocalTrack,
 } from './publishUtils';
 
@@ -857,6 +858,11 @@ export default class LocalParticipant extends Participant {
 
     track.sender = await this.engine.createSender(track, opts, encodings);
 
+    if (track instanceof LocalVideoTrack) {
+      opts.degradationPreference ??= getDefaultDegradationPreference(track);
+      track.setDegradationPreference(opts.degradationPreference);
+    }
+
     if (encodings) {
       if (isFireFox() && track.kind === Track.Kind.Audio) {
         /* Refer to RFC https://datatracker.ietf.org/doc/html/rfc7587#section-6.1,
@@ -889,20 +895,6 @@ export default class LocalParticipant extends Participant {
       }
     }
 
-    if (track.kind === Track.Kind.Video && track.source === Track.Source.ScreenShare) {
-      // a few of reasons we are forcing this setting without allowing overrides:
-      // 1. without this, Chrome seems to aggressively resize the SVC video stating `quality-limitation: bandwidth` even when BW isn't an issue
-      // 2. since we are overriding contentHint to motion (to workaround L1T3 publishing), it overrides the default degradationPreference to `balanced`
-      try {
-        this.log.debug(`setting degradationPreference to maintain-resolution`);
-        const params = track.sender.getParameters();
-        params.degradationPreference = 'maintain-resolution';
-        await track.sender.setParameters(params);
-      } catch (e) {
-        this.log.warn(`failed to set degradationPreference: ${e}`);
-      }
-    }
-
     await this.engine.negotiate();
 
     if (track instanceof LocalVideoTrack) {

src/room/participant/publishUtils.ts

@@ -19,6 +19,7 @@ import {
   isReactNative,
   isSVCCodec,
   isSafari,
+  unwrapConstraint,
 } from '../utils';
 
 /** @internal */
@@ -440,3 +441,17 @@ export class ScalabilityMode {
     return `L${this.spatial}T${this.temporal}${this.suffix ?? ''}`;
   }
 }
+
+export function getDefaultDegradationPreference(track: LocalVideoTrack): RTCDegradationPreference {
+  // a few of reasons we have different default paths:
+  // 1. without this, Chrome seems to aggressively resize the SVC video stating `quality-limitation: bandwidth` even when BW isn't an issue
+  // 2. since we are overriding contentHint to motion (to workaround L1T3 publishing), it overrides the default degradationPreference to `balanced`
+  if (
+    track.source === Track.Source.ScreenShare ||
+    (track.constraints.height && unwrapConstraint(track.constraints.height) >= 1080)
+  ) {
+    return 'maintain-resolution';
+  } else {
+    return 'balanced';
+  }
+}

src/room/track/LocalTrack.ts

@@ -15,8 +15,17 @@ const defaultDimensionsTimeout = 1000;
 export default abstract class LocalTrack<
   TrackKind extends Track.Kind = Track.Kind,
 > extends Track<TrackKind> {
+  protected _sender?: RTCRtpSender;
+
   /** @internal */
-  sender?: RTCRtpSender;
+  get sender(): RTCRtpSender | undefined {
+    return this._sender;
+  }
+
+  /** @internal */
+  set sender(sender: RTCRtpSender | undefined) {
+    this._sender = sender;
+  }
 
   /** @internal */
   codec?: VideoCodec;

src/room/track/LocalVideoTrack.ts

@@ -53,6 +53,15 @@ export default class LocalVideoTrack extends LocalTrack<Track.Kind.Video> {
   // a missing `getParameter` call.
   private senderLock: Mutex;
 
+  private degradationPreference: RTCDegradationPreference = 'balanced';
+
+  override set sender(sender: RTCRtpSender | undefined) {
+    this._sender = sender;
+    if (this.degradationPreference) {
+      this.setDegradationPreference(this.degradationPreference);
+    }
+  }
+
   /**
    *
    * @param mediaTrack
@@ -273,6 +282,20 @@ export default class LocalVideoTrack extends LocalTrack<Track.Kind.Video> {
     }
   }
 
+  async setDegradationPreference(preference: RTCDegradationPreference) {
+    this.degradationPreference = preference;
+    if (this.sender) {
+      try {
+        this.log.debug(`setting degradationPreference to ${preference}`, this.logContext);
+        const params = this.sender.getParameters();
+        params.degradationPreference = preference;
+        this.sender.setParameters(params);
+      } catch (e: any) {
+        this.log.warn(`failed to set degradationPreference`, { error: e, ...this.logContext });
+      }
+    }
+  }
+
   addSimulcastTrack(
     codec: VideoCodec,
     encodings?: RTCRtpEncodingParameters[],

src/room/track/options.ts

@@ -64,6 +64,11 @@ export interface TrackPublishDefaults {
    */
   scalabilityMode?: ScalabilityMode;
 
+  /**
+   * degradation preference
+   */
+  degradationPreference?: RTCDegradationPreference;
+
   /**
    * Up to two additional simulcast layers to publish in addition to the original
    * Track.

src/room/utils.ts

@@ -491,8 +491,10 @@ export function isVideoCodec(maybeCodec: string): maybeCodec is VideoCodec {
   return videoCodecs.includes(maybeCodec as VideoCodec);
 }
 
-export function unwrapConstraint(constraint: ConstrainDOMString): string {
-  if (typeof constraint === 'string') {
+export function unwrapConstraint(constraint: ConstrainDOMString): string;
+export function unwrapConstraint(constraint: ConstrainULong): number;
+export function unwrapConstraint(constraint: ConstrainDOMString | ConstrainULong): string | number {
+  if (typeof constraint === 'string' || typeof constraint === 'number') {
     return constraint;
   }