Set degradationPreference to maintain-resolution for screen share tracks

.changeset/beige-rockets-approve.md

@@ -0,0 +1,5 @@
+---
+"livekit-client": patch
+---
+
+Set degradationPreference to maintain-resolution for screen share tracks

src/room/participant/LocalParticipant.ts

@@ -891,6 +891,20 @@ 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

@@ -169,7 +169,7 @@ export function computeVideoEncodings(
     //      to disable when CPU constrained.
     //      So encodings should be ordered in increasing spatial
     //      resolution order.
-    //   2. ion-sfu translates rids into layers. So, all encodings
+    //   2. livekit-server translates rids into layers. So, all encodings
     //      should have the base layer `q` and then more added
     //      based on other conditions.
     const size = Math.max(width, height);
@@ -241,6 +241,7 @@ export function determineAppropriateEncoding(
       break;
     }
   }
+
   // presets are based on the assumption of vp8 as a codec
   // for other codecs we adjust the maxBitrate if no specific videoEncoding has been provided
   // users should override these with ones that are optimized for their use case