fix(TPC) Set maxbitrates via b=AS line on the remote SDP as well.

This fixes an issue where the bitrates for screenshare were much higher than before for VP9 causing the JVB to suspend SS streams more often.

modules/RTC/TraceablePeerConnection.js

@@ -2359,16 +2359,20 @@ TraceablePeerConnection.prototype._initializeDtlsTransport = function() {
  * Sets the max bitrates on the video m-lines when VP9 is the selected codec.
  *
  * @param {RTCSessionDescription} description - The local description that needs to be munged.
+ * @param {boolean} isLocalSdp - Whether the max bitrate (via b=AS line in SDP) is set on local SDP.
  * @returns RTCSessionDescription
  */
-TraceablePeerConnection.prototype._setVp9MaxBitrates = function(description) {
+TraceablePeerConnection.prototype._setVp9MaxBitrates = function(description, isLocalSdp = false) {
     if (!this.codecPreference) {
         return description;
     }
 
     const parsedSdp = transform.parse(description.sdp);
+
+    // Find all the m-lines associated with the local sources.
+    const direction = isLocalSdp ? MediaDirection.RECVONLY : MediaDirection.SENDONLY;
     const mLines = FeatureFlags.isMultiStreamSupportEnabled()
-        ? parsedSdp.media.filter(m => m.type === MediaType.VIDEO && m.direction !== MediaDirection.RECVONLY)
+        ? parsedSdp.media.filter(m => m.type === MediaType.VIDEO && m.direction !== direction)
         : [ parsedSdp.media.find(m => m.type === MediaType.VIDEO) ];
 
     // Find the mid associated with the desktop track so that bitrates can be configured accordingly on the
@@ -2393,8 +2397,7 @@ TraceablePeerConnection.prototype._setVp9MaxBitrates = function(description) {
     };
 
     for (const mLine of mLines) {
-        if (this.codecPreference.mimeType === CodecMimeType.VP9
-            && this.getConfiguredVideoCodec() === CodecMimeType.VP9) {
+        if (this.codecPreference.mimeType === CodecMimeType.VP9) {
             const bitrates = this.tpcUtils.videoBitrates.VP9 || this.tpcUtils.videoBitrates;
             const hdBitrate = bitrates.high ? bitrates.high : HD_BITRATE;
             const mid = mLine.mid;
@@ -2470,7 +2473,7 @@ TraceablePeerConnection.prototype.setLocalDescription = function(description) {
 
     // Munge the order of the codecs based on the preferences set through config.js.
     localDescription = this._mungeCodecOrder(localDescription);
-    localDescription = this._setVp9MaxBitrates(localDescription);
+    localDescription = this._setVp9MaxBitrates(localDescription, true);
 
     this.trace('setLocalDescription::postTransform', dumpSDP(localDescription));
 
@@ -2564,6 +2567,7 @@ TraceablePeerConnection.prototype.setRemoteDescription = function(description) {
 
     // Munge the order of the codecs based on the preferences set through config.js.
     remoteDescription = this._mungeCodecOrder(remoteDescription);
+    remoteDescription = this._setVp9MaxBitrates(remoteDescription);
     this.trace('setRemoteDescription::postTransform (munge codec order)', dumpSDP(remoteDescription));
 
     return new Promise((resolve, reject) => {

types/auto/modules/RTC/TraceablePeerConnection.d.ts

@@ -656,9 +656,10 @@ export default class TraceablePeerConnection {
      * Sets the max bitrates on the video m-lines when VP9 is the selected codec.
      *
      * @param {RTCSessionDescription} description - The local description that needs to be munged.
+     * @param {boolean} isLocalSdp - Whether the max bitrate (via b=AS line in SDP) is set on local SDP.
      * @returns RTCSessionDescription
      */
-    _setVp9MaxBitrates(description: RTCSessionDescription): RTCSessionDescription;
+    _setVp9MaxBitrates(description: RTCSessionDescription, isLocalSdp?: boolean): RTCSessionDescription;
     /**
      * Configures the stream encodings depending on the video type and the bitrates configured.
      *