Update screenshare logic for svc publishing (#487)

* Update screenshare logic for SVC publishing.

* Handle SVC compatibility with Safari and Chrome prior to M113.

* Update build.gradle

* Update build.yaml

Author: cloudwebrtc

.github/workflows/build.yaml

@@ -55,7 +55,7 @@ jobs:
       - uses: actions/checkout@v2
       - uses: actions/setup-java@v1
         with:
-          java-version: '12.x'
+          java-version: '17.x'
       - uses: actions/checkout@v2
       - uses: subosito/flutter-action@v2
         with:

example/android/app/build.gradle

@@ -26,7 +26,7 @@ apply plugin: 'kotlin-android'
 apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"
 
 android {
-    compileSdkVersion 33
+    compileSdkVersion 34
 
     sourceSets {
         main.java.srcDirs += 'src/main/kotlin'

lib/src/core/transport.dart

@@ -209,31 +209,16 @@ class Transport extends Disposable {
             continue;
           }
 
-          var fmtpFound = false;
           for (var fmtp in media['fmtp']) {
             if (fmtp['payload'] == codecPayload) {
               if (!(fmtp['config'] as String)
                   .contains('x-google-start-bitrate')) {
                 fmtp['config'] +=
                     ';x-google-start-bitrate=${(trackbr.maxbr * startBitrateForSVC).toInt()}';
               }
-              if (!(fmtp['config'] as String)
-                  .contains('x-google-max-bitrate')) {
-                fmtp['config'] += ';x-google-max-bitrate=${trackbr.maxbr}';
-              }
-              fmtpFound = true;
               break;
             }
           }
-
-          if (!fmtpFound) {
-            media['fmtp']?.add({
-              'payload': codecPayload,
-              'config':
-                  'x-google-start-bitrate=${(trackbr.maxbr * startBitrateForSVC).toInt()};x-google-max-bitrate=${trackbr.maxbr}',
-            });
-          }
-
           continue;
         }
       }

lib/src/participant/local.dart

@@ -166,8 +166,7 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
       }
 
       // vp9 svc with screenshare has problem to encode, always use L1T3 here
-      if (track.source == TrackSource.screenShareVideo &&
-          publishOptions.videoCodec.toLowerCase() == 'vp9') {
+      if (track.source == TrackSource.screenShareVideo) {
         publishOptions = publishOptions.copyWith(
           scalabilityMode: 'L1T3',
         );

lib/src/utils.dart

@@ -432,23 +432,23 @@ class Utils {
 
     if (scalabilityMode != null && isSVCCodec(options.videoCodec)) {
       logger.info('using svc with scalabilityMode ${scalabilityMode}');
-
-      //final sm = ScalabilityMode(scalabilityMode);
-
-      List<rtc.RTCRtpEncoding> encodings = [videoEncoding.toRTCRtpEncoding()];
-      /*
-      if (sm.spatial > 3) {
-        throw Exception('unsupported scalabilityMode: ${scalabilityMode}');
+      List<rtc.RTCRtpEncoding> encodings = [];
+      if (lkPlatformIs(PlatformType.web) &&
+          (lkBrowser() == BrowserType.safari ||
+              lkBrowser() == BrowserType.chrome &&
+                  lkBrowserVersion().major < 113)) {
+        final sm = ScalabilityMode(scalabilityMode);
+        for (var i = 0; i < sm.spatial; i += 1) {
+          // in legacy SVC, scaleResolutionDownBy cannot be set
+          encodings.add(rtc.RTCRtpEncoding(
+            rid: videoRids[2 - i],
+            maxBitrate: videoEncoding.maxBitrate ~/ math.pow(3, i),
+            maxFramerate: original.encoding.maxFramerate,
+          ));
+        }
+      } else {
+        encodings.add(videoEncoding.toRTCRtpEncoding());
       }
-      for (int i = 0; i < sm.spatial; i += 1) {
-        encodings.add(rtc.RTCRtpEncoding(
-          rid: videoRids[2 - i],
-          maxBitrate: videoEncoding.maxBitrate ~/ math.pow(3, i),
-          maxFramerate: videoEncoding.maxFramerate,
-          scaleResolutionDownBy: null,
-          numTemporalLayers: sm.temporal.toInt(),
-        ));
-      }*/
       encodings[0].scalabilityMode = scalabilityMode;
       logger.fine('encodings $encodings');
       return encodings;