Add max bitrate calculation for AV1 and VP9. (#348)

lib/src/participant/local.dart

@@ -172,6 +172,7 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
       isScreenShare: track.source == TrackSource.screenShareVideo,
       dimensions: dimensions,
       options: publishOptions,
+      codec: publishOptions.videoCodec,
     );
 
     logger.fine('Using encodings: ${encodings?.map((e) => e.toMap())}');

lib/src/types/video_encoding.dart

@@ -26,6 +26,15 @@ class VideoEncoding implements Comparable<VideoEncoding> {
     required this.maxBitrate,
   });
 
+  VideoEncoding copyWith({
+    int? maxFramerate,
+    int? maxBitrate,
+  }) =>
+      VideoEncoding(
+        maxFramerate: maxFramerate ?? this.maxFramerate,
+        maxBitrate: maxBitrate ?? this.maxBitrate,
+      );
+
   @override
   String toString() =>
       '${runtimeType}(maxFramerate: ${maxFramerate}, maxBitrate: ${maxBitrate})';

lib/src/utils.dart

@@ -271,6 +271,7 @@ class Utils {
     required bool isScreenShare,
     required VideoDimensions dimensions,
     required List<VideoParameters> presets,
+    String? codec,
   }) {
     assert(presets.isNotEmpty, 'presets should not be empty');
     VideoEncoding result = presets.first.encoding;
@@ -283,6 +284,26 @@ class Utils {
       if (preset.dimensions.width >= size) 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
+    // NOTE: SVC codec bitrates are inclusive of all scalability layers. while
+    // bitrate for non-SVC codecs does not include other simulcast layers.
+    if (codec != null) {
+      switch (codec) {
+        case 'av1':
+          result =
+              result.copyWith(maxBitrate: (result.maxBitrate * 0.7) as int);
+          break;
+        case 'vp9':
+          result =
+              result.copyWith(maxBitrate: (result.maxBitrate * 0.85) as int);
+          break;
+        default:
+          break;
+      }
+    }
+
     return result;
   }
 
@@ -371,6 +392,7 @@ class Utils {
     required bool isScreenShare,
     VideoDimensions? dimensions,
     VideoPublishOptions? options,
+    String? codec,
   }) {
     options ??= const VideoPublishOptions();
 
@@ -397,6 +419,7 @@ class Utils {
         isScreenShare: isScreenShare,
         dimensions: dimensions,
         presets: presets,
+        codec: codec,
       );
 
       logger.fine('using video encoding', videoEncoding);