From 4192756f3e7f302adf9713d7183a56c3f56161e6 Mon Sep 17 00:00:00 2001
From: CloudWebRTC <duanweiwei1982@gmail.com>
Date: Wed, 1 Nov 2023 15:49:35 +0800
Subject: [PATCH] handling of incompatible published codecs (#391)

* Improve handling of incompatible published codecs.

* revert changes.

* update.

* check mineType.
---
 lib/src/participant/local.dart | 63 +++++++++++++++++++++-------------
 lib/src/utils.dart             | 11 ++++++
 2 files changed, 51 insertions(+), 23 deletions(-)

diff --git a/lib/src/participant/local.dart b/lib/src/participant/local.dart
index f1490ae5..ea409058 100644
--- a/lib/src/participant/local.dart
+++ b/lib/src/participant/local.dart
@@ -193,7 +193,7 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
         'Compute encodings with resolution: ${dimensions}, options: ${publishOptions}');
 
     // Video encodings and simulcasts
-    final encodings = Utils.computeVideoEncodings(
+    var encodings = Utils.computeVideoEncodings(
       isScreenShare: track.source == TrackSource.screenShareVideo,
       dimensions: dimensions,
       options: publishOptions,
@@ -202,6 +202,21 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
 
     logger.fine('Using encodings: ${encodings?.map((e) => e.toMap())}');
 
+    var simulcastCodecs = <lk_rtc.SimulcastCodec>[
+      lk_rtc.SimulcastCodec(
+        codec: publishOptions.videoCodec,
+        cid: track.getCid(),
+      ),
+    ];
+
+    if (publishOptions.backupCodec != null &&
+        publishOptions.backupCodec!.codec != publishOptions.videoCodec) {
+      simulcastCodecs.add(lk_rtc.SimulcastCodec(
+        codec: publishOptions.backupCodec!.codec.toLowerCase(),
+        cid: '',
+      ));
+    }
+
     final layers = Utils.computeVideoLayers(
       dimensions,
       encodings,
@@ -209,28 +224,6 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
     );
 
     logger.fine('Video layers: ${layers.map((e) => e)}');
-    var simulcastCodecs = <lk_rtc.SimulcastCodec>[];
-
-    if (publishOptions.backupCodec != null &&
-        publishOptions.backupCodec!.codec != publishOptions.videoCodec) {
-      simulcastCodecs = <lk_rtc.SimulcastCodec>[
-        lk_rtc.SimulcastCodec(
-          codec: publishOptions.videoCodec,
-          cid: track.getCid(),
-        ),
-        lk_rtc.SimulcastCodec(
-          codec: publishOptions.backupCodec!.codec.toLowerCase(),
-          cid: '',
-        ),
-      ];
-    } else {
-      simulcastCodecs = <lk_rtc.SimulcastCodec>[
-        lk_rtc.SimulcastCodec(
-          codec: publishOptions.videoCodec,
-          cid: track.getCid(),
-        ),
-      ];
-    }
 
     final trackInfo = await room.engine.addTrack(
       cid: track.getCid(),
@@ -250,6 +243,30 @@ class LocalParticipant extends Participant<LocalTrackPublication> {
 
     await track.start();
 
+    String? primaryCodecMime;
+    for (var codec in trackInfo.codecs) {
+      primaryCodecMime ??= codec.mimeType;
+    }
+
+    if (primaryCodecMime != null) {
+      final updatedCodec = mimeTypeToVideoCodecString(primaryCodecMime);
+      if (updatedCodec != publishOptions.videoCodec) {
+        logger.fine(
+          'requested a different codec than specified by serverRequested: ${publishOptions.videoCodec}, server: ${updatedCodec}',
+        );
+        publishOptions = publishOptions.copyWith(
+          videoCodec: updatedCodec,
+        );
+        // recompute encodings since bitrates/etc could have changed
+        encodings = Utils.computeVideoEncodings(
+          isScreenShare: track.source == TrackSource.screenShareVideo,
+          dimensions: dimensions,
+          options: publishOptions,
+          codec: publishOptions.videoCodec,
+        );
+      }
+    }
+
     final transceiverInit = rtc.RTCRtpTransceiverInit(
       direction: rtc.TransceiverDirection.SendOnly,
       sendEncodings: encodings,
diff --git a/lib/src/utils.dart b/lib/src/utils.dart
index 7c2cc255..cb72ba62 100644
--- a/lib/src/utils.dart
+++ b/lib/src/utils.dart
@@ -620,3 +620,14 @@ class ScalabilityMode {
     return 'L${spatial}T${temporal}${suffix ?? ''}';
   }
 }
+
+String mimeTypeToVideoCodecString(String mimeType) {
+  if (!mimeType.contains('/') && mimeType.split('/').length != 2) {
+    throw Exception('Invalid mimeType: $mimeType');
+  }
+  final codec = mimeType.split('/')[1].toLowerCase();
+  if (!videoCodecs.contains(codec)) {
+    throw Exception('Video codec not supported: $codec');
+  }
+  return codec;
+}