diff --git a/lib/media/media_source_engine.js b/lib/media/media_source_engine.js
index 59e73e0617..2dd1b121b4 100644
--- a/lib/media/media_source_engine.js
+++ b/lib/media/media_source_engine.js
@@ -270,6 +270,11 @@ shaka.media.MediaSourceEngine = class {
     for (const ref of stream.segmentIndex) {
       const mimeType = ref.mimeType || stream.mimeType || '';
       let codecs = ref.codecs || stream.codecs || '';
+      // Optimization for the case where the codecs and mimetype of the stream
+      // match the reference.
+      if (mimeType == stream.mimeType && codecs == stream.codecs) {
+        continue;
+      }
       // Don't check the same combination of mimetype + codecs twice.
       const combo = mimeType + ':' + codecs;
       if (seenCombos.has(combo)) {
diff --git a/lib/util/stream_utils.js b/lib/util/stream_utils.js
index f01a2207f1..0dfbeda86c 100644
--- a/lib/util/stream_utils.js
+++ b/lib/util/stream_utils.js
@@ -461,11 +461,6 @@ shaka.util.StreamUtils = class {
     if (!variantSupported) {
       return false;
     }
-    const ContentType = shaka.util.ManifestParserUtils.ContentType;
-    const Capabilities = shaka.media.Capabilities;
-    const ManifestParserUtils = shaka.util.ManifestParserUtils;
-    const MimeUtils = shaka.util.MimeUtils;
-    const StreamUtils = shaka.util.StreamUtils;
 
     const isXboxOne = shaka.util.Platform.isXboxOne();
     const isFirefoxAndroid = shaka.util.Platform.isFirefox() &&
@@ -483,45 +478,6 @@ shaka.util.StreamUtils = class {
       return false;
     }
 
-    if (video) {
-      let videoCodecs = StreamUtils.getCorrectVideoCodecs(video.codecs);
-      // For multiplexed streams. Here we must check the audio of the
-      // stream to see if it is compatible.
-      if (video.codecs.includes(',')) {
-        const allCodecs = video.codecs.split(',');
-
-        videoCodecs = ManifestParserUtils.guessCodecs(
-            ContentType.VIDEO, allCodecs);
-        videoCodecs = StreamUtils.getCorrectVideoCodecs(videoCodecs);
-        let audioCodecs = ManifestParserUtils.guessCodecs(
-            ContentType.AUDIO, allCodecs);
-        audioCodecs = StreamUtils.getCorrectAudioCodecs(
-            audioCodecs, video.mimeType);
-
-        const audioFullType = MimeUtils.getFullOrConvertedType(
-            video.mimeType, audioCodecs, ContentType.AUDIO);
-
-        if (!Capabilities.isTypeSupported(audioFullType)) {
-          return false;
-        }
-
-        // Update the codec string with the (possibly) converted codecs.
-        videoCodecs = [videoCodecs, audioCodecs].join(',');
-      }
-
-      if (video.codecs != videoCodecs) {
-        const fullType = MimeUtils.getFullOrConvertedType(
-            video.mimeType, videoCodecs, ContentType.VIDEO);
-
-        if (!Capabilities.isTypeSupported(fullType)) {
-          return false;
-        }
-
-        // Update the codec string with the (possibly) converted codecs.
-        video.codecs = videoCodecs;
-      }
-    }
-
     const audio = variant.audio;
 
     // See: https://github.com/shaka-project/shaka-player/issues/6111
@@ -533,22 +489,6 @@ shaka.util.StreamUtils = class {
       return false;
     }
 
-    if (audio) {
-      const codecs = StreamUtils.getCorrectAudioCodecs(
-          audio.codecs, audio.mimeType);
-      if (audio.codecs != codecs) {
-        const fullType = MimeUtils.getFullOrConvertedType(
-            audio.mimeType, codecs, ContentType.AUDIO);
-
-        if (!Capabilities.isTypeSupported(fullType)) {
-          return false;
-        }
-
-        // Update the codec string with the (possibly) converted codecs.
-        audio.codecs = codecs;
-      }
-    }
-
     return true;
   }
 
diff --git a/test/transmuxer/transmuxer_integration.js b/test/transmuxer/transmuxer_integration.js
index 4c7601cb89..400fa9b6f3 100644
--- a/test/transmuxer/transmuxer_integration.js
+++ b/test/transmuxer/transmuxer_integration.js
@@ -340,13 +340,22 @@ describe('Transmuxer Player', () => {
     });
 
     it('H.264+MP3 in TS', async () => {
-      if (!await Util.isTypeSupported('audio/mp4; codecs="mp3"')) {
-        pending('Codec MP3 in MP4 is not supported by the platform.');
+      if (!await Util.isTypeSupported('audio/mp4; codecs="mp3"') &&
+        !await Util.isTypeSupported('audio/mpeg')) {
+        pending('Codec MP3 is not supported by the platform.');
+      }
+      if (!shaka.util.Platform.supportsSequenceMode()) {
+        pending('Sequence mode is not supported by the platform.');
       }
 
       // eslint-disable-next-line max-len
       await player.load('/base/test/test/assets/hls-ts-muxed-mp3-h264/index.m3u8');
-      await video.play();
+      try {
+        await video.play();
+      // eslint-disable-next-line no-restricted-syntax
+      } catch (e) {
+        // Ignore play errors
+      }
       expect(player.isLive()).toBe(false);
 
       // Wait for the video to start playback.  If it takes longer than 10