diff --git a/lib/media/media_source_engine.js b/lib/media/media_source_engine.js
index b83795d6d9..a3ecdef626 100644
--- a/lib/media/media_source_engine.js
+++ b/lib/media/media_source_engine.js
@@ -705,7 +705,8 @@ shaka.media.MediaSourceEngine = class {
           timestamp = startTime;
         }
       }
-    } else if (shaka.util.TsParser.probe(uint8ArrayData)) {
+    } else if (!mimeType.includes('/mp4') && !mimeType.includes('/webm') &&
+        shaka.util.TsParser.probe(uint8ArrayData)) {
       const tsParser = new shaka.util.TsParser().parse(uint8ArrayData);
       const startTime = tsParser.getStartTime()[contentType];
       if (startTime != null) {