fix: Reject Opus encrypted on Firefox Android (#6115)

Fixes #6111

lib/util/platform.js

@@ -220,6 +220,15 @@ shaka.util.Platform = class {
            !shaka.util.Platform.isLegacyEdge();
   }
 
+  /**
+   * Check if the current platform is Firefox.
+   *
+   * @return {boolean}
+   */
+  static isFirefox() {
+    return shaka.util.Platform.userAgentContains_('Firefox');
+  }
+
   /**
    * Check if the current platform is from Apple.
    *
@@ -422,6 +431,15 @@ shaka.util.Platform = class {
     return navigator.platform.toLowerCase().includes('windows');
   }
 
+  /**
+   * Return true if the platform is a Android, regardless of the browser.
+   *
+   * @return {boolean}
+   */
+  static isAndroid() {
+    return shaka.util.Platform.userAgentContains_('Android');
+  }
+
   /**
    * Check if the user agent contains a key. This is the best way we know of
    * right now to detect platforms. If there is a better way, please send a

lib/util/stream_utils.js

@@ -370,6 +370,9 @@ shaka.util.StreamUtils = class {
     const StreamUtils = shaka.util.StreamUtils;
     const isXboxOne = shaka.util.Platform.isXboxOne();
 
+    const isFirefoxAndroid = shaka.util.Platform.isFirefox() &&
+        shaka.util.Platform.isAndroid();
+
     manifest.variants = manifest.variants.filter((variant) => {
       // See: https://github.com/shaka-project/shaka-player/issues/3860
       const video = variant.video;
@@ -425,6 +428,17 @@ shaka.util.StreamUtils = class {
 
       const audio = variant.audio;
 
+      // See: https://github.com/shaka-project/shaka-player/issues/6111
+      // It seems that Firefox Android reports that it supports
+      // Opus + Widevine, but it is not actually supported.
+      // It makes sense to drop early.
+      if (isFirefoxAndroid && audio && audio.encrypted &&
+          audio.codecs.toLowerCase().includes('opus')) {
+        shaka.log.debug('Dropping variant - not compatible with platform',
+            StreamUtils.getVariantSummaryString_(variant));
+        return false;
+      }
+
       if (audio) {
         const codecs = StreamUtils.getCorrectAudioCodecs_(audio.codecs);
         const fullType = MimeUtils.getFullOrConvertedType(