fix: Fix MediaCapabilities polyfill on Playstation 4 (shaka-project#4320

)

Add Playstation 5 detection to the Media Capabilities Polyfill install method.

Fixes shaka-project#4320

lib/polyfill/media_capabilities.js

@@ -37,9 +37,12 @@ shaka.polyfill.MediaCapabilities = class {
     // See: https://github.com/shaka-project/shaka-player/issues/3582
     // TODO: re-evaluate MediaCapabilities in the future versions of PS5
     // Browsers.
+    // Since MediaCapabilities implementation does not exist in PS4 browsers, we
+    // should always install polyfill.
     let canUseNativeMCap = true;
     if (shaka.util.Platform.isApple() ||
         shaka.util.Platform.isPS5() ||
+        shaka.util.Platform.isPS4() ||
         shaka.util.Platform.isChromecast()) {
       canUseNativeMCap = false;
     }

lib/util/platform.js

@@ -198,7 +198,8 @@ shaka.util.Platform = class {
   static isApple() {
     return !!navigator.vendor && navigator.vendor.includes('Apple') &&
         !shaka.util.Platform.isTizen() &&
-        !shaka.util.Platform.isEOS();
+        !shaka.util.Platform.isEOS() &&
+        !shaka.util.Platform.isPS4();
   }
 
   /**
@@ -214,6 +215,13 @@ shaka.util.Platform = class {
     return shaka.util.Platform.userAgentContains_('PlayStation 5');
   }
 
+  /**
+   * Check if the current platform is Playstation 4.
+   */
+  static isPS4() {
+    return shaka.util.Platform.userAgentContains_('PlayStation 4');
+  }
+
   /**
    * Returns a major version number for Safari, or Safari-based iOS browsers.
    *