Use a map instead of multiple ternary statements

lib/file-stream.js

@@ -101,13 +101,11 @@ FileStream.prototype.pipe = function (dst) {
 
   // <video> or <audio> tag
   if (dst && (dst.nodeName === 'VIDEO' || dst.nodeName === 'AUDIO')) {
-    var type = self._extname === '.webm'
-      ? 'video/webm; codecs="vorbis,vp8"'
-      : self._extname === '.mp4'
-        ? 'video/mp4; codecs="avc1.42c01e,mp4a.40.2"'
-        : self._extname === '.mp3'
-          ? 'audio/mpeg'
-          : undefined
+    var type = {
+      '.webm': 'video/webm; codecs="vorbis,vp8"',
+      '.mp4': 'video/mp4; codecs="avc1.42c01e,mp4a.40.2"',
+      '.mp3': 'audio/mpeg'
+    }[self._extname]
     return pipe.call(self, new MediaStream(dst, { type: type }))
   } else
     return pipe.call(self, dst)