fix: Fix audio mime type in multiplexed HLS stream (shaka-project#4241)

lib/util/mime_utils.js

@@ -8,6 +8,7 @@ goog.provide('shaka.util.MimeUtils');
 
 goog.require('shaka.dependencies');
 goog.require('shaka.media.Transmuxer');
+goog.require('shaka.util.ManifestParserUtils');
 
 /**
  * @summary A set of utility functions for dealing with MIME types.
@@ -34,6 +35,8 @@ shaka.util.MimeUtils = class {
   /**
    * Takes a MIME type and a codecs string and produces the full MIME
    * type. If it's a transport stream, convert its codecs to MP4 codecs.
+   * Otherwise for multiplexed content, convert the video MIME types to
+   * their audio equivalents if the content type is audio.
    *
    * @param {string} mimeType
    * @param {string} codecs
@@ -42,13 +45,19 @@ shaka.util.MimeUtils = class {
    */
   static getFullOrConvertedType(mimeType, codecs, contentType) {
     const fullMimeType = shaka.util.MimeUtils.getFullType(mimeType, codecs);
+    const ContentType = shaka.util.ManifestParserUtils.ContentType;
 
-    if (!shaka.dependencies.muxjs() ||
-        !shaka.media.Transmuxer.isTsContainer(fullMimeType)) {
-      return fullMimeType;
+    if (shaka.media.Transmuxer.isTsContainer(fullMimeType)) {
+      if (shaka.dependencies.muxjs()) {
+        return shaka.media.Transmuxer.convertTsCodecs(
+            contentType, fullMimeType);
+      }
+    } else if (contentType == ContentType.AUDIO) {
+      // video/mp2t is the correct mime type for TS audio, so only replace the
+      // word "video" with "audio" for non-TS audio content.
+      return fullMimeType.replace('video', 'audio');
     }
-
-    return shaka.media.Transmuxer.convertTsCodecs(contentType, fullMimeType);
+    return fullMimeType;
   }