diff --git a/dom/media/MediaContentType.h b/dom/media/MediaContentType.h
index a45ee41d4462..08821257c0d3 100644
--- a/dom/media/MediaContentType.h
+++ b/dom/media/MediaContentType.h
@@ -17,6 +17,12 @@ namespace mozilla {
 class MediaContentType
 {
 public:
+  explicit MediaContentType(const MediaMIMEType& aType)
+    : mExtendedMIMEType(aType)
+  {}
+  explicit MediaContentType(MediaMIMEType&& aType)
+    : mExtendedMIMEType(Move(aType))
+  {}
   explicit MediaContentType(const MediaExtendedMIMEType& aType)
     : mExtendedMIMEType(aType)
   {
@@ -26,10 +32,11 @@ public:
   {
   }
 
+  const MediaMIMEType& Type() const { return mExtendedMIMEType.Type(); }
   const MediaExtendedMIMEType& ExtendedType() const { return mExtendedMIMEType; }
 
   // MIME "type/subtype". Guaranteed not to be empty.
-  const nsACString& GetMIMEType() const { return mExtendedMIMEType.Type(); }
+  const nsACString& GetMIMEType() const { return mExtendedMIMEType.Type().AsString(); }
 
   // Was there an explicit 'codecs' parameter provided?
   bool HaveCodecs() const { return mExtendedMIMEType.HaveCodecs(); }
diff --git a/dom/media/MediaMIMETypes.cpp b/dom/media/MediaMIMETypes.cpp
index 403ea98603d7..83dbaeb69302 100644
--- a/dom/media/MediaMIMETypes.cpp
+++ b/dom/media/MediaMIMETypes.cpp
@@ -10,6 +10,44 @@
 
 namespace mozilla {
 
+MediaMIMEType::MediaMIMEType(const nsACString& aType)
+  : mMIMEType(aType)
+{
+}
+
+Maybe<MediaMIMEType>
+MakeMediaMIMEType(const nsAString& aType)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  nsContentTypeParser parser(aType);
+  nsAutoString mime;
+  nsresult rv = parser.GetType(mime);
+  if (!NS_SUCCEEDED(rv) || mime.IsEmpty()) {
+    return Nothing();
+  }
+
+  NS_ConvertUTF16toUTF8 mime8{mime};
+
+  return Some(MediaMIMEType(mime8));
+}
+
+Maybe<MediaMIMEType>
+MakeMediaMIMEType(const nsACString& aType)
+{
+  return MakeMediaMIMEType(NS_ConvertUTF8toUTF16(aType));
+}
+
+Maybe<MediaMIMEType>
+MakeMediaMIMEType(const char* aType)
+{
+  if (!aType) {
+    return Nothing();
+  }
+  return MakeMediaMIMEType(nsDependentCString(aType));
+}
+
+
 static int32_t
 GetParameterAsNumber(const nsContentTypeParser& aParser,
                      const char* aParameter,
@@ -32,9 +70,9 @@ MediaExtendedMIMEType::MediaExtendedMIMEType(const nsACString& aMIMEType,
                                              const nsAString& aCodecs,
                                              int32_t aWidth, int32_t aHeight,
                                              int32_t aFramerate, int32_t aBitrate)
-  : mMIMEType(Move(aMIMEType))
+  : mMIMEType(aMIMEType)
   , mHaveCodecs(aHaveCodecs)
-  , mCodecs(Move(aCodecs))
+  , mCodecs(aCodecs)
   , mWidth(aWidth)
   , mHeight(aHeight)
   , mFramerate(aFramerate)
@@ -42,6 +80,16 @@ MediaExtendedMIMEType::MediaExtendedMIMEType(const nsACString& aMIMEType,
 {
 }
 
+MediaExtendedMIMEType::MediaExtendedMIMEType(const MediaMIMEType& aType)
+  : mMIMEType(aType)
+{
+}
+
+MediaExtendedMIMEType::MediaExtendedMIMEType(MediaMIMEType&& aType)
+  : mMIMEType(Move(aType))
+{
+}
+
 Maybe<MediaExtendedMIMEType>
 MakeMediaExtendedMIMEType(const nsAString& aType)
 {
diff --git a/dom/media/MediaMIMETypes.h b/dom/media/MediaMIMETypes.h
index 35c937c3f967..e44564545696 100644
--- a/dom/media/MediaMIMETypes.h
+++ b/dom/media/MediaMIMETypes.h
@@ -12,13 +12,36 @@
 
 namespace mozilla {
 
+// Class containing only pre-parsed lowercase media MIME type/subtype.
+class MediaMIMEType
+{
+public:
+  // MIME "type/subtype", always lowercase.
+  const nsACString& AsString() const { return mMIMEType; }
+
+private:
+  friend Maybe<MediaMIMEType> MakeMediaMIMEType(const nsAString& aType);
+  friend class MediaExtendedMIMEType;
+  explicit MediaMIMEType(const nsACString& aType);
+
+  nsCString mMIMEType; // UTF8 MIME "type/subtype".
+};
+
+Maybe<MediaMIMEType> MakeMediaMIMEType(const nsAString& aType);
+Maybe<MediaMIMEType> MakeMediaMIMEType(const nsACString& aType);
+Maybe<MediaMIMEType> MakeMediaMIMEType(const char* aType);
+
+
 // Class containing pre-parsed media MIME type parameters, e.g.:
 // MIME type/subtype, optional codecs, etc.
 class MediaExtendedMIMEType
 {
 public:
+  explicit MediaExtendedMIMEType(const MediaMIMEType& aType);
+  explicit MediaExtendedMIMEType(MediaMIMEType&& aType);
+
   // MIME "type/subtype".
-  const nsACString& Type() const { return mMIMEType; }
+  const MediaMIMEType& Type() const { return mMIMEType; }
 
   // Was there an explicit 'codecs' parameter provided?
   bool HaveCodecs() const { return mHaveCodecs; }
@@ -43,13 +66,13 @@ private:
     return (aNumber < 0) ? Maybe<int32_t>(Nothing()) : Some(int32_t(aNumber));
   }
 
-  nsCString mMIMEType; // UTF8 MIME type.
-  bool mHaveCodecs; // If false, mCodecs must be empty.
+  MediaMIMEType mMIMEType; // MIME type/subtype.
+  bool mHaveCodecs = false; // If false, mCodecs must be empty.
   nsString mCodecs;
-  int32_t mWidth; // -1 if not provided.
-  int32_t mHeight; // -1 if not provided.
-  int32_t mFramerate; // -1 if not provided.
-  int32_t mBitrate; // -1 if not provided.
+  int32_t mWidth = -1; // -1 if not provided.
+  int32_t mHeight = -1; // -1 if not provided.
+  int32_t mFramerate = -1; // -1 if not provided.
+  int32_t mBitrate = -1; // -1 if not provided.
 };
 
 Maybe<MediaExtendedMIMEType> MakeMediaExtendedMIMEType(const nsAString& aType);