Add experimental dash support

src/invidious/views/components/player.ecr

@@ -11,6 +11,9 @@
                 <source src="<%= fmt["url"] %>" type='<%= fmt["type"] %>' label="<%= fmt["bitrate"] %>k" selected="<%= i == 0 ? true : false %>">
             <% end %>
         <% else %>
+            <% if params[:quality] == "dash" %>
+                <source src="/api/manifest/dash/id/<%= video.id %>?local=true" type='application/dash+xml' label="dash">
+            <% end %>
             <% fmt_stream.each_with_index do |fmt, i| %>
                 <% if params[:quality] %>
                 <source src="<%= fmt["url"] %>" type='<%= fmt["type"] %>' label="<%= fmt["label"] %>" selected="<%= params[:quality] == fmt["label"].split(" - ")[0] %>">

src/invidious/views/components/player_sources.ecr

@@ -8,4 +8,8 @@
 <script src="/js/videojs-markers.min.js"></script>
 <script src="/js/videojs-share.min.js"></script>
 <script src="/js/videojs-http-streaming.min.js"></script>
+<% if env.get?("user") && env.get("user").as(User).preferences.quality == "dash" %>
+<script src="/js/dash.mediaplayer.min.js"></script>
+<script src="/js/videojs-dash.min.js"></script>
 <script src="/js/videojs-contrib-quality-levels.min.js"></script>
+<% end %>

src/invidious/views/preferences.ecr

@@ -35,7 +35,7 @@ function update_value(element) {
             <div class="pure-control-group">
                 <label for="quality">Preferred video quality: </label>
                 <select name="quality" id="quality">
-                <% {"hd720", "medium", "small"}.each do |option| %>
+                <% {"dash", "hd720", "medium", "small"}.each do |option| %>
                     <option <% if user.preferences.quality == option %> selected <% end %>><%= option %></option>
                 <% end %>
                 </select>