Improve DASH quality preference

Besides `auto`, `best` and `worst` it is now possible to select a target height.
If the target height is not available the closest lower height is selected.

assets/js/player.js

@@ -159,9 +159,26 @@ if (!video_data.params.listen && video_data.params.quality === 'dash') {
         player.ready(() => {
             player.on("loadedmetadata", () => {
                 const qualityLevels = Array.from(player.qualityLevels()).sort((a, b) => a.height - b.height);
-                const targetQualityLevel = video_data.params.quality_dash == "best" ? qualityLevels.length - 1 : 0;
+                let targetQualityLevel;
+                switch (video_data.params.quality_dash) {
+                    case "best":
+                        targetQualityLevel = qualityLevels.length - 1;
+                        break;
+                    case "worst":
+                        targetQualityLevel = 0;
+                        break;
+                    default:
+                        const targetHeight = Number.parseInt(video_data.params.quality_dash, 10);
                         for (let i = 0; i < qualityLevels.length; i++) {
-                    qualityLevels[i].enabled = (i == targetQualityLevel)
+                            if (qualityLevels[i].height <= targetHeight) {
+                                targetQualityLevel = i;
+                            } else {
+                                break;
+                            }
+                        }
+                }
+                for (let i = 0; i < qualityLevels.length; i++) {
+                    qualityLevels[i].enabled = (i == targetQualityLevel);
                 }
             });
         });

src/invidious/views/preferences.ecr

@@ -61,7 +61,7 @@
                 <div class="pure-control-group">
                     <label for="quality_dash"><%= translate(locale, "Preferred dash video quality: ") %></label>
                     <select name="quality_dash" id="quality_dash">
-                        <% {"auto", "best", "worst"}.each do |option| %>
+                        <% {"auto", "best", "4320p", "2160p", "1440p", "1080p", "720p", "480p", "360p", "240p", "144p", "worst"}.each do |option| %>
                             <option value="<%= option %>" <% if preferences.quality_dash == option %> selected <% end %>><%= translate(locale, option) %></option>
                         <% end %>
                     </select>