feat: add support for native PGS subtitle rendering without transcodi…

…ng (#2404)

Co-authored-by: Fernando Fernández <ferferga@hotmail.com>

frontend/package.json

@@ -36,6 +36,7 @@
     "fast-equals": "5.0.1",
     "hls.js": "1.5.14",
     "jassub": "1.7.16",
+    "libpgs": "0.4.1",
     "lodash-es": "4.17.21",
     "marked": "14.0.0",
     "sortablejs": "1.15.2",

frontend/src/store/playback-manager.ts

@@ -291,23 +291,23 @@ class PlaybackManagerStore extends CommonStore<PlaybackManagerState> {
           srcLang: sub.Language ?? undefined,
           type: sub.DeliveryMethod ?? SubtitleDeliveryMethod.Drop,
           srcIndex: sub.srcIndex,
-          codec: sub.Codec === null ? undefined : sub.Codec
+          codec: sub.Codec === null ? undefined : sub.Codec?.toLowerCase()
         }));
     }
   }
 
   /**
    * Filters the native subtitles
    *
-   * As our profile requires either SSA or VTT, if it's not SSA it'll be VTT.
+   * As our profile requires either SSA, PGS or VTT, if it's not SSA or PGS it'll be VTT.
    * This is done this way as server sends as "Codec" the initial value of the track, so it can be webvtt, subrip, srt...
    * This is easier to filter out the SSA subs
    */
   public get currentItemVttParsedSubtitleTracks(): PlaybackExternalTrack[] {
     return (
       this.currentItemParsedSubtitleTracks?.filter(
         (sub): sub is PlaybackExternalTrack =>
-          !!sub.codec && sub.codec !== 'ass' && sub.codec !== 'ssa' && !!sub.src
+          !!sub.codec && sub.codec !== 'ass' && sub.codec !== 'ssa' && sub.codec !== 'pgssub' && !!sub.src
       ) ?? []
     );
   }
@@ -323,6 +323,17 @@ class PlaybackManagerStore extends CommonStore<PlaybackManagerState> {
     );
   }
 
+  public get currentItemPgsParsedSubtitleTracks(): PlaybackExternalTrack[] {
+    return (
+      this.currentItemParsedSubtitleTracks?.filter(
+        (sub): sub is PlaybackExternalTrack =>
+          !!sub.codec
+          && (sub.codec === 'pgssub')
+          && !!sub.src
+      ) ?? []
+    );
+  }
+
   public get currentVideoTrack(): MediaStream | undefined {
     if (
       !isNil(this._state.currentMediaSource?.MediaStreams)

frontend/src/store/player-element.ts

@@ -7,6 +7,8 @@
 import JASSUB from 'jassub';
 import jassubWorker from 'jassub/dist/jassub-worker.js?url';
 import jassubWasmUrl from 'jassub/dist/jassub-worker.wasm?url';
+import { PgsRenderer } from 'libpgs';
+import pgssubWorker from 'libpgs/dist/libpgs.worker.js?url';
 import { computed, nextTick, shallowRef, watch } from 'vue';
 import { playbackManager } from './playback-manager';
 import { isArray, isNil, sealed } from '@/utils/validation';
@@ -35,6 +37,7 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
    */
   private readonly _fullscreenVideoRoute = '/playback/video';
   private _jassub: JASSUB | undefined;
+  private _pgssub: PgsRenderer | undefined;
   protected _storeKey = 'playerElement';
 
   public readonly isStretched = computed({
@@ -105,6 +108,30 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
     );
   };
 
+  private readonly _setPgsTrack = (trackSrc: string): void => {
+    if (
+      !this._pgssub
+      && mediaElementRef.value
+      && mediaElementRef.value instanceof HTMLVideoElement
+    ) {
+      this._pgssub = new PgsRenderer({
+        video: mediaElementRef.value,
+        subUrl: trackSrc,
+        workerUrl: pgssubWorker
+      });
+    } else if (this._pgssub) {
+      this._pgssub.loadFromUrl(trackSrc);
+    }
+  };
+
+  private readonly _freePgsTrack = (): void => {
+    if (this._pgssub) {
+      this._pgssub.dispose();
+    }
+
+    this._pgssub = undefined;
+  };
+
   /**
    * Applies the current subtitle from the playbackManager store
    *
@@ -128,6 +155,9 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
     const ass = playbackManager.currentItemAssParsedSubtitleTracks.find(
       sub => sub.srcIndex === playbackManager.currentSubtitleStreamIndex
     );
+    const pgs = playbackManager.currentItemPgsParsedSubtitleTracks.find(
+      sub => sub.srcIndex === playbackManager.currentSubtitleStreamIndex
+    );
     const attachedFonts
       = playbackManager.currentMediaSource?.MediaAttachments?.filter(a =>
         this._isSupportedFont(a.MimeType)
@@ -155,6 +185,7 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
     }
 
     this._freeSsaTrack();
+    this._freePgsTrack();
 
     if (vttIdx !== -1 && mediaElementRef.value.textTracks[vttIdx]) {
       /**
@@ -166,6 +197,11 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
        * If SSA, using Subtitle Opctopus
        */
       this._setSsaTrack(ass.src, attachedFonts);
+    } else if (pgs?.src) {
+      /**
+       * If PGS, using libpgs to render
+       */
+      this._setPgsTrack(pgs.src);
     }
   };
 
@@ -196,6 +232,7 @@ class PlayerElementStore extends CommonStore<PlayerElementState> {
     watch(videoContainerRef, () => {
       if (!videoContainerRef.value) {
         this._freeSsaTrack();
+        this._freePgsTrack();
       }
     }, { flush: 'sync' });
 

frontend/src/utils/playback-profiles/subtitle-profile.ts

@@ -27,6 +27,10 @@ export function getSubtitleProfiles(): SubtitleProfile[] {
     {
       Format: 'ssa',
       Method: SubtitleDeliveryMethod.External
+    },
+    {
+      Format: 'pgssub',
+      Method: SubtitleDeliveryMethod.External
     }
   );