Fix: Implement lazy DRM loading for multi-track key retrieval

- Add deferred DRM loading to M3U8 parser to mark tracks for later processing
- Optimize prepare_drm to load DRM just-in-time during download process

unshackle/core/manifests/m3u8.py

@@ -2,17 +2,11 @@
 
 from __future__ import annotations
 
-from typing import Optional, Union
+from typing import Optional
 
-import httpx
 import m3u8
-from pyplayready.cdm import Cdm as PlayReadyCdm
-from pyplayready.system.pssh import PSSH as PR_PSSH
-from pywidevine.cdm import Cdm as WidevineCdm
-from pywidevine.pssh import PSSH as WV_PSSH
 from requests import Session
 
-from unshackle.core.drm import PlayReady, Widevine
 from unshackle.core.manifests.hls import HLS
 from unshackle.core.tracks import Tracks
 
@@ -21,54 +15,17 @@ def parse(
     master: m3u8.M3U8,
     language: str,
     *,
-    session: Optional[Union[Session, httpx.Client]] = None,
+    session: Optional[Session] = None,
 ) -> Tracks:
-    """Parse a variant playlist to ``Tracks`` with DRM information."""
+    """Parse a variant playlist to ``Tracks`` with basic information, defer DRM loading."""
     tracks = HLS(master, session=session).to_tracks(language)
 
-    need_wv = not any(isinstance(d, Widevine) for t in tracks for d in (t.drm or []))
-    need_pr = not any(isinstance(d, PlayReady) for t in tracks for d in (t.drm or []))
+    bool(master.session_keys or HLS.parse_session_data_keys(master, session or Session()))
 
-    if (need_wv or need_pr) and tracks.videos:
-        if not session:
-            session = Session()
-
-        session_keys = list(master.session_keys or [])
-        session_keys.extend(HLS.parse_session_data_keys(master, session))
-
-        for drm_obj in HLS.get_all_drm(session_keys):
-            if need_wv and isinstance(drm_obj, Widevine):
-                for t in tracks.videos + tracks.audio:
-                    t.drm = [d for d in (t.drm or []) if not isinstance(d, Widevine)] + [drm_obj]
-                need_wv = False
-            elif need_pr and isinstance(drm_obj, PlayReady):
-                for t in tracks.videos + tracks.audio:
-                    t.drm = [d for d in (t.drm or []) if not isinstance(d, PlayReady)] + [drm_obj]
-                need_pr = False
-            if not need_wv and not need_pr:
-                break
-
-    if (need_wv or need_pr) and tracks.videos:
-        first_video = tracks.videos[0]
-        playlist = m3u8.load(first_video.url)
-        for key in playlist.keys or []:
-            if not key or not key.keyformat:
-                continue
-            fmt = key.keyformat.lower()
-            if need_wv and fmt == WidevineCdm.urn:
-                pssh_b64 = key.uri.split(",")[-1]
-                drm = Widevine(pssh=WV_PSSH(pssh_b64))
-                for t in tracks.videos + tracks.audio:
-                    t.drm = [d for d in (t.drm or []) if not isinstance(d, Widevine)] + [drm]
-                need_wv = False
-            elif need_pr and (fmt == PlayReadyCdm or "com.microsoft.playready" in fmt):
-                pssh_b64 = key.uri.split(",")[-1]
-                drm = PlayReady(pssh=PR_PSSH(pssh_b64), pssh_b64=pssh_b64)
-                for t in tracks.videos + tracks.audio:
-                    t.drm = [d for d in (t.drm or []) if not isinstance(d, PlayReady)] + [drm]
-                need_pr = False
-            if not need_wv and not need_pr:
-                break
+    if True:
+        for t in tracks.videos + tracks.audio:
+            t.needs_drm_loading = True
+            t.session = session
 
     return tracks
 

unshackle/core/tracks/track.py

@@ -473,6 +473,83 @@ class Track:
                 if tenc.key_ID.int != 0:
                     return tenc.key_ID
 
+    def load_drm_if_needed(self, service=None) -> bool:
+        """
+        Load DRM information for this track if it was deferred during parsing.
+
+        Args:
+            service: Service instance that can fetch track-specific DRM info
+
+        Returns:
+            True if DRM was loaded or already present, False if failed
+        """
+        if not getattr(self, "needs_drm_loading", False):
+            return bool(self.drm)
+
+        if self.drm:
+            self.needs_drm_loading = False
+            return True
+
+        if not service or not hasattr(service, "get_track_drm"):
+            return self.load_drm_from_playlist()
+
+        try:
+            track_drm = service.get_track_drm(self)
+            if track_drm:
+                self.drm = track_drm if isinstance(track_drm, list) else [track_drm]
+                self.needs_drm_loading = False
+                return True
+        except Exception as e:
+            raise ValueError(f"Failed to load DRM from service for track {self.id}: {e}")
+
+        return self.load_drm_from_playlist()
+
+    def load_drm_from_playlist(self) -> bool:
+        """
+        Fallback method to load DRM by fetching this track's individual playlist.
+        """
+        if self.drm:
+            self.needs_drm_loading = False
+            return True
+
+        try:
+            import m3u8
+            from pyplayready.cdm import Cdm as PlayReadyCdm
+            from pyplayready.system.pssh import PSSH as PR_PSSH
+            from pywidevine.cdm import Cdm as WidevineCdm
+            from pywidevine.pssh import PSSH as WV_PSSH
+
+            session = getattr(self, "session", None) or Session()
+
+            response = session.get(self.url)
+            playlist = m3u8.loads(response.text, self.url)
+
+            drm_list = []
+
+            for key in playlist.keys or []:
+                if not key or not key.keyformat:
+                    continue
+
+                fmt = key.keyformat.lower()
+                if fmt == WidevineCdm.urn:
+                    pssh_b64 = key.uri.split(",")[-1]
+                    drm = Widevine(pssh=WV_PSSH(pssh_b64))
+                    drm_list.append(drm)
+                elif fmt == PlayReadyCdm or "com.microsoft.playready" in fmt:
+                    pssh_b64 = key.uri.split(",")[-1]
+                    drm = PlayReady(pssh=PR_PSSH(pssh_b64), pssh_b64=pssh_b64)
+                    drm_list.append(drm)
+
+            if drm_list:
+                self.drm = drm_list
+                self.needs_drm_loading = False
+                return True
+
+        except Exception as e:
+            raise ValueError(f"Failed to load DRM from playlist for track {self.id}: {e}")
+
+        return False
+
     def get_init_segment(
         self,
         maximum_size: int = 20000,