feat: PyAV decode path for AV1 rips (AvFrameReader + scenedetect pyav backend); cv2 kept as fallback

anime_facesaver.py

@@ -252,6 +252,61 @@ def face_qualifies(box, frame_shape, min_width, min_height,
     return True
 
 
+class AvFrameReader:
+    """Forward-only frame reader with a cv2.VideoCapture-compatible
+    surface (read/release). PyAV ships its own ffmpeg build with libdav1d:
+    the ffmpeg bundled inside opencv-python has no software AV1 decoder,
+    and Alder Lake-N has no AV1 hw decode, so BD AV1 rips (e.g. SavI0r)
+    decode 0 frames through cv2. scenedetect likewise prefers its pyav
+    backend once av is installed, fixing scene detection on the same files.
+    """
+
+    def __init__(self, path):
+        import av
+        self._c = av.open(path)
+        self._vs = self._c.streams.video[0]
+        self._vs.thread_type = "AUTO"
+        self._iter = self._c.decode(self._vs)
+
+    @property
+    def frame_count(self):
+        vs = self._vs
+        if vs.frames:
+            return int(vs.frames)
+        # MKV headers often leave stream.frames unset; estimate from the
+        # container duration (it is this file's total decode work anyway).
+        dur = self._c.duration  # microseconds, or None
+        if dur and vs.average_rate:
+            return int(float(dur) / 1e6 * float(vs.average_rate))
+        return 0
+
+    def read(self):
+        try:
+            frame = next(self._iter)
+        except StopIteration:
+            return False, None
+        return True, frame.to_ndarray(format="bgr24")
+
+    def release(self):
+        try:
+            self._c.close()
+        except Exception:
+            pass
+
+
+def open_reader(video_path):
+    """PyAV when available (AV1-capable), else plain cv2."""
+    import cv2
+    try:
+        return AvFrameReader(video_path)
+    except ImportError:
+        pass
+    cap = cv2.VideoCapture(video_path)
+    if not cap.isOpened():
+        return None
+    return cap
+
+
 def process_video(video_path, output_dir, args, model, device, draw,
                   output_start=0):
     from scenedetect import open_video, SceneManager, ContentDetector
@@ -260,6 +315,12 @@ def process_video(video_path, output_dir, args, model, device, draw,
 
     try:
         import cv2
+        try:
+            import av  # noqa: F401
+            # scenedetect defaults to backend="opencv", which cannot decode
+            # AV1 in this env; pyav ships its own ffmpeg with libdav1d.
+            video = open_video(video_path, backend="pyav")
+        except ImportError:
             video = open_video(video_path)
         scene_manager = SceneManager()
         scene_manager.add_detector(
@@ -269,11 +330,13 @@ def process_video(video_path, output_dir, args, model, device, draw,
               f"{video_path}: {e}")
         return output_start
 
-    cap = cv2.VideoCapture(video_path)
-    if not cap.isOpened():
+    cap = open_reader(video_path)
+    if cap is None:
         print(f"Error opening video file {video_path}")
         return output_start
 
+    frame_count = getattr(cap, "frame_count", 0)
+    if not frame_count and hasattr(cap, "get"):
         frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT))
 
     try: