[backends] Fix MoviePy 2.0 EOF behavior

Skip corrupt video test on MoviePy awaiting Zulko/moviepy#2253

scenedetect/_cli/controller.py

@@ -16,8 +16,10 @@
 import os
 import time
 import typing as ty
+import warnings
 
 from scenedetect._cli.context import CliContext
+from scenedetect.backends import VideoStreamCv2, VideoStreamMoviePy
 from scenedetect.frame_timecode import FrameTimecode
 from scenedetect.platform import get_and_create_path
 from scenedetect.scene_manager import CutList, SceneList, get_scenes_from_cuts
@@ -39,6 +41,11 @@ def run_scenedetect(context: CliContext):
         logger.debug("No input specified.")
         return
 
+    # Suppress warnings when reading past EOF in MoviePy.
+    is_debug = context.config.get_value("global", "verbosity") != "debug"
+    if isinstance(context.video_stream, VideoStreamMoviePy) and not is_debug:
+        warnings.filterwarnings("ignore", module="moviepy")
+
     if context.load_scenes_input:
         # Skip detection if load-scenes was used.
         logger.info("Skipping detection, loading scenes from: %s", context.load_scenes_input)
@@ -49,7 +56,10 @@ def run_scenedetect(context: CliContext):
         logger.info("Loaded %d scenes.", len(scenes))
     else:
         # Perform scene detection on input.
-        scenes, cuts = _detect(context)
+        result = _detect(context)
+        if result is None:
+            return
+        scenes, cuts = result
         scenes = _postprocess_scene_list(context, scenes)
         # Handle -s/--stats option.
         _save_stats(context)
@@ -110,7 +120,7 @@ def _detect(context: CliContext) -> ty.Optional[ty.Tuple[SceneList, CutList]]:
 
     # Handle case where video failure is most likely due to multiple audio tracks (#179).
     # TODO(#380): Ensure this does not erroneusly fire.
-    if num_frames <= 0 and context.video_stream.BACKEND_NAME == "opencv":
+    if num_frames <= 0 and isinstance(context.video_stream, VideoStreamCv2):
         logger.critical(
             "Failed to read any frames from video file. This could be caused by the video"
             " having multiple audio tracks. If so, try installing the PyAV backend:\n"

scenedetect/backends/moviepy.py

@@ -174,32 +174,38 @@ def seek(self, target: Union[FrameTimecode, float, int]):
             SeekError: An error occurs while seeking, or seeking is not supported.
             ValueError: `target` is not a valid value (i.e. it is negative).
         """
+        success = False
         if not isinstance(target, FrameTimecode):
             target = FrameTimecode(target, self.frame_rate)
         try:
-            self._reader.get_frame(target.get_seconds())
+            self._last_frame = self._reader.get_frame(target.get_seconds())
+            if hasattr(self._reader, "last_read") and target >= self.duration:
+                raise SeekError("MoviePy > 2.0 does not have proper EOF semantics.")
+            self._frame_number = min(
+                target.frame_num,
+                FrameTimecode(self._reader.infos["duration"], self.frame_rate).frame_num - 1,
+            )
+            success = True
         except OSError as ex:
-            # Leave the object in a valid state.
-            self.reset()
             # TODO(#380): Other backends do not currently throw an exception if attempting to seek
             # past EOF. We need to ensure consistency for seeking past end of video with respect to
             # errors and behaviour, and should probably gracefully stop at the last frame instead
             # of throwing an exception.
             if target >= self.duration:
                 raise SeekError("Target frame is beyond end of video!") from ex
             raise
-        self._last_frame = self._reader.lastread
-        self._frame_number = min(
-            target.frame_num,
-            FrameTimecode(self._reader.infos["duration"], self.frame_rate).frame_num - 1,
-        )
+        finally:
+            # Leave the object in a valid state on any errors.
+            if not success:
+                self.reset()
 
-    def reset(self):
+    def reset(self, print_infos=False):
         """Close and re-open the VideoStream (should be equivalent to calling `seek(0)`)."""
-        self._reader.initialize()
-        self._last_frame = self._reader.read_frame()
+        self._last_frame = False
+        self._last_frame_rgb = None
         self._frame_number = 0
         self._eof = False
+        self._reader = FFMPEG_VideoReader(self._path, print_infos=print_infos)
 
     def read(self, decode: bool = True, advance: bool = True) -> Union[np.ndarray, bool]:
         """Read and decode the next frame as a np.ndarray. Returns False when video ends.
@@ -213,21 +219,26 @@ def read(self, decode: bool = True, advance: bool = True) -> Union[np.ndarray, b
             If decode = False, a bool indicating if advancing to the the next frame succeeded.
         """
         if not advance:
+            last_frame_valid = self._last_frame is not None and self._last_frame is not False
+            if not last_frame_valid:
+                return False
             if self._last_frame_rgb is None:
                 self._last_frame_rgb = cv2.cvtColor(self._last_frame, cv2.COLOR_BGR2RGB)
             return self._last_frame_rgb
-        if not hasattr(self._reader, "lastread"):
+        if not hasattr(self._reader, "lastread") or self._eof:
             return False
-        # TODO: In Moviepy2.0 this is broken - lastread is updated in-place in some cases.
-        self._last_frame = self._reader.lastread
+        has_last_read = hasattr(self._reader, "last_read")
+        self._last_frame = self._reader.last_read if has_last_read else self._reader.lastread
+        # Read the *next* frame for the following call to read, and to check for EOF.
         frame = self._reader.read_frame()
         if frame is self._last_frame:
             if self._eof:
                 return False
             self._eof = True
         self._frame_number += 1
         if decode:
-            if self._last_frame is not None:
+            last_frame_valid = self._last_frame is not None and self._last_frame is not False
+            if last_frame_valid:
                 self._last_frame_rgb = cv2.cvtColor(self._last_frame, cv2.COLOR_BGR2RGB)
-            return self._last_frame_rgb if not self._eof else False
+                return self._last_frame_rgb
         return not self._eof

tests/test_video_stream.py

@@ -20,6 +20,7 @@
 from dataclasses import dataclass
 from typing import List, Type
 
+import moviepy
 import numpy
 import pytest
 
@@ -41,6 +42,8 @@
 # The warning occurs when reading the last frame, which VideoStreamMoviePy handles gracefully.
 MOVIEPY_WARNING_FILTER = "ignore:.*Using the last valid frame instead.:UserWarning"
 
+MOVIEPY_MAJOR_VERSION = int(moviepy.__version__.split(".")[0])
+
 
 def calculate_frame_delta(frame_a, frame_b, roi=None) -> float:
     if roi:
@@ -354,10 +357,16 @@ def test_corrupt_video(vs_type: Type[VideoStream], corrupt_video_file: str):
     """Test that backend handles video with corrupt frame gracefully with defaults."""
     if vs_type == VideoManager:
         pytest.skip(reason="VideoManager does not support handling corrupt videos.")
+    if vs_type == VideoStreamMoviePy and MOVIEPY_MAJOR_VERSION >= 2:
+        # Due to changes in MoviePy 2.0, loading this file causes an exception to be thrown.
+        # See https://github.com/Zulko/moviepy/pull/2253 for a PR that attempts to more gracefully
+        # handle this case, however even once that is fixed, we will be unable to run this test
+        # on certain versions of MoviePy.
+        pytest.skip(reason="https://github.com/Zulko/moviepy/pull/2253")
 
     stream = vs_type(corrupt_video_file)
 
-    # OpenCV usually fails to read the video at frame 45, so we make sure all backends can
-    # get to 60 without reporting a failure.
+    # OpenCV usually fails to read the video at frame 45, but the remaining frames all seem to
+    # decode just fine. Make sure all backends can get to 60 without reporting a failure.
     for frame in range(60):
         assert stream.read() is not False, "Failed on frame %d!" % frame