[FIX] VideoManager read function failed on multiple videos

scenedetect/video_manager.py

@@ -739,15 +739,18 @@ def read(self):
         if not self._started:
             raise VideoDecoderNotStarted()
 
-        read_frame = False
         if self._curr_cap is not None and self._end_of_video != True:
-            while not read_frame:
+            read_frame, self._last_frame = self._curr_cap.read()
+
+            # Switch to the next capture when the current one is over
+            if not read_frame and self._get_next_cap():
                 read_frame, self._last_frame = self._curr_cap.read()
-                if not read_frame and not self._get_next_cap():
-                    break
-                if self._downscale_factor > 1:
-                    self._last_frame = self._last_frame[
-                        ::self._downscale_factor, ::self._downscale_factor, :]
+
+            # Downscale frame if there was any
+            if read_frame and self._downscale_factor > 1:
+                self._last_frame = self._last_frame[
+                    ::self._downscale_factor, ::self._downscale_factor, :]
+
         if self._end_time is not None and self._curr_time > self._end_time:
             read_frame = False
             self._last_frame = None

tests/test_video_manager.py

@@ -51,6 +51,7 @@
 import pytest
 import cv2
 
+from scenedetect.scene_manager import SceneManager
 # PySceneDetect Library Imports
 from scenedetect.video_manager import VideoManager
 from scenedetect.video_manager import VideoOpenFailure
@@ -281,3 +282,18 @@ def test_multiple_videos(test_video_file):
         # Will release the VideoManagers in vm_list as well.
         video_manager.release()
 
+def test_many_videos_downscale_detect_scenes(test_video_file):
+    """ Test scene detection on multiple videos in VideoManager. """
+
+    NUM_VIDEOS = 3
+    # Open VideoManager with NUM_VIDEOS test videos
+    video_manager = VideoManager([test_video_file] * NUM_VIDEOS)
+    video_manager.set_downscale_factor()
+
+    try:
+        video_manager.start()
+        scene_manager = SceneManager()
+        scene_manager.detect_scenes(frame_source=video_manager)
+    finally:
+        # Will release the VideoManagers in vm_list as well.
+        video_manager.release()