feat(main.py): enhance video editor with rendering state checks and logging

croppa/main.py

@@ -460,6 +460,12 @@ class VideoEditor:
         # Try to load saved state for this media file
         if self.load_state():
             print("Loaded saved state for this media file")
+            if self.cut_start_frame is not None:
+                print(f"  Cut start frame: {self.cut_start_frame}")
+            if self.cut_end_frame is not None:
+                print(f"  Cut end frame: {self.cut_end_frame}")
+        else:
+            print("No saved state found for this media file")
 
     def switch_to_video(self, index: int):
         """Switch to a specific video by index"""
@@ -511,6 +517,11 @@ class VideoEditor:
         self, direction: int, shift_pressed: bool, ctrl_pressed: bool
     ):
         """Seek video with different frame counts based on modifiers and seek multiplier"""
+        # Don't allow seeking while rendering to prevent crashes
+        if self.is_rendering():
+            print("Cannot seek while rendering is in progress")
+            return
+            
         if ctrl_pressed:
             base_frames = 60  # Ctrl: 60 frames
         elif shift_pressed:
@@ -1500,7 +1511,7 @@ class VideoEditor:
         """Start video rendering in a separate thread"""
         # Check if already rendering
         if self.render_thread and self.render_thread.is_alive():
-            print("Render already in progress!")
+            print("Render already in progress! Use 'X' to cancel first.")
             return False
         
         # Reset render state
@@ -1515,10 +1526,12 @@ class VideoEditor:
         self.render_thread.start()
         
         print(f"Started rendering to {output_path} in background thread...")
+        print("You can continue editing while rendering. Press 'X' to cancel.")
         return True
     
     def _render_video_worker(self, output_path: str):
         """Worker method that runs in the render thread"""
+        render_cap = None
         try:
             if not output_path.endswith(".mp4"):
                 output_path += ".mp4"
@@ -1528,6 +1541,12 @@ class VideoEditor:
             # Send progress update to main thread
             self.render_progress_queue.put(("init", "Initializing render...", 0.0, 0.0))
 
+            # Create a separate VideoCapture for the render thread to avoid thread safety issues
+            render_cap = cv2.VideoCapture(str(self.video_path))
+            if not render_cap.isOpened():
+                self.render_progress_queue.put(("error", "Could not open video for rendering!", 1.0, 0.0))
+                return False
+
             # Determine frame range
             start_frame = self.cut_start_frame if self.cut_start_frame is not None else 0
             end_frame = (
@@ -1583,9 +1602,9 @@ class VideoEditor:
                     self.render_progress_queue.put(("cancelled", "Render cancelled", 0.0, 0.0))
                     return False
 
-                # Read frame
-                self.cap.set(cv2.CAP_PROP_POS_FRAMES, frame_idx)
-                ret, frame = self.cap.read()
+                # Read frame using the separate VideoCapture
+                render_cap.set(cv2.CAP_PROP_POS_FRAMES, frame_idx)
+                ret, frame = render_cap.read()
 
                 if not ret:
                     break
@@ -1634,9 +1653,20 @@ class VideoEditor:
             return True
 
         except Exception as e:
-            self.render_progress_queue.put(("error", f"Render error: {str(e)}", 1.0, 0.0))
-            print(f"Render error: {e}")
+            error_msg = str(e)
+            # Handle specific FFmpeg threading errors
+            if "async_lock" in error_msg or "pthread_frame" in error_msg:
+                error_msg = "FFmpeg threading error - try restarting the application"
+            elif "Assertion" in error_msg:
+                error_msg = "Video codec error - the video file may be corrupted or incompatible"
+            
+            self.render_progress_queue.put(("error", f"Render error: {error_msg}", 1.0, 0.0))
+            print(f"Render error: {error_msg}")
             return False
+        finally:
+            # Always clean up the render VideoCapture
+            if render_cap:
+                render_cap.release()
     
     def update_render_progress(self):
         """Process progress updates from the render thread"""