[cli] Fix reporting unusable subtractor options

Author: Breakthrough

dvr_scan/cli/__init__.py

@@ -23,7 +23,7 @@
 
 import dvr_scan
 from dvr_scan.config import CHOICE_MAP, USER_CONFIG_FILE_PATH, ConfigRegistry
-from dvr_scan.platform import get_system_version_info
+from dvr_scan.platform import HAS_MOG2_CUDA, get_system_version_info
 from dvr_scan.region import RegionValidator
 
 # Version string shown for the -v/--version CLI argument.
@@ -41,6 +41,9 @@
 VALID_OUTPUT_MODES = [mode for mode in CHOICE_MAP["output-mode"] if mode != SCAN_ONLY_MODE]
 
 
+BACKGROUND_SUBTRACTORS = ["MOG2", "CNT", "MOG2_CUDA"] if HAS_MOG2_CUDA else ["MOG2", "CNT"]
+
+
 def timecode_type_check(metavar: Optional[str] = None):
     """Creates an argparse type for a user-inputted timecode.
 
@@ -517,14 +520,15 @@ def get_cli_parser(user_config: ConfigRegistry):
         ),
     )
 
+    MOG2_CUDA = ", MOG2_CUDA (Nvidia GPU)" if HAS_MOG2_CUDA else ""
     parser.add_argument(
         "-b",
         "--bg-subtractor",
         metavar="type",
-        type=string_type_check(["MOG2", "CNT", "MOG2_CUDA"], False, "type"),
+        type=string_type_check(BACKGROUND_SUBTRACTORS, False, "type"),
         help=(
             "The type of background subtractor to use, must be one of: "
-            " MOG2 (default), CNT (parallel), MOG2_CUDA (Nvidia GPU).%s"
+            f" MOG2 (default), CNT (parallel){MOG2_CUDA}.%s"
         )
         % user_config.get_help_string("bg-subtractor"),
     )

dvr_scan/cli/controller.py

@@ -16,7 +16,6 @@
 import argparse
 import glob
 import logging
-import sys
 import time
 import typing as ty
 
@@ -182,19 +181,12 @@ def parse_settings(args: ty.List[str] = None) -> ty.Optional[ProgramSettings]:
         logger.error("Error: Unknown background subtraction type: %s", detector_type)
         return None
     if not bg_subtractor.value.is_available():
-        if getattr(sys, "frozen", False) and hasattr(sys, "_MEIPASS"):
-            # This should only happen for MOG2_CUDA (currently).
-            assert bg_subtractor == DetectorType.MOG2_CUDA
-            logger.error(
-                "Method %s is not available. To enable it, use a CUDA-enabled build of DVR-Scan.",
-                bg_subtractor.name,
-            )
+        if bg_subtractor == DetectorType.MOG2_CUDA:
+            logger.error("MOG2_CUDA requires a CUDA-enabled build of the `opencv-python` package!")
         else:
             logger.error(
-                "Method %s is not available. To enable CNT, you can try `pip install "
-                "opencv-contrib-python`. MOG2_CUDA requires building OpenCV with Python and CUDA "
-                "support enabled.",
-                bg_subtractor.name,
+                f"Method {bg_subtractor.name} is not available, you may need to run: "
+                "`pip install opencv-contrib-python`"
             )
         return None
 

dvr_scan/platform.py

@@ -33,9 +33,20 @@
 except ImportError:
     tkinter = None
 
+try:
+    import cv2
+    import cv2.cuda
+
+    HAS_MOG2_CUDA = bool(hasattr(cv2.cuda, "createBackgroundSubtractorMOG2"))
+except:  # noqa: E722
+    # We make sure importing OpenCV succeeds elsewhere so it's okay to suppress any exceptions here.
+    HAS_MOG2_CUDA = False
+
 
 HAS_TKINTER = tkinter is not None
 
+IS_FROZEN = bool(not (getattr(sys, "frozen", False) and hasattr(sys, "_MEIPASS")))
+
 
 def get_min_screen_bounds():
     """Attempts to get the minimum screen resolution of all monitors using the `screeninfo` package.
@@ -181,13 +192,18 @@ def get_system_version_info(separator_width: int = 40) -> str:
             out_lines.append(output_template.format(module_name, not_found_str))
 
     # External Tools
-    out_lines += ["", "Tools", line_separator]
+    out_lines += ["", "Features", line_separator]
 
-    tool_version_info = (("ffmpeg", get_ffmpeg_version()),)
+    ffmpeg_version = get_ffmpeg_version()
+    feature_version_info = [("ffmpeg", ffmpeg_version)] if ffmpeg_version else []
+    feature_version_info += [("tkinter", "Installed")] if HAS_TKINTER else []
+    feature_version_info += [("cv2.cuda", "Installed")] if HAS_MOG2_CUDA else []
 
-    for tool_name, tool_version in tool_version_info:
+    for feature_name, feature_version in feature_version_info:
         out_lines.append(
-            output_template.format(tool_name, tool_version if tool_version else not_found_str)
+            output_template.format(
+                feature_name, feature_version if feature_version else not_found_str
+            )
         )
 
     return "\n".join(out_lines)