generalize webcam detection with opt.source.isnumeric() (yolov3 #1462)

detect.py

@@ -21,7 +21,7 @@ from utils.torch_utils import select_device, load_classifier, time_synchronized
 def detect(save_img=False):
     out, source, weights, view_img, save_txt, imgsz = \
         opt.output, opt.source, opt.weights, opt.view_img, opt.save_txt, opt.img_size
-    webcam = source == '0' or source.startswith('rtsp') or source.startswith('http') or source.endswith('.txt')
+    webcam = source.isnumeric() or source.startswith('rtsp') or source.startswith('http') or source.endswith('.txt')
 
     # Initialize
     set_logging()

utils/datasets.py

@@ -235,7 +235,7 @@ class LoadStreams:  # multiple IP or RTSP cameras
         for i, s in enumerate(sources):
             # Start the thread to read frames from the video stream
             print('%g/%g: %s... ' % (i + 1, n, s), end='')
-            cap = cv2.VideoCapture(0 if s == '0' else s)
+            cap = cv2.VideoCapture(eval(s) if s.isnumeric() else s)
             assert cap.isOpened(), 'Failed to open %s' % s
             w = int(cap.get(cv2.CAP_PROP_FRAME_WIDTH))
             h = int(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))