all video processing samples use camera as default source (and fallback to synth in case of capture error)

samples/python2/camshift.py

@@ -98,7 +98,7 @@ class App(object):
 if __name__ == '__main__':
     import sys
     try: video_src = sys.argv[1]
-    except: video_src = video.presets['chess']
+    except: video_src = 0
     print help_message
     App(video_src).run()
 

samples/python2/color_histogram.py

@@ -23,8 +23,8 @@ if __name__ == '__main__':
     cv2.createTrackbar('scale', 'hist', hist_scale, 32, set_scale)
 
     try: fn = sys.argv[1]
-    except: fn = 'synth:bg=../cpp/baboon.jpg:class=chess:noise=0.05'
-    cam = video.create_capture(fn)
+    except: fn = 0
+    cam = video.create_capture(fn, fallback='synth:bg=../cpp/baboon.jpg:class=chess:noise=0.05')
 
     while True:
         flag, frame = cam.read()

samples/python2/edge.py

@@ -4,7 +4,7 @@ import sys
 
 if __name__ == '__main__':
     try: fn = sys.argv[1]
-    except: fn = video.presets['chess']
+    except: fn = 0
 
     def nothing(*arg):
         pass

samples/python2/facedetect.py

@@ -25,7 +25,7 @@ if __name__ == '__main__':
     
     args, video_src = getopt.getopt(sys.argv[1:], '', ['cascade=', 'nested-cascade='])
     try: video_src = video_src[0]
-    except: video_src = 'synth:bg=../cpp/lena.jpg:noise=0.05'
+    except: video_src = 0
     args = dict(args)
     cascade_fn = args.get('--cascade', "../../data/haarcascades/haarcascade_frontalface_alt.xml")
     nested_fn  = args.get('--nested-cascade', "../../data/haarcascades/haarcascade_eye.xml")
@@ -33,7 +33,7 @@ if __name__ == '__main__':
     cascade = cv2.CascadeClassifier(cascade_fn)
     nested = cv2.CascadeClassifier(nested_fn)
 
-    cam = create_capture(video_src)
+    cam = create_capture(video_src, fallback='synth:bg=../cpp/lena.jpg:noise=0.05')
 
     while True:
         ret, img = cam.read()

samples/python2/lk_track.py

@@ -77,7 +77,7 @@ class App:
 def main():
     import sys
     try: video_src = sys.argv[1]
-    except: video_src = video.presets['chess']
+    except: video_src = 0
 
     print help_message
     App(video_src).run()

samples/python2/motempl.py

@@ -12,21 +12,21 @@ def draw_motion_comp(vis, (x, y, w, h), angle, color):
     cv2.rectangle(vis, (x, y), (x+w, y+h), (0, 255, 0))
     r = min(w/2, h/2)
     cx, cy = x+w/2, y+h/2
-    angle = angle*3.1415926/180
+    angle = angle*np.pi/180
     cv2.circle(vis, (cx, cy), r, color, 3)
     cv2.line(vis, (cx, cy), (int(cx+np.cos(angle)*r), int(cy+np.sin(angle)*r)), color, 3)
 
 if __name__ == '__main__':
     import sys
     try: video_src = sys.argv[1]
-    except: video_src = 'synth:class=chess:bg=../cpp/lena.jpg:noise=0.01'
+    except: video_src = 0
 
     cv2.namedWindow('motempl')
     visuals = ['input', 'frame_diff', 'motion_hist', 'grad_orient']
     cv2.createTrackbar('visual', 'motempl', 2, len(visuals)-1, nothing)
     cv2.createTrackbar('threshold', 'motempl', DEFAULT_THRESHOLD, 255, nothing)
 
-    cam = video.create_capture(video_src)
+    cam = video.create_capture(video_src, fallback='synth:class=chess:bg=../cpp/lena.jpg:noise=0.01')
     ret, frame = cam.read()
     h, w = frame.shape[:2]
     prev_frame = frame.copy()

samples/python2/opt_flow.py

@@ -47,7 +47,7 @@ if __name__ == '__main__':
     import sys
     print help_message
     try: fn = sys.argv[1]
-    except: fn = video.presets['chess']
+    except: fn = 0
 
     cam = video.create_capture(fn)
     ret, prev = cam.read()

samples/python2/video.py

@@ -39,6 +39,9 @@ class VideoSynthBase(object):
             buf = cv2.add(buf, noise, dtype=cv2.CV_8UC3)
         return True, buf
 
+    def isOpened(self):
+        return True
+
 class Chess(VideoSynthBase):
     def __init__(self, **kw):
         super(Chess, self).__init__(**kw)
@@ -87,34 +90,41 @@ class Chess(VideoSynthBase):
         self.draw_quads(dst, self.black_quads, (10, 10, 10))
 
 
-
 classes = dict(chess=Chess)
 
-def create_capture(source):
-    '''
-      source: <int> or '<int>' or '<filename>' or 'synth:<params>'
-    '''
-    try: source = int(source)
-    except ValueError: pass
-    else:
-        return cv2.VideoCapture(source)
-    source = str(source).strip()
-    if source.startswith('synth'):
-        ss = filter(None, source.split(':'))
-        params = dict( s.split('=') for s in ss[1:] )
-        try: Class = classes[params['class']]
-        except: Class = VideoSynthBase
-
-        return Class(**params)
-    return cv2.VideoCapture(source)
-
-
 presets = dict(
     empty = 'synth:',
     lena = 'synth:bg=../cpp/lena.jpg:noise=0.1',
     chess = 'synth:class=chess:bg=../cpp/lena.jpg:noise=0.1:size=640x480'
 )
 
+
+def create_capture(source = 0, fallback = presets['chess']):
+    '''
+      source: <int> or '<int>' or '<filename>' or 'synth:<params>'
+    '''
+    cap = None
+    try: source = int(source)
+    except ValueError: pass
+    else:
+        cap = cv2.VideoCapture(source)
+    if cap is None:
+        source = str(source).strip()
+        if source.startswith('synth'):
+            ss = filter(None, source.split(':'))
+            params = dict( s.split('=') for s in ss[1:] )
+            try: Class = classes[params['class']]
+            except: Class = VideoSynthBase
+            try: cap = Class(**params)
+            except: pass
+    if cap is None:
+        cap = cv2.VideoCapture(source)
+    if not cap.isOpened():
+        print 'Warning: unable to open video source: ', source
+        if fallback is not None:
+            return create_capture(fallback, None)
+    return cap
+
 if __name__ == '__main__':
     import sys
     import getopt
@@ -127,7 +137,7 @@ if __name__ == '__main__':
     args = dict(args)
     shotdir = args.get('--shotdir', '.')
     if len(sources) == 0:
-        sources = [ presets['chess'] ]
+        sources = [ 0 ]
 
     print 'Press SPACE to save current frame'