Needing some help on integration of the webcam I am getting these errors on ubuntu 15
HIGHGUI ERROR: V4L2: Unable to get property <unknown property="" string="">(7) - Invalid argument
HIGHGUI ERROR: V4L2: Unable to get property <unknown property="" string="">(5) - Invalid argument
import cv2.cv as cv
capture = cv.CaptureFromFile('cartrim.mp4')
capture = cv.CaptureFromCAM(0)
-- Informations about the video --
nbFrames = int(cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_COUNT))
fps = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FPS)
wait = int(1/fps * 1000/20)
width = int(cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_WIDTH))
height = int(cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FRAME_HEIGHT))
For recording
codec = cv.GetCaptureProperty(capture, cv.CV_CAP_PROP_FOURCC)
writer=cv.CreateVideoWriter("img/output.avi", int(codec), int(fps), (width,height), 1) #Create writer with same parameters
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prev_gray = cv.CreateImage((width,height), 8, 1) #Will hold the frame at t-1
gray = cv.CreateImage((width,height), 8, 1) # Will hold the current frame
prevPyr = cv.CreateImage((height / 3, width + 8), 8, cv.CV_8UC1) #Will hold the pyr frame at t-1
currPyr = cv.CreateImage((height / 3, width + 8), 8, cv.CV_8UC1) # idem at t
max_count = 500
qLevel= 0.01
minDist = 10
prev_points = [] #Points at t-1
curr_points = [] #Points at t
lines=[] #To keep all the lines overtime
for f in xrange( nbFrames ):
frame = cv.QueryFrame(capture) #Take a frame of the video
cv.CvtColor(frame, gray, cv.CV_BGR2GRAY) #Convert to gray
output = cv.CloneImage(frame)
prev_points = cv.GoodFeaturesToTrack(gray, None, None, max_count, qLevel, minDist) #Find points on the image
#Calculate the movement using the previous and the current frame using the previous points
curr_points, status, err = cv.CalcOpticalFlowPyrLK(prev_gray, gray, prevPyr, currPyr, prev_points, (10, 10), 3, (cv.CV_TERMCRIT_ITER|cv.CV_TERMCRIT_EPS,20, 0.03), 0)
#If points status are ok and distance not negligible keep the point
k = 0
for i in range(len(curr_points)):
nb = abs( int(prev_points[i][0])-int(curr_points[i][0]) ) + abs( int(prev_points[i][1])-int(curr_points[i][1]) )
if status[i] and nb > 2 :
prev_points[k] = prev_points[i]
curr_points[k] = curr_points[i]
k += 1
prev_points = prev_points[:k]
curr_points = curr_points[:k]
#At the end only interesting points are kept
#Draw all the previously kept lines otherwise they would be lost the next frame
for (pt1, pt2) in lines:
cv.Line(frame, pt1, pt2, (255,255,255))
#Draw the lines between each points at t-1 and t
for prevpoint, point in zip(prev_points,curr_points):
prevpoint = (int(prevpoint[0]),int(prevpoint[1]))
cv.Circle(frame, prevpoint, 25, 255)
point = (int(point[0]),int(point[1]))
#cv.Circle(frame, point, 3, 255)
#cv.Line(frame, prevpoint, point, (255,255,255))
#lines.append((prevpoint,point)) #Append current lines to the lines list
cv.Copy(gray, prev_gray) #Put the current frame prev_gray
prev_points = curr_points
cv.ShowImage("Object Detection", frame)
#cv.WriteFrame(writer, frame)
cv.WaitKey(wait)
