Opening video with openCV +python

Question

I using python 2.7 and openCV 2.3.1 (win 7). I trying open video file:

stream = cv.VideoCapture("test1.avi")
if stream.isOpened() == False:
print "Cannot open input video!"
exit()

But I have warning:

warning: Error opening file (../../modules/highgui/src/cap_ffmpeg_impl_v2.hpp:394)

If use video camera (stream = cv.VideoCapture(0)), this code works. Any ideas as to what I'm doing wrong? Thanks a lot to all!

Solution 1

Try using cv.CaptureFromFile() instead.

Copy this code if you must: Watch Video in Python with OpenCV.

Solution 2

you can use the new interface of OpenCV (cv2), the object oriented one, which is binded from c++. I find it easier and more readable.

note: if your open a picture with this, the fps doesn't mean anything, so the picture stays still.

import cv2
import sys

try:
    vidFile = cv2.VideoCapture(sys.argv[1])
except:
    print "problem opening input stream"
    sys.exit(1)
if not vidFile.isOpened():
    print "capture stream not open"
    sys.exit(1)

nFrames = int(vidFile.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT)) # one good way of namespacing legacy openCV: cv2.cv.*
print "frame number: %s" %nFrames
fps = vidFile.get(cv2.cv.CV_CAP_PROP_FPS)
print "FPS value: %s" %fps

ret, frame = vidFile.read() # read first frame, and the return code of the function.
while ret:  # note that we don't have to use frame number here, we could read from a live written file.
    print "yes"
    cv2.imshow("frameWindow", frame)
    cv2.waitKey(int(1/fps*1000)) # time to wait between frames, in mSec
    ret, frame = vidFile.read() # read next frame, get next return code