I have the following code, which it just created a video of a set length recorded from a camera (USB camera connected to the computer):
##############################################################################
# Reads from the cam and makes a video until user press q or timeout
##############################################################################
import cv2
import threading
import time, random, string, sys
class RecordVideo():
def __init__(self, user_time):
self.duration = user_time
def random_filename(self, size):
''' to create random names for the dataset pictures '''
w = ''.join(random.choice(string.ascii_lowercase) for i in range(size))
return w+'.avi'
def kill_video(self, event, time_to_wait):
'''Waits for time_wait time. Then sets and event so that the timeout
is marked and the video recording stops'''
time.sleep(time_to_wait+1) # cam always takes around 1s to warm up
event.set()
def record_video(self, filename):
vc = cv2.VideoCapture(2)
vc.set(cv2.CAP_PROP_FRAME_WIDTH, 1024) #frame resolution for CA
vc.set(cv2.CAP_PROP_FRAME_HEIGHT, 576)
cv2.namedWindow("video")
fourcc = cv2.VideoWriter_fourcc(*'X264')
random_name = self.random_filename(1)
out = cv2.VideoWriter(filename+random_name, fourcc, 15.0, (1024,576))
event = threading.Event()
if self.duration > 0:
timer = threading.Thread(target=self.kill_video,
args=(event,self.duration))
timer.start()
frame_counter = 0
while(1):
frame_counter += 1
ret,frame = vc.read()
out.write(frame)
cv2.imshow("video",frame)
key = cv2.waitKey(1)
if key == ord('q') or event.is_set():
break
vc.release()
out.release()
cv2.destroyAllWindows()
def record_threaded(self, filename):
threading.Thread(target=self.record_video, args=(filename,)).start()
if __name__ == "__main__":
if len(sys.argv) > 1:
user_time = float(sys.argv[1])
else:
user_time = 0
rv = RecordVideo(user_time)
rv.record_threaded()
The code does work and makes videos, but they have the wrong length when I change the FPS. If I set the camera to 15FPS, and this code as you can see goes to 15FPS, and then I execute this code for let's say 30 seconds, then it will make a 30 seconds video, but if I change the FPS - both in the camera or the code- then the length of the video will change depending on the FPSs set, it will either be longer or short, but never the length I asked it for.
There's the line "key = cv2.waitKey(1)" and I have changed its value, but it seems to sort of ignore it. I cannot control the FPS with that, or with the property.
I have been having this problem for a very long time. With Python 3.3.0 it was fine, but the moment it got updated to 3.3.1, then everything went wrong.
I am using Python3, Ubuntu, Opencv 3.4.4
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