Here's some simple code to save frames into a video file. I recommend creating another thread for obtaining the frames since cv2.VideoCapture.read()
is blocking. This can be expensive and cause latency as the main thread has to wait until it has obtained a frame. By putting this operation into a separate thread that just focuses on grabbing frames and processing/saving the frames in the main thread, it dramatically improves performance due to I/O latency reduction. You also can experiment with other codecs but using MJPG should be safe since its built into OpenCV.
from threading import Thread
import cv2
class WebcamVideoWriter(object):
def __init__(self, src=0):
# Create a VideoCapture object
self.capture = cv2.VideoCapture(src)
# Default resolutions of the frame are obtained (system dependent)
self.frame_width = int(self.capture.get(3))
self.frame_height = int(self.capture.get(4))
# Set up codec and output video settings
self.codec = cv2.VideoWriter_fourcc('M','J','P','G')
self.output_video = cv2.VideoWriter('output.avi', self.codec, 30, (self.frame_width, self.frame_height))
# Start the thread to read frames from the video stream
self.thread = Thread(target=self.update, args=())
self.thread.daemon = True
self.thread.start()
def update(self):
# Read the next frame from the stream in a different thread
while True:
if self.capture.isOpened():
(self.status, self.frame) = self.capture.read()
def show_frame(self):
# Display frames in main program
if self.status:
cv2.imshow('frame', self.frame)
# Press Q on keyboard to stop recording
key = cv2.waitKey(1)
if key == ord('q'):
self.capture.release()
self.output_video.release()
cv2.destroyAllWindows()
exit(1)
def save_frame(self):
# Save obtained frame into video output file
self.output_video.write(self.frame)
if __name__ == '__main__':
webcam_videowriter = WebcamVideoWriter()
while True:
try:
webcam_videowriter.show_frame()
webcam_videowriter.save_frame()
except AttributeError:
pass
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