I have the following code, which continuously fetches all the frames from a video by using VideoCapture library in opencv in python:
import cv2
def frame_capture:
cap = cv2.VideoCapture("video.mp4")
while not cap.isOpened():
cap = cv2.VideoCapture("video.mp4")
cv2.waitKey(1000)
print "Wait for the header"
pos_frame = cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES)
while True:
flag, frame = cap.read()
if flag:
# The frame is ready and already captured
cv2.imshow('video', frame)
pos_frame = cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES)
print str(pos_frame)+" frames"
else:
# The next frame is not ready, so we try to read it again
cap.set(cv2.cv.CV_CAP_PROP_POS_FRAMES, pos_frame-1)
print "frame is not ready"
# It is better to wait for a while for the next frame to be ready
cv2.waitKey(1000)
if cv2.waitKey(10) == 27:
break
if cap.get(cv2.cv.CV_CAP_PROP_POS_FRAMES) == cap.get(cv2.cv.CV_CAP_PROP_FRAME_COUNT):
# If the number of captured frames is equal to the total number of frames,
# we stop
break
But I want to grab a specific frame in a specific timestamp in the video.
How can I achieve this?
You can use set() function of VideoCapture.
You can calculate total frames:
cap = cv2.VideoCapture("video.mp4")
total_frames = cap.get(7)
Here 7 is the prop-Id. You can find more here http://docs.opencv.org/2.4/modules/highgui/doc/reading_and_writing_images_and_video.html
After that you can set the frame number, suppose i want to extract 100th frame
cap.set(1, 100)
ret, frame = cap.read()
cv2.imwrite("path_where_to_save_image", frame)