每 10 秒后从视频文件中捕获一帧

Question

I want to capture from a video file one frame after every 10 seconds, So if anyone can help me for that i will be very thankful. my python code is like that:

import cv2


print(cv2.__version__)
vidcap = cv2.VideoCapture('Standoff.avi')
vidcap.set(cv2.CAP_PROP_POS_MSEC,96000)  
success,image = vidcap.read()
count = 0
success = True
while success:
  success,image = vidcap.read()
  print 'Read a new frame: ', success
  cv2.imwrite("frame%d.jpg" % count, image)     # save frame as JPEG file
  cv2.waitKey(200)
  count += 1

Answer 1

Here i am capturing frames after 10 conversion of frames.you can use time function and similarly capture frames in if condition statement

import cv2

vidcap = cv2.VideoCapture('testing.mp4')
count = 0
success = True
fps = int(vidcap.get(cv2.CAP_PROP_FPS))

while success:
    success,image = vidcap.read()
    print('read a new frame:',success)
    if count%(10*fps) == 0 :
         cv2.imwrite('frame%d.jpg'%count,image)
         print('successfully written 10th frame')
    count+=1

Answer 2

If you can get the framerate of the video from the file the following should work (You may need to check the syntax as I have not tested it):

import cv2

cap = cv2.VideoCapture('Standoff.avi')
framerate = cap.get(cv2.cv.CV_CAP_PROP_FPS)
framecount = 0

while(True):
    # Capture frame-by-frame
    success, image = cap.read()
    framecount += 1

    # Check if this is the frame closest to 10 seconds
    if framecount == (framerate * 10)
      framecount = 0
      cv2.imshow('image',image)

    # Check end of video
    if cv2.waitKey(1) & 0xFF == ord('q'):
          break

# When everything done, release the capture
cap.release()
cv2.destroyAllWindows()

Answer 3

You should use this code. Code gets fps and multiplies it by 10, that defines that, how many frames creates 10 seconds of video. Lets call that multiplier. Script captures first frame and multiplies frame counter by multiplier. Script captures frame every 10 second.

import cv2 as cv
import os
from time import time

file = "videos/mouthwash.avi"

if not os.path.isfile(file):
print("File not found!")

# images forder name
folder_name = base=os.path.basename(file) + " frames"

# create folder for images in current path if not exists
current_path = os.getcwd()
folder_path = os.path.join(current_path, folder_name)

if not os.path.exists(folder_path):
    os.mkdir(folder_path)

cap = cv.VideoCapture(file)

total_frame = int(cap.get(cv.CAP_PROP_FRAME_COUNT))

# save frame every # seconds
seconds = 10
fps = cap.get(cv.CAP_PROP_FPS) # Gets the frames per second
# calculates number of frames that creates 10 seconds of video
multiplier = fps * seconds

# Check if camera opened successfully
if (cap.isOpened()== False):
    print("Error opening video stream or file")

frame_counter = 1

while frame_counter <= total_frame:

    cap.set(cv.CAP_PROP_POS_FRAMES, frame_counter)

    ret, frame = cap.read()

    # save frame
    # file path
    file_path = os.path.join(folder_path, str(time()) + ".jpg")
    cv.imwrite(file_path, frame)

    frame_counter += multiplier