CODEWITHSUNDEEP
python-3.xlistopencvvideocomputer-vision
feed_me_pi
feed_me_pi

Reputation: 177

OpenCV to extract n-th frames from multiple files

I am trying to capture every 200th frame from each video in a directory. I wrote a code to solve that, but the problem is it extracts all the frames from one video and then move to the next video. But I am trying to extract frame from one video and then the same frame from the next video and so on and once that n-th frame is extracted from all the videos then increase the frame counter and start extracting the next frame in the same order.

My code snippet is as follow:

for samples in path: # path is a list of all the video samples
  video = os.path.join(rootDir, samples)

  cap = cv2.VideoCapture(video)
  frameRate = 200 # frame rate
  currentframe=1

  while(cap.isOpened()):
    frameId = cap.get(1)
    ret, frame = cap.read() # reading from frame
    if (ret != True):
        break
    currentframe+=1
    if (currentframe % math.floor(frameRate) == 0):
      filename = './'+str(samples[:-4])+'/image'+str(int(currentframe))+".jpg"
      print('Creating...'+filename)
      cv2.imwrite(filename, frame)

# Release all the sape and windows once done
cap.release()

Upvotes: 2

Views: 310

Answers (1)

roygbiv
roygbiv

Reputation: 369

A solution could be something like this, creating a list of cap objects called caps and iterate over it.

caps = []

for samples in path: # path is a list of all the video samples
  video = os.path.join(rootDir, samples)

  cap = cv2.VideoCapture(video)
  caps.append(cap)


frameRate = 200 # frame rate
currentframe=1

while(caps[0].isOpened()):

    frames = []

    for cap in caps:
        ret, frame = cap.read() # reading from frame
        frames.append(frame)

    if (ret != True):
        break
    currentframe+=1

    if (currentframe % math.floor(frameRate) == 0):
        for frame in frames:
            #filename = './'+str(samples[:-4])+'/image'+str(int(currentframe))+".jpg"
            #print('Creating...'+filename)
            #cv2.imwrite(filename, frame)

# Release all the sape and windows once done
for cap in caps:
    cap.release()

Upvotes: 1

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