OpenCV从多个文件中提取第n帧

Question

我正在尝试从目录中的每个视频中捕获每 200 帧。我写了一个代码来解决这个问题，但问题是它从一个视频中提取所有帧，然后移动到下一个视频。但是我试图从一个视频中提取帧，然后从下一个视频中提取相同的帧，依此类推，一旦从所有视频中提取了第 n 帧，然后增加帧计数器并开始以相同的顺序提取下一帧.

我的代码 sn-p 如下：

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()

Answer 1

一个解决方案可能是这样的，创建一个称为 caps 的 cap 对象列表并对其进行迭代。

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()