Question

我想以最快的方式解析特定帧频的视频。我正在使用机器学习来分析视频中的帧，但是我不需要分析每个帧。

这是一项功能，可以在可变帧频下测试视频解析时间。

def extract_img_from_vid(path_in, desired_fps):
    cap = cv2.VideoCapture(path_in)
    count = 0
    frame_count = 0


    length = int(cap.get(cv2.cv2.CAP_PROP_FRAME_COUNT))
    width  = int(cap.get(cv2.cv2.CAP_PROP_FRAME_WIDTH))
    height = int(cap.get(cv2.cv2.CAP_PROP_FRAME_HEIGHT))
    fps    = cap.get(cv2.cv2.CAP_PROP_FPS)
    print ('Length: {:.2f} | Width: {:.2f} | Height: {:.2f} | Fps: {:.2f}'.format(length, width, height, fps))

    skip = round(int(fps)/desired_fps) #determine how ofter to skip a frame

    start = time.time()

    while cap.isOpened():
        success, frame = cap.read()

        if success:
            count += 1

            if count % skip != 0:
                continue

            #do some analysis on the frame

            frame_count += 1
        else:
            break

    end = time.time()
    print("Time to analyze individual frame: {:.4f}sec | Total Time: {:.3f} ".format(((end-start)/count), end-start))
    print('Total Frames: {} | Frames Analyzed {}'. format(count, frame_count))

这是FPS为1时的输出。您可以使用此方法推断出帧速率不影响解析速度。

Length: 10887.00 | Width: 1920.00 | Height: 1080.00 | Fps: 60.00
Time to analyze individual frame: 0.0082sec | Total Time: 88.798 
Total Frames: 10886 | Frames Analyzed 181

有人有这样做的更有效方法吗？

以特定帧速率解析视频

0 个答案: