python - 使用 OpenCv (cv2) 保存时帧数据发生变化

Question

我正在尝试对视频实施隐写术。为此，我必须提取每个视频帧并在其中隐藏秘密消息。现在我已经成功提取帧，在其中隐藏消息并使用 OpenCv cv2 保存它。但是当我再次从隐秘视频中提取帧时，这些帧的像素值完全不同。

即使我没有应用隐写术，只是将帧提取并保存为新视频，当我再次提取它们时，这些帧完全不同。

这是我用来使用 OpenCv2 提取和保存帧的代码

import cv2

def get_frame_count(cap):        
     frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) - 1
     return frame_count

def get_fps_rate(cap):
     fps = cap.get(cv2.CAP_PROP_FPS)
     return fps

video_input_path = "./sample4.mp4"
cap = cv2.VideoCapture(video_input_path)
width = (int)(cap.get(cv2.CAP_PROP_FRAME_WIDTH ))   
height = (int)(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
frame_count = get_frame_count(cap)
fps = get_fps_rate(cap)
fourcc = cv2.VideoWriter_fourcc(*'mp4v')
video = cv2.VideoWriter('newVideo.mp4', fourcc, fps, (width, height))

count = 0
while cap.isOpened():
    ret, frame = cap.read()
    video.write(frame)
    count = count + 1

    if (count >= (frame_count)):
        cap.release()
        break
video.release
cv2.destroyAllWindows()

要检查两个视频（sample4.mp4 和 newVideo.mp4）中第一帧的相等性，我使用以下代码：

import cv2

def get_frame_count(cap):

        frame_count = int(cap.get(cv2.CAP_PROP_FRAME_COUNT)) - 1
        return frame_count

video_input_path = "./sample4.mp4"
cap = cv2.VideoCapture(video_input_path)
frame_count = get_frame_count(cap)
width = (int)(cap.get(cv2.CAP_PROP_FRAME_WIDTH ))   
height = (int)(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
ret, frame = cap.read()
print frame
cap.release()

video_input_path = "./newVideo.mp4"
cap = cv2.VideoCapture(video_input_path)
frame_count = get_frame_count(cap)
width = (int)(cap.get(cv2.CAP_PROP_FRAME_WIDTH ))   
height = (int)(cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
ret, frame = cap.read()
print frame
cap.release()

并且两帧的帧数据完全不同。这怎么可能？

标签： pythonsteganographycv2