我正在尝试编写一段简单的代码来获取视频、裁剪视频并写入输出文件。

系统设置：

OS: Windows 10
Conda Environment Python Version: 3.7
OpenCV Version: 3.4.2
ffmpeg Version: 2.7.0

文件输入规范：

Codec: H264 - MPEG-4 AVC (part 10)(avc1)
Type: Video
Video resolution: 640x360
Frame rate: 5.056860

代码无法产生输出（它创建文件但不写入文件）：

import numpy as np
import cv2

cap = cv2.VideoCapture('croptest1.mp4')

# Define the codec and create VideoWriter object
fourcc = cv2.VideoWriter_fourcc('F', 'M', 'P', '4')
out = cv2.VideoWriter('output.avi', fourcc, 20.0,
                      (int(cap.get(3)), int(cap.get(4))))

# Verify input shape
width = cap.get(3)
height = cap.get(4)
fps = cap.get(5)
print(width, height, fps)

while(cap.isOpened()): …