如何使用OpenCV将一些png文件转换为视频？

import cv2
import os

png_folder = 'path/to/png/files'
png_files = os.listdir(png_folder)

output_file = 'output_video.mp4'
fps = 30  # 视频帧率
width, height = 640, 480  # 视频分辨率
fourcc = cv2.VideoWriter_fourcc(*'mp4v')  # 视频编码器

video_writer = cv2.VideoWriter(output_file, fourcc, fps, (width, height))

for png_file in png_files:
    if png_file.endswith('.png'):
        png_path = os.path.join(png_folder, png_file)
        frame = cv2.imread(png_path)
        video_writer.write(frame)

video_writer.release()