如何用python在cv2中降低.PNG到MP4转换中的帧率？

import cv2
import os

input_path = 'path/to/png/sequence'
output_path = 'path/to/output.mp4'

png_files = sorted(os.listdir(input_path))

fourcc = cv2.VideoWriter_fourcc(*'mp4v')
fps = 24  # 设置输出视频的帧率
video_writer = cv2.VideoWriter(output_path, fourcc, fps, (width, height))

frame_count = 0
for png_file in png_files:
    if png_file.endswith('.png'):
        frame_count += 1
        if frame_count % 2 == 0:  # 降低帧率，这里示例为每两帧取一帧
            png_path = os.path.join(input_path, png_file)
            frame = cv2.imread(png_path)
            video_writer.write(frame)

video_writer.release()