ffmpeg webm 透明通道视频转成rgba图片

import subprocess
def webm_to_bgrapng(webm_video_path,bgra_dir):command = ['ffmpeg','-vcodec', 'libvpx-vp9',  # 指定输入视频编码为 VP9'-i', webm_video_path,  # 输入视频路径'-pix_fmt', "rgba",  # 输出 RGBA 格式（保留 Alpha 通道）bgra_dir # 输出 PNG 序列路径]try:subprocess.run(command, check=True, stderr=subprocess.PIPE, text=True)print(f"转换成功！PNG 序列已保存到：{bgra_dir}")except subprocess.CalledProcessError as e:print(f"转换失败！错误信息：\n{e.stderr}")raise