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