根据主视频，自动设置片头的分辨率、Fps、编码器

根据主视频，自动设置片头的分辨率、Fps、编码器：

• 前提：
  • 安装：ffmpeg
  • 安装：python库 opencv-python pip3 install opencv-python

def set_start_video(self, video_path, start_video_path):
  """
    :param video_path: 原始mp4 绝对路径
    :param start_video_path:   片头的绝对路径
    :return: 
  """
    video = cv2.VideoCapture(f"{video_path}")
    # print(height, width)
    # resolution1 = (int(video.get(cv2.CAP_PROP_FRAME_WIDTH)), int(video.get(cv2.CAP_PROP_FRAME_HEIGHT)))
    # print(resolution1)

    # 获取高度
    height = int(video.get(cv2.CAP_PROP_FRAME_HEIGHT))

    # 获取宽度
    width = int(video.get(cv2.CAP_PROP_FRAME_WIDTH))

    # 获取帧率
    fps = video.get(cv2.CAP_PROP_FPS)

    # # 向上取整
    # fps_a = math.ceil(fps)
	
    # 保留2位小数
    fps_a = '%.2f' % fps
    # "ffmpeg -i a.mp4 -r 30 b.mp4"
    # print(fps_a)

    # 退出cv2
    video.release()
    cv2.destroyAllWindows()
    
	# 开始获取编码器 因为我的本地opencv库版本低，尝试获取编码器格式失败，所以这里用另一种方式获取
    command = f"ffprobe -v quiet -select_streams v:0 -show_entries stream=codec_name -of default '{video_path}/v1.mp4'"
    result = subprocess.run(command, shell=True, stdout=subprocess.PIPE)
    encoder = result.stdout.decode().strip()
    new_encoder = re.search("codec_name=(?P<codec_name>.*?)\n", encoder)
	
    # 编写执行命令字符串
    cmd_str = f"ffmpeg -i {start_video_path} -vf scale={width}:{height} -r {fps_a} -acodec aac -vcodec {new_encoder.group('codec_name')} {video_path}/xxx.ts"   # 这里的xxx.ts 就是我们根据主视频修改后的片头
    # 开始执行命令
    os.system(cmd_str)