参考

https://video.stackexchange.com/questions/16564/how-to-trim-out-black-frames-with-ffmpeg-on-windows

需求描述

有时候需要检测视频开头是否存在纯黑色的帧，从而可以截取掉。

需求实现

ffprobe命令

  1. ffprobe -f lavfi -i "movie=dc1a1f56bf611dc90eb4e707ba3e3c10.webm,blackdetect[out0]" -show_entries tags=lavfi.black_start,lavfi.black_end -of default=nw=1 -v quiet

输出结果如下：

TAG:lavfi.black_start=0.32 TAG:lavfi.black_start=0.32 TAG:lavfi.black_end=0.68 TAG:lavfi.black_end=0.68

python脚本

下面是基于上面ffprobe命令构建的python3脚本：

  1. def detect_black(media_file: str):
  2.     """
  3.     探测视频前2秒钟第一段黑屏的开始和结束时间，便于截掉
  4.     :param media_file:
  5.     :return:
  6.     """
  8.     media_path, filename = os.path.split(media_file)
  10.     cmd = f'ffprobe -f lavfi -i "movie={filename},blackdetect[out0]" -show_entries tags=lavfi.black_start,lavfi.black_end -of default=nw=1 -v quiet -read_intervals %+2'
  11.     args = shlex.split(cmd)
  13.     result = subprocess.run(args, cwd=media_path, stderr=subprocess.PIPE, stdout=subprocess.PIPE)
  14.     content = result.stdout.decode('utf-8')
  16.     start = None
  17.     stop = None
  18.     if content and content.strip():
  19.         for line in content.split('\n'):
  20.             line: str = line.strip()
  21.             if 'start' in line:
  22.                 start = line.split('=')[1]
  23.             elif 'end' in line:
  24.                 stop = line.split('=')[1]
  26.     print(f'content: {content}, start:{start}, stop:{stop}')
  27.     return (start,stop)

-read_intervals %+2 用于控制截取的时长是前2秒