python how to write commands in cmd? for example --ffmpeg

I'm sorry I really tried, ffmpeg library python if not, then can not get the data returned, under the command cmd is

ffprobe -count_frames -select_streams v:0 -show_entries stream=nb_read_frames -i p25390261-102-009-183937.mp4

I wanted to get nb _ **, however, can not be achieved, envisions nb incoming commands, but does not perform the assignment of nb, this is really embarrassing.

But if it is a Python library, so easy to achieve.

I will not go into the search that was. so easy. byebye

import ffmpeg

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