This gist is for Linux. For windows is the same thing.
create a file .login_info as below:
connect your.server.url
usernanme
https://www.ffmpeg.org/doxygen/trunk/dump_8c_source.html#l00454
st->avg_frame_ratest->r_frame_ratest->time_basest->codec->time_baseAverage framerate.
avformat_find_stream_info().avformat_write_header().