查看I帧：
ffprobe xxx.mpu8 -show_frames -of csv|grep I
推流：
ffmpeg -re -stream_loop -1 -i .\xxx.mp4 -c:v libx264 -f flv "rtmp://xxx"
转码：
ffmpeg -i "xxx.mp4" -c:a copy -c:v libopenh264 -maxrate 3M -minrate 3M -bf 1 -b_strategy 0 -keyint_min 25 -r 25 -g 25 -sc_threshold 0 -hls_playlist_type vod -hls_time 1 -hls_flags split_by_time -hls_list_size 0 -f hls .\xxx\index.m3u8
ffmpeg -i "xxx.mp4" -c:a copy -c:v libx264 -maxrate 10M -minrate 10M -bf 1 -b_strategy 0 -keyint_min 25 -r 25 -g 25 -sc_threshold 0 -hls_playlist_type vod -hls_time 1 -hls_flags split_by_time -hls_list_size 0 -f hls .\xxx\index.m3u8
