ffmpeg -i elva.mp4 -ss 00:00:20 -t 00:00:30 -c:v copy -c:a copy output1.mp4 视频截取，开始时间和时长,-ss 00:00:20 -t 00:00:30
ffmpeg -i output1.mp4 -c:v libx265 output265.mp4 -c:v libx265,264转265
ffmpeg -i output1.mp4 -c:v libx264 output264.mp4 -c:v libx264,265转264
ffmpeg -i output1.mp4 -r 30 output_264_30.mp4 -r 改变帧率
ffmpeg -i output1.mp4 -s 8192x8192 output_8192_8192.mp4 -s改变分辨率
ffmpeg -i output1.mp4 -vf scale=4096:2160 -y output4096.mp4 改变分辨率
ffprobe -select_streams v:0 -show_entries frame=pict_type -of csv -i output1.mp4 查看每帧帧类型