将mov视频解码300帧，并保存为1024：576分辨率，yuv420格式
ffmpeg -i Community_SneakAttack.mov -aspect 16:9 -vf scale=1024:576 -vframes 300 -pix_fmt yuv420p Community_SneakAttack.yuv
将mov视频解码300帧，并保存为1024：576分辨率，yuv420格式
ffmpeg -i Community_SneakAttack.mov -aspect 16:9 -vf scale=1024:576 -vframes 300 -pix_fmt yuv420p Community_SneakAttack.yuv