树莓4b arm64 系统，安装ffmpeg 并使用opencv推流

一. 编译安装ffmpeg

sudo apt-get install libdav1d-dev
sudo apt-get install kvazaar
sudo apt-get install libkvazaar-dev
sudo apt-get install -y build-essential git cmake libdrm-dev libomxil-bellagio-dev libass-dev libfreetype6-dev \
libsdl2-dev libtool libva-dev libvdpau-dev libvorbis-dev libxcb1