Option to specify ffmpeg and aomenc path

[acedogblast]

It would be nice to use our own custom builds for both ffmpeg and aomenc so we can use the latest version of them instead of using the ones installed by our package managers.

[natis1]

I can look into this for a future release, but it's not a huge priority for me.

For now, here is a workaround on linux/mac to customizing your ffmpeg and aomenc path by editing your path. For instance, let's assume that modern ffmpeg/aomenc are located in ~/.local/bin and modern ffmpeg/aomenc libraries are ~/.local/lib

you could do this

export PATH=~/.local/bin:$PATH
export LD_LIBRARY_PATH=~/.local/lib:$LD_LIBRARY_PATH

Add it to your ~/.bash_rc (or relevant rc for your shell) file and it will apply on all terminals, this is a super useful change to make if you install a lot of programs outside your package manager. Not just for ffmpeg either, pip for instance installs binaries to ~/.local/bin if you run it with pip install -U program which is usually recommended if you want to avoid polluting /usr/local/lib and /usr/local/bin