I don't have the answer, but here is a hint:
https://docs.julialang.org/en/latest/manual/embedding/
If you can successfully call a Julia routine from within a generic C program then there is no reason I can think that you can't do this from the RT thread. In this case you would put your Julia wrapper into render(), give Julia the inputs/outputs and let it do its thing.
feima0011 I have to do some complicated filtering with the microphone input, and using C language is not convinient.
It looks like you can go both directions with Julia, so if there is a specific function that you DO need to optimize (like math_neon functions or other hardware optimization) you can farm these single demanding functions out to a routine coded in C or assembly if needed.
I am not familiar with Julia, but seeing that it is based on LLVM it probably has mechanisms to directly support hardware optimization. Now you have tipped me off to another language I need to learn 🙂 Thanks.