Show HN: A realtime node-based audio synth based on LLVM

This is a project I’ve been working on since the start of the year. We’ve just released 0.4.0, so I figured now would be a nice time to start making it a bit more public. There’s a bunch of interesting tech under the hood which I thought you all would definitely be interested in :)

Axiom’s a project that grew out of my third try at building a realtime software synthesizer for 64k intros in the demoscene. You can’t really fit an mp3 file in an executable that small and expect for it to sound any good, so instead we synthesize the audio and play it in realtime. A few other groups have written synthesizers for 4k and 64k productions, however I built this for two reasons: I wanted to make one myself, and I wanted to try some interesting things with combining node graphs and basic scripting. At some point, however, I realized that this could actually be a really useful tool for any musician to have, since it really flips things on its head and allows much more control than just stringing together a bunch of plugins (the question is, of course, do people who make music _want_ this control - I'm not sure on the answer yet).

Technology-wise, Axiom compiles 'node surfaces' with LLVM (no interpreters here, the code has to run comfortably 44100 times per second!). The editor, written in C++ with Qt, builds a MIR and passes it into the compiler, written in Rust. This was my first large project in C++ and first project in Rust... ultimately I think the Rust learning curve has definitely been worth it, as it's by far the stablest part of the program!

Ultimately I’m hoping to somehow be able to turn this into a real product, possibly by offering what you see as the core open-source software and then building on it, into something like a DAW or plugin for procedural audio in game engines (which a few people have suggested to me, and I think would be a really cool application of the technology!).

Check it out, let me know what you think (either here, or shoot me an email, chat on twitter, etc), ask questions, build something cool, have fun!

Can you give a little more detail in how this compares architecturally with something like PD? I imagine a tradeoff of generating LLVM MIR and compiling it is that you can get better performance, but don't get the interactive experience of hearing changes immediately as you tweak the object graph.

Does the DSP graph operate on blocks or sample-by-sample?

But that said, I haven't actually gotten to writing the 'exporter' yet (up to this point I've mostly been focused on usability and stability), so I can understand that it's not entirely clear.