Can we author Surge oscillators or FX in Faust?

[baconpaul]

Filters are super hard because of the SSE architecture, but oscillators and fx may be less so. the faust architecture is basically a templating model. The sliders are basically params. Can I take this simple oscillator and make it show up in surge?

https://github.com/magnetophon/faustOscillators/blob/master/example.dsp

declare author "Bart Brouns";
declare license "GPLv3";
declare name "osc-example";
import("stdfaust.lib");

process = sineSquarePulse~_;

sineSquarePulse(FB) =
  it.interpolate_linear(sinSquare,sine,square):clip
with {
  sine = os.osc(f);
  square = os.pulsetrain(f,width);
  clip = _*drive:max(-1):min(1);
  f = freq+(FM*FB);
};

freq      = hslider ("[0]freq", 440, 27.5, 3520, 0.1) :si.smoo;
sinSquare = hslider ("[1]sinSquare", 0.5, 0, 1, 0.1)  :si.smoo;
width     = hslider ("[2]width", 0.5, 0, 1, 0.1)      :si.smoo;
drive     = hslider ("[3]drive", 1, 1, 100, 0.1)       :si.smoo;
FM        = hslider ("[4]FM", 0, 0, 100, 0.1)         :si.smoo;

[magnetophon]

Awesome! I hope this gets in! :D

Filters are super hard because of the SSE architecture

Would you mind explaining like i'm an audio-engineer, not a coder?

[baconpaul]

Would you mind explaining like i'm an audio-engineer, not a coder?

There is no non-coder explanation really. The filters use a particular style of coding to do voice-level parallelism which isn’t how Faust outputs C++. It’s described here https://github.com/surge-synthesizer/surge/blob/main/src/common/dsp/QuadFilterChain.h

[magnetophon]

So you think faust filters will be too CPU intensive?

[baconpaul]

I think implementing a voice filter in Faust (like another one int he filter bank next to obxd) would not have the right code structure; and unrolling that code structure would yes increase cpu at least 4x over coding them in parallel

[magnetophon]

OK, thanks for the explanation!

[baconpaul]

That said: prototyping a filter in Faust is easy to do. And then we just have to re-code it as parallel stuff. But the idea of “you write a Faust function and have production ready oscillator or fx with no c++” is not one available for our filter architecture as easily.

I’m also looking at libfaust.... man it is tempting for the scripting language rather than LuaJIT. I really need to understand what the full set of dependencies would be. Is there a Faust dev forum where I can hang out which is friendly and responsive?

[magnetophon]

I’m also looking at libfaust.... man it is tempting for the scripting language rather than LuaJIT.

Woohooo!!!!!!!!!!!!!!!!!!!! Very exiting!!! :D

I really need to understand what the full set of dependencies would be.

Going by the package I wrote for a faust JIT lv2, it can't be much, as far as I can tell, just faust.

BTW: personally I like the approach they take to get an editor: they include libvterm and run $EDITOR inside that in the plugin.
Probably not compatible with windows though.
Just a side-note...

Is there a Faust dev forum where I can hang out which is friendly and responsive?

I recommend the faustaudio slack channel
You usually get an answer from one of the main faust devs: @sletz (Hi Stephan! Hope you don't mind the ping!)

[mkruselj]

I’m also looking at libfaust.... man it is tempting for the scripting language rather than LuaJIT.

What do we gain by using Faust for function modulator/waveform generator, instead of Lua? I know the con to using it already - Lua is a lot more established.

[sletz]

I’m also looking at libfaust.... man it is tempting for the scripting language rather than LuaJIT.

What do we gain by using Faust for function modulator/waveform generator, instead of Lua? I know the con to using it already - Lua is a lot more established.

• Faust probably generates faster code than Lua
• the Faust libraries now contain a lot of DSP code and is regularly improved, see here https://faustlibraries.grame.fr
• some info on how to embed the compiler: https://faustdoc.grame.fr/manual/embedding/
• and yes the Faust Slack channel is a possible place to continue the discussion if needed

[magnetophon]

Familiarity is indeed an advantage of LuaJIT.

Faust OTOH has advantages in this use case too, appart from the ones Paul mentioned:

• Made for audio and real time:
  Everything has a very low, but more importantly constant cpu usage.
  AFAIK, in a general purpose language like LuaJIT, that is the responsibility of the person writing the code.
• Produces a nice block diagram svg of your code, with clickable hierarchy, that can be shown in the plugin.
  Very handy for debugging and understanding others peoples code.
• Everything is a stream, reducing boilerplate code
• The synthax and features lend themselves very well to audio. For example pattern matching is very handy.
• Quite well established in the audio community.

EDIT:

• if one of the users comes up with a cool LFO or something, it's usually trivial to turn into production ready C++ fro inclusion in Surge.

[baconpaul]

So now don’t get all excited. JUCe has to come first.

But short answer to @mkruselj question is exactly as @magnetophon said: Faust is a language for signal manipulation Lua is for general purpose scripting. We want signal manipulation....

But both require careful consideration and nothing is decided yet. Anything including nothing at all may be what we do in the short term :)

[baconpaul]

Ha well the real trick is I have to not get excited. We can’t have surge 1.9 be an unrunnable pile of semi finished ideas. Gotta wrap things up in order.

[magnetophon]

Hmm, github is messing with me: my excited comment was displayed twice, so I deleted it, and now both are gone.
In order to make Paul not sound like a lunatic, I'll add it here:

I know all that, but I'm still exCited!

[sletz]

Note that libfaust even contains an interpreter, much simpler to deploy compared to the LLVM backend. It has been used in the Faust support for VCV Prototype here: https://github.com/VCVRack/VCV-Prototype/tree/faust, https://github.com/VCVRack/VCV-Prototype/blob/faust/Faust.md, https://github.com/VCVRack/VCV-Prototype/blob/faust/src/FaustEngine.cpp

[baconpaul]

https://faustdoc.grame.fr/manual/architectures/

and pushing this (compile time only) into 1.9

[mkruselj]

@baconpaul Move to XT?

[baconpaul]

I have still not given up on doing this one this cycle!

[baconpaul]

from eyal on tap discord (to be clear he's working with JOS not me)

Hey, so I started working on a hobby project with Julius Smith lately.
https://github.com/eyalamirmusic/FaustCPPConverter

This is a project that as a part of the cmake build runs the Faust compiler and generates C++ files you can use directly in your project - I also wrote a C++ wrapper to make that part slightly easier.

Unlike the faust native JUCE exporters and all that, this doesn't give you a ready to go plugin, but it will give you all your .dsp files as classes that are more flexible to use in a "regular" JUCE plugin.

It's in very early stages so we'd appreciate any ideas/feedbacks!
Our next project would probably be to write JUCE module wrappers.