augmented-dsp-filters

Mechanical port of Vinnie Falco's https://github.com/vinniefalco/DSPFilters/.

Only RBJ filters are ported over. No introspection is supported & the implementation is quite a different (as Rust would prefer composition to multiple inheritance).

Very untested, be careful with your speakers.

Depends on audio-processor-traits. Exports FilterProcessor which may be used for general filtering needs.

See synth on this repository for a nice working example.

Low-pass filter example

```rust use audioprocessortraits::{ AudioBuffer, AudioProcessor, AudioProcessorSettings }; use augmenteddspfilters::rbj::{FilterProcessor, FilterType};

pub struct YourProcessor { filter: FilterProcessor, // <- f32 may be f64 if you wish }

impl YourProcessor { fn new() -> Self { Self { filter: FilterProcessor::new(FilterType::LowPass), } }

fn set_cutoff(&mut self, midi_value_between_0_and_127: f32) {
    let cutoff_ratio = midi_value_between_0_and_127 / 127.0;
    let cutoff_freq_hz = 22000.0 * cutoff_ratio;
    self.filter.set_cutoff(cutoff_freq_hz);
}

fn set_q(&mut self, q: f32) {
    self.filter.set_q(q);
}

}

impl AudioProcessor for YourProcessor { type SampleType = f32;

fn prepare(&mut self, settings: AudioProcessorSettings) {
    self.filter.prepare(settings);
}

fn process<BufferType: AudioBuffer<SampleType = Self::SampleType>>(
    &mut self,
    data: &mut BufferType,
) {
    self.filter.process(data);
}

} ```

Multi-threading

The filter mutate functions recalculate coefficients for the filter. This should run on the audio-thread only.

In order to integrate with MIDI, see synth; this won't be a problem as AudioProcessor (stand-alone) will receive MIDI on the audio-thread.

For integrating with a GUI thread, the best would probably be to have the audio-thread read the parameters from an atomic store & update the filter when they change (see audio-parameter-store in this repository).

License

MIT licensed as the original.