initial formant synth

src/dsp/mod.rs

@@ -23,6 +23,8 @@ mod node_delay;
 #[allow(non_upper_case_globals)]
 mod node_fbwr_fbrd;
 #[allow(non_upper_case_globals)]
+mod node_formant;
+#[allow(non_upper_case_globals)]
 mod node_map;
 #[allow(non_upper_case_globals)]
 mod node_mix3;
@@ -108,6 +110,7 @@ use node_cqnt::CQnt;
 use node_delay::Delay;
 use node_fbwr_fbrd::FbRd;
 use node_fbwr_fbrd::FbWr;
+use node_formant::Formant;
 use node_map::Map;
 use node_mix3::Mix3;
 use node_mux9::Mux9;
@@ -1001,6 +1004,8 @@ macro_rules! node_list {
                (14 mix   n_id      d_id  r_id   f_def stp_d  0.0, 1.0, 0.5)
                [0 sig_l]
                [1 sig_r],
+            formant => Formant UIType::Generic UICategory::Signal
+               (0),
             test => Test UIType::Generic UICategory::IOUtil
                (0 f     n_id      d_id   r_id   f_def stp_d 0.0, 1.0, 0.5)
                {1 0 p     param(0.0) knob fa_test_s 0  10}

src/dsp/node_formant.rs

@@ -0,0 +1,127 @@
+use super::helpers::{sqrt4_to_pow4, TrigSignal, Trigger};
+use crate::dsp::{
+    DspNode, GraphAtomData, GraphFun, LedPhaseVals, NodeContext, NodeId, ProcBuf, SAtom,
+};
+use crate::nodes::{NodeAudioContext, NodeExecContext};
+
+/// A simple amplifier
+#[derive(Debug, Clone)]
+pub struct Formant {
+    inv_sample_rate: f32,
+    phase: f32,
+}
+
+impl Formant {
+    pub fn new(_nid: &NodeId) -> Self {
+        Self { inv_sample_rate: 1.0 / 44100.0, phase: 0.0 }
+    }
+    pub const inp: &'static str =
+        "Ad inp\nSignal input. If you don't connect this, and set this to 1.0 \
+        this will act as envelope signal generator. But you can also just \
+        route a signal directly through this of course.\nRange: (-1..1)\n";
+    pub const trig: &'static str =
+        "Ad trig\nTrigger input that starts the attack phase.\nRange: (0..1)\n";
+    pub const atk: &'static str =
+        "Ad atk\nAttack time of the envelope. You can extend the maximum \
+        range of this with the 'mult' setting.\nRange: (0..1)\n";
+    pub const dcy: &'static str = "Ad atk\nDecay time of the envelope. You can extend the maximum \
+        range of this with the 'mult' setting.\nRange: (0..1)\n";
+    pub const ashp: &'static str = "Ad ashp\nAttack shape. This allows you to change the shape \
+        of the attack stage from a logarithmic, to a linear and to an \
+        exponential shape.\nRange: (0..1)\n";
+    pub const dshp: &'static str = "Ad dshp\nDecay shape. This allows you to change the shape \
+        of the decay stage from a logarithmic, to a linear and to an \
+        exponential shape.\nRange: (0..1)\n";
+    pub const mult: &'static str = "Ad mult\nAttack and Decay time range multiplier. \
+        This will extend the maximum range of the 'atk' and 'dcy' parameters.";
+    pub const sig: &'static str =
+        "Ad sig\nEnvelope signal output. If a signal is sent to the 'inp' port, \
+        you will receive an attenuated signal here. If you set 'inp' to a \
+        fixed value (for instance 1.0), this will output an envelope signal \
+        in the range 0.0 to 'inp' (1.0).\nRange: (-1..1)\n";
+    pub const eoet: &'static str =
+        "Ad eoet\nEnd of envelope trigger. This output sends a trigger once \
+        the end of the decay stage has been reached.\nRange: (0..1)";
+    pub const DESC: &'static str = r#"A direct formant synthesizer
+
+This generates a single formant from a given frequency, formant frequency, as well as attack and decay frequencies.
+The attack and decay frequencies both control the bandwidth of the formant, decay the peak of the bandwidth, attack peak.
+"#;
+    pub const HELP: &'static str = r#"Formant - Single formant synthesizer
+This is a formant synthesizer that directly generates the audio, no filters needed.
+"#;
+}
+
+impl DspNode for Formant {
+    fn outputs() -> usize {
+        1
+    }
+
+    fn set_sample_rate(&mut self, srate: f32) {
+        self.inv_sample_rate = 1.0 / srate;
+    }
+
+    fn reset(&mut self) {
+        self.phase = 0.0;
+    }
+
+    #[inline]
+    fn process<T: NodeAudioContext>(
+        &mut self,
+        ctx: &mut T,
+        _ectx: &mut NodeExecContext,
+        _nctx: &NodeContext,
+        atoms: &[SAtom],
+        inputs: &[ProcBuf],
+        outputs: &mut [ProcBuf],
+        ctx_vals: LedPhaseVals,
+    ) {
+        use crate::dsp::{at, denorm, inp, out};
+
+        let base_freq = inp::Formant::freq(inputs);
+        let formant_freq = inp::Formant::fmt(inputs);
+        let attack_freq = inp::Formant::atk(inputs);
+        let decay_freq = inp::Formant::dcy(inputs);
+        let out = out::Formant::sig(outputs);
+
+        for frame in 0..ctx.nframes() {
+            // where the two decays meet
+            let carrier_center = decay_freq / (attack_freq + decay_freq);
+
+            // where they meet in amplitude
+            let carrier_lowest_amplitude =
+                (-std::f32::consts::TAU * base_freq * carrier_center * decay_freq).exp();
+
+            // turn it into a triangle wave
+            let carrier_attack = (1.0 - self.phase) / carrier_center;
+            let carrier_decay = self.phase / (1.0 - carrier_center);
+
+            // actual triangle wave
+            let carrier_base = 1.0 - carrier_attack.min(carrier_decay);
+
+            // smoothstep
+            let carrier =
+                carrier_base * carrier_base * (3.0 - 2.0 * carrier_base) * carrier_lowest_amplitude
+                    + (1.0 - carrier_lowest_amplitude);
+
+            // multiple of the frequency the modulators are at
+            let multiple = formant_freq / base_freq;
+
+            // round them to the closest integer of the formant freq
+            let freq_a = multiple.floor();
+            let freq_b = freq_a + 1.0;
+
+            // and how much to lerp between them
+            let blend = multiple.fract();
+
+            // get the true modulator
+            let modulator = (1.0 - blend) * (std::f32::consts::TAU * self.phase * freq_a).cos()
+                + blend * (std::f32::consts::TAU * self.phase * freq_b).cos();
+
+            // entire wave
+            let wave = carrier * modulator;
+
+            out.write(frame, wave);
+        }
+    }
+}

src/nodes/node_conf.rs

@@ -3,8 +3,8 @@
 // See README.md and COPYING for details.
 
 use super::{
-    FeedbackFilter, GraphMessage, NodeOp, NodeProg, MAX_ALLOCATED_NODES,
-    MAX_AVAIL_TRACKERS, MAX_INPUTS, UNUSED_MONITOR_IDX,
+    FeedbackFilter, GraphMessage, NodeOp, NodeProg, MAX_ALLOCATED_NODES, MAX_AVAIL_TRACKERS,
+    MAX_INPUTS, UNUSED_MONITOR_IDX,
 };
 use crate::dsp::tracker::{PatternData, Tracker};
 use crate::dsp::{node_factory, Node, NodeId, NodeInfo, ParamId, SAtom};
@@ -245,12 +245,7 @@ impl SharedNodeConf {
         }
 
         (
-            Self {
-                node_ctx_values,
-                graph_update_prod: rb_graph_prod,
-                monitor,
-                drop_thread,
-            },
+            Self { node_ctx_values, graph_update_prod: rb_graph_prod, monitor, drop_thread },
             SharedNodeExec {
                 node_ctx_values: exec_node_ctx_vals,
                 graph_update_con: rb_graph_con,

src/nodes/node_exec.rs

@@ -3,8 +3,8 @@
 // See README.md and COPYING for details.
 
 use super::{
-    DropMsg, GraphMessage, NodeProg, FB_DELAY_TIME_US, MAX_ALLOCATED_NODES,
-    MAX_FB_DELAY_SIZE, MAX_SMOOTHERS, UNUSED_MONITOR_IDX,
+    DropMsg, GraphMessage, NodeProg, FB_DELAY_TIME_US, MAX_ALLOCATED_NODES, MAX_FB_DELAY_SIZE,
+    MAX_SMOOTHERS, UNUSED_MONITOR_IDX,
 };
 use crate::dsp::{Node, NodeContext, NodeId, MAX_BLOCK_SIZE};
 use crate::monitor::{MonitorBackend, MON_SIG_CNT};