spectrum

Cargo.toml

@@ -28,3 +28,4 @@ arboard = "3"
 minimad = "0.13"
 crossbeam-channel = "0.5"
 confy = "2"
+rustfft = "6"

src/app.rs

@@ -85,6 +85,8 @@ impl App {
             display: crate::settings::DisplaySettings {
                 fps: self.audio.config.refresh_rate.to_fps(),
                 runtime_highlight: self.ui.runtime_highlight,
+                show_scope: self.audio.config.show_scope,
+                show_spectrum: self.audio.config.show_spectrum,
             },
             link: crate::settings::LinkSettings {
                 enabled: link.is_enabled(),

src/engine/audio.rs

@@ -2,6 +2,7 @@ use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};
 use cpal::Stream;
 use crossbeam_channel::Receiver;
 use doux::{Engine, EngineMetrics};
+use rustfft::{num_complex::Complex, FftPlanner};
 use std::sync::atomic::{AtomicU32, Ordering};
 use std::sync::Arc;
 
@@ -50,6 +51,106 @@ impl ScopeBuffer {
     }
 }
 
+pub struct SpectrumBuffer {
+    pub bands: [AtomicU32; 32],
+}
+
+impl SpectrumBuffer {
+    pub fn new() -> Self {
+        Self {
+            bands: std::array::from_fn(|_| AtomicU32::new(0)),
+        }
+    }
+
+    pub fn write(&self, data: &[f32; 32]) {
+        for (atom, &val) in self.bands.iter().zip(data.iter()) {
+            atom.store(val.to_bits(), Ordering::Relaxed);
+        }
+    }
+
+    pub fn read(&self) -> [f32; 32] {
+        std::array::from_fn(|i| f32::from_bits(self.bands[i].load(Ordering::Relaxed)))
+    }
+}
+
+const FFT_SIZE: usize = 512;
+const NUM_BANDS: usize = 32;
+
+struct SpectrumAnalyzer {
+    ring: Vec<f32>,
+    pos: usize,
+    fft: Arc<dyn rustfft::Fft<f32>>,
+    window: [f32; FFT_SIZE],
+    scratch: Vec<Complex<f32>>,
+    band_edges: [usize; NUM_BANDS + 1],
+}
+
+impl SpectrumAnalyzer {
+    fn new(sample_rate: f32) -> Self {
+        let mut planner = FftPlanner::new();
+        let fft = planner.plan_fft_forward(FFT_SIZE);
+        let scratch_len = fft.get_inplace_scratch_len();
+
+        let window: [f32; FFT_SIZE] = std::array::from_fn(|i| {
+            0.5 * (1.0 - (2.0 * std::f32::consts::PI * i as f32 / (FFT_SIZE - 1) as f32).cos())
+        });
+
+        let nyquist = sample_rate / 2.0;
+        let min_freq: f32 = 20.0;
+        let log_min = min_freq.ln();
+        let log_max = nyquist.ln();
+        let band_edges: [usize; NUM_BANDS + 1] = std::array::from_fn(|i| {
+            let freq = (log_min + (log_max - log_min) * i as f32 / NUM_BANDS as f32).exp();
+            let bin = (freq * FFT_SIZE as f32 / sample_rate).round() as usize;
+            bin.min(FFT_SIZE / 2)
+        });
+
+        Self {
+            ring: vec![0.0; FFT_SIZE],
+            pos: 0,
+            fft,
+            window,
+            scratch: vec![Complex::default(); scratch_len],
+            band_edges,
+        }
+    }
+
+    fn feed(&mut self, samples: &[f32], output: &SpectrumBuffer) {
+        for &s in samples {
+            self.ring[self.pos] = s;
+            self.pos += 1;
+            if self.pos >= FFT_SIZE {
+                self.pos = 0;
+                self.run_fft(output);
+            }
+        }
+    }
+
+    fn run_fft(&mut self, output: &SpectrumBuffer) {
+        let mut buf: Vec<Complex<f32>> = (0..FFT_SIZE)
+            .map(|i| {
+                let idx = (self.pos + i) % FFT_SIZE;
+                Complex::new(self.ring[idx] * self.window[i], 0.0)
+            })
+            .collect();
+
+        self.fft.process_with_scratch(&mut buf, &mut self.scratch);
+
+        let mut bands = [0.0f32; NUM_BANDS];
+        for (band, mag) in bands.iter_mut().enumerate() {
+            let lo = self.band_edges[band];
+            let hi = self.band_edges[band + 1].max(lo + 1);
+            let sum: f32 = buf[lo..hi].iter().map(|c| c.norm()).sum();
+            let avg = sum / (hi - lo) as f32;
+            let amplitude = avg / (FFT_SIZE as f32 / 2.0);
+            let db = 20.0 * amplitude.max(1e-10).log10();
+            *mag = ((db + 60.0) / 60.0).clamp(0.0, 1.0);
+        }
+
+        output.write(&bands);
+    }
+}
+
 pub struct AudioStreamConfig {
     pub output_device: Option<String>,
     pub channels: u16,
@@ -60,6 +161,7 @@ pub fn build_stream(
     config: &AudioStreamConfig,
     audio_rx: Receiver<AudioCommand>,
     scope_buffer: Arc<ScopeBuffer>,
+    spectrum_buffer: Arc<SpectrumBuffer>,
     metrics: Arc<EngineMetrics>,
     initial_samples: Vec<doux::sample::SampleEntry>,
 ) -> Result<(Stream, f32), String> {
@@ -95,6 +197,8 @@ pub fn build_stream(
     let mut engine = Engine::new_with_metrics(sample_rate, channels, Arc::clone(&metrics));
     engine.sample_index = initial_samples;
 
+    let mut analyzer = SpectrumAnalyzer::new(sample_rate);
+
     let stream = device
         .build_output_stream(
             &stream_config,
@@ -128,6 +232,12 @@ pub fn build_stream(
                 engine.metrics.load.set_buffer_time(buffer_time_ns);
                 engine.process_block(data, &[], &[]);
                 scope_buffer.write(&engine.output);
+
+                // Feed mono mix to spectrum analyzer
+                let mono: Vec<f32> = engine.output.chunks(channels)
+                    .map(|ch| ch.iter().sum::<f32>() / channels as f32)
+                    .collect();
+                analyzer.feed(&mono, &spectrum_buffer);
             },
             |err| eprintln!("stream error: {err}"),
             None,

src/engine/mod.rs

@@ -2,7 +2,7 @@ mod audio;
 mod link;
 mod sequencer;
 
-pub use audio::{build_stream, AudioStreamConfig, ScopeBuffer};
+pub use audio::{build_stream, AudioStreamConfig, ScopeBuffer, SpectrumBuffer};
 pub use link::LinkState;
 pub use sequencer::{
     spawn_sequencer, AudioCommand, PatternChange, PatternSnapshot, SeqCommand, SequencerSnapshot,

src/input.rs

@@ -601,6 +601,12 @@ fn handle_audio_page(ctx: &mut InputContext, key: KeyEvent) -> InputResult {
                 AudioFocus::RuntimeHighlight => {
                     ctx.app.ui.runtime_highlight = !ctx.app.ui.runtime_highlight
                 }
+                AudioFocus::ShowScope => {
+                    ctx.app.audio.config.show_scope = !ctx.app.audio.config.show_scope;
+                }
+                AudioFocus::ShowSpectrum => {
+                    ctx.app.audio.config.show_spectrum = !ctx.app.audio.config.show_spectrum;
+                }
                 AudioFocus::SamplePaths => ctx.app.audio.remove_last_sample_path(),
                 AudioFocus::LinkEnabled => ctx.link.set_enabled(!ctx.link.is_enabled()),
                 AudioFocus::StartStopSync => ctx
@@ -622,6 +628,12 @@ fn handle_audio_page(ctx: &mut InputContext, key: KeyEvent) -> InputResult {
                 AudioFocus::RuntimeHighlight => {
                     ctx.app.ui.runtime_highlight = !ctx.app.ui.runtime_highlight
                 }
+                AudioFocus::ShowScope => {
+                    ctx.app.audio.config.show_scope = !ctx.app.audio.config.show_scope;
+                }
+                AudioFocus::ShowSpectrum => {
+                    ctx.app.audio.config.show_spectrum = !ctx.app.audio.config.show_spectrum;
+                }
                 AudioFocus::SamplePaths => {}
                 AudioFocus::LinkEnabled => ctx.link.set_enabled(!ctx.link.is_enabled()),
                 AudioFocus::StartStopSync => ctx

src/main.rs

@@ -28,7 +28,7 @@ use ratatui::prelude::CrosstermBackend;
 use ratatui::Terminal;
 
 use app::App;
-use engine::{build_stream, spawn_sequencer, AudioStreamConfig, LinkState, ScopeBuffer};
+use engine::{build_stream, spawn_sequencer, AudioStreamConfig, LinkState, ScopeBuffer, SpectrumBuffer};
 use input::{handle_key, InputContext, InputResult};
 use settings::Settings;
 use state::audio::RefreshRate;
@@ -84,9 +84,12 @@ fn main() -> io::Result<()> {
     app.audio.config.sample_paths = args.samples;
     app.audio.config.refresh_rate = RefreshRate::from_fps(settings.display.fps);
     app.ui.runtime_highlight = settings.display.runtime_highlight;
+    app.audio.config.show_scope = settings.display.show_scope;
+    app.audio.config.show_spectrum = settings.display.show_spectrum;
 
     let metrics = Arc::new(EngineMetrics::default());
     let scope_buffer = Arc::new(ScopeBuffer::new());
+    let spectrum_buffer = Arc::new(SpectrumBuffer::new());
 
     let mut initial_samples = Vec::new();
     for path in &app.audio.config.sample_paths {
@@ -114,6 +117,7 @@ fn main() -> io::Result<()> {
         &stream_config,
         sequencer.audio_rx.clone(),
         Arc::clone(&scope_buffer),
+        Arc::clone(&spectrum_buffer),
         Arc::clone(&metrics),
         initial_samples,
     ) {
@@ -157,6 +161,7 @@ fn main() -> io::Result<()> {
                 &new_config,
                 sequencer.audio_rx.clone(),
                 Arc::clone(&scope_buffer),
+                Arc::clone(&spectrum_buffer),
                 Arc::clone(&metrics),
                 restart_samples,
             ) {
@@ -182,6 +187,7 @@ fn main() -> io::Result<()> {
             app.metrics.schedule_depth = metrics.schedule_depth.load(Ordering::Relaxed) as usize;
             app.metrics.scope = scope_buffer.read();
             (app.metrics.peak_left, app.metrics.peak_right) = scope_buffer.peaks();
+            app.metrics.spectrum = spectrum_buffer.read();
         }
 
         let seq_snapshot = sequencer.snapshot();

src/settings.rs

@@ -21,6 +21,8 @@ pub struct AudioSettings {
 pub struct DisplaySettings {
     pub fps: u32,
     pub runtime_highlight: bool,
+    pub show_scope: bool,
+    pub show_spectrum: bool,
 }
 
 #[derive(Debug, Serialize, Deserialize)]
@@ -46,6 +48,8 @@ impl Default for DisplaySettings {
         Self {
             fps: 60,
             runtime_highlight: false,
+            show_scope: true,
+            show_spectrum: true,
         }
     }
 }

src/state/audio.rs

@@ -56,6 +56,8 @@ pub struct AudioConfig {
     pub sample_paths: Vec<PathBuf>,
     pub sample_count: usize,
     pub refresh_rate: RefreshRate,
+    pub show_scope: bool,
+    pub show_spectrum: bool,
 }
 
 impl Default for AudioConfig {
@@ -69,6 +71,8 @@ impl Default for AudioConfig {
             sample_paths: Vec::new(),
             sample_count: 0,
             refresh_rate: RefreshRate::default(),
+            show_scope: true,
+            show_spectrum: true,
         }
     }
 }
@@ -82,6 +86,8 @@ pub enum AudioFocus {
     BufferSize,
     RefreshRate,
     RuntimeHighlight,
+    ShowScope,
+    ShowSpectrum,
     SamplePaths,
     LinkEnabled,
     StartStopSync,
@@ -97,6 +103,7 @@ pub struct Metrics {
     pub scope: [f32; 64],
     pub peak_left: f32,
     pub peak_right: f32,
+    pub spectrum: [f32; 32],
 }
 
 impl Default for Metrics {
@@ -110,6 +117,7 @@ impl Default for Metrics {
             scope: [0.0; 64],
             peak_left: 0.0,
             peak_right: 0.0,
+            spectrum: [0.0; 32],
         }
     }
 }
@@ -149,7 +157,9 @@ impl AudioSettings {
             AudioFocus::Channels => AudioFocus::BufferSize,
             AudioFocus::BufferSize => AudioFocus::RefreshRate,
             AudioFocus::RefreshRate => AudioFocus::RuntimeHighlight,
-            AudioFocus::RuntimeHighlight => AudioFocus::SamplePaths,
+            AudioFocus::RuntimeHighlight => AudioFocus::ShowScope,
+            AudioFocus::ShowScope => AudioFocus::ShowSpectrum,
+            AudioFocus::ShowSpectrum => AudioFocus::SamplePaths,
             AudioFocus::SamplePaths => AudioFocus::LinkEnabled,
             AudioFocus::LinkEnabled => AudioFocus::StartStopSync,
             AudioFocus::StartStopSync => AudioFocus::Quantum,
@@ -165,7 +175,9 @@ impl AudioSettings {
             AudioFocus::BufferSize => AudioFocus::Channels,
             AudioFocus::RefreshRate => AudioFocus::BufferSize,
             AudioFocus::RuntimeHighlight => AudioFocus::RefreshRate,
-            AudioFocus::SamplePaths => AudioFocus::RuntimeHighlight,
+            AudioFocus::ShowScope => AudioFocus::RuntimeHighlight,
+            AudioFocus::ShowSpectrum => AudioFocus::ShowScope,
+            AudioFocus::SamplePaths => AudioFocus::ShowSpectrum,
             AudioFocus::LinkEnabled => AudioFocus::SamplePaths,
             AudioFocus::StartStopSync => AudioFocus::LinkEnabled,
             AudioFocus::Quantum => AudioFocus::StartStopSync,

src/views/audio_view.rs

@@ -47,7 +47,7 @@ fn render_audio_section(frame: &mut Frame, app: &App, area: Rect) {
     let [devices_area, _, settings_area, _, samples_area] = Layout::vertical([
         Constraint::Length(4),
         Constraint::Length(1),
-        Constraint::Length(6),
+        Constraint::Length(8),
         Constraint::Length(1),
         Constraint::Min(3),
     ])
@@ -112,8 +112,12 @@ fn render_settings(frame: &mut Frame, app: &App, area: Rect) {
     let buffer_focused = app.audio.focus == AudioFocus::BufferSize;
     let fps_focused = app.audio.focus == AudioFocus::RefreshRate;
     let highlight_focused = app.audio.focus == AudioFocus::RuntimeHighlight;
+    let scope_focused = app.audio.focus == AudioFocus::ShowScope;
+    let spectrum_focused = app.audio.focus == AudioFocus::ShowSpectrum;
 
     let highlight_text = if app.ui.runtime_highlight { "On" } else { "Off" };
+    let scope_text = if app.audio.config.show_scope { "On" } else { "Off" };
+    let spectrum_text = if app.audio.config.show_spectrum { "On" } else { "Off" };
 
     let rows = vec![
         Row::new(vec![
@@ -147,6 +151,14 @@ fn render_settings(frame: &mut Frame, app: &App, area: Rect) {
             Span::styled("Highlight", label_style),
             render_selector(highlight_text, highlight_focused, highlight, normal),
         ]),
+        Row::new(vec![
+            Span::styled("Scope", label_style),
+            render_selector(scope_text, scope_focused, highlight, normal),
+        ]),
+        Row::new(vec![
+            Span::styled("Spectrum", label_style),
+            render_selector(spectrum_text, spectrum_focused, highlight, normal),
+        ]),
         Row::new(vec![
             Span::styled("Rate", label_style),
             Span::styled(

src/views/main_view.rs

@@ -5,7 +5,7 @@ use ratatui::Frame;
 
 use crate::app::App;
 use crate::engine::SequencerSnapshot;
-use crate::widgets::{Orientation, Scope, VuMeter};
+use crate::widgets::{Orientation, Scope, Spectrum, VuMeter};
 
 pub fn render(frame: &mut Frame, app: &mut App, snapshot: &SequencerSnapshot, area: Rect) {
     let [left_area, _spacer, vu_area] = Layout::horizontal([
@@ -15,13 +15,31 @@ pub fn render(frame: &mut Frame, app: &mut App, snapshot: &SequencerSnapshot, ar
     ])
     .areas(area);
 
-    let [scope_area, sequencer_area] = Layout::vertical([
+    let show_scope = app.audio.config.show_scope;
-        Constraint::Length(14),
+    let show_spectrum = app.audio.config.show_spectrum;
+    let viz_height = if show_scope || show_spectrum { 14 } else { 0 };
+
+    let [viz_area, sequencer_area] = Layout::vertical([
+        Constraint::Length(viz_height),
         Constraint::Fill(1),
     ])
     .areas(left_area);
 
+    if show_scope && show_spectrum {
+        let [scope_area, _, spectrum_area] = Layout::horizontal([
+            Constraint::Percentage(50),
+            Constraint::Length(2),
+            Constraint::Percentage(50),
+        ])
+        .areas(viz_area);
         render_scope(frame, app, scope_area);
+        render_spectrum(frame, app, spectrum_area);
+    } else if show_scope {
+        render_scope(frame, app, viz_area);
+    } else if show_spectrum {
+        render_spectrum(frame, app, viz_area);
+    }
+
     render_sequencer(frame, app, snapshot, sequencer_area);
     render_vu_meter(frame, app, vu_area);
 }
@@ -166,6 +184,12 @@ fn render_scope(frame: &mut Frame, app: &App, area: Rect) {
     frame.render_widget(scope, area);
 }
 
+fn render_spectrum(frame: &mut Frame, app: &App, area: Rect) {
+    let area = Rect { height: area.height.saturating_sub(1), ..area };
+    let spectrum = Spectrum::new(&app.metrics.spectrum);
+    frame.render_widget(spectrum, area);
+}
+
 fn render_vu_meter(frame: &mut Frame, app: &App, area: Rect) {
     let vu = VuMeter::new(app.metrics.peak_left, app.metrics.peak_right);
     frame.render_widget(vu, area);

src/widgets/mod.rs

@@ -1,11 +1,13 @@
 mod confirm;
 mod modal;
 mod scope;
+mod spectrum;
 mod text_input;
 mod vu_meter;
 
 pub use confirm::ConfirmModal;
 pub use modal::ModalFrame;
 pub use scope::{Orientation, Scope};
+pub use spectrum::Spectrum;
 pub use text_input::TextInputModal;
 pub use vu_meter::VuMeter;

src/widgets/spectrum.rs

@@ -0,0 +1,62 @@
+use ratatui::buffer::Buffer;
+use ratatui::layout::Rect;
+use ratatui::style::Color;
+use ratatui::widgets::Widget;
+
+const BLOCKS: [char; 8] = ['\u{2581}', '\u{2582}', '\u{2583}', '\u{2584}', '\u{2585}', '\u{2586}', '\u{2587}', '\u{2588}'];
+
+pub struct Spectrum<'a> {
+    data: &'a [f32; 32],
+}
+
+impl<'a> Spectrum<'a> {
+    pub fn new(data: &'a [f32; 32]) -> Self {
+        Self { data }
+    }
+}
+
+impl Widget for Spectrum<'_> {
+    fn render(self, area: Rect, buf: &mut Buffer) {
+        if area.width == 0 || area.height == 0 {
+            return;
+        }
+
+        let height = area.height as f32;
+        let band_width = area.width as usize / 32;
+        if band_width == 0 {
+            return;
+        }
+
+        for (band, &mag) in self.data.iter().enumerate() {
+            let bar_height = mag * height;
+            let full_cells = bar_height as usize;
+            let frac = bar_height - full_cells as f32;
+            let frac_idx = (frac * 8.0) as usize;
+
+            let x_start = area.x + (band * band_width) as u16;
+
+            for row in 0..area.height as usize {
+                let y = area.y + area.height - 1 - row as u16;
+                let ratio = row as f32 / area.height as f32;
+                let color = if ratio < 0.33 {
+                    Color::Rgb(40, 180, 80)
+                } else if ratio < 0.66 {
+                    Color::Rgb(220, 180, 40)
+                } else {
+                    Color::Rgb(220, 60, 40)
+                };
+                for dx in 0..band_width as u16 {
+                    let x = x_start + dx;
+                    if x >= area.x + area.width {
+                        break;
+                    }
+                    if row < full_cells {
+                        buf[(x, y)].set_char(BLOCKS[7]).set_fg(color);
+                    } else if row == full_cells && frac_idx > 0 {
+                        buf[(x, y)].set_char(BLOCKS[frac_idx - 1]).set_fg(color);
+                    }
+                }
+            }
+        }
+    }
+}