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KN-86 Deckline

AetherTune

What it is

Section titled “What it is”

AetherTune is a Rust TUI for browsing and streaming internet radio via the RadioBrowser API — but the radio surface is the demo; the engineering surfaces are what make it the strongest single inspiration in this batch for KN-86’s runtime architecture. It ships:

  • A real 16-band spectrum visualizer powered by an actual sliding-window radix-2 FFT at ~94 frames per second, with CAVA-inspired gravity-fall-off, integral smoothing, and automatic sensitivity. Audio is captured from PulseAudio/PipeWire monitor on Linux or WASAPI loopback on Windows.
  • CRT boot and power-off animations that bracket the application — the runtime opens with a CRT-warmup scroll and closes with a power-off shrink. Identity branding, not skinning.
  • 8 named themes with live preview: CRT (default — phosphor cyan/magenta/neon green), Gruvbox, Nord, Dracula, Monokai, Catppuccin, Hacker, Solarized. Theme picker (t) shows live color swatches and previews each theme on navigation.
  • Fully remappable keybindings — every keyboard shortcut can be rebound from an in-app overlay (S), persisted to ~/.aethertune/config.json.
  • Stream health monitor + song log + favorites + history, persisted to JSON.
  • Built-in profiler with per-frame timing breakdown for performance tuning.
  • A fallback simulated visualizer when audio capture isn’t available (e.g., macOS, or Linux without PulseAudio) — degrades gracefully, doesn’t crash.

The src/ui/ module layout is clean enough that the user’s prompt called it out as a starting-architecture reference.

Aspirational features for KN-86

Section titled “Aspirational features for KN-86”
  • Real FFT visualizer pipeline as the reference. When KN-86 implements the PSG-driven CIPHER-LINE visualizer (per the v0.1 ship list in the Batch-2 visual identity brief), the AetherTune pipeline is the reference: a sliding-window radix-2 FFT, ~94 Hz update rate, CAVA-style gravity fall-off for the visual smoothing, automatic sensitivity adjustment so the bands fill nicely across loud and quiet passages. On KN-86 the input source is YM2149 PSG output from the Pico 2 coprocessor rather than a system audio loopback, but the DSP is the same.
  • CRT boot + power-off animations as identity branding. The Deckline should open with a CRT-warmup animation and close with a power-off shrink. Not optional, not skippable (or skippable only by an explicit --no-cinema flag the user has to discover). This is the kind of small, deliberate touch that makes the device read as the Deckline rather than as a Linux machine running a TUI.
  • 8 themes, live preview, fully persisted in JSON. Same direction as audium.md but with the CRT-as-default theme call-out. Direct cite for the v0.1 aesthetic-mode roster decision.
  • Fully remappable keybindings. Every action’s key binding is data, not code. KN-86 should ship the same — keybindings live in nosh-config.toml, picker UI on the SYS tab. This handles edge cases (an operator with reduced motor function rebinding to one-hand operation, a left-handed operator swapping the numpad cluster) without any code changes.
  • Graceful capability degradation (fallback simulated visualizer). Matches the Batch-1 NetWatch + PulseDeck graceful-degradation doctrine. When audio capture isn’t available, AetherTune still renders a visualizer — just driven by a simulator. KN-86 should do the same for the coprocessor-offline case: if the Pico 2 isn’t responding, the CIPHER-LINE visualizer should run on a synthesized stream rather than going blank.
  • src/ui/ module split as a starting architecture. The Rust source layout is clean, with src/ui/ carrying the rendering, src/audio/ carrying the capture + DSP, src/api/ carrying the RadioBrowser client, and src/config/ carrying the keybinding + theme + favorites + history persistence. KN-86’s runtime architecture should follow a similar split — particularly the isolation of UI rendering from the data sources behind it, which is what makes themability, remappable keybinds, and the fallback visualizer all work without architectural surgery.
  • Built-in profiler. Per-frame timing breakdown, toggleable in-app. KN-86 already has an F12 debug overlay in the emulator (kn86-emulator/src/debug.c); a per-frame profiler view there is a strong cart-development affordance.

Image

Section titled “Image”

AetherTune showcase animation

Source: AetherTune img/showcase.gif. Shows the CRT-themed UI in motion — the visualizer responding to audio, the station browser, the rolling song log, the stream health monitor — all in the CRT default theme.

Notes

Section titled “Notes”
  • The strongest single inspiration in this batch alongside l123.md and 4trk.md. Direct cite candidate as a Batch-3 north star (see index.md synthesis).
  • Cross-link pulsedeck.md for the cassette-deck identity branding parallel — both projects commit hard to a retro-software identity through visual cinema (deck metaphor + visualizer in PulseDeck; CRT boot/power animations + visualizer in AetherTune). Both are doing the same thing and KN-86 should learn from both.
  • The CAVA reference is worth chasing — https://github.com/karlstav/cava is the longstanding terminal audio visualizer that AetherTune cites for its gravity-falloff approach. Worth a read when implementing KN-86’s CIPHER-LINE visualizer.