terminal-oscilloscope

A terminal-based oscilloscope with CRT phosphor physics, written in Nim. Zero dependencies — 200KB binary, just libc.

Braille renderer (amber palette)

Half-block renderer

Features

• CRT boot/shutdown animations — phosphor ramp, beam sweep, vertical collapse, dot fade
• Y-T and X-Y modes — time-domain waveform or Lissajous figures
• Phosphor persistence — beam bloom, decay trails, intensity-based shading
• Two renderers — half-block (▀▄█) or braille dots for 4× resolution
• Live audio capture — direct libav bindings via dlopen, zero install
• Threaded audio — 60fps rendering, audio capture on separate thread
• 6 CRT phosphor palettes — green, amber, cyan, blue, white, red

Install

Requires Nim 2.x.

git clone https://github.com/rolandnsharp/terminal-oscilloscope.git
cd terminal-oscilloscope

Half-block version (chunky CRT look):

nim c -d:release --threads:on -o:osc src/osc.nim
./osc

Braille version (high-resolution dots):

nim c -d:release --threads:on -o:osc_braille src/osc_braille.nim
./osc_braille

Install globally:

sudo ln -s $(pwd)/osc /usr/local/bin/osc

Controls

Key	Action
m	Toggle Y-T / X-Y mode
+ / -	Increase / decrease gain (amplitude)
] / [	Zoom in / out time axis
q	Quit (with CRT shutdown effect)

Configuration

Edit the constants at the top of src/osc.nim or src/osc_braille.nim:

const
  # Phosphor physics
  Decay = 0.85           # persistence per frame (0.0–1.0)
  Beam = 0.4             # intensity at beam impact
  Bloom = 0.08           # horizontal glow spread

  # Phosphor glow thresholds
  HotGlow = 0.7          # white-hot beam core
  WarmGlow = 0.4         # bright phosphor
  CoolGlow = 0.15        # dim persistence trail

  # Palette: green, amber, cyan, blue, white, red
  Palette = "green"

Palettes

Name	Phosphor	Look
green	P31	classic oscilloscope
amber	P12	warm retro terminal
cyan	P7	Tektronix blue-green
blue	P11	cool/modern
white	P4	TV phosphor
red	P22-R	radar display

Audio

Captures system audio by opening the PulseAudio/PipeWire monitor of your default output sink directly via libavformat and libavdevice. Libraries are loaded at runtime with dlopen — no dev packages, no subprocess, no extra dependencies.

Credits

CRT turn-on/off animations inspired by AetherTune.