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
Runtime options can be passed via CLI flags:
./osc --palette:amber --decay:0.92 --beam:0.6 --bloom:0.12
./osc_braille --palette:green --hot:0.8 --warm:0.45 --cool:0.12
Available options:
| Option | Description | Default |
|---|---|---|
-p, --palette:NAME |
Palette name | green |
-d, --decay:FLOAT |
Phosphor persistence per frame | 0.85 |
--beam:FLOAT |
Beam impact intensity | 0.4 |
--bloom:FLOAT |
Horizontal glow spread | 0.08 |
--hot:FLOAT |
White-hot beam core threshold | 0.7 |
--warm:FLOAT |
Bright phosphor threshold | 0.4 |
--cool:FLOAT |
Dim persistence trail threshold | 0.15 |
Show help:
./osc --help
./osc_braille --help
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.