scope-tui

A simple oscilloscope/vectorscope in your terminal

Currently only for Linux (with Pulseaudio)

Why

I really love cava. It provides a crude but pleasant frequency plot for your music: just the bare minimum to see leads solos and basslines. I wanted to also be able to see waveforms, but to my knowledge nothing is available. There is some soundcard oscilloscope software available, but the graphical GUI is usually dated and breaks the magic. I thus decided to solve this very critical issue with my own hands! And over a night of tinkering with pulseaudio (via libpulse-simple-binding) and some TUI graphics (via tui-rs), the first version of scope-tui was developed, with very minimal settings given from command line, but a bonus vectorscope mode baked in.

Usage

$ scope-tui [OPTIONS] [DEVICE]

Arguments:
  [DEVICE]  Audio device to attach to

Options:
  -b, --buffer <SIZE>          Size of audio buffer, and width of scope [default: 8192]
  -r, --range <SIZE>           Max value, positive and negative, on amplitude scale [default: 20000]
      --scatter                Use vintage looking scatter mode instead of line mode
      --vectorscope            Combine left and right channels into vectorscope view
      --tune <NOTE>            Tune buffer size to be in tune with given note (overrides buffer option)
      --channels <N>           Number of channels to open [default: 2]
      --sample-rate <HZ>       Sample rate to use [default: 44100]
      --server-buffer <N>      Pulseaudio server buffer size, in block number [default: 32]
      --triggering             Start drawing at first rising edge
      --threshold <THRESHOLD>  Threshold value for triggering [default: 0]
      --no-reference           Don't draw reference line
      --no-ui                  Hide UI and only draw waveforms
      --no-braille             Don't use braille dots for drawing lines
  -h, --help                   Print help information
  -V, --version                Print version information

The audio buffer size directly impacts resource usage, latency and refresh rate and its limits are given by the audio refresh rate. Larger buffers are slower but less resource intensive. A good starting value might be 8192 or tuning to the 0th octave.

To change audio buffer size, the PulseAudio client must be restarted. Because of this, such option is configurable only at startup.

Controls

• Use q or CTRL+C to exit
• Use t to toggle triggered mode
• Use <SPACE> to pause and resume display
• Use <LEFT> and <RIGHT> to increase or decrease time range by 25
• Use <UP> and <DOWN> to increase or decrease amplitude scale by 250
• Use <PG-UP> and <PG-DOWN> to increase or decrease threshold by 250
  • Combine arrows with <SHIFT> to increase or decrease by x4
  • Combine arrows with <CTRL> to increase or decrease by /5
  • Press <TAB> to restore width and scale to default values
• Use v to toggle vectorscope mode
• Use s to toggle scatter mode
• Use b to toggle braille characters
• Use h to toggle interface
• Use r to toggle reference lines
• Use <ESC> to show ui and revert to oscilloscope
• Use <C-R> to reset all options to startup values

About precision

While "scatter" plot mode is as precise as Pulseaudio and the terminal lets us be, "line" plot mode simply draws a straight line across points, meaning high frequencies don't get properly represented.

Latency is kept to a minimum thanks to small buffer and block sizes.

Sample rate can be freely specified but will ultimately be limited by source's actual sample rate.

Decrease/increase terminal font size to increase/decrease scope resolution.