agg - asciinema gif generator

agg is a command-line tool for generating animated GIF files from asciicast v2 files produced by asciinema terminal recorder.

It uses Kornel Lesiński's excellent gifski library to produce optimized, high quality GIF output with accurate frame timing.

agg is a successor to asciicast2gif.

Building

Building from source requires Rust compiler and Cargo package manager. You can install both with rustup.

To build agg run:

cargo build -r

This produces an executable file at target/release/agg. There are no other build artifacts so you can copy the binary to a directory in your $PATH.

Usage

Basic usage:

agg demo.cast demo.gif

The above command renders a GIF file with default theme (dracula), font size 14px.

Additional options are available for customization. For example, the following command selects Monokai theme, larger font size, 2x playback speed:

agg --theme monokai --font-size 20 --speed 2 demo.cast demo.gif

Run agg -h to see all available options. Current options are:

    --font-dir <FONT_DIR>
        Use additional font directory

    --font-family <FONT_FAMILY>
        Specify font family [default: "JetBrains Mono,Fira Code,SF Mono,Menlo,Consolas,DejaVu
        Sans Mono,Liberation Mono"]

    --font-size <FONT_SIZE>
        Specify font size (in pixels) [default: 14]

    --fps-cap <FPS_CAP>
        Set FPS cap [default: 30]

-h, --help
        Print help information

    --idle-time-limit <IDLE_TIME_LIMIT>
        Limit idle time to max number of seconds [default: 5]

    --line-height <LINE_HEIGHT>
        Specify line height [default: 1.4]

    --renderer <RENDERER>
        Select frame rendering backend [default: fontdue] [possible values: fontdue, resvg]

    --speed <SPEED>
        Adjust playback speed [default: 1]

    --theme <THEME>
        Select color theme [possible values: asciinema, dracula, monokai, solarized-dark,
        solarized-light, custom]

-v, --verbose
        Enable verbose logging

-V, --version
        Print version information

Color themes

There are several built-in color themes you can use with --theme option:

• asciinema
• dracula (default)
• monokai
• solarized-dark
• solarized-light

If your asciicast file includes theme definition then it's used automatically unless --theme option is explicitly specified.

A custom, ad-hoc theme can be used with --theme option by passing a series of comma-separated hex triplets defining terminal background color, default text color and a color palette:

--theme bbbbbb,ffffff,000000,111111,222222,333333,444444,555555,666666,777777

The above sets terminal background color to bbbbbb, default text color to ffffff, and uses remaining 8 colors as SGR color palette.

Additional bright color variants can be specified by adding 8 more hex triplets at the end. For example, the equivalent of the built-in Monokai theme is:

--theme 272822,f8f8f2,272822,f92672,a6e22e,f4bf75,66d9ef,ae81ff,a1efe4,f8f8f2,75715e,f92672,a6e22e,f4bf75,66d9ef,ae81ff,a1efe4,f9f8f5

Additional GIF optimization

agg's GIF encoder, gifski, produces great looking GIF files, although this often comes at a cost - file size.

gifsicle can be used to shrink the produced GIF file:

gifsicle --lossy=80 -k 128 -O2 -Okeep-empty demo.gif -o demo-opt.gif

Every recording is different so you may need to tweak the lossiness level (--lossy), number of colors (-k) and other options to suit your needs.

License

Copyright © 2022 Marcin Kulik.

All code is licensed under the Apache License, Version 2.0. See LICENSE file for details.