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 (1.56.0 or later) and Cargo package manager. You can install both with rustup.

To download source code, build agg binary and install it in $HOME/.cargo/bin run:

cargo install --git https://github.com/asciinema/agg

You need to ensure $HOME/.cargo/bin is in your shell's $PATH.

Alternatively, you can manually download source code and build agg binary with:

git clone https://github.com/asciinema/agg
cd agg
cargo build --release

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

Building via Docker

Alternatively, if you have Docker, Podman or another Docker-compatible tool installed you can use it to build agg container image. This doesn't require Rust toolchain installed on your machine.

Build the image with the following command:

docker build -t agg .

Then run agg like this:

docker run --rm -it -u $(id -u):$(id -g) -v $PWD:/data agg demo.cast demo.gif

If you use Podman in root-less mode:

podman run --rm -it -v $PWD:/data agg demo.cast demo.gif

Usage

Basic usage:

agg demo.cast demo.gif

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

You can also provide an asciinema.org URL as the first argument:

agg https://asciinema.org/a/569727 starwars.gif

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:

    --cols <COLS>
        Override terminal width (number of columns)

    --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]

    --no-loop
        Disable animation loop

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

    --rows <ROWS>
        Override terminal height (number of rows)

    --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

Fonts

By default agg uses common monospaced font for a given platform, that can be found on its default font family list. The list includes DejaVu Sans Mono and Liberation Mono (found on most Linux distros), SF Mono and Menlo (found on macOS), Consolas (found on Windows), with addition of my personal favourites like JetBrains Mono and Fira Code. The fonts are not included in agg and must be present on the system. To see the default value run agg --help and look for --font-family. In addition there's implicit fallback to DejaVu Sans (not Mono) which helps with rendering symbols like ⣽ or ✔ amongst others.

If you want to use another font family then pass a comma-separated list like this:

agg --font-family "Source Code Pro,Fira Code" demo.cast demo.gif

As long as the fonts you want to use are installed in one of standard system locations (e.g. /usr/share/fonts or ~/.local/share/fonts on Linux) agg will find them. You can also use --font-dir=/path/to/fonts option to include extra fonts. --font-dir can be specified multiple times.

To verify agg picks up your font run it with -v (verbose) flag:

agg -v --font-family "Source Code Pro,Fira Code" demo.cast demo.gif

It should print something similar to:

[INFO agg] selected font families: ["Source Code Pro", "Fira Code", "DejaVu Sans", "Noto Emoji"]

This list may also include implicit addition of DejaVu Sans fallback (mentioned earlier), as well as Noto Emoji (see section below).

Here's how to use Nerd Fonts with agg:

1. Download one of the patched font sets from https://github.com/ryanoasis/nerd-fonts/releases/latest , e.g. JetBrainsMono.zip
2. Unzip them into ~/.local/share/fonts (on Linux) or install with system font manager (macOS, Windows)
3. Specify font family like this:

agg --font-family "JetBrainsMono Nerd Font Mono" demo.cast demo.gif

Emoji

Currently agg supports only monochrome emojis via Noto Emoji font.

Install Noto Emoji font on your system or, point agg to a folder containing NotoEmoji-*.ttf files with --font-dir.

Note that Noto Color Emoji font is not supported. Be aware that some distros ship this color font by name like "noto-fonts-emoji". This is not what you need.

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

GIF encoder used by agg, 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.

Consulting

I offer consulting services for asciinema project. See https://asciinema.org/consulting for more information.

License

© 2022 Marcin Kulik.

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