Add Deckboy

[Utopian-Academy]

Deckboy — cue-based media playback and show control for live video. GPL-3.0, native C++/SDL3, Windows/macOS/Linux.

https://github.com/Utopian-Academy/Deckboy/

The AppImage is published on the Releases page as Deckboy-<version>-x86_64.AppImage (current: Deckboy-0.99.367-x86_64.AppImage), which follows the standard nomenclature, so newer releases should be picked up automatically.

It is a live-events video player: clips, stills, slides and live sources on one cue list, sent to fullscreen outputs with fades, loops and hold-last-frame, driven from a Stream Deck, Bitfocus Companion, OSC, MIDI or LTC timecode. The AppImage bundles ffmpeg and its own libraries; the host provides GPU/X11/audio, and it runs offline — nothing in it needs a network.

[Utopian-Academy]

Updated: the AppImage this entry points at is now built on Ubuntu 22.04.

Your test rig caught a real fault when I first submitted this — thank you. Two things were wrong and both are fixed in the releases from v0.99.369:

1. Blacklisted libraries are gone. The AppDir was carrying libgpg-error, libgcrypt, the p11-kit/tasn1/krb5 cluster and the glib family. They arrived as transitive dependencies of ffmpeg's TLS stack rather than because anything of ours wanted them. The AppImage is about 3MB smaller without them.

2. The glibc floor came down. That was the deeper problem: the build ran on the newest runner image, so the binary and everything bundled with it wanted glibc 2.39 and could not start on 22.04 at all. The Linux job builds on ubuntu-22.04 now.

The floor is checked rather than assumed — the build extracts the packaged AppImage and runs objdump -T over every ELF inside it, failing if anything needs more than 2.35. On the v0.99.369 build that check reported:

highest glibc required: 2.35  (squashfs-root/usr/lib/libSDL3_ttf.so.0)

An AppStream metainfo file is in usr/share/metainfo now as well, so the catalogue entry has a description and screenshots.

Nothing else about the submission has changed: it is still one line pointing at the releases page, and the AppImage follows the standard naming (Deckboy-0.99.369-x86_64.AppImage).