Record LED panel animations → video

[electronicbites]

Adds an optional subsystem to record the frames sent to the LED panels and convert them to video. Recording is off by default and designed to never affect the running installation.

What's included

• Recorder (Octopus.Recording + PanelRecorder): passively subscribes to the mixer's frame feed and writes an append-only .octorec file. Safe by design — passive PubSub subscriber, subscribe-only-while-active, per-frame try/rescue, and drop-on-overload so it can never block or crash the app.
• Pluggable sinks (Sink behaviour):
  • Sink.File — local file
  • Sink.Remote — stream to a TCP server (bounded connect/send timeouts)
  • Sink.Gzip — optional gzip compression via built-in :zlib (no native deps; runs on the Raspberry Pi). Typically 1.3× smaller for busy content, 10–1000× for sparse/dark.
• Encoder (mix octopus.recording.encode): offline ffmpeg step producing one video per panel plus a mixed video; reads .gz transparently.
• Docs: docs/recording.md (usage, storage sizing, compression) and docs/recording_architecture.md (design & rationale).

Usage

Octopus.Recording.start()                 # or start(compress: true)
Octopus.Recording.stop()

mix octopus.recording.encode recordings/panels-<stamp>.octorec

Enable via config :octopus, Octopus.Recording, enabled: true, compress: true.

Notes

• Only additive change to existing code: a new Mixer.unsubscribe/0 and wiring the supervisor into the app tree.
• Tests cover the format, recorder, both encoders, and the file/remote/gzip sinks (ffmpeg-dependent tests tagged :ffmpeg).