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Video Calls Addendum (PairUX over SSH)

Join a PairUX video call from a terminal: the platform subscribes to the call's LiveKit room and renders participant video as truecolor ASCII — each character cell is two pixels via the upper-half block (▀), the same technique doom-ascii uses.

SSH routes

Command What happens
ssh video-<code>@profullstack.com join call <code> directly
ssh video@profullstack.com prompted for a code

Codes are minted by PairUX. The SSH surface never creates calls — to start one you must already have a code (create the call in PairUX first).

Pipeline

PairUX / LiveKit room
   └─ VP8 RTP track  ── PLI keyframe requests ──┐
        └─ ivfwriter remux → ffmpeg (decode + scale) → RGB24 frames
             └─ half-block ANSI (internal/ascii) → bubbletea → SSH PTY
  • Subscriber-only: the terminal viewer publishes nothing.
  • A PLI is sent on subscribe and every 2s — without it the SFU never starts forwarding video to a fresh subscriber, and the periodic refresh bounds packet-loss artifacts.
  • Audio is not rendered (it's a terminal); v2 could downlink Opus → local audio out for desktop SSH clients.
  • Frame size locks to the terminal geometry at join (scale= in ffmpeg); ~10–15 fps at typical terminal sizes costs a few hundred KB/s of SSH bandwidth.

Configuration

Shares PairUX's env shape:

Var Meaning
AGENTBBS_LIVEKIT_URL (or LIVEKIT_URL / NEXT_PUBLIC_LIVEKIT_URL) LiveKit ws URL
AGENTBBS_LIVEKIT_KEY (or LIVEKIT_API_KEY) API key
AGENTBBS_LIVEKIT_SECRET (or LIVEKIT_API_SECRET) API secret
AGENTBBS_VIDEO_DEBUG dump the received IVF stream to this path

Unconfigured hosts refuse with a clear message.

Dev testing

docker run -d -p 7880:7880 -p 7881:7881 -p 7882:7882/udp \
  livekit/livekit-server --dev --bind 0.0.0.0   # devkey/secret
ffmpeg -f lavfi -i testsrc=size=320x240:rate=15 -t 900 \
  -c:v libvpx -b:v 400k -g 15 -y test.ivf
go run ./cmd/lkpublish -room demo1 -fps 15 -file test.ivf
ssh -p 2222 video-demo1@localhost

Note: lkpublish passes an explicit frame duration — lksdk's IVF replay pacing can't be trusted from the file timebase alone (we measured 1fps from a 15fps file without it). Real PairUX publishers are browsers, which pace correctly on their own.