video-setup

A graph-based multi-peer video routing system written in C11. Nodes are media processes connected by typed transport edges; the graph carries video streams between sources, relays, and sinks with priority as a first-class property — so a low-latency monitoring feed and a high-quality archival feed can coexist on the same source.

Designed to run on resource-constrained hardware (Raspberry Pi capturing raw MJPEG, forwarding over TCP) alongside more capable machines that handle processing, relay, display, and archival.

Documentation

• architecture.md — system design: graph model, transport protocol, relay design, codec layer, discovery, multi-site plan, device resilience, X11 integration
• docs/protocol.md — wire protocol reference: frame format, all message types, payload schemas, stream lifecycle, discovery
• planning.md — module build order and current status
• conventions.md — C code and project conventions

CLI Tools

• docs/cli/media_ctrl_cli.md — media device and topology tool
• docs/cli/v4l2_ctrl_cli.md — V4L2 camera control tool
• transport_cli — send/receive framed messages, inspect transport frame headers
• discovery_cli — announce and discover peers over UDP multicast; print found/lost events
• config_cli — load an INI config file and print the resolved values after applying schema defaults
• protocol_cli — send and receive typed protocol messages; inspect frame payloads
• query_cli — wait for first discovered node, send ENUM_DEVICES, print results
• test_image_cli — generate test patterns and write PPM output for visual inspection
• xorg_cli — display a test pattern in the viewer window; exercises scale/anchor modes and text overlays
• v4l2_view_cli — live camera viewer; auto-selects highest-FPS format, displays FPS overlay
• stream_send_cli — capture MJPEG from V4L2, connect to a receiver over TCP, stream VIDEO_FRAME messages with per-stream stats
• stream_recv_cli — listen for incoming TCP stream, display received MJPEG frames with fps/Mbps overlay
• reconciler_cli — simulated state machine experiment; validate the reconciler with fake resources before wiring into the node
• controller_cli — interactive REPL; connects to nodes by peer index or host:port; enum-devices, enum-controls, get/set-control, start/stop-ingest, start/stop-display

Structure

src/modules/     C modules, one directory each
include/         public headers
dev/cli/         CLI driver programs for each module
dev/web/         development web UI (Node.js/Express) — connects to live nodes for V4L2 inspection and control
tools/           build-time code generators (e.g. gen_font_atlas — bitmap font atlas for xorg text overlays)
docs/            documentation

Status

Core modules and the video node binary are working end-to-end. The node can be queried over the wire protocol for device enumeration and V4L2 camera control. V4L2 ingest is live — a source node captures MJPEG and streams it to a sink node which displays it in an xorg window. The node supports both source (START_INGEST) and display sink (START_DISPLAY) roles. A reconciler manages V4L2 device and transport connection state. The development web UI connects to live nodes for inspection and control. Relay, archive, and codec have not started.

Module	Status	Notes
common	done	Error types, base definitions
config	done	INI file loader, schema-driven defaults, typed getters
media_ctrl	done	Media Controller topology, pad format config
v4l2_ctrl	done	V4L2 control enumeration, get/set
serial	done	Little-endian binary serialization primitives
transport	done	Framed TCP stream, single-write send
discovery	done	UDP multicast announcements, peer table, found/lost callbacks
protocol	done	Typed write/read functions for all message types
test_image	done	Test pattern generator — colour bars, luminance ramp, grid; YUV420/BGRA output
xorg	done	GLFW+OpenGL viewer sink — YUV420/BGRA/MJPEG input, all scale/anchor modes, bitmap font atlas text overlays; screen grab and XRandR queries not yet implemented
reconciler	done	Generic wanted/current state machine reconciler — BFS pathfinding, event + periodic tick
ingest	done	V4L2 capture loop — open device, negotiate MJPEG, MMAP buffers, capture thread with on_frame callback
node	done	Video node binary — source role (START/STOP_INGEST) and display sink role (START/STOP_DISPLAY); multi-window xorg viewer; declarative reconciler for device and connection state
dev/web	done	Development web UI — connects to live nodes, V4L2 inspection and control
frame_alloc	not started	Per-frame allocation with byte budget and ref counting
relay	not started	Input dispatch to output queues (low-latency and completeness modes)
archive	not started	Write frames to disk, control messages to binary log
codec	not started	Per-frame encode/decode (MJPEG, QOI, ZSTD-raw, VA-API H.264)
web node	not started	Node.js peer — binary protocol socket side + HTTP/WebSocket to browser