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Architecture

Rivet is a local bridge between a Canon EOS Wi-Fi camera and OBS.

The runtime is split into explicit boundaries:

  • src/canon: Canon PTP/IP transport, MTP session control, EOS Live View bootstrap, frame polling, and reconnection.
  • src/network: local IPv4 interface discovery.
  • src/server: local HTTP dashboard, status endpoint, snapshots, and MJPEG streaming.
  • src/config.ts: CLI argument parsing and validation.
  • src/main.ts: process orchestration.

Frame Contract

The server depends on the FrameSource port. Canon-specific code owns camera state and frame production; HTTP code owns projection to local operator and OBS surfaces.

interface FrameSource {
  latestFrame(): VideoFrame | null;
  frames(signal: AbortSignal): AsyncIterable<VideoFrame>;
}

This keeps Canon protocol concerns out of the HTTP server and keeps OBS-specific behavior out of the Canon runtime.

Capture Lifecycle

  1. Open the PTP/IP command channel.
  2. Open the PTP/IP event channel with the command connection number.
  3. Open an MTP session over the command channel.
  4. Request device information.
  5. Enable Canon remote mode and event mode.
  6. Enable Canon EVF output device 8.
  7. Poll Canon events and request Live View data.
  8. Publish marker-valid JPEG frames through the shared frame source.

The local HTTP server starts before the Canon handshake completes. This gives OBS and the dashboard a stable URL while the camera connects or reconnects in the background.

Runtime Ownership

SharedFrameSource starts one camera capture loop and shares its latest frame with all HTTP clients. OBS, dashboard preview, and snapshot requests never start independent camera polling loops.

ReconnectingFrameSource owns recovery after Canon connection failures. It retries camera connection attempts without manipulating Windows networking.

Build Model

Bun is used for package management, tests, typechecking, and bundling. The bundled runtime executes under Node because Node TCP sockets behave reliably with the verified Windows Wi-Fi routing setup.