everything-claude-code/skills/videodb/reference/capture.md

Capture Guide

Overview

VideoDB Capture enables real-time screen and audio recording with AI processing. Desktop capture currently supports macOS only.

For code-level details (SDK methods, event structures, AI pipelines), see capture-reference.md.

Quick Start

1. Start WebSocket listener: python scripts/ws_listener.py --clear &
2. Run capture code (see Complete Capture Workflow below)
3. Events written to: /tmp/videodb_events.jsonl

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Complete Capture Workflow

No webhooks or polling required. WebSocket delivers all events including session lifecycle.

CRITICAL: The CaptureClient must remain running for the entire duration of the capture. It runs the local recorder binary that streams screen/audio data to VideoDB. If the Python process that created the CaptureClient exits, the recorder binary is killed and capture stops silently. Always run the capture code as a long-lived background process (e.g. nohup python capture_script.py &) and use signal handling (asyncio.Event + SIGINT/SIGTERM) to keep it alive until you explicitly stop it.

1. Start WebSocket listener in background with --clear flag to clear old events. Wait for it to create the WebSocket ID file.

2. Read the WebSocket ID. This ID is required for capture session and AI pipelines.

3. Create a capture session and generate a client token for the desktop client.

4. Initialize CaptureClient with the token. Request permissions for microphone and screen capture.

5. List and select channels (mic, display, system_audio). Set store = True on channels you want to persist as a video.

6. Start the session with selected channels.

7. Wait for session active by reading events until you see capture_session.active. This event contains the rtstreams array. Save session info (session ID, RTStream IDs) to a file (e.g. /tmp/videodb_capture_info.json) so other scripts can read it.

8. Keep the process alive. Use asyncio.Event with signal handlers for SIGINT/SIGTERM to block until explicitly stopped. Write a PID file (e.g. /tmp/videodb_capture_pid) so the process can be stopped later with kill $(cat /tmp/videodb_capture_pid). The PID file should be overwritten on every run so reruns always have the correct PID.

9. Start AI pipelines (in a separate command/script) on each RTStream for audio indexing and visual indexing. Read the RTStream IDs from the saved session info file.

10. Write custom event processing logic (in a separate command/script) to read real-time events based on your use case. Examples:

    • Log Slack activity when visual_index mentions "Slack"
    • Summarize discussions when audio_index events arrive
    • Trigger alerts when specific keywords appear in transcript
    • Track application usage from screen descriptions

11. Stop capture when done — send SIGTERM to the capture process. It should call client.stop_capture() and client.shutdown() in its signal handler.

12. Wait for export by reading events until you see capture_session.exported. This event contains exported_video_id, stream_url, and player_url. This may take several seconds after stopping capture.

13. Stop WebSocket listener after receiving the export event. Use kill $(cat /tmp/videodb_ws_pid) to cleanly terminate it.

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Shutdown Sequence

Proper shutdown order is important to ensure all events are captured:

1. Stop the capture session — client.stop_capture() then client.shutdown()
2. Wait for export event — poll /tmp/videodb_events.jsonl for capture_session.exported
3. Stop the WebSocket listener — kill $(cat /tmp/videodb_ws_pid)

Do NOT kill the WebSocket listener before receiving the export event, or you will miss the final video URLs.

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Scripts

Script	Description
scripts/ws_listener.py	WebSocket event listener (dumps to JSONL)

ws_listener.py Usage

# Start listener in background (append to existing events)
python scripts/ws_listener.py &

# Start listener with clear (new session, clears old events)
python scripts/ws_listener.py --clear &

# Custom output directory
python scripts/ws_listener.py --clear /path/to/events &

# Stop the listener
kill $(cat /tmp/videodb_ws_pid)

Options:

• --clear: Clear the events file before starting. Use when starting a new capture session.

Output files:

• videodb_events.jsonl - All WebSocket events
• videodb_ws_id - WebSocket connection ID (for ws_connection_id parameter)
• videodb_ws_pid - Process ID (for stopping the listener)

Features:

• Auto-reconnect with exponential backoff on connection drops
• Graceful shutdown on SIGINT/SIGTERM
• PID file for easy process management
• Connection status logging