Subscribing to Tracks

Using the CLI

# Subscribe to a track and stream objects to the terminal
moqtap peek moqt://relay.example.com data live video

# Fetch only the latest object
moqtap peek moqt://relay.example.com data live video latest

# Raw payload output (for piping to other tools)
moqtap peek moqt://relay.example.com data live video --raw

# JSON output
moqtap peek moqt://relay.example.com data live video -j

The CLI auto-detects the payload format (JSON, fMP4, LOC/MSF binary, text) and renders it accordingly.

Using the desktop app

1. Enter the namespace (e.g., ["chat"])
2. Enter the track name (e.g., "messages")
3. Select a filter type:
   • LatestObject — start from the latest available object
   • NextGroupStart — wait for the next group boundary
   • AbsoluteStart — start from group 0, object 0
   • AbsoluteRange — specific range of groups/objects
4. Click Subscribe

The subscription lifecycle

SUBSCRIBE (sent) → SUBSCRIBE_OK (received) → objects flow → UNSUBSCRIBE (sent) → PUBLISH_DONE (received)

In draft-17, UNSUBSCRIBE is removed — the subscription lifecycle uses the consolidated request/response pattern with REQUEST_OK / REQUEST_ERROR.

moqtap shows each state transition in the control message log with timestamps.

Viewing objects

Objects arrive on unidirectional QUIC streams (subgroup streams) or datagrams. Each object shows:

• Group ID and Object ID
• Subgroup assignment
• Publisher priority and status
• Payload — auto-detected as text, JSON, fMP4, or binary

Using the browser extension

The extension passively decodes subscription messages and object delivery from your application’s WebTransport connections. The DevTools panel shows subscriptions with namespace/track name display, live bitrate, and a stream data viewer with hex and JSON modes.

Unsubscribing

In the desktop app, click Unsubscribe to end the subscription. The relay responds with PUBLISH_DONE.