bricks/docs/en/rtc.md

VideoBox

Functionality: Used to create and manage <video> elements within a page, supporting the setting of audio/video streams (MediaStream). Commonly used for rendering local or remote video.
Type: Regular widget (UI component)
Parent Widget: bricks.JsWidget

Initialization Parameters

No explicit constructor; DOM element is automatically created and default attributes are set when calling the create() method:

• autoplay: true: Enables automatic playback
• muted: true: Mutes the audio by default

Main Events

No custom events exposed, but internal logic uses native <video> element events (e.g., play, pause). The following methods are provided for external control:

• set_stream(stream): Binds a MediaStream to the video element
• get_stream(): Retrieves the currently bound MediaStream

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Signaling

Functionality: Implements a WebSocket signaling channel for login, heartbeat, message transmission/reception, and session management. It serves as the core coordination module for multi-party WebRTC communication. Supports registering message handlers for different types of sessions.
Type: Regular widget (non-UI module)
Parent Widget: None (standalone class)

Initialization Parameters

Parameter	Type	Description
signaling_url	String	WebSocket server URL
info	Object	Identity information of the current client (e.g., user ID), sent with every message
connect_opts	Object	Connection options passed to session handlers
onclose	Function	Callback triggered when WebSocket connection closes
onlogin	Function	Triggered upon successful login, returns list of currently online users
onopen	Function	Callback when WebSocket connection opens (optional)
heartbeat_period	Number	Heartbeat interval in seconds; 0 means disabled

Main Events

Incoming data is dispatched via recvdata_handler. Key message types include:

• online: Login response containing the list of currently online users
• new_session: Request to create a new session
• Custom sessiontype messages: Handled by processors registered via add_sessionhandler()

Supports dynamic registration of session handlers:

• add_sessionhandler(sessiontype, handlerClass): Registers a handler class for a specific session type
• add_handler(key, handler): Adds a message handler for a specific session ID

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RTCP2PConnect

Functionality: Encapsulates WebRTC peer-to-peer connection logic, including media stream handling, data channels, signaling interaction, and ICE negotiation. Enables audio/video calling and data transfer.
Type: Regular widget (communication module)
Parent Widget: None (standalone class)

Initialization Parameters

Parameter	Type	Description
signaling	Signaling instance	Upper-layer signaling instance for sending and receiving signaling messages
session	Object	Current session object {sessionid, sessiontype}
opts	Object	Configuration options, structured as follows:

{
  ice_servers: [],           // STUN/TURN server configuration
  peer_info: {},             // Remote peer information (used in callrequest)
  auto_callaccept: true,     // Automatically accept incoming calls
  media_options: {           // Parameters for getUserMedia
    video: true,
    audio: true
  },
  data_connect: true,        // Whether to establish a data channel
  on_pc_connected: Function, // Callback when PeerConnection is successfully established
  on_pc_disconnected: Function, // Callback when PeerConnection disconnects
  on_dc_open: Function,      // Callback when DataChannel opens
  on_dc_close: Function,     // Callback when DataChannel closes
  on_dc_message: Function    // Callback when a message is received via DataChannel
}

Main Events

Listens for and responds to the following signaling message types through built-in handlers:

• sessioncreated: Session successfully created; initiates connection process
• callrequest: Incoming call request; automatically responds if auto_callaccept is enabled
• callaccepted: Call accepted by remote party; begins SDP negotiation
• offer: Receives SDP Offer; replies with Answer
• answer: Receives SDP Answer; completes negotiation
• icecandidate: Receives ICE candidate; adds it to PeerConnection
• sessionquit: Session ends; closes connection

Other runtime events:

• oniceconnectionstatechange: ICE connection state changes
• onconnectionstatechange: Overall connection state changes (e.g., connected/disconnected)
• ondatachannel / ontrack: Fired when remote data channel or media track arrives

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✅ Summary:

• VideoBox is a visual component used to display video streams.
• Signaling acts as the signaling hub, managing communication with the server.
• RTCP2PConnect is the WebRTC connection controller, handling the full lifecycle of peer-to-peer connections.

Together, these three components form a complete real-time communication system.