Last updated: 2022-01-19 15:04:38

    This document explains some of the basic concepts you may encounter while using TRTC services.


    TRTC manages businesses or projects as applications. You can create different applications for your businesses or projects in the TRTC console to separate their data. Each Tencent Cloud account can create up to 100 TRTC applications.


    Tencent Cloud uses SDKAppID (application ID) to uniquely identify TRTC applications. It is generated automatically when an application is created in the TRTC console. Applications with different SDKAppID cannot communicate data with each other.


    UserID (user ID) uniquely identifies a user in a TRTC application.

    • UserID is a mapping of the user accounts of your project in Tencent Cloud. Normally, you can use user names as UserID.
    • UserID should preferably be 32 bytes or shorter. It can contain digits, letters (case sensitive), and underscores, but must not include only digits.


    A room is a space where users can receive each other’s audio and video data in real time.

    • Rooms are virtual spaces TRTC uses to separate one user group from another.
    • Only users in the same room can receive each other’s audio and video.
    • A user can be in only one room at a time. A user who is already in a room must exit the room first in order to enter another.

    • The first user who enters a room is the owner of the room. Room owners cannot close rooms manually.
    • In the call modes, TRTC closes a room when all users in the room exit.
    • In the live streaming modes, if the last user who exits a room is an anchor, TRTC will close the room immediately; if the user is audience, TRTC will close the room in 10 minutes.
    • A user will be removed from a room 90 seconds after unexpected disconnection. If all users are unexpectedly disconnected, the room will be closed after 90 seconds. The waiting time after disconnection is also billed.
    • If a user attempts to enter a room that does not exist, TRTC will create a room automatically.

    Room ID

    RoomID (room number/ID) uniquely identifies a room in a TRTC application. It is a number in the uint32 range and is assigned and maintained by yourself. Its value range is 1-4294967295.


    UserSig (user signature) is a security signature designed by Tencent Cloud to authenticate user logins, check whether a user is real, and thus prevent attackers from accessing your Tencent Cloud account. For more information, please see FAQs > UserSig.


    Push is the operation where a user uploads local audio/video data to the TRTC server.


    Subscription is the operation where a user sends a request to the TRTC server to pull the audio/video data of a specified user.


    In TRTC, users can have either of two roles: anchor (TRTCRoleAnchor) and audience (TRTCRoleAudience).

    • An anchor can push local audio/video data to the server and subscribe to and play back the audio/video data of other anchors.
    • Audience can only subscribe to and play back the audio/video data of anchors.

    In the call modes, all users in a room are in the anchor role. In the live streaming modes, users in a room may be divided into anchors and audience. A user can switch roles whenever needed.

    CDN Live Watching

    CDN live watching is also known as CDN relayed live streaming. TRTC uses relayed transcoding clusters to convert its UDP audio/video streams into RTMP streams in the cloud, which are then pushed to a standard live streaming system and distributed through CDNs to audience. For details, see CDN Relayed Live Streaming.

    On-cloud recording

    TRTC leverages the capabilities of VOD to record entire calls (video/audio) in the cloud and save the recording files securely and in real time in VOD. For details, see On-Cloud Recording and Playback.

    On-Cloud MixTranscoding

    In scenarios such as CDN live watching and on-cloud recording, you may need to mix multiple audio/video streams in a TRTC room into one stream, which can be achieved using TRTC’s stream mixing and transcoding MCU cluster. The MCU cluster can mix multiple audio/video streams as needed and distribute the mixed stream to live streaming CDNs and the on-cloud recording system. For more information, please see On-Cloud MixTranscoding.

    Dumb terminal

    A user entering a room on a dumb terminal will not be detected by the SDK, and remote users will not receive notifications about the user’s entry or exit.