ARTC overview

Architecture

ARTC provides SDKs and APIs for iOS, Android, Web, and Windows. Combine ARTC with other Alibaba Cloud services to build solutions for broader use cases.

Use cases

Voice chat

Supports up to 50 simultaneous speakers with 150–400 ms end-to-end latency. Audio features include voice changer, reverberation, and voice enhancement, plus built-in and third-party content moderation. For scenario-based solutions, see Voice chat room, Online karaoke, One-on-one audio and video calls.

Co-streaming

Viewers chat with streamers, and streamers in different rooms compete in popularity battles. End-to-end latency: 150–400 ms with seamless join/leave. Supports standard streaming and Real-Time Streaming (RTS) with 100,000+ concurrent viewers. For more information, see Multi-host streaming.

Co-streaming

Streamer battle

Real-time Conversational AI

Build AI-powered audio and video interaction apps in under 10 minutes. Configure a dedicated agent in the console to interact with end users in real time over the Global Realtime Transport Network (GRTN). For more information, see Real-time Conversational AI Overview.

Voice call

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Avatar call

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Vision call

Features

Feature	Description	Scenarios	Billing
Video call	One-on-one or group video calls at 480p to 1080p.	Personal calls, conferences, video customer service	Billing for audio/video communication
Voice call	One-on-one or group audio calls.	Personal calls, group chat, voice chat
Video interaction	Multi-person video interaction at 480p to 1080p with sub-300 ms latency.	RTS, cross-channel streamer battle
Voice interaction	High-fidelity voice interaction at 48 kHz sampling rate.	Voice chat room, online karaoke, multi-host streaming
Recording	Records audio and video streams to OSS or ApsaraVideo VOD.	Archiving, compliance review	Billing of live stream recording
Transcoding	Converts streams for smooth cross-platform transmission and playback.	Recording format conversion	Live stream transcoding fees
Stream mixing and relay	Mixes multiple streams into one and relays the result to ApsaraVideo Live or a third-party platform.	Multi-view live streaming, large-scale multi-party conferences, multi-teacher collaborative teaching	Live stream relay fees
Audio moderation	Reviews audio content through Alibaba Cloud or third-party moderation services.	Business security checks, content compliance	Automated review fees
Video moderation	Reviews video content through Alibaba Cloud or third-party moderation services.	Business security checks, content compliance	Automated review fees
Face retouching	Multiple retouching effects.	Video calls, interactive streaming, online classes	Retouching and Effects Pricing
Reverberation	Reverberation effects including hallway, church, studio, basement, and concert hall.	Voice calls, video calls, voice chat rooms, online karaoke.	Free
Voice Changer	Effects include electric sound, old man voice, husky male voice, and lively female voice.	Online karaoke rooms, voice chat rooms
Smart noise reduction	Eliminates ambient noise, suppresses sudden loud sounds, and cancels multi-device feedback while preserving voice quality.	Voice calls, multi-person conferences
Low-latency in-ear monitoring	Feeds a user's voice back through headphones or other audio output devices with minimal delay during capture, processing, and playback.	Interactive streaming, online karaoke, recording room
Audio 3A processing	Acoustic Echo Cancellation (AEC), Automatic Noise Suppression (ANS), and Automatic Gain Control (AGC).	Voice-related scenarios
Screen sharing	Shares desktop, window, or screen regions with other users. Supports simultaneous camera feed.	Online classes, remote assistance
Spatial audio	Simulates 3D sound propagation, creating an immersive audio experience with directional and positional cues.	Online karaoke rooms, voice chat rooms
Custom audio/ video input	Accepts external audio and video streams as input.	Custom beauty effects, custom sound effects

Benefits

High-quality service worldwide

ApsaraVideo Live has an extensive global presence:

9 live centers: China (Beijing), China (Shenzhen), China (Shanghai), China (Qingdao), Singapore, Germany (Frankfurt), Japan (Tokyo), Indonesia (Jakarta), and Saudi Arabia (Riyadh) regions
3 stream relay hubs: China (Shanghai), Singapore, and Saudi Arabia (Riyadh) regions
Over 3200 nodes worldwide

This infrastructure ensures reliable, high-availability services globally.

Security compliance

ARTC complies with global calling regulations and stringent privacy standards.

Diverse product combinations

ARTC integrates with ECS, OSS, security services, live streaming, VOD, avatars, and AI for one-stop solutions.

Easy to use

Scenario-based API integration: Wraps low-level APIs by scenario for simpler development. For more information, see Client-side API.
Multi-scenario practices: Covers one-on-one calls, co-streaming, voice chat rooms, and online karaoke. For more information, see Scenario-specific solutions.

Limitations

User capacity per channel:
- Interactive mode: By default, a channel supports up to 17 streamers (on-stage) and 1,000 viewers (off-stage).
  
  Note
  To support unlimited viewers in interactive mode, relay streams to ApsaraVideo Live.
- Communication mode: By default, a channel supports up to 50 users.
Each user can publish one main stream (audio-video, audio-only, or video-only) and one screen-sharing stream simultaneously.

Concepts

Key ARTC concepts:

Concept	Description
SDKAppID	A unique identifier for applications. Create a separate SDKAppID for each service to isolate configurations and data.
ChannelID	An audio and video space identified by a ChannelID. Users in the same channel can interact; cross-channel interaction is supported in certain scenarios.
UserID	Uniquely identifies a user within an application.
Token	A security signature that prevents unauthorized access to your cloud resources. Provide the SDKAppID, UserID, ChannelID, timestamp, and token in the SDK login function.
Stream	A continuous flow of compressed, encoded audio and video data transmitted over a network for instant playback.
Publish	Uploading local audio and video data to Alibaba Cloud servers. Also called stream ingest.
Subscribe	Pulling audio and video data from Alibaba Cloud servers to local devices. Also called stream pulling.
Role	Two roles exist: streamer (can publish and subscribe) and viewer (subscribe only). Users can switch roles during a session.
Stream mixing and relay	Mixes multiple audio and video streams with configurable layout and encoding, then relays the result to ApsaraVideo Live or a third-party platform. After relaying to ApsaraVideo Live, you can use its transcoding, recording, and live viewing features.
Supplemental Enhancement Information (SEI)	A mechanism in H.264/AVC and H.265/HEVC that embeds metadata and ancillary data directly into video streams.