The Alibaba Cloud Real-Time Communication (RTC) service supports simulcast mode. In this mode, the service simultaneously publishes up to three video layers with different specifications based on the maximum resolution. This allows the stream to automatically adapt to a subscriber's network conditions, whether static or dynamic.
Implementation
You can call the setVideoEncoderConfiguration interface to set the maximum video resolution and frame rate for the publisher. Subscribers can call the setRemoteVideoStreamType interface to set the maximum subscription specifications, or let the RTC server decide the specifications.
Simulcast is an important, always-enabled feature. In Alibaba Cloud RTC, simulcast lets you subscribe to streams as needed, which saves upstream bandwidth.
Video specifications
The Alibaba Cloud SDK provides a set of video specifications that you can use to define the resolution, frame rate, and bitrate of the highest video layer in a simulcast. Note: The SDK automatically calculates the resolution and bitrate for the other layers based on the settings of the highest layer, so your application does not need to configure them.
Resolution (Width:Height) | Frame rate (fps) | Bitrate (Kbps) | ||
Minimum | Recommended | Maximum (multiple of recommended value) | ||
320 × 180 | 5 | 30 | 60 | x2 |
10 | 40 | 100 | x2 | |
15 | 50 | 150 | x2 | |
20 | 60 | 220 | x2 | |
30 | 100 | 300 | x2 | |
640 × 360 | 5 | 200 | 400 | x2 |
10 | 400 | 600 | x2 | |
15 | 600 | 800 | x2 | |
20 | 800 | 1000 | ×2 | |
30 | 1200 | 1500 | ×2 | |
1280 × 720 | 5 | 400 | 400 | ×1.5 |
10 | 800 | 800 | ×1.5 | |
15 | 1200 | 1200 | ×1.5 | |
20 | 1600 | 1600 | ×1.5 | |
30 | 2000 | 2000 | ×1.5 | |
1920 × 1080 | 5 | 500 | 500 | ×1.5 |
10 | 1000 | 1000 | ×1.5 | |
15 | 1500 | 1500 | ×1.5 | |
20 | 2000 | 2000 | ×1.5 | |
30 | 3000 | 3000 | ×1.5 | |