Alibaba Cloud's low-latency live broadcast RTS capability has been upgraded to make the live streaming effect better

Introduction to uses RTMP for the host to push the stream. The TCP link is too long, the congestion control is completely dependent on the TCP transport layer, and the real-time bandwidth data cannot be provided to dynamically adjust the video encoding rate. Alibaba Cloud's low-latency live RTS (Real-time Streaming) product is based on the transformation of the downlink UDP, and optimizes the underlying WebRTC technology of the uplink UDP, and promotes the streaming of the entire industry by releasing the RTS SDK plug-in for the mobile and PC end. Quality, providing low-latency, low-latency, safe and reliable live viewing experience. Client access is simple. You only need to embed the RTS SDK on the OBS side to add a push stream protocol without changing the original push stream collection architecture.

Industry background
The rapid development of live broadcast technology has made the user experience of various industries diversified and personalized, and innovative practices in different business scenarios meet the high standards of the public for audio and video interactive experience and participation. After the great changes in early 2020, the Internet economy, dominated by video, games, e-commerce, and education, has ushered in rapid development. "Live +" has become a trend and is widely integrated into people's work and life. When building a live broadcast system, you will often hear two high-frequency words: RTMP (Real Time Messaging Protocol) and OBS (Open Broadcaster Software).

The RTMP protocol is a TCP-based application layer protocol proposed by Adobe to solve the problems of multiplexing and packetizing of multimedia data transmission streams. RTMP has a history of nearly 20 years and is widely used in the live streaming industry to push streams and intercommunication between different systems.

OBS is an easy-to-use live streaming media content production software that provides users with video, text, image capture and recording functions. The OBS interface is simple, professional and powerful. The OBS program and its source code are all freely available for everyone to use. The version update has been relatively active. It supports OS X, Windows, and Linux operating systems. It is suitable for a variety of live broadcast scenarios and meets the operational needs of most live broadcasts.

Upgrade plan
For the host to push the stream using RTMP, the existing TCP link takes too long, congestion control completely relies on the TCP transport layer, and the inability to provide real-time bandwidth data to dynamically adjust the video encoding rate and other problems caused by the delay and stagnation of the stream. Alibaba Cloud's low-latency live RTS (Real-time Streaming) product is based on the transformation of the downlink UDP, and optimizes the underlying WebRTC technology of the uplink UDP, and promotes the streaming of the entire industry by releasing the RTS SDK plug-in for the mobile and PC end. Quality, providing low-latency, low-latency, safe and reliable live viewing experience. client is easy to access. You only need to embed the RTS SDK on the OBS side to add a push stream protocol, without changing the original push stream collection architecture.

effect comparison

anchor end 100ms RTT10% loss	1 minute		5 minutes		20 is minutes
	viewer delay	viewing quality	viewer delay	viewing quality	viewer delay	visual quality
ARTC push pull stream stream flv	4.75s	smooth	4.72s	smooth	4.79s	smooth
RTMP flv pull plug flow stream	19.91s	fuzzy screen, occasionally Severe mosaic	21.30s	picture is blurred, mosaic, and occasionally no sound	No	Basically no picture, no sound

The data comes from internal experimental calculations. Use step Step 1. Push streaming domain name to open RTS After adding a good plug flow domain in the live console, in domain management page plug flow domain domain configuration by low-latency plug flow switch is turned on, turn it off. Step 2. Integrate RTS SDK The RTS SDK is tailor-made for OBS. There is no need to change the OBS native framework, just connect to the RTS SDK to implement the obs-output plug-in, as shown in the figure below. You can refer to the integrated document https://help.aliyun.com/document\_detail/272525.html complete autonomous access. In order to facilitate user access, the obs-output plugin of artc-stream is also encapsulated. It can be integrated and used only by adding OBS compilation. For details, please refer to the "OBS Sample Plug-in Artc-Stream Integration Instructions". Step 3. Use RTS push address to push the stream The splicing method of the push stream address is the same as RTMP, only the new protocol header artc:// is needed to distinguish it. For example, the RTMP address generated by the console is: rtmp://push.rts***.grtn.aliyunlive.com/live/123?auth\_key=1624860195-* You only need to change rtmp to artc: artc://push.rts***.grtn.aliyunlive.com/live/123?auth\_key=1624860195-* Demo experience https://help.aliyun.com/document\_detail/177373.html#title-xgu-5k1-2vx > Copyright notice: content of this article is contributed spontaneously by Alibaba Cloud real-name registered users, and the copyright belongs to the original author. The Alibaba Cloud Developer Community does not own its copyright and does not assume corresponding legal responsibilities. For specific rules, please refer to the "Alibaba Cloud Developer Community User Service Agreement" and the "Alibaba Cloud Developer Community Intellectual Property Protection Guidelines". If you find suspected plagiarism in this community, fill in the infringement complaint form to report it. Once verified, the community will immediately delete the suspected infringing content.