Applying CDN Technology to Live Streaming: Benefits, Workflow, and Protocols

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With the rise of the live streaming industry, a myriad of live streaming applications, platforms, and products have emerged, and live streaming scenarios are becoming increasingly diverse, demanding rapid advancements in video technology. Today, let's discuss the application of CDN technology in live streaming.

Why do live streaming platforms need CDN?

① Live streaming platforms regularly experience sudden traffic spikes, and scaling quickly to handle peak loads is a critical challenge. Especially in mobile live streaming, wireless networks and mobile broadband cannot match the stability of fixed broadband; CDN and cloud service providers' technical support have become the most essential guarantee for content delivery and also support the expansion of business models.

② Live streaming has stringent network requirements; any issue can cause stuttering, visual artifacts, or disconnections. CDN, as a content delivery network, uses load balancing to push content to edge nodes near users, greatly improving access speed and stability, which aligns perfectly with live streaming needs.

What is CDN?

CDN stands for Content Delivery Network. Its basic concept is to bypass internet bottlenecks that can affect data transmission speed and stability, delivering content faster and more reliably. The goal is to enable users to obtain needed content from nearby locations, alleviating internet congestion and improving website response times.

The main CDN workflow is shown in the figure below:

The main process is:

1. The broadcaster starts streaming and sends a request to the scheduler server; the scheduler returns the push domain and stream identifier (sn).

2. The broadcaster captures audio and video data and sends it to a CDN node, which processes the stream.

3. The viewer requests to watch the stream; the scheduler returns the pull domain.

4. The viewer requests audio/video data from the CDN node.

Common streaming protocols used in CDN live streaming include RTMP, HLS, and FLV.

1. RTMP (Real Time Messaging Protocol) is a TCP‑based open protocol developed by Adobe for audio/video transmission between Flash players and servers.

2. HLS (HTTP Live Streaming) is an HTTP‑based streaming protocol proposed by Apple. An HLS live stream URL points to an .m3u8 playlist that references several small .ts video segments; for example, three 5‑second segments result in about 15 seconds of latency, which can be reduced by shortening the playlist or segment size.

HLS segment format:

3. FLV differs little from RTMP; the main difference lies in the delivery method.

RTMP streams directly over the RTMP protocol, whereas HTTP‑FLV adds a transcoding layer between RTMP and the client.

Protocol comparison:

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