Use CDN for Live Streaming

Overview

ZEGO Express SDK supports publishing streams to CDN (Content Delivery Network), including two functions: relaying to CDN and direct publishing to CDN. Based on this function, developers can connect RTC products and CDN live streaming products, making it convenient for users to directly watch and listen to live content from web pages or third-party players. To ensure security, CDN authentication is enabled by default when publishing streams to CDN.

To prevent attackers from stealing or forging your publishing stream URL address, you can refer to CDN Stream Publishing Authentication to improve the security of your publishing stream usage.

Relay to CDN

Relaying to CDN refers to the process of pushing audio and video streams from ZEGO audio and video cloud to ZEGO's own CDN or third-party CDN.

Relaying to CDN includes the following three methods:

Direct Publishing to CDN

Direct publishing to CDN refers to the process of pushing audio and video streams directly from the local client to the CDN. Users can watch directly from web pages or third-party players through the playing stream URL address. However, because the direct publishing to CDN function does not pass through ZEGOCLOUD during network transmission, developers cannot use ZEGO's real-time audio and video services.

Function Comparison

The descriptions and usage scenarios of the two functions are as follows:

Prerequisites

Before using CDN for live streaming, please ensure:

• You have created a project in the ZEGO Console and applied for a valid AppID and AppSign. For details, please refer to Console - Project Information.
• You have integrated ZEGO Express SDK into the project and implemented basic audio and video streaming functionality. For details, please refer to Quick Start - Integration and Quick Start - Implementation.

Relay to CDN

Initialize and Login Room

Please refer to "Create engine" and "Login room" in Quick Start - Implementing Video Call.

Start Publishing Stream

Please refer to "Publish stream" in Quick Start - Implementing Video Call.

Start Relay

After the publishing stream is successful, call the addPublishCdnUrl interface to add the URL for dynamic relay to CDN, so that the audio and video stream that has been successfully published to ZEGO real-time cloud can be dynamically relayed to third-party CDN. The supported relay address format is "rtmp".

// After publishing stream successfully, start relaying to CDN

// Stream ID used when publishing stream
let streamID = "STREAM_ID";
// CDN address to be relayed, please fill in according to the actual URL, streamID is the stream name of publishing stream, can be customized
let URL = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().addPublishCdnUrl(streamID, URL).then((result) => {
    if(result.errorCode == 0) {
        // Relay successful
    } else {
        // Relay failed, possibly due to network reasons causing relay request sending to fail
    }
});

// After publishing stream successfully, start relaying to CDN

// Stream ID used when publishing stream
let streamID = "STREAM_ID";
// CDN address to be relayed, please fill in according to the actual URL, streamID is the stream name of publishing stream, can be customized
let URL = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().addPublishCdnUrl(streamID, URL).then((result) => {
    if(result.errorCode == 0) {
        // Relay successful
    } else {
        // Relay failed, possibly due to network reasons causing relay request sending to fail
    }
});

(Optional) Listen to CDN Relay Status Notification

Add/Remove Relay CDN Address Status Callback

Developers can register publisherRelayCDNStateUpdate to get add/remove relay CDN address status callbacks. After ZEGO RTC server relays the audio and video stream to CDN, if the CDN relay status changes, such as relay stopping or relay retrying, this callback will be received.

ZegoExpressEngine.instance().on("publisherRelayCDNStateUpdate", (streamID, infoList) => {
    console.log(`publisherRelayCDNStateUpdate:streamID:${streamID}, infoList:${JSON.stringify(infoList)}`);
});

ZegoExpressEngine.instance().on("publisherRelayCDNStateUpdate", (streamID, infoList) => {
    console.log(`publisherRelayCDNStateUpdate:streamID:${streamID}, infoList:${JSON.stringify(infoList)}`);
});

Detailed Explanation of Relay CDN Information

Relay CDN information ZegoStreamRelayCDNInfo contains the URL of CDN publishing stream, relay status, reason for relay status change, and time when the status occurred. All parameters in ZegoStreamRelayCDNInfo are as follows:

Among them, state values are as follows:

updateReason values are as follows:

Stop Relay

Call the removePublishCdnUrl interface to delete the URL dynamically relayed to CDN. When calling the removePublishCdnUrl interface to stop relay, please ensure that the current stream streamID exists.

// Stream ID used when publishing stream
let streamID = "STREAM_ID";
// CDN address to stop relay, please fill in according to the actual URL, streamID is the stream name of publishing stream
let URL = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().removePublishCdnUrl(streamID, URL).then((result) => {
    if(result.errorCode == 0) {
        // Stop relay successful
    } else {
       // Stop relay failed, possibly due to network reasons causing stop relay request sending to fail
    }
});

// Stream ID used when publishing stream
let streamID = "STREAM_ID";
// CDN address to stop relay, please fill in according to the actual URL, streamID is the stream name of publishing stream
let URL = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().removePublishCdnUrl(streamID, URL).then((result) => {
    if(result.errorCode == 0) {
        // Stop relay successful
    } else {
       // Stop relay failed, possibly due to network reasons causing stop relay request sending to fail
    }
});

Direct Publishing to CDN

Start Direct Publishing to CDN

Before publishing stream, call the enablePublishDirectToCDN interface to directly publish audio and video streams to CDN.

let config = new ZegoCDNConfig();
// URL needs to be filled in by developers according to the actual situation, streamID is the stream name of publishing stream, can be customized
config.url = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().enablePublishDirectToCDN(true, config);
ZegoExpressEngine.instance().startPublishingStream("STREAM_ID");

let config = new ZegoCDNConfig();
// URL needs to be filled in by developers according to the actual situation, streamID is the stream name of publishing stream, can be customized
config.url = "rtmp://publishing domain/ingest point/streamID";
ZegoExpressEngine.instance().enablePublishDirectToCDN(true, config);
ZegoExpressEngine.instance().startPublishingStream("STREAM_ID");

Stop Direct Publishing to CDN

To stop direct publishing to CDN, call the stopPublishingStream interface to stop publishing stream.

After stopping publishing stream, if the next publishing stream does not need direct publishing to CDN, you can call the enablePublishDirectToCDN interface and pass the value "false" to turn off the direct publishing to CDN function. Calling this interface during publishing stream will not affect this publishing stream.

ZegoExpressEngine.instance().stopPublishingStream();
let config = new ZegoCDNConfig();
ZegoExpressEngine.instance().enablePublishDirectToCDN(false, config);

ZegoExpressEngine.instance().stopPublishingStream();
let config = new ZegoCDNConfig();
ZegoExpressEngine.instance().enablePublishDirectToCDN(false, config);

Audience Plays Stream

• When the publishing party directly publishes to CDN, the playing party can directly play stream through streamID. Please refer to "Play stream" in Quick Start - Implementation.

• After the audio and video stream is successfully relayed to CDN, when developers want users to play stream from CDN, they need to use the custom playing stream method that passes in the URL, and cannot play stream through the stream ID. For the operation steps of URL playing stream, please refer to "Configure Playing Stream Parameters" and "Start Playing Stream" in Play Stream by URL.