Using CDN for Live Streaming

Feature Overview

ZEGO Express SDK supports publishing streams to CDN (Content Delivery Network), including two features: relay-to-CDN and direct-to-CDN. Based on this feature, 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 to CDN.

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

Relay-to-CDN

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

Relay-to-CDN includes the following three methods:

Direct-to-CDN

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

Feature 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 ZEGOCLOUD Console and applied for a valid AppID and AppSign. For details, please refer to Console - Project Information.
• You have integrated ZEGO Express SDK in your project and implemented basic audio and video publish/play stream functionality. For details, please refer to Quick Start - Integration and Quick Start - Implementation.

Example Source Code Download

Please refer to Download Example Source Code to get the source code.

For related source code, please check the files in the "/ZegoExpressExample/AdvancedStreaming/src/main/java/im/zego/advancedstreaming/streamByCdn" directory.

Relay-to-CDN

Initialize and Login to Room

Please refer to Quick Start - Implementation for "Create Engine" and "Login to Room".

Start Publishing Stream

Please refer to Quick Start - Implementation for "Publish Stream".

Start Relay-to-CDN

After successful publishing, call the addPublishCdnUrl interface to add a dynamically relayed CDN URL, which allows you to dynamically relay audio and video streams that have been successfully published to ZEGO real-time cloud to third-party CDNs. The supported relay address format is "rtmp".

// After successful publishing, start relay to CDN

// Stream ID used when publishing
String streamID = "STREAM_ID";
// CDN address that needs to be relayed. Developers should fill in according to the actual URL. streamID is the stream name for publishing and can be customized
String URL = "rtmp://publishing domain name/access point/streamID";
engine.addPublishCdnUrl(streamID, URL, new IZegoPublisherUpdateCdnUrlCallback() {
    @Override
    public void onPublisherUpdateCdnUrlResult(int errorCode) {
    if(errorCode == 0) {
        // Relay successful
        } else {
            // Relay failed, possibly due to network reasons causing relay request sending to fail
        }
    }
});

// After successful publishing, start relay to CDN

// Stream ID used when publishing
String streamID = "STREAM_ID";
// CDN address that needs to be relayed. Developers should fill in according to the actual URL. streamID is the stream name for publishing and can be customized
String URL = "rtmp://publishing domain name/access point/streamID";
engine.addPublishCdnUrl(streamID, URL, new IZegoPublisherUpdateCdnUrlCallback() {
    @Override
    public void onPublisherUpdateCdnUrlResult(int errorCode) {
    if(errorCode == 0) {
        // Relay successful
        } else {
            // Relay failed, possibly due to network reasons causing relay request sending to fail
        }
    }
});

(Optional) Listen to CDN Relay Status Notifications

Add/Remove Relay CDN Address Status Callback

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

engine.setEventHandler(new IZegoEventHandler() {
    @Override
    public void onPublisherRelayCDNStateUpdate(String streamID, ArrayList<ZegoStreamRelayCDNInfo> infoList) {
    super.onPublisherRelayCDNStateUpdate(streamID, infoList);
    }
}

engine.setEventHandler(new IZegoEventHandler() {
    @Override
    public void onPublisherRelayCDNStateUpdate(String streamID, ArrayList<ZegoStreamRelayCDNInfo> infoList) {
    super.onPublisherRelayCDNStateUpdate(streamID, infoList);
    }
}

Relay CDN Information Details

Relay CDN information ZegoStreamRelayCDNInfo includes the URL of the 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 remove the dynamically relayed CDN URL. When calling the removePublishCdnUrl interface to stop relay, please ensure that the current stream streamID exists.

// Stream ID used when publishing
String streamID = "STREAM_ID";
// CDN address that needs to stop relay. Developers should fill in according to the actual URL. streamID is the stream name for publishing
String URL = "rtmp://publishing domain name/access point/streamID";
engine.removePublishCdnUrl(streamID, URL, new IZegoPublisherUpdateCdnUrlCallback() {
    @Override
    public void onPublisherUpdateCdnUrlResult(int errorCode) {
        if(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
String streamID = "STREAM_ID";
// CDN address that needs to stop relay. Developers should fill in according to the actual URL. streamID is the stream name for publishing
String URL = "rtmp://publishing domain name/access point/streamID";
engine.removePublishCdnUrl(streamID, URL, new IZegoPublisherUpdateCdnUrlCallback() {
    @Override
    public void onPublisherUpdateCdnUrlResult(int errorCode) {
        if(errorCode == 0) {
        // Stop relay successful
        } else {
            // Stop relay failed, possibly due to network reasons causing stop relay request sending to fail
        }
    }
});

Direct-to-CDN

Start Direct-to-CDN

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

ZegoCDNConfig config = new ZegoCDNConfig();
// URL needs to be filled in by developers according to actual conditions. streamID is the stream name for publishing and can be customized
config.url = "rtmp://publishing domain name/access point/streamID";
engine.enablePublishDirectToCDN(true, config);
engine.startPublishingStream("STREAM_ID");

ZegoCDNConfig config = new ZegoCDNConfig();
// URL needs to be filled in by developers according to actual conditions. streamID is the stream name for publishing and can be customized
config.url = "rtmp://publishing domain name/access point/streamID";
engine.enablePublishDirectToCDN(true, config);
engine.startPublishingStream("STREAM_ID");

Stop Direct-to-CDN

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

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

engine.stopPublishingStream();
ZegoCDNConfig config = new ZegoCDNConfig();
engine.enablePublishDirectToCDN(false, config);

engine.stopPublishingStream();
ZegoCDNConfig config = new ZegoCDNConfig();
engine.enablePublishDirectToCDN(false, config);

Audience Play Stream

• When the publishing end publishes directly to CDN, the playing end can directly play the stream by streamID. Please refer to Quick Start - Implementation for "Play Stream".

• After audio and video streams are successfully relayed to CDN, when developers want users to play streams from CDN, they need to use the custom play stream method with URL, and cannot play streams by stream ID. For URL play stream operation steps, please refer to "1 Configure Play Stream Parameters" and "2 Start Playing Stream" in Playing Stream by URL.