Using CDN for Live Streaming

Feature Introduction

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 streaming 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 URL addresses, you can refer to CDN Stream Publishing Authentication to improve the security of your stream publishing usage.

Relaying to CDN

Relaying to CDN refers to the process of pushing audio and video streams from ZEGOCLOUD 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 CDN. Users can directly watch from web pages or third-party players by playing stream URL addresses. 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.

Feature Comparison

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

Prerequisites

Before using CDN live streaming, ensure that:

• 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 into your project and implemented basic audio and video stream publishing and playing 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 relevant source code, please see files in the "/ZegoExpressExample/Examples/AdvancedStreaming/StreamByCDN" directory.

Relaying to CDN

Initialize and Login to Room

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

Start Publishing Stream

Please refer to "Publishing Stream" in Quick Start - Implementation.

Start Relaying

After publishing stream successfully, call the addPublishCdnUrl interface to add dynamically relaying to CDN URLs, 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 publishing stream successfully, start relaying to CDN

// Stream ID used when publishing stream
std::string streamID = "STREAM_ID";
// CDN address to be relayed, please fill in according to the actual URL, streamID is the stream name for publishing, can be customized
std::string URL = "rtmp://domain_name/ingest_point/streamID";
engine->addPublishCdnUrl(streamID, URL, [=](int errorCode){
    if(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
std::string streamID = "STREAM_ID";
// CDN address to be relayed, please fill in according to the actual URL, streamID is the stream name for publishing, can be customized
std::string URL = "rtmp://domain_name/ingest_point/streamID";
engine->addPublishCdnUrl(streamID, URL, [=](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 Callback State Notifications

If you need to listen to CDN callback state notifications, please refer to Monitor CDN Relay Status.

Stop Relaying

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

// Stream ID used when publishing stream
std::string streamID = "STREAM_ID";
// CDN address to stop relaying, please fill in according to the actual URL, streamID is the stream name for publishing
std::string URL = "rtmp://domain_name/ingest_point/streamID";
engine->removePublishCdnUrl(streamID, URL, [=](int errorCode){
    if(errorCode == 0)
    {
        // Stop relaying successful
    } else
    {
        // Stop relaying failed, possibly due to network reasons causing stop relaying request sending to fail
    }
});

// Stream ID used when publishing stream
std::string streamID = "STREAM_ID";
// CDN address to stop relaying, please fill in according to the actual URL, streamID is the stream name for publishing
std::string URL = "rtmp://domain_name/ingest_point/streamID";
engine->removePublishCdnUrl(streamID, URL, [=](int errorCode){
    if(errorCode == 0)
    {
        // Stop relaying successful
    } else
    {
        // Stop relaying failed, possibly due to network reasons causing stop relaying request sending to fail
    }
});

Direct Publishing to CDN

Start Direct Publishing to CDN

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

ZegoCDNConfig config;
// URL needs to be filled in by developers according to actual situation, streamID is the stream name for publishing, can be customized
config.url = "rtmp://domain_name/ingest_point/streamID";
engine->enablePublishDirectToCDN(true, &config);
engine->startPublishingStream("STREAM_ID");

ZegoCDNConfig config;
// URL needs to be filled in by developers according to actual situation, streamID is the stream name for publishing, can be customized
config.url = "rtmp://domain_name/ingest_point/streamID";
engine->enablePublishDirectToCDN(true, &config);
engine->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 "false" to disable the direct publishing to CDN function. Calling this interface during publishing stream will not affect the current publishing stream.

engine->stopPublishingStream();
ZegoCDNConfig cdnConfig;
engine->enablePublishDirectToCDN(false, &cdnConfig);

engine->stopPublishingStream();
ZegoCDNConfig cdnConfig;
engine->enablePublishDirectToCDN(false, &cdnConfig);

Audience Playing Stream

• When the publishing end directly publishes to CDN, the playing end can directly play streams through streamID, please refer to "Playing Stream" in Quick Start - Implementation.

• 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 playing method of passing in URL to play streams, and cannot play streams through stream ID. For URL playing operation steps, please refer to "1 Configure Stream Playing Parameters" and "2 Start Playing Stream" in Playing Stream by URL.