Quickly Build a Video RTSP Streaming Service with Zlm4j and Spring Boot

Purpose

The author needed a video push‑pull streaming service. Implementing RTSP directly with Netty proved difficult, so they turned to the Zlm4j library, a JNA wrapper for ZLMediaKit, which can be easily embedded in a Spring Boot application.

1. Maven Dependencies

Add the local zlm4j JAR and the JNA library to your pom.xml:

<dependency>
  <groupId>com.aizuda</groupId>
  <artifactId>zlm4j</artifactId>
  <version>1.0.4</version>
  <scope>system</scope>
  <systemPath>${project.basedir}/lib/zlm4j-1.0.4.jar</systemPath>
</dependency>
<dependency>
  <groupId>net.java.dev.jna</groupId>
  <artifactId>jna</artifactId>
  <version>5.14.0</version>
</dependency>

2. Configuration Class

The configuration creates a ZLMApi instance via JNA, initializes the SDK, and starts HTTP, RTSP, RTMP, and RTP servers on specific ports. It also provides a MK_EVENTS bean for handling authentication and stream‑change callbacks.

HTTP: 7788

RTSP: 9758

RTMP: 9759

RTP: 32000

package org.example;

import com.aizuda.zlm4j.core.ZLMApi;
import com.aizuda.zlm4j.structure.MK_EVENTS;
import com.sun.jna.Native;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

@Configuration
public class ZlmServerConfig {
    @Bean
    public ZLMApi zlmApi() {
        // Load native mk_api library
        ZLMApi ZLM_API = Native.load("mk_api", ZLMApi.class);
        // Initialize SDK (parameters are placeholders)
        ZLM_API.mk_env_init1(1,1,1,null,0,0,null,0,null,null,null);
        short http_server_port = ZLM_API.mk_http_server_start((short)7788, 0);
        short rtsp_server_port = ZLM_API.mk_rtsp_server_start((short)9758, 0);
        short rtmp_server_port = ZLM_API.mk_rtmp_server_start((short)9759, 0);
        short rtp_server_port = ZLM_API.mk_rtp_server_start((short)32000);
        return ZLM_API;
    }

    @Bean
    public MK_EVENTS mkEvents() {
        return new MK_EVENTS();
    }
}

3. Event Implementation

In the application’s main class a separate thread registers callbacks for publishing authentication and stream state changes. The authentication callback extracts URL parameters and approves the request, while the state‑change callback logs app, stream, and schema information.

package org.example;

import com.aizuda.zlm4j.core.ZLMApi;
import com.aizuda.zlm4j.structure.MK_EVENTS;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.CommandLineRunner;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class Main implements CommandLineRunner {
    @Autowired
    MK_EVENTS mkEvents;
    @Autowired
    ZLMApi zlmApi;

    public static void main(String[] args) {
        SpringApplication.run(Main.class, args);
    }

    @Override
    public void run(String... args) throws Exception {
        // Publish authentication callback
        mkEvents.on_mk_media_publish = (url_info, invoker, sender) -> {
            String param = zlmApi.mk_media_info_get_params(url_info);
            System.err.println("Authentication reminder:");
            zlmApi.mk_publish_auth_invoker_do(invoker, "", 0, 0);
        };
        // Stream state change callback
        mkEvents.on_mk_media_changed = (regist, sender) -> {
            System.out.println("app:" + zlmApi.mk_media_source_get_app(sender));
            System.out.println("stream:" + zlmApi.mk_media_source_get_stream(sender));
            System.out.println("schema:" + zlmApi.mk_media_source_get_schema(sender));
            System.out.println("Stream change notification:" + regist);
        };
        zlmApi.mk_events_listen(mkEvents);
    }
}

4. Testing the Push‑Pull Flow

Use ffmpeg to push a local video file to the RTSP server, attaching a token query parameter to trigger the authentication callback:

ffmpeg -re -an -i /home/seaua/Desktop/input.mp4 -c:v libx264 -f rtsp rtsp://127.0.0.1:9758/steam/1?token=112233

When the stream starts, the server console prints the token and stream‑state change messages.

5. Playback Verification

Open VLC (or any RTMP/FLV capable player) and play the stream using the URL: rtmp://127.0.0.1:9759/steam/1 The same ports and protocols defined in the configuration are used, and additional playback‑time authentication can be added by implementing the corresponding callbacks.