如何在Unity下采集音视频实现轻量级RTSP服务(类似于IPC)

好多开发者在做虚拟仿真、VR教育等场景的时候，遇到个问题，想把头显里面的画面在内网环境下低延迟的同步出来，又不想单独部署流媒体服务器。为此，我们在Unity下，添加了轻量级RTSP服务模块，通过头显端启动个轻量级RTSP服务，把采集到的音视频数据，通过对外提供RTSP拉流URL的形式，供内网其他终端调用，废话不多说，先上图看效果：

 上图展示的是，Android的Unity下Camera场景获取到texture数据编码后，注入RTSP服务和RTMP推送模块。二者可以单独使用，也可同时使用，相互不影响。其中轻量级RTSP服务，可实时查看链接的RTSP会话数。

由于我们原生Android平台轻量级RTSP服务已经有多年积累，本次只是把相关的接口，同步过来。

首先来看RTSP Server相关的接口设计：

  /*
   * SmartPublisherAndroidMono.cs
   *
   * Github: https://github.com/daniulive/SmarterStreaming
   */
    
    /*+++++++++++++++SmartRTSPServerSDK+++++++++++++++*/
    /// 
    /// Init rtsp server(和UnInitRtspServer配对使用，即便是启动多个RTSP服务，也只需调用一次InitRtspServer，请确保在OpenRtspServer之前调用)
    /// 
    public int NT_PB_U3D_InitRtspServer()
    {
        return pusher_obj_.Call<int>("InitRtspServer");
    }
 
    /// 
    /// 创建一个rtsp server
    /// 
    public long NT_PB_U3D_OpenRtspServer(int reserve)
    {
        return pusher_obj_.Call<long>("OpenRtspServer", reserve);
    }
 
    /// 
	/// 设置rtsp server 监听端口, 在StartRtspServer之前必须要设置端口
   	/// @param rtsp_server_handle: rtsp server 句柄
	/// @param port: 端口号，可以设置为554,或者是1024到65535之间,其他值返回失败
    /// 
    public int NT_PB_U3D_SetRtspServerPort(long rtsp_server_handle, int port)
    {
        return pusher_obj_.Call<int>("SetRtspServerPort", rtsp_server_handle, port);
    }
 
    /// 
	/// 设置rtsp server 鉴权用户名和密码, 这个可以不设置，只有需要鉴权的再设置
   	/// @param rtsp_server_handle: rtsp server 句柄
	/// @param user_name: 用户名(必须是英文), password：密码(必须是英文)
    /// 
    public int NT_PB_U3D_SetRtspServerUserNamePassword(long rtsp_server_handle, String user_name, String password)
    {
        return pusher_obj_.Call<int>("SetRtspServerUserNamePassword", rtsp_server_handle, user_name, password);
    }
 
    /// 
    /// 设置rtsp server 组播, 如果server设置成组播就不能单播，组播和单播只能选一个, 一般来说单播网络设备支持的好，wifi组播很多路由器不支持
    /// @param rtsp_server_handle: rtsp server 句柄
    /// @param is_multicast: 是否组播, 1为组播, 0为单播, 其他值接口返回错误, 默认是单播
    /// 
    public int NT_PB_U3D_SetRtspServerMulticast(long rtsp_server_handle, int is_multicast)
    {
        return pusher_obj_.Call<int>("SetRtspServerMulticast", rtsp_server_handle, is_multicast);
    }
 
    /// 
    /// 设置rtsp server 组播组播地址
    /// @param rtsp_server_handle: rtsp server 句柄
    /// 如果设置的不是组播地址, 将返回错误
    /// 组播地址范围说明: [224.0.0.0, 224.0.0.255] 为组播预留地址, 不能设置. 可设置范围为[224.0.1.0, 239.255.255.255], 其中SSM地址范围为[232.0.0.0, 232.255.255.255]
    /// 
    public int NT_PB_U3D_SetRtspServerMulticastAddress(long rtsp_server_handle, String multicast_address)
    {
        return pusher_obj_.Call<int>("SetRtspServerMulticastAddress", rtsp_server_handle, multicast_address);
    }
 
    /// 
    /// 获取rtsp server当前的客户会话数, 这个接口必须在StartRtspServer之后再调用
    /// @param rtsp_server_handle: rtsp server 句柄
    /// @return {当前rtsp server会话数}
    /// 
    public int NT_PB_U3D_GetRtspServerClientSessionNumbers(long rtsp_server_handle)
    {
        return pusher_obj_.Call<int>("GetRtspServerClientSessionNumbers", rtsp_server_handle);
    }
 
    /// 
    /// 启动rtsp server
    /// @param rtsp_server_handle: rtsp server 句柄
    /// @param reserve: 保留参数传0
    /// 
    public int NT_PB_U3D_StartRtspServer(long rtsp_server_handle, int reserve)
    {
        return pusher_obj_.Call<int>("StartRtspServer", rtsp_server_handle, reserve);
    }
 
    /// 
    /// 停止rtsp server
    /// @param rtsp_server_handle: rtsp server 句柄
    /// 
    public int NT_PB_U3D_StopRtspServer(long rtsp_server_handle)
    {
        return pusher_obj_.Call<int>("StopRtspServer", rtsp_server_handle);
    }
 
    /// 
    /// 关闭rtsp server
    /// @param rtsp_server_handle: rtsp server 句柄
    /// NOTE: 调用这个接口之后rtsp_server_handle失效，
    /// 
    public int NT_PB_U3D_CloseRtspServer(long rtsp_server_handle)
    {
        return pusher_obj_.Call<int>("CloseRtspServer", rtsp_server_handle);
    }
 
    /// 
    /// UnInit rtsp server(和InitRtspServer配对使用，即便是启动多个RTSP服务，也只需调用一次UnInitRtspServer)
    /// 
    public int NT_PB_U3D_UnInitRtspServer()
    {
        return pusher_obj_.Call<int>("UnInitRtspServer");
    }
    /*---------------SmartRTSPServerSDK---------------*/

其次是，用于publisher实例操作的接口，把publisher实例和rtsp实例串起来：

    /*+++++++++++++++SmartRTSPServerSDK供Publisher调用的接口+++++++++++++++*/
    /// 
    /// 设置rtsp的流名称
    /// @param handle: 推送实例句柄
    /// @param stream_name: 流程名称，不能为空字符串，必须是英文
    /// 这个作用是: 比如rtsp的url是:rtsp://192.168.0.111/test, test就是设置下去的stream_name
    /// 
    public int NT_PB_U3D_SetRtspStreamName(long handle, String stream_name)
    {
        return pusher_obj_.Call<int>("SetRtspStreamName", handle, stream_name);
    }
 
    /// 
    /// 给要发布的rtsp流设置rtsp server, 一个流可以发布到多个rtsp server上，rtsp server的创建启动请参考OpenRtspServer和StartRtspServer接口
    /// @param handle: 推送实例句柄
    /// @param rtsp_server_handle：rtsp server句柄
    /// @param reserve：保留参数，传0
    /// 
    public int NT_PB_U3D_AddRtspStreamServer(long handle, long rtsp_server_handle, int reserve)
    {
        return pusher_obj_.Call<int>("AddRtspStreamServer", handle, rtsp_server_handle, reserve);
    }
 
    /// 
    /// 清除设置的rtsp server
    /// @param handle: 推送实例句柄
    /// 
    public int NT_PB_U3D_ClearRtspStreamServer(long handle)
    {
        return pusher_obj_.Call<int>("ClearRtspStreamServer", handle);
    }
 
    /// 
    /// 启动rtsp流
    /// @param handle: 推送实例句柄
    /// @param reserve: 保留参数，传0
    /// 
    public int NT_PB_U3D_StartRtspStream(long handle, int reserve)
    {
        return pusher_obj_.Call<int>("StartRtspStream", handle, reserve);
    }
 
    /// 
    /// 停止rtsp流
    /// @param handle: 推送实例句柄
    /// 
    public int NT_PB_U3D_StopRtspStream(long handle)
    {
        return pusher_obj_.Call<int>("StopRtspStream", handle);
    }
    /*---------------SmartRTSPServerSDK供Publisher调用的接口---------------*/

Unity调用demo如下：

启动、停止轻量级服务：

    private void OnRtspServiceBtnClicked()
    {
        if (is_rtsp_service_running_) {
            StopRtspService();
 
            btn_rtsp_service_.GetComponentInChildren().text = "启动RTSP服务";
            btn_rtsp_publisher_.GetComponent().interactable = false;
            return;
        }
 
        rtsp_handle_ = NT_PB_U3D_OpenRtspServer(0);
 
        if (rtsp_handle_ == 0) {
            Debug.LogError("创建rtsp server实例失败! 请检查SDK有效性");
        } else {
            int port = 8554;
            if (NT_PB_U3D_SetRtspServerPort(rtsp_handle_, port) != 0) {
                NT_PB_U3D_CloseRtspServer(rtsp_handle_);
                rtsp_handle_ = 0;
                Debug.LogError("创建rtsp server端口失败! 请检查端口是否重复或者端口不在范围内!");
            }
 
            if (NT_PB_U3D_StartRtspServer(rtsp_handle_, 0) == DANIULIVE_RETURN_OK) {
                is_rtsp_service_running_ = true;
                Debug.Log("启动rtsp server 成功!");
            } else {
                NT_PB_U3D_CloseRtspServer(rtsp_handle_);
                rtsp_handle_ = 0;
                Debug.LogError("启动rtsp server失败! 请检查设置的端口是否被占用!");
            }
 
           btn_rtsp_service_.GetComponentInChildren().text = "停止RTSP服务";
           btn_rtsp_publisher_.GetComponent().interactable = true;
        }
    }

服务启动后，可以发布或停止RTSP流：

    private void OnRtspPublisherBtnClicked()
    {
        if (is_rtsp_publisher_running_) 
        {
            StopRtspPublisher();
 
            if (!is_pushing_rtmp_)
            {
                StopCaptureAvData();
 
                if (coroutine_ != null) {
                    StopCoroutine(coroutine_);
                    coroutine_ = null;
                }
            }
 
            btn_rtsp_publisher_.GetComponentInChildren().text = "发布RTSP流";
            btn_get_rtsp_session_numbers_.GetComponentInChildren().text = "RTSP会话数";
            btn_get_rtsp_session_numbers_.GetComponent().interactable = false;
            btn_rtsp_service_.GetComponent().interactable = true;
            input_url_.GetComponentInChildren().text = "";
         }
        else
        {
            bool is_started = StartRtspPublisher();
 
            if(is_started)
            {
                btn_rtsp_publisher_.GetComponentInChildren().text = "停止RTSP流";
                btn_get_rtsp_session_numbers_.GetComponent().interactable = true;
                btn_rtsp_service_.GetComponent().interactable = false;
            
                if(!is_pushing_rtmp_)
                {
                    StartCaptureAvData();
                    coroutine_ = StartCoroutine(OnPostVideo());
                }
            }
        }
    }

发布RTSP流：

    private bool StartRtspPublisher()
    {
        if (is_rtsp_publisher_running_)
        {
            Debug.Log("已推送..");   
            return false;
        }
 
        if (!is_pushing_rtmp_) 
        {
            InitAndSetConfig();
        }
 
        if (pusher_handle_ == 0) {
             Debug.LogError("Start rtsp publisher, pusher handle is null..");
            return false;
        }
 
        String rtsp_stream_name = "stream1";
        NT_PB_U3D_SetRtspStreamName(pusher_handle_, rtsp_stream_name);
        NT_PB_U3D_ClearRtspStreamServer(pusher_handle_);
 
        NT_PB_U3D_AddRtspStreamServer(pusher_handle_, rtsp_handle_, 0);
 
        int is_suc = NT_PB_U3D_StartRtspStream(pusher_handle_, 0);
 
        if (is_suc == DANIULIVE_RETURN_OK)
        {
            Debug.Log("StartRtspStream success..");
            is_rtsp_publisher_running_ = true;
        }
        else
        {
            Debug.LogError("StartRtspStream failed!");
            return false;
        }
 
        return true;
    }

停止发布RTSP流：

    //停止发布RTSP流
    private void StopRtspPublisher() {
        if(!is_rtsp_publisher_running_)
            return;
 
        NT_PB_U3D_StopRtspStream(pusher_handle_);
 
        if(!is_pushing_rtmp_)
        {
            NT_PB_U3D_Close(pusher_handle_);
            pusher_handle_ = 0;
 
            NT_PB_U3D_UnInit();
        }
        
        is_rtsp_publisher_running_ = false;
    }

发布RTSP流后，我们可以实时获取到链接的RTSP会话数：

    private void OnGetRtspSessionNumbersBtnClicked()
    {
        if (rtsp_handle_ != 0) 
        {
            int session_numbers = NT_PB_U3D_GetRtspServerClientSessionNumbers(rtsp_handle_);
            Debug.Log("GetRtspSessionNumbers: " + session_numbers);
            btn_get_rtsp_session_numbers_.GetComponentInChildren().text = "RTSP会话数:" + session_numbers.ToString();
        }
    }

轻量级RTSP服务，由于不需要单独部署流媒体服务器，在内网小并发场景下，使用起来非常方便，感兴趣的开发者可酌情参考。