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技术背景

随着VR技术在医疗、军事、农业、学校、景区、消防、公共安全、研学机构、展厅展馆，商场等场所普及，开发者对Unity平台下的直播体验提出了更高的要求。

技术实现

Unity平台下的RTMP推流、RTMP、RTSP播放前几年已经覆盖了Windows、Linux、Android、iOS平台。本文主要介绍Windows平台Unity环境下的轻量级RTSP服务。通过对外提供RTSP拉流URL的形式，供内网其他终端调用。

RTMP的技术方案，我们之前有探讨过，这里先说轻量级RTSP服务，轻量级RTSP服务，我们的设计是，可以启动一个RTSP Service，然后发布多个RTSP流实例，这个在多实例的设计，非常有价值，简单来说，一个RTSP Service下面挂载多个RTSP Stream，对外提供RTSP拉流的URL，整体设计方案如下：

我们看看支持的音视频采集选项，其中视频这块，除了Unity下的Camera场景覆盖，还有Windows摄像头、屏幕数据，音频采集覆盖了Unity声音、扬声器、麦克风，还有混音数据。

音视频原始数据采集到后，编码注入RTSP服务和RTMP推送模块。二者可以单独使用，也可同时使用。其中轻量级RTSP服务，可实时查看链接的RTSP会话数。

首先看启动RTSP service封装:

/** PublisherWrapper.cs* Author: daniusdk.com*/
public bool StartRtspService()
{if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_OpenRtspServer(ref rtsp_handle_, 0)){Debug.LogError("创建rtsp server实例失败! 请检查sdk有效性.");return false;}if (IntPtr.Zero == rtsp_handle_){Debug.LogError("创建rtsp server实例失败! 请检查sdk有效性.");return false;}int port = 28554;if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_SetRtspServerPort(rtsp_handle_, port)){NTSmartPublisherSDK.NT_PB_CloseRtspServer(rtsp_handle_);rtsp_handle_ = IntPtr.Zero;Debug.LogError("设置rtsp server端口失败,请检查端口是否重复或者端口不在范围内!");return false;}//String user_name = "admin";//String password = "123456";//NTSmartPublisherSDK.NT_PB_SetRtspServerUserNamePassword(rtsp_handle, user_name, password);if (NTBaseCodeDefine.NT_ERC_OK == NTSmartPublisherSDK.NT_PB_StartRtspServer(rtsp_handle_, 0)){Debug.Log("StartRtspServer suc..");}else{NTSmartPublisherSDK.NT_PB_CloseRtspServer(rtsp_handle_);rtsp_handle_ = IntPtr.Zero;Debug.LogError("启动rtsp server失败, 请检查设置的端口是否被占用!");return false;}is_rtsp_service_running_ = true;return true;
}

停止RTSP Service：

public void StopRtspService()
{if (is_rtsp_service_running_ == false) return;NTSmartPublisherSDK.NT_PB_StopRtspServer(rtsp_handle_);NTSmartPublisherSDK.NT_PB_CloseRtspServer(rtsp_handle_);rtsp_handle_ = IntPtr.Zero;is_rtsp_service_running_ = false;
}

服务启动后，可以发布或停止RTSP流：

public bool StartRtspStream()
{if (CheckPublisherHandleAvailable() == false) return false;if (publisher_handle_ == IntPtr.Zero){return false;}if (publisher_handle_count_ < 1){SetCommonOptionToPublisherSDK();}String rtsp_stream_name = "stream1";NTSmartPublisherSDK.NT_PB_SetRtspStreamName(publisher_handle_, rtsp_stream_name);NTSmartPublisherSDK.NT_PB_ClearRtspStreamServer(publisher_handle_);NTSmartPublisherSDK.NT_PB_AddRtspStreamServer(publisher_handle_, rtsp_handle_, 0);if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_StartRtspStream(publisher_handle_, 0)){if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}Debug.LogError("调用发布rtsp流接口失败");return false;}publisher_handle_count_++;is_rtsp_publisher_running_ = true;return true;
}

停止RTSP流：

public void StopRtspStream()
{publisher_handle_count_--;NTSmartPublisherSDK.NT_PB_StopRtspStream(publisher_handle_);if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}is_rtsp_publisher_running_ = false;
}

获取RTSP session连接数：

public int GetRtspSessionNumbers()
{int num = 0;if (rtsp_handle_!=IntPtr.Zero){if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_GetRtspServerClientSessionNumbers(rtsp_handle_, ref num)){Debug.LogError("Call NT_PB_GetRtspServerClientSessionNumbers failed..");}}return num;
}

封装部分看过后，我们看看我们Unity下调用示例：

启动、停止RTSP服务：

public void btn_rtsp_service_Click()
{if (publisher_wrapper_.IsRtspServiceRunning()){publisher_wrapper_.StopRtspService();btn_rtsp_service_.GetComponentInChildren<Text>().text = "启动RTSP服务";btn_rtsp_publisher_.interactable = false;return;}if (!publisher_wrapper_.StartRtspService()){Debug.LogError("调用StartRtspService失败..");return;}btn_rtsp_publisher_.interactable = true;btn_rtsp_service_.GetComponentInChildren<Text>().text = "停止RTSP服务";
}

发布、停止RTSP流：

public void btn_rtsp_publisher_Click()
{if (publisher_wrapper_.IsRtspPublisherRunning()){publisher_wrapper_.StopRtspStream();if (!publisher_wrapper_.IsPreviewing() && !publisher_wrapper_.IsPushingRtmp()){StopCaptureAvData();if (coroutine_ != null){StopCoroutine(coroutine_);coroutine_ = null;}}btn_rtsp_service_.interactable = true;btn_rtsp_publisher_.GetComponentInChildren<Text>().text = "发布RTSP";}else{if (!publisher_wrapper_.IsRtspServiceRunning()){Debug.LogError("RTSP service is not running..");return;}if (!publisher_wrapper_.IsPreviewing() && !publisher_wrapper_.IsPushingRtmp()){publisher_wrapper_.SetVideoPushType(video_push_type_);publisher_wrapper_.SetAudioPushType(audio_push_type_);}publisher_wrapper_.StartRtspStream();if (!publisher_wrapper_.IsPreviewing() && !publisher_wrapper_.IsPushingRtmp()){StartCaptureAvData();coroutine_ = StartCoroutine(OnPostVideo());}btn_rtsp_publisher_.GetComponentInChildren<Text>().text = "停止RTSP";btn_rtsp_service_.interactable = false;}
}

获取RTSP Session链接数：

public void btn_get_rtsp_session_numbers_Click()
{if (publisher_wrapper_.IsRtspServiceRunning()){btn_get_rtsp_session_numbers_.GetComponentInChildren<Text>().text = "RTSP会话数:" + publisher_wrapper_.GetRtspSessionNumbers();}
}

RTMP推送、停止推送：

public void btn_start_rtmp_pusher_Click()
{if (publisher_wrapper_.IsPushingRtmp()){StopPushRTMP();btn_rtmp_pusher_.GetComponentInChildren<Text>().text = "推送RTMP";return;}String url = rtmp_pusher_url_.text;if (url.Length < 8){publisher_wrapper_.Close();Debug.LogError("请输入RTMP推送地址");return;}if (!publisher_wrapper_.IsPreviewing() && !publisher_wrapper_.IsRtspPublisherRunning()){publisher_wrapper_.SetVideoPushType(video_push_type_);publisher_wrapper_.SetAudioPushType(audio_push_type_);}if (!publisher_wrapper_.StartRtmpPusher(url)){Debug.LogError("调用StartPublisher失败..");return;}btn_rtmp_pusher_.GetComponentInChildren<Text>().text = "停止推送";if (!publisher_wrapper_.IsPreviewing() && !publisher_wrapper_.IsRtspPublisherRunning()){StartCaptureAvData();coroutine_ = StartCoroutine(OnPostVideo());}
}

总结

轻量级RTSP服务和RTMP推送的区别在于，轻量级RTSP服务不需要单独部署流媒体服务器（类似于网络摄像头），在内网小并发场景下，使用起来非常方便，如果需要上公网，还是需要用RTMP推送，感兴趣的开发者可酌情参考。