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。
