Windows平台实现Unity下窗体|摄像头|屏幕采集推送

技术背景

随着Unity3D的应用范围越来越广，越来越多的行业开始基于Unity3D开发产品，如传统行业中虚拟仿真教育、航空工业、室内设计、城市规划、工业仿真等领域。

基于此，好多开发者苦于在Unity环境下，没有低延迟的推拉流解决方案，前几年，我们在Unity环境下推出了跨平台低延迟的RTMP|RTSP直播播放器，很好的解决了好多对延迟要求苛刻的使用场景。

随着时间的推移，越来越多的开发者联系我们，希望我们能推出Unity环境下的RTMP推送模块，获取到unity的实时数据，更低延迟更高效率的实现数据传输推送，基于此，我们发布了Unity环境下的RTMP推送模块。

本文以Windows平台为例，数据源分别为Unity的窗口、摄像头或整个屏幕，编码传输模块，还是调用大牛直播SDK（官方）的原生接口，简单界面先睹为快：

技术实现

1. 基础初始化

private bool InitSDK(){if (!is_pusher_sdk_init_){// 设置日志路径(请确保目录存在)String log_path = "D:\\pulisherlog";NTSmartLog.NT_SL_SetPath(log_path);UInt32 isInited = NTSmartPublisherSDK.NT_PB_Init(0, IntPtr.Zero);if (isInited != 0){Debug.Log("调用NT_PB_Init失败..");return false;}is_pusher_sdk_init_ = true;}return true;}

2. 调用Open()接口，获取推送实例

       public bool OpenPublisherHandle(uint video_option, uint audio_option){if (publisher_handle_ != IntPtr.Zero){return true;}publisher_handle_count_ = 0;if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_Open(out publisher_handle_,video_option, audio_option, 0, IntPtr.Zero)){return false;}if (publisher_handle_ != IntPtr.Zero){pb_event_call_back_ = new NT_PB_SDKEventCallBack(PbEventCallBack);NTSmartPublisherSDK.NT_PB_SetEventCallBack(publisher_handle_, IntPtr.Zero, pb_event_call_back_);return true;}else{return false;}}

3. 初始化参数配置

这里需要注意下，如果要采集unity窗口，需要设置图层模式，先填充一层RGBA黑色背景，然后再添加一层，用于叠加外部数据。

       private void SetCommonOptionToPublisherSDK(){if (!IsPublisherHandleAvailable()){Debug.Log("SetCommonOptionToPublisherSDK, publisher handle with null..");return;}NTSmartPublisherSDK.NT_PB_ClearLayersConfig(publisher_handle_, 0,0, IntPtr.Zero);if (video_option == NTSmartPublisherDefine.NT_PB_E_VIDEO_OPTION.NT_PB_E_VIDEO_OPTION_LAYER){// 第0层填充RGBA矩形, 目的是保证帧率, 颜色就填充全黑int red = 0;int green = 0;int blue = 0;int alpha = 255;NT_PB_RGBARectangleLayerConfig rgba_layer_c0 = new NT_PB_RGBARectangleLayerConfig();rgba_layer_c0.base_.type_ = (Int32)NTSmartPublisherDefine.NT_PB_E_LAYER_TYPE.NT_PB_E_LAYER_TYPE_RGBA_RECTANGLE;rgba_layer_c0.base_.index_ = 0;rgba_layer_c0.base_.enable_ = 1;rgba_layer_c0.base_.region_.x_ = 0;rgba_layer_c0.base_.region_.y_ = 0;rgba_layer_c0.base_.region_.width_ = video_width_;rgba_layer_c0.base_.region_.height_ = video_height_;rgba_layer_c0.base_.offset_ = Marshal.OffsetOf(rgba_layer_c0.GetType(), "base_").ToInt32();rgba_layer_c0.base_.cb_size_ = (uint)Marshal.SizeOf(rgba_layer_c0);rgba_layer_c0.red_ = System.BitConverter.GetBytes(red)[0];rgba_layer_c0.green_ = System.BitConverter.GetBytes(green)[0];rgba_layer_c0.blue_ = System.BitConverter.GetBytes(blue)[0];rgba_layer_c0.alpha_ = System.BitConverter.GetBytes(alpha)[0];IntPtr rgba_conf = Marshal.AllocHGlobal(Marshal.SizeOf(rgba_layer_c0));Marshal.StructureToPtr(rgba_layer_c0, rgba_conf, true);UInt32 rgba_r = NTSmartPublisherSDK.NT_PB_AddLayerConfig(publisher_handle_, 0,rgba_conf, (int)NTSmartPublisherDefine.NT_PB_E_LAYER_TYPE.NT_PB_E_LAYER_TYPE_RGBA_RECTANGLE,0, IntPtr.Zero);Marshal.FreeHGlobal(rgba_conf);NT_PB_ExternalVideoFrameLayerConfig external_layer_c1 = new NT_PB_ExternalVideoFrameLayerConfig();external_layer_c1.base_.type_ = (Int32)NTSmartPublisherDefine.NT_PB_E_LAYER_TYPE.NT_PB_E_LAYER_TYPE_EXTERNAL_VIDEO_FRAME;external_layer_c1.base_.index_ = 1;external_layer_c1.base_.enable_ = 1;external_layer_c1.base_.region_.x_ = 0;external_layer_c1.base_.region_.y_ = 0;external_layer_c1.base_.region_.width_ = video_width_;external_layer_c1.base_.region_.height_ = video_height_;external_layer_c1.base_.offset_ = Marshal.OffsetOf(external_layer_c1.GetType(), "base_").ToInt32();external_layer_c1.base_.cb_size_ = (uint)Marshal.SizeOf(external_layer_c1);IntPtr external_layer_conf = Marshal.AllocHGlobal(Marshal.SizeOf(external_layer_c1));Marshal.StructureToPtr(external_layer_c1, external_layer_conf, true);UInt32 external_r = NTSmartPublisherSDK.NT_PB_AddLayerConfig(publisher_handle_, 0,external_layer_conf, (int)NTSmartPublisherDefine.NT_PB_E_LAYER_TYPE.NT_PB_E_LAYER_TYPE_EXTERNAL_VIDEO_FRAME,0, IntPtr.Zero);Marshal.FreeHGlobal(external_layer_conf);}else if (video_option == NTSmartPublisherDefine.NT_PB_E_VIDEO_OPTION.NT_PB_E_VIDEO_OPTION_CAMERA){CameraInfo camera = cameras_[cur_sel_camera_index_];NT_PB_VideoCaptureCapability cap = camera.capabilities_[cur_sel_camera_resolutions_index_];SetVideoCaptureDeviceBaseParameter(camera.id_.ToString(), (UInt32)cap.width_, (UInt32)cap.height_);}SetFrameRate((UInt32)CalBitRate(edit_key_frame_, video_width_, video_height_));Int32 type = 0;   //软编码Int32 encoder_id = 1;UInt32 codec_id = (UInt32)NTCommonMediaDefine.NT_MEDIA_CODEC_ID.NT_MEDIA_CODEC_ID_H264;Int32 param1 = 0;SetVideoEncoder(type, encoder_id, codec_id, param1);SetVideoQualityV2(CalVideoQuality(video_width_, video_height_, is_h264_encoder));SetVideoMaxBitRate((CalMaxKBitRate(edit_key_frame_, video_width_, video_height_, false)));SetVideoKeyFrameInterval((edit_key_frame_));if (is_h264_encoder){SetVideoEncoderProfile(1);}SetVideoEncoderSpeed(CalVideoEncoderSpeed(video_width_, video_height_, is_h264_encoder));// 音频相关设置SetAuidoInputDeviceId(0);SetPublisherAudioCodecType(1);SetPublisherMute(is_mute);SetEchoCancellation(0, 0);SetNoiseSuppression(0);SetAGC(0);SetVAD(0);SetInputAudioVolume(Convert.ToSingle(edit_audio_input_volume_));}

4. 数据采集

摄像头和屏幕的数据采集，还是调用原生的SDK接口，本文不再赘述，如果需要采集Unity窗体的数据，可以用参考以下代码：

        if ( texture_ == null || video_width_ != Screen.width || video_height_ != Screen.height){Debug.Log("OnPostRender screen changed++ scr_width: " + Screen.width + " scr_height: " + Screen.height);if (screen_image_ != IntPtr.Zero){Marshal.FreeHGlobal(screen_image_);screen_image_ = IntPtr.Zero;}if (texture_ !=  null){UnityEngine.Object.Destroy(texture_);texture_ = null;}video_width_ = Screen.width;video_height_ = Screen.height;texture_ = new Texture2D(video_width_, video_height_, TextureFormat.BGRA32, false);screen_image_ = Marshal.AllocHGlobal(video_width_ * 4 * video_height_);Debug.Log("OnPostRender screen changed--");return;}texture_.ReadPixels(new Rect(0, 0, video_width_, video_height_), 0, 0, false);texture_.Apply();

从 texture里面，通过调用 GetRawTextureData()，获取到原始数据。

5. 数据对接

获取到数据后，通过调用 OnPostRGBAData()接口，传递给SDK层。

6. 本地数据预览

        public bool StartPreview(){if(CheckPublisherHandleAvailable() == false)return false;video_preview_image_callback_ = new NT_PB_SDKVideoPreviewImageCallBack(SDKVideoPreviewImageCallBack);NTSmartPublisherSDK.NT_PB_SetVideoPreviewImageCallBack(publisher_handle_, (int)NTSmartPublisherDefine.NT_PB_E_IMAGE_FORMAT.NT_PB_E_IMAGE_FORMAT_RGB32, IntPtr.Zero, video_preview_image_callback_);if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_StartPreview(publisher_handle_, 0, IntPtr.Zero)){if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}return false;}publisher_handle_count_++;is_previewing_ = true;return true;}

设置preview后，处理preview的数据回调

        //预览数据回调public void SDKVideoPreviewImageCallBack(IntPtr handle, IntPtr user_data, IntPtr image){NT_PB_Image pb_image = (NT_PB_Image)Marshal.PtrToStructure(image, typeof(NT_PB_Image));NT_VideoFrame pVideoFrame = new NT_VideoFrame();pVideoFrame.width_ = pb_image.width_;pVideoFrame.height_ = pb_image.height_;pVideoFrame.stride_ = pb_image.stride_[0];Int32 argb_size = pb_image.stride_[0] * pb_image.height_;pVideoFrame.plane_data_ = new byte[argb_size];if (argb_size > 0){Marshal.Copy(pb_image.plane_[0],pVideoFrame.plane_data_,0, argb_size);}{cur_image_ = pVideoFrame;}}

7. 相关event回调处理

        private void PbEventCallBack(IntPtr handle, IntPtr user_data, UInt32 event_id,Int64 param1,Int64 param2,UInt64 param3,UInt64 param4,[MarshalAs(UnmanagedType.LPStr)] String param5,[MarshalAs(UnmanagedType.LPStr)] String param6,IntPtr param7){String event_log = "";switch (event_id){case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_CONNECTING:event_log = "连接中";if (!String.IsNullOrEmpty(param5)){event_log = event_log + " url:" + param5;}break;case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_CONNECTION_FAILED:event_log = "连接失败";if (!String.IsNullOrEmpty(param5)){event_log = event_log + " url:" + param5;}break;case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_CONNECTED:event_log = "已连接";if (!String.IsNullOrEmpty(param5)){event_log = event_log + " url:" + param5;}break;case (uint)NTSmartPublisherDefine.NT_PB_E_EVENT_ID.NT_PB_E_EVENT_ID_DISCONNECTED:event_log = "断开连接";if (!String.IsNullOrEmpty(param5)){event_log = event_log + " url:" + param5;}break;default:break;}if(OnLogEventMsg != null) OnLogEventMsg.Invoke(event_id, event_log);}

8. 开始推送、停止推送

       public bool StartPublisher(String url){if (CheckPublisherHandleAvailable() == false) return false;if (publisher_handle_ == IntPtr.Zero){return false;}if (!String.IsNullOrEmpty(url)){NTSmartPublisherSDK.NT_PB_SetURL(publisher_handle_, url, IntPtr.Zero);}if (NTBaseCodeDefine.NT_ERC_OK != NTSmartPublisherSDK.NT_PB_StartPublisher(publisher_handle_, IntPtr.Zero)){if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}is_publishing_ = false;return false;}publisher_handle_count_++;is_publishing_ = true;return true;}public void StopPublisher(){if (is_publishing_ == false) return;publisher_handle_count_--;NTSmartPublisherSDK.NT_PB_StopPublisher(publisher_handle_);if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}is_publishing_ = false;}

9. 关闭实例

        public void Close(){if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}}

总结

经测试，Unity环境下，通过高效率的数据采集、编码和推送，配合SmartPlayer播放器播放，整体延迟可控制在毫秒级，可适用于大多数Unity环境下对延迟和稳定性要求苛刻的场景。