Unity3D下实现Linux平台RTMP推流（以采集Unity窗体和声音为例）

技术背景

随着物联网等行业的崛起，越来越多的传统行业如虚拟仿真、航天工业、工业仿真、城市规划等，对Linux下的生态构建，有了更大的期望，Linux平台下，可选的直播推拉流解决方案相对Windows和移动端，非常少，基于Unity的Linux推送方案，更是几无参考。本文以Unity3d环境下Linux平台推送Unity窗体和Unity采集的音频，然后编码推送到RTMP服务器为例，大概说下实现过程。

技术实现

本文以采集Unity窗体数据为例，如果需要对接摄像头和屏幕亦可。简单来说，高效率的获取到原始的窗体Texture，拿到对应的RGB数据，传给现有的RTMP推送模块，音频的话，只要获取到AudioClip数据，实时读取然后传PCM数据。如需2路PCM数据混音，可以采集两路AudioClip数据，分别调用原生的Linux推送RTMP模块的PCM数据投递接口，编码打包推送即可，无图无真相：

下图以Linux平台下，unity3d环境采集窗体（为方便测试，加了个实时时间显示）和unity声音为例，整体延迟可达毫秒级。

音频的话，可以循环采集播放、也可以播放完毕后，加实时静音。

AudioClip数据采集，如需audiosource数据播放完毕后，填充静音帧，可调用FillPcmMuteData()接口。

    /// <summary>/// 获取AudioClip数据/// </summary>private void PostUnityAudioClipData(){//重新初始化TimerManager.UnRegister(this);audio_clip_info_ = new AudioClipInfo();audio_clip_info_.audio_source_ = GameObject.Find("Canvas/Panel/AudioSource").GetComponent<AudioSource>();if (audio_clip_info_.audio_source_ == null){Debug.LogError("audio source is null..");return;}if (audio_clip_info_.audio_source_.clip == null){Debug.LogError("audio clip is null..");return;}audio_clip_info_.audio_clip_ = audio_clip_info_.audio_source_.clip;audio_clip_info_.audio_clip_offset_ = 0;audio_clip_info_.audio_clip_length_ = audio_clip_info_.audio_clip_.samples * audio_clip_info_.audio_clip_.channels;pcm_mute_data_ = FillPcmMuteData(audio_clip_info_.audio_clip_);TimerManager.Register(this, 0.019999f, (PostPCMData), false);}

采集后的数据，定时调用原生接口，发送到原生接口：

var sample_length = sizeof(float) * pcm_sample.Length;pcm_data.data_ = Marshal.AllocHGlobal(sample_length);
Marshal.Copy(pcm_sample, 0, pcm_data.data_, pcm_sample.Length);
pcm_data.size_ = (uint)sample_length;publisher_wrapper_.OnPostAudioPCMFloatData(pcm_data.data_,pcm_data.size_,pcm_time_stamp_,pcm_data.sample_rate_,pcm_data.channels_,pcm_data.per_channel_sample_number_);Marshal.FreeHGlobal(pcm_data.data_);
pcm_data.data_ = IntPtr.Zero;
pcm_data = null;
pcm_time_stamp_ += 10;  //时间戳自增10毫秒

视频窗体数据采集：

        if (video_push_type_ != (uint)NTSmartPublisherDefine.NT_PB_E_VIDEO_OPTION.NT_PB_E_VIDEO_OPTION_LAYER)return;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;}

从Texture拿到数据，然后调用OnPostRGBAData()数据传递到原生接口即可。

原生接口模块初始化：

        /** nt_publisher_wrapper.cs* Github：https://github.com/daniulive/SmarterStreaming** InitSDK主要完成原生模块的初始化工作 */private bool InitSDK(){if (!is_pusher_sdk_init_){// 设置日志路径(请确保目录存在)Debug.LogError("NT_SL_SetPath++");String log_path = "./";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;}

RTMP推送模块基础参数配置：

        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_ == (uint)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_ == (uint)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(), cap.width_, cap.height_);}SetFrameRate((uint)video_fps_);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);SetVideoQuality(CalVideoQuality(video_width_, video_height_, is_h264_encoder_));SetVideoBitRate(CalBitRate(video_fps_, video_width_, video_height_));SetVideoMaxBitRate((CalMaxKBitRate(video_fps_, video_width_, video_height_, false)));SetVideoKeyFrameInterval((key_frame_interval_));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(audio_input_volume_));}

开始和停止预览：

        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;}public void StopPreview(){if (is_previewing_ == false) return;is_previewing_ = false;publisher_handle_count_--;NTSmartPublisherSDK.NT_PB_StopPreview(publisher_handle_);if (0 == publisher_handle_count_){NTSmartPublisherSDK.NT_PB_Close(publisher_handle_);publisher_handle_ = IntPtr.Zero;}}

预览数据回调：

        //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;}}

开始推送和停止推送：

        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;}

对应Unity层调用：

    public void btn_publish_Click(){if (publisher_wrapper_.IsPublishing()){return;}String url = rtmp_pusher_url.text;if (url.Length < 8){publisher_wrapper_.Close();Debug.Log("请输入RTMP推送地址");return;}publisher_wrapper_.SetVideoPushType(video_push_type_);publisher_wrapper_.SetAudioPushType(audio_push_type_);if (!publisher_wrapper_.StartPublisher(url)){Debug.LogError("调用StartPublisher失败..");return;}startPublishBtn.interactable = false;stopPublishBtn.interactable = !startPublishBtn.interactable;videoOptionSel.interactable = false;audioOptionSel.interactable = false;if (audio_push_type_ == (uint)NTSmartPublisherDefine.NT_PB_E_AUDIO_OPTION.NT_PB_E_AUDIO_OPTION_EXTERNAL_PCM_DATA|| audio_push_type_ == (uint)NTSmartPublisherDefine.NT_PB_E_AUDIO_OPTION.NT_PB_E_AUDIO_OPTION_TWO_EXTERNAL_PCM_MIXER){PostUnityAudioClipData();}}public void btn_stop_publish_Click(){if (!publisher_wrapper_.IsPublishing()){return;}StopAudioSource();if (texture_ != null){UnityEngine.Object.Destroy(texture_);texture_ = null;}if (screen_image_ != IntPtr.Zero){Marshal.FreeHGlobal(screen_image_);screen_image_ = IntPtr.Zero;}publisher_wrapper_.StopPublisher();videoOptionSel.interactable = true;audioOptionSel.interactable = true;startPublishBtn.interactable = true;stopPublishBtn.interactable = !startPublishBtn.interactable;}

总结

以上是Unity环境下，以采集Unity窗体和unity声音为例，对接Linux平台RTMP推送，整体延迟也可以达到毫秒级，基本满足常用场景了，感兴趣的开发者可酌情参考。