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
代码语言：javascript复制 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
代码语言：javascript复制 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。
代码语言：javascript复制 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：
代码语言：javascript复制 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
拿到原始数据后，通过调用系统封装的OnPostRGBAData()接口，把数据传递给SDK层。
6. 本地数据预览
代码语言：javascript复制 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
代码语言：javascript复制 //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
代码语言：javascript复制 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
代码语言：javascript复制 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
代码语言：javascript复制 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。
