能用D3D要啥自行车？Windows平台播放RTSP或RTMP渲染模式比较

废话不多说，先说结论，Windows平台播放渲染这块，支持D3D的前提下，优先D3D，如果检测到不支持D3D，数据回调上来，GDI模式绘制。

相比GDI模式，D3D绘制更细腻，绘制效率更高，CPU占用低，只要是系统检测支持，一般建议D3D模式。

无图无真相：

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本文以1920*1080分辨率、30帧、固定码率（采集屏幕左侧区域）为例，通过大牛直播SDK ( github) 的Windows平台SmartPublisherDemo.exe工具推送到内网nginx服务器，然后分别以D3D模式和GDI模式拉流（播放端缓冲设置为0）。

可以看到：

D3D模式，CPU占用只有2.7%，延迟：249-156 = 93ms；

GDI模式，CPU占用19.5%，延迟249-73 = 176ms。

无论是从延迟和CPU占用上看，D3D模式都占优。

实现思路：

以C#的demo为例：

1. 先检测系统是否支持D3D模式：

                if (NT.NTBaseCodeDefine.NT_ERC_OK == NTSmartPlayerSDK.NT_SP_IsSupportD3DRender(player_handle_, playWnd.Handle, ref in_support_d3d_render))
                {
                    if (1 == in_support_d3d_render)
                    {
                        is_support_d3d_render = true;
                    }
                }

2. 如不支持D3D，数据回到上层，做绘制：

                if (is_support_d3d_render)
                {
                    is_gdi_render_ = false;

                    // 支持d3d绘制的话，就用D3D绘制
                    NTSmartPlayerSDK.NT_SP_SetRenderWindow(player_handle_, playWnd.Handle);

                    if (btn_check_render_scale_mode.Checked)
                    {
                        NTSmartPlayerSDK.NT_SP_SetRenderScaleMode(player_handle_, 1);
                    }
                    else
                    {
                        NTSmartPlayerSDK.NT_SP_SetRenderScaleMode(player_handle_, 0);
                    }
                    
                }
                else
                {
                    is_gdi_render_ = true;

                    playWnd.Visible = false;

                    // 不支持D3D就让播放器吐出数据来，用GDI绘制

                    //video frame callback (YUV/RGB)
                    //format请参见 NT_SP_E_VIDEO_FRAME_FORMAT，如需回调YUV，请设置为 NT_SP_E_VIDEO_FRAME_FROMAT_I420
                    video_frame_call_back_ = new SP_SDKVideoFrameCallBack(SetVideoFrameCallBack);
                    NTSmartPlayerSDK.NT_SP_SetVideoFrameCallBack(player_handle_, (Int32)NT.NTSmartPlayerDefine.NT_SP_E_VIDEO_FRAME_FORMAT.NT_SP_E_VIDEO_FRAME_FORMAT_RGB32, IntPtr.Zero, video_frame_call_back_);
                }

        public void SetVideoFrameCallBack(IntPtr handle, IntPtr userData, UInt32 status, IntPtr frame)
        {
            if (frame == IntPtr.Zero)
            {
                return;
            }

            //如需直接处理RGB数据，请参考以下流程
            NT_SP_VideoFrame video_frame = (NT_SP_VideoFrame)Marshal.PtrToStructure(frame, typeof(NT_SP_VideoFrame));

            NT_SP_VideoFrame pVideoFrame = new NT_SP_VideoFrame();

            pVideoFrame.format_ = video_frame.format_;
            pVideoFrame.width_ = video_frame.width_;
            pVideoFrame.height_ = video_frame.height_;

            pVideoFrame.timestamp_ = video_frame.timestamp_;
            pVideoFrame.stride0_ = video_frame.stride0_;
            pVideoFrame.stride1_ = video_frame.stride1_;
            pVideoFrame.stride2_ = video_frame.stride2_;
            pVideoFrame.stride3_ = video_frame.stride3_;

            Int32 argb_size = video_frame.stride0_ * video_frame.height_;

            pVideoFrame.plane0_ = Marshal.AllocHGlobal(argb_size);
            CopyMemory(pVideoFrame.plane0_, video_frame.plane0_, (UInt32)argb_size);


            if (playWnd.InvokeRequired)
            {
                BeginInvoke(set_video_frame_call_back_, status, pVideoFrame);
            }
            else
            {
                set_video_frame_call_back_(status, pVideoFrame);
            }
        }

具体绘制代码：

        private void SmartPlayerForm_Paint(object sender, PaintEventArgs e)
        {
            if (player_handle_ == IntPtr.Zero || !is_gdi_render_ || !is_playing_)
            {
                return;
            }

            if (cur_video_frame_.plane0_ == IntPtr.Zero)
            {
                return;
            }

            Bitmap bitmap = new Bitmap(cur_video_frame_.width_, cur_video_frame_.height_, cur_video_frame_.stride0_,
                 System.Drawing.Imaging.PixelFormat.Format32bppRgb, cur_video_frame_.plane0_);

            int image_width = cur_video_frame_.width_;
            int image_height = cur_video_frame_.height_;

            Graphics g = e.Graphics;    //获取窗体画布
            g.SmoothingMode = SmoothingMode.HighSpeed;

            int limit_w = this.Width - 60;
            int limit_h = this.Height - playWnd.Top - 60;

            if (btn_check_render_scale_mode.Checked)
            {
                int d_w = 0, d_h = 0;
                int left_offset = 0;
                int top_offset = 0;

                Brush brush = new SolidBrush(Color.Black);
                g.FillRectangle(brush, playWnd.Left, playWnd.Top, limit_w, limit_h);

                GetRenderRect(limit_w, limit_h, image_width, image_height, ref left_offset, ref top_offset, ref d_w, ref d_h);
                g.DrawImage(bitmap, playWnd.Left + left_offset, playWnd.Top + top_offset, d_w, d_h);   //在窗体的画布中绘画出内存中的图像
            }
            else
            {
                g.DrawImage(bitmap, playWnd.Left, playWnd.Top, limit_w, limit_h);   //在窗体的画布中绘画出内存中的图像
            }
        }

目前来看，不支持D3D的机器少之又少，在环境具备的情况下，优先建议考虑D3D模式绘制，感兴趣的开发者可以尝试看看。