wpf下如何实现超低延迟的RTMP或RTSP播放

技术背景

我们在做Windows平台RTMP和RTSP播放模块对接的时候，有开发者需要在wpf下调用，如果要在wpf下使用，只需要参考C#的对接demo即可，唯一不同的是，视频流数据显示的话，要么通过控件模式，要么可以让RTMP、RTSP播放模块回调rgb数据上来，在wpf直接绘制即可。

技术实现

本文以大牛直播SDK的Windows平台SmartPlayer为例，回调数据的模式，其他不再说明，只要处理好上来的数据就好：

播放之前，设置回调，选择NT_SP_E_VIDEO_FRAME_FORMAT_RGB32：

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_);

处理rgb数据回调：

       /*
        * nt_player_wrapper.cs
        * Author: daniusdk.com
        */
        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));

            if (video_frame.format_ != (Int32)NT.NTSmartPlayerDefine.NT_SP_E_VIDEO_FRAME_FORMAT.NT_SP_E_VIDEO_FRAME_FORMAT_RGB32)
                return;

            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);
        }

另外一种，可以用picturebox，在MainWindow.xaml 做以下设置：

        <WindowsFormsHost HorizontalAlignment="Left" Height="338" Margin="10,10,0,0" VerticalAlignment="Top" Width="480" Background="Black">
            <wf:PictureBox x:Name="RealPlayWnd"></wf:PictureBox>
        </WindowsFormsHost>

为了便于多实例集成参考，以播放2路为例（一路2560*1440，一路1920*1080）：

具体实现如下：

       /*
        * MainWindow.xaml.cs
        * Author: daniusdk.com
        */
        public MainWindow()
        {
            InitializeComponent();

            if (!InitSDK())
                return;

            UIDispatcher = Dispatcher.CurrentDispatcher;

            player1_ = new nt_player_wrapper(RealPlayWnd, UIDispatcher);
            player1_.EventGetPlayerEventMsg += new DelGetPlayerEventMsg(GetPlayerEventMsgInfo);
            player1_.EventGetVideoSize += new DelGetVideoSize(GetVideoSize);

            player2_ = new nt_player_wrapper(RealPlayWnd1, UIDispatcher);
            player2_.EventGetPlayerEventMsg += new DelGetPlayerEventMsg(GetPlayerEventMsgInfo);
            player2_.EventGetVideoSize += new DelGetVideoSize(GetVideoSize);
        }

        private void GetPlayerEventMsgInfo(IntPtr handle, String msg)
        {
            this.Dispatcher.Invoke((Action)delegate()
            {
                event_label.Content = msg;
            });
        }

        private void GetVideoSize(IntPtr handle, String size)
        {
            this.Dispatcher.Invoke((Action)delegate()
            {
                video_size.Content = size;
            });
        }

        private bool InitSDK()
        {
            if (!is_player_sdk_init_)
            {
                UInt32 isPlayerInited = NT.NTSmartPlayerSDK.NT_SP_Init(0, IntPtr.Zero);
                if (isPlayerInited != 0)
                {
                    MessageBox.Show("调用NT_SP_Init失败..");
                    return false;
                }

                is_player_sdk_init_ = true;
            }

            return true;
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            if (!player1_.IsPlaying())
            {
                player1_.SetBuffer(0);
                bool is_mute = true;

                if (!player1_.StartPlay("rtsp://admin:daniulive12345@192.168.0.120:554/h264/ch1/main/av_stream", false, is_mute))
                    return;

                btn_playback1.Content = "停止播放";
            }
            else
            {
                player1_.StopPlay();
                btn_playback1.Content = "开始播放";
            }
        }

        private void Button_Click_2(object sender, RoutedEventArgs e)
        {
            if (!player2_.IsPlaying())
            {
                player2_.SetBuffer(0);
                bool is_mute = true;

                if (!player2_.StartPlay("rtsp://admin:admin123456@192.168.0.121:554/cam/realmonitor?channel=1&subtype=0", false, is_mute))
                    return;

                btn_playback2.Content = "停止播放";
            }
            else
            {
                player2_.StopPlay();
                btn_playback2.Content = "开始播放";
            }
        }

        protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
        {
            if (MessageBox.Show("确定要关闭窗口吗？", "确认", MessageBoxButton.YesNo) != MessageBoxResult.Yes)
            {
                // 如果用户选择“否”，取消关闭
                e.Cancel = true;
            }

            if (player1_.IsPlaying())
            {
                player1_.StopPlay();
            }

            player1_.Dispose();

            if (player2_.IsPlaying())
            {
                player2_.StopPlay();
            }

            player2_.Dispose();

            if (is_player_sdk_init_)
            {
                NTSmartPlayerSDK.NT_SP_UnInit();
                is_player_sdk_init_ = false;
            }    

            base.OnClosing(e);
        }

延迟依旧毫秒级，CPU占用如下，如果用硬解码，体验会更好：