Cgw.T28181.T28181VideoMonitor.StartReceiveVideo C# (CSharp) Method

        public SmcErr StartReceiveVideo(string cameraNo)
        {
            NLogEx.LoggerEx logEx = new NLogEx.LoggerEx(log);
            logEx.Trace("Enter: T28181VideoMonitor.StartReceiveVideo({0}).", cameraNo);
            SmcErr err = new CgwError();

            //打开通道，开始接收实况RTP数据流
            UInt32 channel = sipStack.StartRecvStream(cameraNo, domain, sipPort);

            //如果为0，表示预览失败
            if (channel == CgwConst.T28181_ERROR_HANDLE)
            {
                err.SetErrorNo(CgwError.START_RECEIVE_VIDEO_FAILED);
                logEx.Error("Start Receive camera video data failed.Camera No:{0}.Handle:{1}.", cameraNo, channel);
                return err;
            }
            else
            {
                logEx.Info("Start Receive camera video data success.Camera No:{0},Handle:{1}.", cameraNo, channel);
            }

            //设置rtp解析回调函数
            rtpAdapter.ESDK_RTP_OpenChannel(frameDataCallBack, channel);

            //预览成功，需要停止原来的预览，并将预览句柄添加到缓存
            //需要停止的预览句柄
            UInt32 needToStopChannel = CgwConst.T28181_ERROR_HANDLE;
            if (this.handelOperateLock.TryEnterWriteLock(CgwConst.ENTER_LOCK_WAIT_TIME))
            {
                try
                {
                    //如果预览句柄已经存在，删除掉原来的句柄,用新的句柄替换
                    if (this.cameraVideoChannelDic.ContainsKey(cameraNo))
                    {
                        needToStopChannel = this.cameraVideoChannelDic[cameraNo];
                        this.videoChannelDataSenderDic.Remove(needToStopChannel);
                        this.cameraVideoChannelDic.Remove(cameraNo);
                        //关闭rtp回调
                        rtpAdapter.ESDK_RTP_CloseChannel(needToStopChannel);
                    }
                    this.cameraVideoChannelDic.Add(cameraNo, channel);
                    MediaDataSender mediaDataSender = new MediaDataSender(cameraNo, this.dataCallBack);
                    this.videoChannelDataSenderDic.Add(channel, mediaDataSender);
                }
                finally
                {
                    this.handelOperateLock.ExitWriteLock();
                }
            }

            //重新预览后，更新了预览句柄，需要将原来的预览停止，放在handelOperateLock外面，防止长时间占用锁
            if (needToStopChannel != CgwConst.T28181_ERROR_HANDLE)
            {
                int result = sipStack.StopRecvStream(needToStopChannel);
                //如果不为0，表示停止原来的预览失败，只记录日志，不返回错误，不设置错误码
                if (result != CgwConst.IVS_SDK_SUCCESS_TAG)
                {
                    err.SetErrorNo(CgwError.START_RECEIVE_VIDEO_FAILED);
                    logEx.Error("Get a new preview success. But stop old preview failed.CameraNo:{0},Ivs sdk error code:{0}", cameraNo, result);
                    return err;
                }
            }
            return err;
        }