IWMSTransportProperties.GetStreamProperties (Visual Basic .NET)

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IWMSTransportProperties.GetStreamProperties (Visual Basic .NET)

The GetStreamProperties method retrieves properties of a stream.

• **Note   **This method is available only on Windows Server 2003, Enterprise Edition with Service Pack 1; Windows Server 2003, Datacenter Edition with Service Pack 1; and Windows Server 2008.

Syntax

  IWMSTransportProperties
  .GetStreamProperties(
  dwStreamId As UInt32,
  dwAlternateIndex As UInt32,
  ByRef ppProps As IWMSContext
);

Parameters

dwStreamId

UInt32 containing the stream ID of the stream.

dwAlternateIndex

UInt32 containing the unique alternate index of the stream.

ppProps

Reference to an IWMSContext object containing the properties of the stream.

Return Values

This method does not return a value.

Remarks

If you are using RTSP to stream content, you can retrieve the UDP port number of a connected client. To retrieve this value, you must create a custom event notification plug-in that accesses the RTSP SETUP request sent by the client during the initial setup process. You can then use GetStreamProperties to retrieve an IWMSContext object that contains the transport settings that were defined in the SETUP request.

Example Code

The following example shows how to retrieve the UDP port number of a connected client through the use of a user-defined method. Add WMS_EVENT_SELECT_STREAMS to the list of handled events for your plug-in and call this user-defined method within the IWMSEventNotificationPlugin.OnEvent method.

Function GetPortNumber(ByVal pCommandCtx As IWMSCommandContext) As Integer

    ' Declare variables.
    Dim TransportProperties_Guid As Guid = _
        GetType(IWMSTransportProperties).GUID
    Dim StreamSwitchDescriptionList_Guid As Guid = _
        GetType(IWMSStreamSwitchDescriptionList).GUID
    Dim oUnknownXPort As Object
    Dim oUnknownSS As Object
    Dim iPortNumber As Integer = 0
    Dim dwStreamId As Int64 = -1
    Dim cmdCtx As IWMSContext
    Dim transCtx As IWMSContext
    Dim oTransProps As IWMSTransportProperties
    Dim oSwitchList As IWMSStreamSwitchDescriptionList
    Dim dwCount As System.UInt32

    Try
        ' Retrieve the command request context.
        pCommandCtx.GetCommandRequest(cmdCtx)

        ' Retrieve an object and explicitly cast it as an 
        ' IWMSStreamSwitchDescriptionList object.
        cmdCtx.GetAndQueryIUnknownValue( _
            WMSDefines.WMS_COMMAND_CONTEXT_STREAM_SWITCH, _
            WMSDefines.WMS_COMMAND_CONTEXT_STREAM_SWITCH_ID, _
            StreamSwitchDescriptionList_Guid, oUnknownSS, 0)
        oSwitchList = CType(oUnknownSS, IWMSStreamSwitchDescriptionList)

        ' Retrieve the number of stream descriptions in the stream 
        ' descriptions list.
        oSwitchList.GetDescriptionCount(dwCount)

        ' After the correct stream is found, retrieve the new stream 
        ' number for that stream.
        Dim z As Integer
        For z = 0 To System.Convert.ToInt32(dwCount) - 1
            Dim objStreamSwitch As CWMSStreamSwitch
            oSwitchList.GetIndexedDescription( _
                System.Convert.ToUInt32(z), objStreamSwitch)

            If objStreamSwitch.ModifierType = _
                WMS_STREAM_MODIFIERS.WMS_NO_MODIFIER Or _
                (objStreamSwitch.ModifierType = _
                WMS_STREAM_MODIFIERS.WMS_THINNING_MODIFIER And _
                (System.Convert.ToInt32(objStreamSwitch.dwModifier) = 0 _
                Or System.Convert.ToInt32(objStreamSwitch.dwModifier) = _
                1)) Then
                dwStreamId = _
                System.Convert.ToInt64(objStreamSwitch.dwNewStreamNumber)
                Exit For
            End If
        Next z

        ' Retrieve an object and explicitly cast it as an 
        ' IWMSTransportProperties object.
        cmdCtx.GetAndQueryIUnknownValue( _
            WMSDefines.WMS_COMMAND_CONTEXT_TRANSPORT, _
            WMSDefines.WMS_COMMAND_CONTEXT_TRANSPORT_ID, _
            TransportProperties_Guid, oUnknownXPort, 0)
        oTransProps = CType(oUnknownXPort, IWMSTransportProperties)

        ' Use the new stream number to retrieve the UDP port number 
        ' through the stream properties.
        If dwStreamId <> -1 Then
            oTransProps.GetStreamProperties( _
            System.Convert.ToUInt32(dwStreamId), _
            System.Convert.ToUInt32(0), transCtx)

            ' Retrieve the UDP port number of the client.
            transCtx.GetLongValue( _
            WMSDefines.WMS_TRANSPORT_CONTEXT_CLIENT_PORT, _
            WMSDefines.WMS_TRANSPORT_CONTEXT_CLIENT_PORT_ID, _
            iPortNumber, 0)
        End If
    Catch ex As Exception
        If Not ex.Message.ToLower().StartsWith("invalid index") Then
            ' TODO: Handle exception.
        End If
    End Try 

    ' Return the port number.
    Return iPortNumber
End Function

Requirements

Reference: Add a reference to Microsoft.WindowsMediaServices.

Namespace: Microsoft.WindowsMediaServices.Interop.

Assembly: Microsoft.WindowsMediaServices.dll.

Library: WMSServerTypeLib.dll.

Platform: Windows Server 2003, Enterprise Edition with Service Pack 1; Windows Server 2003, Datacenter Edition with Service Pack 1; Windows Server 2008.

See Also

• IWMSTransportProperties Object (Visual Basic .NET)

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