学步园

           确定流媒体服务器中每客户端带宽使用量

概要

   某些时候，了解连接到服务器的单个客户端使用的带宽很有用。有时由于一些功能（例如，快速启动和快速缓存），使用的带宽可能大于内

容的传输率。本文说明了如何添加上下文值，使开发者利用这些值以编程方式检索此信息。

   要确定 Windows Media Services 9 Series 最准确的每客户端带宽统计信息，您必需定义下面的两个演示上下文值。您必须将这些值添加

到项目中的标头文件中或 WmsContextNames.h 中。

// Type: long
// Description: Bandwidth allocated.
DEFINE_NAME_AND_HINT( WMS_PRESENT_ALLOCATED_BANDWIDTH, "WMS_PRESENT_ALLOCATED_BANDWIDTH", 30 )

// Type: long
// Description: Bandwidth allocated by network sink.
DEFINE_NAME_AND_HINT( WMS_PRESENT_BANDWIDTH_ALLOCATED_BY_NETWORKSINK, "WMS_PRESENT_BANDWIDTH_ALLOCATED_BY_NETWORKSINK", 48)

添加演示上下文值后，您可以利用客户端的演示上下文，通过检索这两个值然后加在一起得出总值来快速确定总的带宽使用量。下面的代码示例显示了操作步骤：

// Declare variables.
long lSinkAllocatedBandwidth = 0;
long lDatapathAllocatedBandwidth = 0;
long lTotalBandwidth = 0;

hr = pPresentationContext->GetLongValue(
                        WMS_PRESENT_BANDWIDTH_ALLOCATED_BY_NETWORKSINK,
                        WMS_PRESENT_BANDWIDTH_ALLOCATED_BY_NETWORKSINK_ID,
                        &lSinkAllocatedBandwidth,
                        0);
if( FAILED( hr ) )
{
   hr = S_OK;
   lSinkAllocatedBandwidth = 0;
}

hr = pPresentationContext->GetLongValue(
                       WMS_PRESENT_ALLOCATED_BANDWIDTH,
                       WMS_PRESENT_ALLOCATED_BANDWIDTH_ID,
                       &lDatapathAllocatedBandwidth,
                       0);
if( FAILED( hr ) )
{
   hr = S_OK;
   lDatapathAllocatedBandwidth = 0;
}

lTotalBandwidth = lSinkAllocatedBandwidth + lDatapathAllocatedBandwidth;