Audio-Streaming Tests
Architecture of WTJU Streaming Service
This page is a description of the WTJU streaming architecture, including an explanation of network multicasting.
This system was built using Dell computers and the Microsoft Windows Media Encoder and the Microsoft Windows Media component of the Windows 2003 Server operating system.
The operating system on the encoder PC is Windows XP Pro. The server for on Grounds uses multicast, so the Enterprise version of Windows Server 2003 had to be used. The unicast server for off Grounds uses the standard version.
Equipment requirements are listed on the Microsoft site. Systems using Real Networks software or QuickTime software can be constructed to accomplish the same sort of service.
The WTJU signal is fed into a Creative SoundBlaster PCI card and encoded by the Windows Media Encoder software. The high bandwidth stream is made available on one port, whule the lower bandwidth stream is made available on another. The on-Grounds server, wtju-l.eservices.virginia.edu, is accessible only by machines on the local UVa network. The off-Grounds server, wtju–r.eservices.virginia.edu, can be accessed by a machine on any network.
Multicast vs Unicast
A unicast connection is a standard client/server network connection. A dedicated stream of data packets is directed from the server to the client software. If there are 10 unicast clients, there are 10 streams of data leaving the server. A multicast connection includes intelligent routing hardware along the data path that will send only a single stream of data along to the next router rather than sending duplicate streams.
Example 1 (below) : Multicast-enabled network. There are eight clients on a network where all five routers have been enabled for multicast. The server only transmits one stream of data for these eight clients.
Example 2 (below) : Mixed multicast/unicast network.Two of the eight clients are attached to the network via a router without the ability to multicast. Those clients each require a stream of data from the server. The server must provide three streams of data to serve eight clients.
The on-Grounds server is configured to multicast whenever possible. When a multicast connection is not possible, a unicast connection is established. This conserves network bandwidth.
Page Updated: 2011-06-28
