Technology

To complete an executive broadcast stream using our technology, you must use a compatible encoder, server, and player. This section describes the functional purpose of these components as well as the other processes associated with the components.

The capture phase takes place when you pull audio and video from its source and onto the computer using a capture card. If the source is analog, then the capture card converts the analog data to digital form before depositing it on the computer. As is the case during conversion from analog to digital, a slight quality loss occurs.

Data originally captured through a digital device, such as a digital video card, requires that the data be run through a capture card suitable for digital devices to get data onto the computer, and must be completed whether the data is analog or digital.

Many capture cards include a simple capture program that allows you to save the digitized media as an uncompressed .avi file, which is a standard Microsoft video file format. If you are streaming a live event, saving the content into a file is not necessary because, live or on-demand, the next phase of this process is encoding.

Without compression, much content would never be suitable for streaming; its large size would choke network infrastructure. Encoding compresses content so it can be streamed over a network such as a LAN. Encoders use codecs (compressor/decompressor), which are algorithms that calculate and apply the amount of necessary compression, based on the quality of the content and the intended transfer bit rate. After compression, the data is encoded into a streaming media format, such as Windows Media Video (WMV) or Windows Media Audio (WMA). Encoding sources from your raw captured data, and connects to the server that you use for distribution.

Capturing and compressing content is a CPU-intensive process, and maintaining connections with multiple Players during the streaming process is memory-intensive. To improve performance and encoding quality, you may want to use:

• Fast processors as well as dedicated computers for the encoding process
• A high-performance hard disk for the dedicated computer
• Audio and video cards
• Windows XP Professional/Windows Vista as the operating system
• A network that can accommodate the bandwidth required by both the stream from the encoder and the overhead for other network traffic

Distributing with Media Services

With your content digitized to a file on your computer from the capture phase of the process, the next step is to distribute it. Because of the protocols used and the limitations of Web servers, streaming content requires a streaming media server. These servers support a different protocol that maintains a constant connection with the Player, and thus delivers a successful, live multicast broadcast. They can log user data, which allows you to understand trends, identify bottlenecks, or troubleshoot performance issues on your server. Streaming media servers support streaming content at multiple bit rates, which can be useful when you need to stream content to a number of clients who are accessing your server at various connection speeds. Although Web servers support multiple connection speeds, they do not provide this same kind of functionality and support.

Distribution of your compressed and encoded content sources from the encoding process, and ends with the sending of the content to the end user. As you consider your distribution options, you may want to consider the following network performance and capacity issues:

Because multicasting on a large network can result in a diminishment of network capacity, ensure that your network has adequate capacity.

Minimize network bandwidth deficiencies. Do this by: setting limits to Player connections and bandwidth used; creating a server cluster; adding distribution servers; implementing a cache/proxy server system; and modifying your streaming content.

For large-scale deployments, the following modifications have improved results: Upgrading from a single-CPU server to a multiple-CPU server; installing additional or improved network interface cards; adding additional servers to your system; using network load balancing; adding cache/proxy servers to your system; implementing a content replication program closer to Players using the server; setting the network switches that  process streaming media requests and transmissions to full duplex mode to maintain an uninterrupted information flow.
Using Media Player

After your content is distributed through your corporate network, it is ready for your employees to view it. To play back a streamed file, your employees either click a link on a Web page or enter the location of the content in their player application, which contacts the server to start the stream. Windows Media Player is included in the Windows XP operating system, where it is best experienced.