Dummies, Wireless

Chapter 12: Networking Your Entertainment Center
Here are the two predominant ways that audio and video files are handled
with your entertainment/PC combo:
� Streaming: The file is accessed from your PC’s hard drive (or over the
Internet) and sent via a continuous signal to your entertainment hardware
for live playback. This is the way most media content is handled
in home networks today.
� File transfer: The file is sent from your PC to your stereo system components,
where it’s stored for later playback.
These two applications have different effects on your wireless home network.
Streaming applications are real-time applications (meaning that what you are
hearing or seeing, or both, is what’s being streamed over the network right
now), and any problems with the network, such as not having enough bandwidth
to support the media you’re playing, has a noticeable effect in your
playback experience (for example, dropped audio or blocky video). File transfers,
on the other hand, can pretty much work over any network connection.
With file transfer, lots of transmissions take place in the background. For
example, many audio programs allow for automatic synchronization between
file repositories, which can be scheduled during off hours to minimize the
effect on your network traffic when you’re using your home network. And, in
these cases, you’re not as concerned with how long it takes as you would be
if you were watching or listening to it live while it plays.
A streaming application is sensitive to network delays and lost data packets.
You tend to notice a bad picture pretty quickly. Also, with a file transfer, any
lost data can be retransmitted when its loss is detected. But with streaming
video and audio, you need to get the packets right the first time because most
of the transmission protocols don’t even allow for retransmission, even if you
want to. You just get clipped and delayed sound, which sounds bad.
A good-quality 802.11g signal is fine in most instances for audio or video file
transfers and is also more than adequate for audio streaming. Whether it’s
okay for video streaming depends a great deal on how the video was encoded
and the size of the file. The larger the file size for the same amount of running
time, the larger the bandwidth that’s required to transmit it for steady video
performance. Video is a bandwidth hog; whereas audio streaming might
require a few hundred Kbps of bandwidth (or maybe one or two Mbps for
uncompressed audio), video can require much more. Low-resolution Internet
video (for example, YouTube videos) doesn’t require a lot of bandwidth; it
also doesn’t look all that great on your TV. If you want to send DVD-quality
video across your wireless network, you need several Mbps’s worth of wireless
bandwidth to do so — HDTV can require as much as 20 Mbps.
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