Wireless streaming scenarios apply primarily to three kinds of
devices that are or very soon will be capable of rendering
streaming media content: portable computers, personal digital
assistants, and Internet-capable phones. If your target audience
includes these devices, consider the following:
Enable forward error correction on your publishing points.
Forward error correction (FEC) is a common method of preserving the
integrity of data transmitted over unreliable or slow network
connections. When forward error correction is used, the server
broadcasts extra packets on the assumption that some of the packets
will be lost before they reach the client. This process enables the
client to reconstruct the original transmission even if a
significant portion of the packets are missing.
PDAs typically have a much smaller viewing area than desktop
computers or even portable computers. When encoding video for a
PDA, you must accommodate not only the PDA's small screen size, but
also its modest computing power. For example, the screen size of a
Pocket PC is 320 pixels by 240 pixels, but the best compromise of
picture quality, frame rate, and bit rate suggests a frame size of
208 pixels by 160 pixels and a frame rate of 20 frames per second.
In order to render streaming video at full screen size, the frame
rate must be reduced, which often makes movement on the screen
excessively jerky. Additional encoding profiles for encoding
content for mobile devices are available from the Windows Media
Encoder page at the Microsoft Web site
Cellular data transfer technology has not advanced to the point
of permitting broadband access to streaming media. Devices that use
Cellular Digital Packet Data (CDPD) or other cellular modem
technology are generally restricted to a bit rate of 9.6 kilobits
per second (Kbps or less). Bit rates in this range cannot support
streaming video.
Note
Forward error correction is available only if
Windows Media Services 9 Series is running on the following
editions of the operating system: Windows Server 2003, Enterprise
Edition and Windows Server 2003, Datacenter Edition. If you are
running Windows Server 2003, Standard Edition, this feature is not
supported.
Note