VBrick Systems VB5000, VB6000, VB4000 manual

	WM Configuration
Target Bit Rate (bits	This number represents how much data the VBrick will send out each
per second)	second to carry video to a player. The word target is used because the
	appliance can vary its bit rate slightly in response to the amount of
	detail in the movie or camera output. Bit rate determines how much
	data the appliance sends in one second to contain one second of the
	video or camera output. The more data the VBrick sends in one
	second, the more clearly the details of the video will be seen on a
	player. It is not always possible to send the most possible data, since
	that requires a large network "pipe" (connection). The trade-off is the
	level of detail in the video with the use of smaller network
	connections. The encoder tries to encode the video at a quality that
	will (on average) match the Target Bit Rate. The larger the number, the
	better the quality but this can potentially limit the number of clients that can
	connect to the encoder. Note that Video Rates1, 2, and 3 must have
	different Target Bit Rates.
Target Frame Rate	Sets the video target frame rate in frames per second, for a VBrick
	WM Appliance. For a WM Appliance in NTSC mode the supported
	values are 30, 15, 10, 7.5, and 1. For a WM Appliance in PAL mode the
	supported values are 25, 12.5, 10, 5, and 1. This number represents
	how many frames the VBrick will send out each second to carry the
	video to a player. The word target is used because in VFR mode the
	VBrick can vary its frame rate slightly in response to the amount of
	motion in the movie or camera output.
	Frame rate is the number of "frames" the VBrick sends in a second for
	a Windows Media player to display. Moving pictures are made up of a
	rapid series of "still" pictures that move so fast that the "illusion" of
	motion is produced. A frame is one such "still" picture. Regular TV
	programs in the U.S. run at about 30 frames in a second; and the more
	frames presented in a second; the smoother the motion contained
	within the video will appear. Encoding and transmitting a frame
	requires the use of data, so that, when considering a particular bit rate,
	sending more frames demands that each frame contain fewer fine
	details. Similar to bit rate, the difference between "constant" and
	"variable" frame rate is that if "constant" is chosen, then the VBrick
	will ensure that the chosen frame rate is maintained by reducing the
	quality of the frames if necessary. The "variable frame rate" setting
	allows the VBrick to change how many frames it uses in a second
	(within limits), so that frame quality is maintained.
Key Frame Interval	A key frame is guaranteed to be sent at this interval although it may be
(in seconds)	sent more frequently depending on the content being encoded. This
	interval allows a player to "sync up" with a video stream already in
	progress by providing basic anchoring and orienting data. If "key
	frames" are sent less frequently, it will take longer for the video to
	begin playing after a player is started on a PC. Key Frames create
	overhead, lowering the amount of data available to carry the details of
	the video. As a result, VBrick appliances are often set to send key
	frames at infrequent intervals. You can set the Key Frame Interval to
	zero which will provide all key frames but for most content this will
	result in an actual bit rate far above the target.
Smoothness	Range 0–100. Default = zero. Use the default except as directed.

VBrick WM Appliance Admin Guide 31