JVC VN-V686WPU VFS, AFS, Size, Size, rate, Total, Maximum, VGA File, QVGA File, maximum bit, Control Method, Picture Quality, Distribution at, (Average File Size)

Connection/Installation

Network Requirements

●Ensure that there is sufficient network bandwidth for the data volume to be sent out by VN- V686WPU. Do not send multicast stream that exceeds the bandwidth. If the entire bandwidth is used by the multicast stream, control of this camera via the network may fail.

●Data volume to be sent by VN-V686WPU varies with the settings and number of distributions.

●The maximum bit rate for transmission is about 20 Mbps.

Estimation of Total Bit Rate

The total JPEG bit rate from VN-V686WPU is determined by the VN-V686WPU settings, number of clients, and the client’s requested number of frames. The total MPEG4 bit rate from VN-V686WPU is determined by the number of distributions. Develop a design upon taking the above into consideration.

Bit Rate of JPEG Stream

The JPEG file size per frame varies with the encoding settings as well as input video signals. The following table may be used as a reference. When VFS is selected, the quantization table during JPEG encoding will be maintained, and the file size will increase/decrease according to the input signals. When AFS is selected, encoding will be performed such that the target file size is the average size of multiple JPEG images.

Picture Quality			VGA File	QVGA File
Control Method			Size	Size
VFS	1	(High)	80 KB	27 KB
(Variable
	2		60 KB	20 KB
File Size)
	3		40 KB	13 KB
	4 (Medium)		30 KB	10 KB
	5		25 KB	8 KB
	6		20 KB	7 KB
	7	(Low)	15 KB	5 KB
AFS			Selectable	Selectable
			between	between
(Average File Size)			10 KB to 100	3 KB to
			KB	33 KB

The maximum number of distributions varies with the bit rate settings as well as the client’s requested frame rate. Up to 20 streams can be distributed (including multicast). The total frame rate refers to the sum of these frame rates.

For example, when 10 fps is requested by two clients, and in addition, multicast is transmitted at a rate of 10 fps, the total frame rate will be:

10 + 10 + 10 = 30 fps

If the JPEG file size per frame is 30 KB, then the total bit rate will be:

30 KB x 30 fps = 900 KB/s = Approx. 7.2 MbpsBit Rate of MPEG4 Stream

You can select either the Variable Bit Rate (VBR) or Constant Bit Rate (CBR) system for MPEG4 stream. When the VBR system is selected, the bit rate varies according to the condition of the input video signals. The VBR system delivers a stable picture quality, but forecast of the bit rate is difficult.

When the CBR system is selected, encoding is performed at a fixed bit rate regardless of the condition of the input video signals. The picture quality varies under the CBR system, but the bit rate can be easily forecast.

You can specify an estimated bit rate for both VBR and CBR. (64 kbps to 8000 kbps)

Restrictions on the Number ofDistributions for VN-V686WPU

The maximum number of distributions for VN- V686WPU is determined by the settings as well as requirements from the client.

When only JPEG images are distributed, the maximum number of distributions is determined based on the highest bit rate within the stream. When a distribution request that exceeds the maximum number of distributions is received, this request is denied. For example, if Client A requests for and receives data at 1 Mbps, while Client B requests for and receives data at 5 Mbps, the maximum number of distributions is 4 streams according to the table below.

Maximum number of distributions when only JPEG data is distributed

Distribution at	Maximum	Total
maximum bit	number of	maximum bit
rate	distributions	rate
1 Mbps and	20	20 Mbps
below
5 Mbps and	4	20 Mbps
below
10 Mbps and	2	20 Mbps
below
Larger than 10	1	Maximum
Mbps		configurable
		value (24 Mbps)

24