User manual

ARECONT VISION USER MANUAL 58

Arecont Vision 425 E Colorado St, 7

Floor Glendale, CA 91205 8/1/2012

www.arecontvision.com

 QP is the quantization parameter for H.264 encoder. To achieve a higher quality video, a low

needed. Recommended values are in the range (16..37);

 Doublescan allows the user to specify whether the camera should delay the image output until a new

image is available from the sensor (doublescan = 0) or the image request should be serviced by

outputting the content of the image buffer that has been already once output (useful for picture-in-

picture display).

 SSN

specifies the stream identifier. MPEG codecs including H.264 codecs are context dependent

(decoding of the current frame depends on the previous frame(s)). The stream is a sequence of

frames of the same resolution which can be decoded sequentially by one instance of an MPEG

decoder. Accordingly, SSN

is a means to distinguish different streams from one another. Use a

unique SSN

for each stream with a unique image size, quality, and/or frame rate. Each camera

supports up to eight simultaneous non-identical streams. Each individual client must have a unique

(ip:

ssn)

 Bitrate is used to set up a constant bitrate of the H.264 stream in kilobits per second. If this parameter

is present in the request string and is larger than zero then the QP parameter is ignored and the

camera adjusts quantization parameters automatically to maintain the specified bitrate.

 FPS specifies the requested frame rate. Values 1 to 15 result in the specified frame rate. Omitting the

fps parameter or using fps values of 0 or any values above 16 will result in maximum frame rate

which is model dependent.

The first frame or the stream is always an IDR (Intra) frame followed by multiple P (Inter) frames. The default

number of P-frames is 50, and can be modified via register 3:21 using the following HTTP command:

http://camera/setreg?page=3&reg=21&val=(number of P-frames)

For the 8185/8365 cameras, P-frame interval can be modified using the following HTTP command:

http://camera_IP/setreg?page=3&reg=100&val=(number of P-frames)

The current P-frames setting can be checked using the following HTTP command:

http://camera/getreg?page=3&reg=21

Each frame sent by the camera may contain multiple zero bytes at the end. There is no Unit Delimiter (UD)

used. Although this does not contradict the ITU-T H.264 standard (ISO/IEC 14496-10), some decoders may

delay decoded frames by one due to the absence of the UD. If this presents a problem, replace all zero bytes

at the end with the UD, a sequence of the following five bytes: 0x00 0x00 0x01 0x09 0x10. In addition, the

number of zero bytes at the end of a frame may be significant, up to a few hundred bytes. Replacing them

with the UD will also reduce the stream size.