User`s manual

AXIS 282/AXIS 282A - Video and Audio Streams

Video and Audio Streams

The AXIS 282/AXIS 282A provides several different video and audio stream formats. The

type to use depends on your requirements and on the properties of your network.

The Live View page in the AXIS 282/AXIS 282A provides

access to Motion JPEG and

MPEG-4 video and audio streams, as well as to single JPEG images. Other applications and

clients can also access these video and audio streams/images directly, without going via

the Live View page.

Video Stream Types

Motion JPEG

This format uses standard JPEG still images in the vi

deo stream. These images are then

displayed and updated at a rate sufficient to create a stream that shows constantly updated

motion.

The Motion JPEG stream uses considerable

amounts of bandwidth, but also provides

excellent image quality and access to every individual image contained in the stream.

Note also that multiple clients

accessing Motion JPEG streams can use different image

settings.

MPEG-4

This is a video compression standard that makes good

use of bandwidth, and which can

provide high-quality video streams at less than 1 Mbit/s.

The MPEG-4 standard provides scope for a large

range of different coding tools for use by

various applications in different situations, and the AXIS 282/AXIS 282A provides certain

subsets of these tools. These are represented as Video object types, which are selected for

use with different viewing clients. The supported video object types are:

• Simple - sets the coding

type to H.263

• Ad

vanced Simple - in Axis products, this sets the coding type to MPEG-4 Part 2

AMC (AXIS Media Control) supports both object types, whilst QuickTime™

for example,

requires the Simple object type.

When using MPEG-4 it is also possible to control the bit rate,

which in turn allows the

amount of bandwidth usage to be controlled. CBR (constant bit rate) is used to achieve a

specific bit rate by varying the quality of the MPEG-4 stream. When using VBR (variable

bit rate), the quality of the video stream is kept as constant as possible, at the cost of a

varying bit rate.