Axis Communications AXIS 213 PTZ user manual Advanced MPEG-4, Client Compatability, GOV Settings

AXIS 213 PTZ 17

Advanced - MPEG-4

Client Compatability

The AXIS 213 PTZ supports the following different MPEG-4 profiles and levels:

Profile@Level	Properties
Advanced Simple Profile @ Level 3	Max bit rate = 768 kbit/s, ISMA compliant
Advanced Simple Profile @ Level 5	Max Bit rate = 8 Mbit/s

To use Advanced Simple Profile @ Level 3, select ISMA compliant and click the Save button.

Level 5 is preferred if there is enough bandwidth available, as the image quality of the video stream will be better than at level 3. The viewing client must support the profile used for the video stream, otherwise the MPEG-4 stream cannot be viewed.

Note: The Axis Media Control supports all the configuration possibilities described on this page.

GOV Settings

The GOV structure can be set to either I or IP, which describes the type of images included in the video stream, as well as their internal order. The IP-structure generally sends the differences compared to the previous image and far fewer complete images, so this method uses much less bandwidth than the I-structure. The I-structure gives higher frame rates when using a high resolution, but requires more bandwidth.

The GOV length determines the sum total of P-images and I-images in a GOV. Setting the GOV length to a high value saves considerably on bandwidth. However there may be noticeable decay in the image at high values.

Notes: •GOV = Group of VOPs •VOP = Video Object Plane •Video Object Plane = image

Bit Rate Control

Limiting the maximum bit rate is a good way of controlling the bandwidth used by the MPEG-4 video stream. Leaving the Maximum bit rate as unlimited will provide consistently good image quality, but at the expense of increased bandwith usage whenever there is more activity in the image. Limiting the bit rate to a defined value will prevent excessive bandwidth usage, but images will be lost when the limit is exceeded.

Note that a maximum bit rate can be used for both variable and constant bit rates.