Axis Communications M3007-PV user manual 264, Mjpeg

AXIS M3007–PV

Video

This option is only available for the following view modes:

•Panorama

•Double Panorama

•Quad View

H.264

H.264, also known as MPEG-4 Part 10/AVC, is a video compression standard that provides high quality video streams at low bit rates. An H.264 video stream consists of different types of frames such as I-frames and P-frames. An I-frame is a complete image whereas P-frames only contain the differences from previous frames.

The GOV length is the number of frames between two consecutive I-frames. Increasing the GOV length may save considerably on bandwidth requirements in some cases, but may also have an adverse affect on image quality.

The Axis product supports two H.264 profiles. The Main profile provides higher compression than the Baseline profile with the same video quality, but requires more processing power to decode.

The bit rate can be set as Variable bit rate (VBR) or Constant bit rate (CBR). VBR adjusts the bit rate according to the image complexity, using up more bandwidth for increased activity in the image, and less for lower image activity. When the activity in the scene increases, the bit rate would usually increase as well. If there is a surplus in bandwidth, this may not be an issue and selecting Variable bit rate (VBR) will be sufficient. But if bandwidth is limited, it is recommended to control the bit rate by selecting Constant bit rate (CBR). When the activity in the scene increases, VBR adjusts the bit rate according to the complexity, using up more bandwidth for increased activity in the scene, and less for lower scene activity. CBR allows you to set a target bit rate that limits the bandwidth consumption.

The CBR target bit rate works like the ceiling of a tent. It limits the bit rate, while maintaining some flexibility. The bit rate may bounce up and down within the set target but when it nears the set target value, the limitation kicks in. However, because CBR will always prioritize a continuous video stream, it allows temporary overshoots from the target bit rate. Because setting a target value prevents the bit rate from increasing, frame rate and image quality are affected negatively. To partly compensate for this, select which variable shall be prioritized, frame rate or image quality. Not setting a priority means that frame rate and image quality are equally affected.

The current bit rate can be set to appear as text overlay. Under Overlay Settings, select Include text and enter the modifier #b in the field.

To apply the settings, click Save.

MJPEG

Sometimes the image size is large due to low light or complex scenery. Adjusting the maximum frame size helps to control the bandwidth and storage used by the Motion JPEG video stream in these situations. Setting the frame size to the Default setting provides consistently good image quality at the expense of increased bandwidth and storage usage in low light. Limiting the frame

19