Axis Communications Q2901-E Clock Radio User Manual


 
AXIS Q2901-E Temperature Alarm Camera
Video and Audio
Overlay settings. See Overlay on page 18.
Click Save to apply the new settings.
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 H.264 stream settings can be congured from the Video & Audio > Video Stream page. Select the H.264 tab. The settings
dened in this page will apply to all H.264 streams that do not use a stream prole.
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 the following H.264 prole(s):
Baseline. The Baseline prole is recommended for clients that don’t support CABAC entropy coding.
Main. The Main prole provides higher compression with maintained video quality compared to the Baseline prole 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 sufcient. 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 exibility. 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 modier
#b in the eld.
To apply the settings, click Save.
MJPEG
Sometimes the image size is large due to low dynamic 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 dynamic. Limiting the
frame size optimizes bandwidth and storage usage, but may give poor image quality. To prevent increased bandwidth and storage
usage, the maximum frame size should be set to an optimal value.
Stream Proles
A stream prole is a set of predened stream settings including resolution, compression, frame rate and overlay settings. Stream
proles can be used:
When setting up recording using action rules. See Events on page 38.
When setting up continuous recording. See Continuous Recording on page 42.
In the Live View page – select the stream prole from the Stream prole drop-down list.
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