Axis Q3708-PVE User Manual page 17

AXIS Q3708-PVE Network Camera
Video
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 configured from the Video > Video Stream page. Select the H.264 tab. The settings defined in this
page will apply to all H.264 streams that do not use a stream profile.
The GOP length is the number of frames between two consecutive I-frames. Increasing the GOP 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 profile(s):
• Baseline. The Baseline profile is recommended for clients that don't support CABAC entropy coding.
• Main. The Main profile provides higher compression with maintained video quality compared to the Baseline profile but
requires more processing power to decode.
• High. The High profile provides reduced bit rate and higher compression with maintained video quality compared to the
Main profile but requires more processing power to decode.
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
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.
Axis' Zipstream Technology
Zipstream is a bit rate-reduction technology optimized for video surveillance. Zipstream reduces the average bit rate in the H.264
stream by removing unnecessary data and makes it possible to allow higher resolutions, reduce storage cost or to keep recordings for
a longer time. To reduce the bit rate, Zipstream reduces the number of bits in the areas of the image that are less interesting from a
video surveillance perspective, for example the background. Image details that are important for forensic video analysis, for example
faces and license plates, are preserved with enough number of bits.
These Zipstream strength options are available:
• Off. Zipstream disabled.
• Lowest Zipstream strength. Low bandwidth reduction. No visible quality degradation in most scenes
• Medium Zipstream strength. Medium bandwidth reduction. Limited visual quality degradation in not prioritized areas in
some scenes
• Highest Zipstream strength. High bandwidth reduction. Visible quality degradation in not prioritized areas in many scenes
Lowest Zipstream strength is the default setting for the product. This configuration is very safe to use in all applications while still
reducing the bit rate.
For cloud-connected cameras or cameras using edge storage that need to limit the bit rate for increased storage time it is
recommended to select the Highest Zipstream strength. This setting is very good to combine with motion detection triggering and
variable bit rate (VBR) where the bit rate is allowed to adapt to changes in complexity in the scene.
Axis' Zipstream Technology for H.264 conforms to the H.264 standard and is compatible with third-party clients and VMS solutions
that decode H.264 video.
The bit rate controller built into the product can be combined with Zipstream to enforce a maximum bit rate (MBR) limit. Axis
Communications recommends using VBR or MBR with a rather high bit rate limit to enable the full potential of Axis' Zipstream
Technology.
17