Axis Communications 2460 - Manual (Page 50)

Recording Storage and Reduction AXIS 2460 User’s Manual 50
Appendix A - Recording Storage and Reduction
The AXIS 2460 records and manages the stored images on the connected disks so that the
storage capacity is always used to its maximum extent. Once the disks are filled,
something must be done to make space available for new recordings. The AXIS 2460 does
this by gradually reducing the frame rate of recorded sequences so that eventually there
are no more frames and the recording has effectively been deleted. An important recording
that needs to be kept at its original frame rate indefinitely can be explicitly locked and thus
protected against the reduction process.
The rate and amount of frame rate reduction for an individual recording is controlled by a
number of factors:
• the Recording Mode set for the whole system
• the Priority set for the event that created the individual recording
• other factors that affect file size and thus hard disk space, e.g. image resolution, image
compression, etc.
Selecting the Recording Mode
The technology used for image storage on the AXIS 2460 is called APViS™ (Axis
Prioritized Video Storage). This technology (invented by Axis and patent pending) extends
the length of time recordings are stored for by intelligently reducing the frame rate of all
recordings not explicitly locked. Older recordings and those of less importance (see Priority
below) will thus gradually be reduced until finally deleted.
As the available recording modes all describe a ratio between the length of time the
recordings are stored for and the frame rate at which they stored, you should consider
what you require from your recordings when selecting the mode.
• Normal Mode - a standard FIFO (First In - First Out) algorithm that simply overwrites
older recordings with new ones, with no prior reduction in frame rate. Normal mode will
keep all of your recordings at the original frame rate for their entire lifespan, but they will
be overwritten relatively quickly.
• Extended Mode - stores recordings for longer than Normal mode, but at the expense of
frame rate reductions in older and less important recordings.
• Extended Long Mode - extends storage time by using even greater reduction, and even
earlier in the recording. This mode also reduces the frame rate of more recent recordings.
If you need to save recordings for as long as possible and can accept the highest degree of
frame rate reduction, then this is the best choice.