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The Pre-alarm record mode is the record mode for recording a pre-alarm events event for a specified period before recording an alarm. Pre-alarm record recording is performed at the hot record rate. If you don't specify the hot record rate is not specified, then the recording is performed at the standard record rate.
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For Video isn't recorded in Pre-alarm record mode for cameras without video compression that have been added to the corresponding list in the Video subsystem section in the tweaki.exe utility (see The Settings panel of the Video subsystem section), video is not recorded in Pre-alarm record mode. |
By default, the recording in this mode is disabled. To enable the pre-alarm recording, do the following:
- Go to the Hardware tab in the System settings dialog box (1) window.
- Select the Camera object corresponding to the required camera in the objects tree (2). The settings panel for the selected object is displayed on the right of the Hardware tab.
- Go to the Basic settings tab on the settings panel of the Camera object (3).
- In the Pre-alarm record field, specify the required time interval (sec) of pre-alarm events recording (4).
- Click the Apply button (5).
Information The table provides the information on pre-alarm recording options is given in the table.
Camera state | Recording initiator | Recording |
Armed | Macro | Without pre-alarm recording |
Armed | Manually | Without pre-alarm recording |
Armed | Alarm | With pre-alarm recording |
Armed | Program | With pre-alarm recording |
Disarmed | Macro | Without pre-alarm recording |
Disarmed | Manually | Without pre-alarm recording |
Disarmed | Alarm | -Na |
Disarmed | Program | With pre-alarm recording |
In Axxon PSIM one can make perform pre-alarm recording if camera is disarmed. One You can do it with the help of the DoReact("CAM","1","REC","rollback<1>") program; (see The Script object. Programming using the JScript language).
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To count the memory consumption ascertain , figure out the average size of the video signal frame. To perform do this, you must record the video fragment of 500 frames length to the archive (maximal maximum size on , by default) and use the following formula:
Frame size = Fragment size / 500
The Note, that the frame size is also depends on percent of motion in the frame.
It is possible to You can count the size of pre-record buffer for one camera it if the frame size is known:
Size of pre-record buffer for one camera, MB = Pre-record time, sec * Frame frequency in the pre-record mode, fps * Frame size, MB.
General memory consumption in the pre-record mode is defined by sum of values for each camera.
It is possible to use the following formula in case of If cameras perform pre-record with equal frame frequency, you can use the following formula:
Size of pre-record buffer for all cameras in the system, MB = Number of cameras * Pre-record time, sec * Frame frequency in the pre-record mode, fps * Frame size, MB
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Example. Camera The camera performs pre-record for 15 seconds with the hot record speed 25 fps. Size of 500-frames fragment is 20 Mb. It is required to define the size of pre-record buffer for such camera. First, you it is necessary to define the average frame size: Frame size = Fragment size / 500 = 20 MB/500 frames = 0.04 MB. So, the size of pre-record buffer is: The memory consumption in the pre-record mode for one camera, MB = Pre-record time, sec * Frame frequency in the pre-record mode, fps * Frame size, MB = 15 sec * 25 fps * 0.04 MB = 15 MB. |
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Configuring video in the pre-alarm record mode is complete.
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