What our experts say…
Over the past two decades the PC has proved to be a invaluable tool for the security industry though it hasn’t always been at the cutting edge and in the early days it was largely used in supporting and administrative roles. Gradually, as the technology has developed, it has moved to frontline operations in many different fields, from alarms and access control to more exotic applications such as biometrics and image processing. However, in one area the impact of the PC has only just begun to be felt: video surveillance, where the incumbent technology has proved to be more resilient than expected.
When it comes to recording and archiving video images, magnetic tape is still the simplest, cheapest and most flexible option. But maybe not for much longer …
Hard disk digital video recorders (DVRs) have been around for at least the past six or seven years and the technology is by now well established. The cost of the hardware, while still relatively high when compared with a mid-range time-lapse VCR, has fallen dramatically in the past couple of years. Picture quality has always had the potential to be at least as good as (and in most cases better than) that available from analogue video recorders. So what is the hold-up?
Cost is obviously a major consideration; a hard disk recorder with comparable capabilities to a VCR costs between three and five times as much, though that is usually offset by HDD recorders usually having many additional facilities, including on-board camera multiplexing, and the higher image quality is an important plus. Nevertheless HDD recorders tend to fall down when it comes to archiving recordings, the complexity of installation and use may also be a consideration and then there is the question of reliability, which on any new technology tends to be a bit variable.
The plettac senti0-50 digital video disk recorder and its companion software is a good example of the current state of the art in hard disk video recorders. While it is not going to make analogue VCRs obsolete overnight, it is yet another nail in the coffin of VHS and a tantalising taste of what is to come. The Senti0-50 DVR is basically a 1.6GHz Pentium PC with a 60Gb hard disk drive, (extra hard disk drives can be added if required), 256Mb of RAM, CD-RW drive and Windows 2000 operating system.
The key differences between it and a regular desktop machine are the case and expansion cards. Senti0-50 is available in a standard rack-mount housing or a more conventional freestanding PC style case, in both types access to the CD drive and reset button are protected by a hinged and lockable access door and the front panel is virtually featureless, apart from a couple of LEDs that indicate power on and disk activity.
The extra expansion cards take the form of video and alarm inputs/outputs occupying PCI slots on the motherboard. Various configurations are available. Our test sample was a top-of-the line model fitted with four cards, each with four inputs giving a total of 16 channels, plus their associated alarm inputs, accessible through a bank of sockets on the rear panel.
Since the Senti0-50 is expected to operate 24/7, cooling has been given a very high priority. In addition to the standard cooking fans in the power supply and on the main processor chip there is a large cooling fan on the front directing air onto the video boards and three smaller fans fitted to a blanking plate on the back panel.
Needless to say six fans on full song make a significant amount of noise and in a quiet environment it could be quite intrusive, so some thought needs to be given to location and possibly sound insulation. It puts out a fair amount of warm air too, which might also be a consideration in some installations.
Keeping everything under control is a suite of programs called Senti0-Review. This is responsible for video recording and playback, display, archiving, motion detection, alarm management, camera control (PTZ), record scheduling and Ethernet network communications. The latter allows the Senti0-50 to connect to a server and lets authorised network users view and record images from any selected camera.
Network users with the necessary authority can also alter configuration and alarm settings, and remotely control any PTZ cameras. All of the software is pre-installed and ready to run so all the installer has to do is plug in the monitor, keyboard and mouse and connect the cameras and alarms. The video inputs are via BNC sockets, in addition to the standard VGA output for the monitor there are also composite and/or S-Video outputs for additional video monitors. The alarm inputs and outputs are via multi-way connectors on the back panel. The powerful video motion detection (VMD) utility is called MotionTrack, which is integrated into the software package. This allows the user or operator to specify any number of variable-sized triggers or ‘regions of interest’ (ROIs) for each camera. Sensitivity can be varied to reduce the likelihood of false alerts, caused by changes in light level or natural motion.
At switch on senti0-50 boots up to the normal Windows 2000 desktop, then after a few seconds the Review software loads and the user screen is displayed. From that point on normal PC functions are disabled and it is not possible to exit the program or access any other programs without going into Supervisor mode.
There is a minor security loophole: if the Windows key is pressed before the senti0 software loads it is possible for the operator to access Windows, however this would be a relatively simple thing to fix and it would be logged by the administrator software.
The main user screen automatically defaults to a live display of connected cameras. A narrow control panel is displayed on the left of the screen showing time and date at the top. Below are three buttons for Supervisor, Live and Playback modes. Underneath are six icons for selecting display mode (single screen, 3×3, 2×2, 8+2, 4×4 and 12+1) which sit on top of a list of the available input channels, with green indicators showing which ones are currently active. It is possible to switch from any display mode to full screen by double-clicking on an image; double clicking a second time changes the display back to its previous state. Images in multi-mode displays can be rearranged by dragging and dropping the picture into its preferred position.
The operator has full access to Playback mode. When selected a new control panel appears at the bottom of the screen displaying a timeline, there is also a time and date readout, VCR type controls, a set of replay ‘speed’ buttons (1x, 2x, 4x & 8x), two Event buttons and an Export button, for ‘burning’ a CD-R disk or printing a still image.
The timeline shows the duration of the current recording as a white band; yellow markers indicate VMD events and red markers show alarm triggers. By clicking on the timeline or an event marker it is possible to go more or less instantly to any part of a recording, or times can be entered manually from the keyboard. When archived recordings are burnt onto CD-R disks the system automatically includes a player utility on the disk, so that the recording can be viewed on any Windows PC. Critical settings can only be accessed from the password-protected Supervisor mode. This opens a tabbed dialogue box. There are also buttons for configuration settings, exiting to user mode or closing the application and returning to the Windows 2000 desktop.
Tab 1 is labelled Cameras and this includes fields for composing camera titles, specifying record mode (Always, Never Default), record speed (one to 25 images per second), image quality/compression (level 1 = high quality/low compression, level 11 = low quality/high compression), Alarm enable, VMD enable, Data Archiving enable/disable, Archive record speed and quality. Tab 2 deals with the alarm settings, specifying recording speed and quality, duration, pre-alarm recording time, alarm inputs and output states. Video motion detection is handled on tab 3, the selected camera input is shown on a sub screen and the ROI is defined using the mouse. There are three sensitivity settings (low, medium and high) and buttons to show and deselect targets. The Preview tab provides access to image quality settings for normal recording and archive recording, showing the effects of different compression settings in an inset sub-screen. The Patrol tab is used when one or more PTZ cameras are connected.
Tab 6 ‘Hard Disk’ displays a pie chart showing the amount of space being used by each camera channel, and space remaining. There is also archiving information and an estimate of disk usage. Tab 7 ‘Time Zones’ is used to schedule recordings for regular events such as cash collections and deliveries. It displays a grid with days of the week divided into 96 15-minute slots; there is provision to skip holidays, set recording speed, image quality and enable alarms and motion detection. This particular aspect of the setup is slightly convoluted and it pays to keep the manual (on CD-ROM) close to hand. Tab 7 is for managing any additional hard disk drives fitted to the system, Tab 8 is the Event Log that records all system activities and tab 9 is for managing the User list and changing passwords.
There are a couple of small operational annoyances. Firstly the maximum 8x search speed is not fast enough for skimming through a recording and it would have been helpful to have some way of changing the timeline scale. As it is, it displays a 13-hour time segment. Finding a particular event without alarm or VMD indicators would be a lot easier if the scale could be compressed, to say an hour or 30 minutes. Lastly, when switching between Play and Live modes the display always reverts to the default 4×4 layout. It would be more convenient if it returned to the previously selected display mode.
Picture quality and recording times depend on a number of factors including the amount of compression, recording interval or speed and the number of camera channels being recorded. At the lowest picture quality setting and slowest interval (one image per second), the output from a single camera the 60Gb drive can hold is a little under 30 days of recordings. Increasing any or all of those values has a big impact on duration. For example, changing to the mid quality setting and using a recording speed of 25 ips, the output from a single camera will fill the drive in a little less than 36 hours.
Picture quality on settings between 3 and 5 are comparable with the best that high and low band analogue tape has to offer with a fair amount of detail and reasonably natural-looking colours. The picture is rock solid. It really comes into its own during replay, with the facility to step forwards or backwards through a recording a frame at a time or in search mode at the click of a mouse and without any picture disturbance or noise bars.
What the manufacturer says …
THE Plettac sentio-50 timelapse video recorder and network server is ideally suited for every type of application where motion detection, time-lapse and event recording facilities are required. Passenger termini, hospitals, museums, art galleries, shopping malls as well as banks and other sensitive applications are seen as potential market sectors.
The sentiO-50 runs under the robust Windows 2000/XP operating system. Recording, playback, live display, compression and archival operate concurrently, enabling playback and live display while recording.
The Graphical User Interface (GUI) is simple and easily understood as only essential functions are accessible from the main screen. Information about alarms is immediately visible in playback mode, with the innovative time line display allowing any event to be found with ease.
Each camera can be recorded for any length of time on a circular basis. Outdated video can be archived, overwritten, or further compressed and stored.
The sentiO-50 features four, eight, 12, and 16 channels, with unlimited expansion over a network. Up to 16 active cameras can be viewed simultaneously during live mode. Live mode displays all cameras at 25 ips, real time.
The sophisticated Video Motion Detection module can monitor up to 16 camera inputs in real time. Any number of regions may be selected for motion trigger in any one view and the different sensitivity levels allow the user to select the required level of motion to generate triggers.
