All About Surveillance Systems

Recording Surveillance Video

Most people purchase a surveillance systems for two main reasons: To view live action, and to record activity for future viewing and evidence. If having recorded data is important to you, you will want to read the following to determine which method is best for you. Recording methods can be divided into two main groups:

Analogue (VCR)
Digital (DVR)

VCR Playback       

         DVR Playback

View, Record, and Playback Video

Analogue - The Old Way

 

 

 

 

 

 

Digital - The New Way

 

Monitor

 DVR (Digital Video Recorder) 

Switcher or Multiplexer

 

VCR

Video Capture Card

The cameras are connected to a Switcher or Multiplexer which then forwards the video to a VCR for recording and a Monitor for viewing. A switcher  literally switches from one camera to the next, and only one camera gets viewed/recorded at a time, missing a lot of action if there are several cameras. A multiplexer allows all or some cameras to be viewed/recorded at the same time with full resolution. You can likewise playback  any single camera on full screen, or groups of cameras. A multiplexer divides the total frame rate (usually 30 frames per second) amongst the cameras on the system – so the more cameras you have, the more choppy the video is.

The weak link is the VCR. You only get 24 hours on the tape (some machines can be set for longer, but the picture gets really choppy), and you have to replace the tapes every 2 weeks to preserve the heads – which need to be cleaned or replaced periodically anyway, at no small expense.

When viewing video on playback, you have to painstakingly watch the whole thing to find the action – including the hours of dead space, when nothing is happening.

VCRs have very poor playback resolution. A picture that looked fairly clear on the monitor during live viewing, looks much worse on playback due to the fact that the VCR only records at 350 TV lines; whereas the monitor could have a resolution of up to 1000 TV lines. Hence the VCR is the weak link .

A DVR is a computer with Video Capture Cards installed. The cameras connect right to this card and you have beautiful crisp color video right on the PC. It would be very difficult to go back to a VCR once you've seen digitally recorded video. You can get capture cards for from 4 – 16 cameras. You can view all cameras or selected cameras, and you can simultaneously record all or selected cameras.  The video is recorded directly on your hard drive with date and time. The system can be set to record only when there is motion, so you get only the action without the dead space. You can playback any camera you want, pause, reverse, zoom in, or scan the whole day with a slide bar.

The system will retain the video for the last several weeks and even months depending on the amount of motion and the size and number of hard drives.

Remember those pesky VCR tapes? Not any more! When the hard drive gets near full, the system automatically erases the oldest video to make room for the new.  If there are snapshots or video segments you want to save, just copy them onto a CD or other storage media and you have them forever. It’s quick, easy, crisp, and the stored video can be viewed back on any  PC with basic Windows software.

You’ve got to see it! Come on into our showroom and see our live demonstration. You’ll be impressed!

What to Look for in a DVR

PC Based vs Standalone

 There are two main categories of DVRs: PC Based and "Standalone". PC based systems run on a computer using a Windows platform such XP or Vista, and operate like a traditional computer. Standalone systems use an operating system which is embedded on a chip or flash type drive rather than the hard drive, and operate more like a VCR. We have found the PC based DVRs to be much much (repetition intended) more user-friendly, particularly when looking for and saving recorded video. Standalone units were created as a cost saving measure in an attempt to make the DVRs more affordable, but the quality of the saved video usually suffers to, in our opinion, an unacceptable level. We also find that most standalone units have cut corners in order to cut price, but most consumers do not know enough to know the difference, so they buy the cheapest and end up with a boat load of frustration. Many standalones do not even have an acceptable way of backing up video that you want to keep. We have yet to find a standalone system that performs even close to the recommended PC based systems at a similar cost, but we're still looking. Until then, we'll stick with the PC based systems.
 

Number of Channels

 DVRs can be purchased to handle a certain number of cameras (channels). They come in 4 channel, 8 channel, and 16 channel. Some are now emerging with more than 16 channels, but you are usually better to get 2 DVRs rather than get one with more than 16 channels. The whole system is working very hard to handle 16 channels and something is going to be sacrificed when that is increased - perhaps the CPU or the hard drive?

Frame Rate

 The frame rate is the number of snapshots or images that are recorded each second. Frame rates range from 30 fps (frames per second) to 480 fps or more. A basic 4 channel DVR may have a frame rate of 30 fps, which means that it can record a TOTAL of 30 frames per second. This gets divided among the 4 cameras so that if all 4 cameras are recording, each camera is recording at 7.5 fps. This makes the playback a little choppy, but is usually considered acceptable in most applications. A higher frame rate will make the playback smoother. A 16 channel DVR with 30 fps would miss a lot of action and would likely be unacceptable. 120 fps or 240 fps would be more appropriate for 16 channels. Beware - when DVR makers spec their frame rates, they are at the lowest resolution, usually 360x240 which gives a very poor image. Once the resolution is bumped up, the frame rate declines sharply - so don't be fooled by the specs.
 

Recording Time

 DVRs record onto hard drives, which eventually will fill up. Since you don't want to keep swapping hard drives, the systems are set up so that when the hard drive is nearly full, the oldest data is erased to make room for the new data. This way, you always have the most recent video available at any given time. How much video? There are many factors which determine this:
Size of hard drive(s): Obviously, the larger the hard drive, the more video that can be stored. Most systems allow for more than one hard drive.
Frame Rate: (see above) A higher frame rate will take more hard drive space because there are more files being generated.
Image Quality: DVRs have setting controls which allow you to set the quality of the stored video images. A higher setting will produce the best quality images, but the file sizes will be larger - hence the hard drive will fill up faster. A lower setting will produce poorer quality images, but you will have more history on the DVR at any given time.
Recording Mode: Each camera can be set to record constantly or only when there is motion detected. Most people choose the motion detection mode because when they watch playback, they watch only when there is action, skipping the dead space. In this case, the amount of history available at any given time depends on the amount of activity there has been.
Compression Method: DRVs utilize video compression to store images. This allows for more data to be stored on a smaller area of the hard drive. There are various methods such as MPEG, MPEG4, MJPEG, H.263, and several others. Each compresses the video in a different way, and can effect the length of recording time.

Remote Viewing

 Most DVRs have the capability of being connected to a LAN (Local Area Network) such as a business internal network or a home network for viewing from any PC on the network, and can also be viewed from anywhere in the world by connecting the DVR to the Internet. These programs are password protected so that only authorized people can view your video. This allows you to tap into your DVR from virtually anywhere and watch what is going on, or what went on. In most cases, you will want to have a high speed internet connection to the DVR with a static IP, and you will want to view it remotely from a high speed connection. Otherwise, the frame rate is very slow on dial-up connections. Remember, if you are viewing video across a network, video uses a lot of bandwidth, so you can slow your network down substantially while viewing video from another computer.

Beware

 Some DVRs are now on the market which record on a hard drive, but you use an analogue monitor for viewing. Some require that you hook up a VCR to backup any needed video. This way, they can make it sound like you have a state-of-the-art "DVR", but in reality, the net effect to you is no better than the old way. We call these "fake" DVRs. Don't be hookwinked into thinking all DVRs are created equal. As with anything else, there are differences - some obvious, some hidden. You need to know what questions to ask, or you may be dooped.
 

Prices

 In Canada, prices for real DVRs can range from approx. 2,000.00 for a basic 4 channel unit up to 10,000.00 or more for a fast 16 channel unit with lots of bells and whistles. There is a correlation between price and quality, so if the price sounds too good to be true, it probably is and there will likely be a reason. The fake DVRs can run closer to 1,000.00

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