F.A.Q.:::DIGITAL VIDEO RECORDING BASICS
   

1.

What is DVR?

2.

Do I still need a VCR if I purchase a DVR?

3.

Does learning how to operate a DVR require knowledge of PC's?

4.

How many days of recording can I expect the DVR to store?

5.

What happens in the event of a power outage?

6.

Can I view the DVR from somewhere other than the physical DVR location?

7.

How do I view the camera images from my PC, laptop or PDA?

8.

Can I use my existing cameras?

9.

How do I control a camera with Pan/Tilt and Zoom functions?
 

1.

What is DVR?

 

Previous method for recording CC-TV on tape with tape-recording equipment is an analog type. Therefore, it is very inconvenient to change the tapes frequently and it lowers the quality of image. However, a Digital Video Recorder or DVR, digitally records the video image so it provides clear image like a picture. It also has a function to record continuously so you don't have to worry about the frequent change of tapes. DVR, therefore, is a video recording surveillance system for the next generation and it is growing very rapidly. In addition to that, it has communication function which enables you to detect remoteness screen even from household and it contains a multi branch of up-to-date function.
2. Do I still need a VCR if I purchase a DVR?
  There is no need for the video cassette recorder unless you wish to store video on cassette for your own reasons. You can record on the VCR as well the DVR at the same time.
3. Does learning how to operate a DVR require knowledge of PC's?
  While knowledge of using a mouse and keyboard is helpful it is not required. Anyone can learn to operate and program any of the DVRs functions, as the systems were designed with the non-PC friendly person in mind.
4. How many days of recording can I expect the DVR to store?
  This is probably the single most difficult question with the most confusing of answers and where one needs to be very analytical and read the fine print. The answer is, there is no individual answer. So we need to break down the answer into components.

. Hard drive space
. Video compression method (MPEG, MJPEG, wavelet, h.263, etc.)
. Video compression rate
. Number of frames per second being recorded on each camera
. Resolution of frames being recorded (320 x 240, 640 x 480, etc.)
. Is video being recorded full time or only on motion detection?
. How many cameras are being recorded

A DVR stores the video images on hard drives. Storage capacity is dependent upon the amount of hard drive space. Hard drives come in a variety of sizes. A DVR may have from a single to multiple hard drives built-in. The DVR can be attached to external PC-like devices called RAID (Redundant Array Inexpensive Disks), which can virtually supply an unlimited number of hard drives.

The file size of the video images, vary radically from one video compression method to another. To further confuse the issue there are different flavors of the same video compression methods, and as such the different flavors produce different file sizes.

Video compression rates can be adjusted within most DVR programs. The more you compress the video the poorer the quality of the video, but the faster the transmission speed since the packet is smaller. Video can be compressed as many as 300 times.

If you require real motion video on a camera you are recording 30 images per second. If you do not need to record in real motion you obviously can save hard drive space proportionately by reducing the number of images per second being recorded.

Images are made up of little dots (pixels). The pixels in an image make up what is known as the resolution. The more pixels in an image (the higher the resolution); the higher the quality of the image and the larger the size of the file to be stored.

If video is being recorded only when motion is detected (if that feature is available on a DVR) then you reduce the amount of storage requirements.

If you are recording on multiple cameras then you increase proportionately the amount of data being stored up to the maximum capacity of the video capture board. If the video board capacity is 120 frames per second then it can never exceed that amount.

In a corporate or retail environment that is not high security and does not require the highest of video image quality and utilizes motion detection, using a 60 image per second video capture board, where they operate 8 - 12 hours a day, a 40GB hard drive should provide 3 - 4 weeks of storage. Remember, certain things can skew these numbers significantly, such as blinking lights or something that causes the video to continually record that may not be obvious to the eye.

The other extreme is recording using MJPEG, real motion, high resolution recording, on a 240 frame per second video capture board, which can chew up as much as 30GB - 40GB per hour.
Most claims for video storage capacity are usually accompanied by a statement in parentheses that states "under normal conditions." Good luck defining what are normal conditions!

 
5. What happens in the event of a power outage?
  To protect the DVR you want to use a power backup, which serves as a surge protection device and a power source for a limited period of time in the event of a power failure. If the power failure continues for an extended period of time, the DVR will intelligently shut itself down. When the power returns it will return to its mode immediately prior to the interruption of power.
6. Can I view the DVR from somewhere other than the physical DVR location?
  Yes. With the majority of DVR’s you can connect via a Internet connection, Local or Wide-Area-Network.
7. How do I view the camera images from my PC, laptop or PDA?
  TOPS DVR come with remote client software that has to be installed on your computer. The remote software allows you to view the cameras once you are connected to the DVR via a phone line modem, Internet connection, or Local or Wide-Area-Network connection.    
  You may access DVR through web browser as well if you have Internet connection
8. Can I use my existing cameras?
  Yes. Your existing cameras will work and simply plug into the back of the DVR which replaces the VCR. If your cameras are not so current you may want to investigate some of the newer cameras which are higher in resolution and may have more features. Typically, higher resolution cameras mean higher quality images.
8. How do I control a camera with Pan/Tilt and Zoom functions?
  TOPS DVRs have some sort of control on the monitor that operates like a joystick and by clicking the mouse over the appropriate function the camera responds.
You can fully control DVRs if you use a TOPS joystick or TOPS certified joystick.
   
 
 

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