Digital Video Recorder - DVR FAQ

Updated July 11, 2007
Welcome to my DVR FAQ page.  Here I will go through some of the commonly asked questions I get from enquiring customers in email and on the phone.

Q-What is a PC based DVR ?
A-A PC-based DVR is a DVR built around a computer .  You have a case either a tower or a rack mount.  Inside you have your usual mother board, LAN board, video board CPU Hard Drive and memory.  To this we add a CD-writer to burn and archive any prerecorded video.  And inside is a DVR board.  This board receives the video from the cameras and working in conjunction with the DVR software provides all the necessary, video functions like, Video compression, converting the video to a file, camera controls and display, record and playback functions.  

Q-What is a Stand-alone DVR?
A-A Stand Alone DVR is an all in one unit,  it consist of a cabinet (like a VCR) and inside all components, boards, power supplies, CPU and all DVR related components are manufactured  on one board.  On the one main board there are IC Chips which contain the operating and DVR software.

Q-What is the difference between a PC based DVR and a Stand-alone DVR?
A-Because Stand Alone DVRs are built completely on just one circuit board.  They are very reliable and very easy to use.  Their software is simple reliable and easy to use.  Basically there are no conflicts and all hardware and software are matched exactly in this (all on one board) embedded style system.  PC-Based DVR's give you more advanced features, and they are upgradeable and expandable.  They have more crunching power  by way of their bigger CPUs and memory.  You can easily add Hard Drives, DVD burners, CD-Burners and advanced internet and telephone access options.  If advanced viewing, playback and video file saving over the internet is important to you, consider a PC-Based DVR.  PC-Based DVRs are typically used in Banks, Malls, Airports and large department stores. We have Systems with 16, 32, 64 and 128 camera inputs.  

Q-What is a network DVR
A-A network DVR is a DVR that has a standard Ethernet connector on the back.  These DVR's can plug right into you computer network.  They can also plug right into a ADSL or cable modem.  If you have a computer and you want to run both your DVR and your computer off your ADSL line you will need a Router or Hub some high speed modems come with built in routers so you might have multiple ports on the back of your modem for multiple devices.

Q-How do DVR's work with motion sensing and cameras?
A-DVR's detect motion by looking at the video pixels (little light and dark dots that make up the video picture).  as the pixels change the DVR sees motion.  DVR's have a "Mask" or over lay for each camera, the screen is divide up into many small boxes called cells.  Each cell can be individually turned on or off to enable or disable motion detection in that cell.  This allows a camera not to see normally moving objects Like  tress or fans.  Each camera also has a sensitivity level setting this controls the amount of change in motion before the systems triggers.  All motion sensing is done in the DVR.  the camera has nothing to do with motion sensing it just provides the video to the DVR because of this, most any camera will work with our DVR's.

Q-What are some of the major features and differences between DVR's?
A-Check out our Compare DVR's chart to help give you a better idea what features are available at what price. 

Q-How long can the DVR record video for?
A-All DVR's record to a Hard Disc.  Each frame of video has a specific size (from 0.5Kb to 5KB for PC-Based DVRs and from 10kb to 15Kb for Stand Alone DVRs are typical) one second of video can be made from one digital picture (1fps) to 30 digital pictures (30fps) The video we see on TV,s is 30fps so how long you can record for depends on how your settings are set on the DVR.  Typically in security applications we look for 4fps to see things like people working down hallways in and out offices or rooms.  We use 7.5fps for better streaming video.  This might be for watching peoples hand movements, cash draws or faster moving objects like capturing cars license plates.  15fps per camera is for "Like live video recording"  almost perfect video streaming .  And at the top of streaming video list is 30fps which is live streaming video, like a TV Program.  Customers who demand the absolute best chose these DVRs We sell many of these DVRs to Police stations, the Military, Government Building, institutions and Casinos.

Here is an example of how long you can record Example: recording at 4fps on a system with an image size of 12kb would be 12kb*4=48k per second. if you have four cameras 
then 48k *4=192k per second.  One hour would use this much space 192k *60(miniute)*60(hour) =
691200k (per hour) or .69 GB so if you have a 80 GB hard disk 80/.69 =115.94 hours = 4.8 days 

New check out our DVR time Calqlator.

Here are some last minute notes: Image size varies depending on DVR typically (from 0.5Kb to 5KB for PC-Based DVRs and from 10kb to 15Kb for Stand Alone DVRs are typical)
DVR's record in different file formats jpeg, mpeg-4 and AVI each has its particular characteristics (quality varies with file size and video formats)

Q-Can I review recorded video and keep recording at the same time so I don't lose any recording time.? 
A-It depends on the   this feature is called Duplex, you can review reordered video (what happened yesterday) and continue recording the live events. None duplex machines will have to stop recording to go back and view previously recorder video these machines are called simplex.  
our Protech DVR series are Duplex and Triplex which means you can keep recording while playing back Pre-recorded video and also keep recording while reviewing or playing back video over the internet.

Q-What is the guarantee on the DVR?
A-7 day money back, and one year parts and labor repair or exchange at no charge.  Here is the full warranty

Q-Can I switch from a split screen view (4,8,9, or 16 cameras per screen) to a single camera view and keep recording all the time.
A- Yes

Q-What kind of phone line do I need to view my cameras over the internet while I am using a DVR?
A- It is best to have a high speed internet connection (ADSL, DSL, SDSL, ISDN, T1 or Cable modem) with a static IP address.  A static IP address is a specific electronic identification number that identifies your specific machine when you sign on the internet you are assigned a new IP address each time (dynamic IP address) this makes it cumbersome to know what your IP address is and you would have to look it up each time you got on the net to connect to your cameras.  With a static IP address, you can just program that number in once and that is it.  Then just push a button and your on the net.

Q-How can I save or Archive recorded video I want to keep?
A-For most Stand-Alone DVRs The easiest way to save video is on a VCR.  The VCR can be wired through the output of the DVR and then to the monitor.  You just find the video you want on your DVR hit play and then record on your VCR.  Now available some Stand-Alone DVRs come with built in CDROM Burners.

PC-Based DVR's have CD-Burners  this saves your video as an AVI file on a CD Disc.  Most PC-Based DVR's can be upgraded to DVD Burners but, this is expensive and the DVD disc are also expensive.  

Q-Can I record audio on my DVR?
A-This depends on the model dvr, check the specs of the dvr you are purchasing or ask one of our friendly customer service reps.

Q-Tell me about the hard drive , how long will they last, how difficult are they to change?
A-No telling exactly they haven't been doing this job for all that long and we don't have enough history to really say.  They haven't given us any trouble in the last year and these are the same Hard Drives we have used for years in computers.  The good news is, these are standard Hard Drive that you can buy in Best Buy , Circuit City, or Comp USA. some DVR's have removable trays in the front, these drives pop out and can be changed in about 3 minutes. 
There is only two plugs to hook up and you cant mix them up.  Stand-Alone  DVR's automatically format the drives and are ready to go in about 30 seconds.  With PC-Based DVRs it is just a matter of installing a new hard drive just like in your computer.

Q-Can I add more hard drives and a DVD burner?
A- Yes if you have a PC-based DVR

Q-If I have a 9 channel when I review the recorded video can I see all  9 channels at once as well as,  just select a single channel to view in the full screen mode.?
A- Yes

Q-What are the different performance characteristics of a DVR.  What do I look for to compare the specifications?
A-Number of channels typically between 4 and 32.  Number of fps typically between 30and 480 this is the total performance for the box and you would divide that number by the number of channels to get the maximum fps per channel.  Is it a Network DVR? this means does it have the ability to put your cameras up on the internet.  Does it record audio?, what hard drive size does it have?  does it have motion sensor capability?  does it have a built in CD-Rom burner?  These are just some of the major considerations.  check a more detailed list at our Compare DVRs chart.  

Q-How many cameras can I record at the same time with a DVR?
A- This all depends on how many channel DVR you have, they come in 1,4,8,9,12,16,32,64,128 
most 1,4,8,9,16 stand-alone DVR's are on this page.  Most 4,8,12,16 PC Based DVR's are on this page and our Industrial DVR's are on this page 

Q-What connections do I need on the DVR (BNC OR RCA or F Type)?
A-Our DVR's have female BNC connectors on the back.  You need a male BNC to hook up to that type of connector.  Typically most times you will be using a Male BNC to Female RCA type of connector this is the type of connector that is used in our systems and hooks directly to our all in one cable.

Q-How difficult is it to get these DVR's hook up to the internet?
A-When you buy a network DVR they come with an Ethernet connection on the back.  just run a Cat-5 cable to your DSL modem and set your IP address, you may also need to program your router and firewall if you have them to allow the link to your DVR.  These are relatively easy adjustments if you have this type of experience.  We have technicians on staff to help and guide you though this process if you need it.  Keep in mind your network DVR will be easiest to use if you have a Static IP address.  However, even if you only have a standard dynamic IP you may get your DVR on line.

Q-Can I view the video from the DVR with my TV or do I need a monitor?
A- Stand-Alone DVR's have a standard video output.  You can use any TV to view the signal.  Security monitors typically have a better picture unless your using a high quality TV or Plasma TV. You can also wire the video output into your home TV distribution system or combine it with cable so you can see your cameras on all of your TVs.  Some DVR's have a jack of the back so you can plug in a computer monitor (VGA Output), These give a really good picture. PC-Based DVRs have two outputs VGA for the Multiplexed output and they have a slandered TV video output which displays "Switched Camera outputs" 

Q-Why are the new DVR's better then the old Time Lapse video recorders?
A- DVR's are digital, like Digital cameras, digital camcorders, DVD's and digital TVs, like Plasma TVs.  This type of format is much better then analog recording like VCR.s, cassette players, Time Laps Recorders, and yes the old 8 track tapes.  analog devises need more information to reconstruct a good image.  They have a tendency to smear be dull and cloudy.  A digital image is clear easier to store, is easily compatible to your computer and the internet.  DVR's have the advantage of being able to have a perfect picture if even that is only one picture, just like a digital camera picture.  It doesn't matter if you are recording at 30fps or 1fps they are all digital images   When you are recording at 30fps you are just collecting more digital information.  This is useful for viewing counting money or other fast events (like how your money going into other people pockets).  DVR's also have the advantage in that you do not have to change tapes, tapes don't get old and stretch and You don't have to remember to put a tape in.  They are just more reliable their more secure and some models also allow you to view your cameras over the internet.  Some DVR's also give you the ability to just record motion.  This way your not taking dozens of tapes home for hours upon hours of viewing.  No more looking at hours of tape when your business was closed.  No more worrying about, did you miss something in the hyper fast mode while you were reviewing the tapes.  If you have a network DVR you can even review your video from home on the internet or in Spain when your away and want to see what they stole from you over the last week.

Businesses are are beginning to see many new benefits to DVR's one of the latest is POS (Point of sale).  This technology lets businesses integrate their cash registrars with their video.
When a customer makes a purchases not only is the customer video recorded but the transactions that were rung up by the cashier are over laid on that video clip.  This type of system insures all items are being rung up by the casher and prevents "Special Treatment"  and sales between cashier and customer.  

All this information is recorded by the DVR and is available for live viewing, and is recorded for later review.  Because this information is recorded on a network   a business owner or loss prevention person can review this information over the internet or can review previously reordered information over the internet. 

Many small satellite and franchise businesses, can be easily managed from their corporate office.
And many small business, can reduce their loss and increase their profits by managing what was sold, to whom for how much.  I bet a lot of you wish you had this system in place last year!