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You are here: RootDVRsGeneral  General  No sub-categories FAQs in current category: Are there differences among DVR software? Are there differences among DVR software?  Print Absolutely. Just as important as the hardware is the software that operates the hardware. The software that runs the principal functions of the DVR is driven by a database. The architecture and design of the database are crucial for system stability and speed of which it processes the data. Quite often poor database structure will slow down even the best hardware and in many cases, cause system crashes. Are there really differences between cameras and lenses? Are there really differences between cameras and lenses?  Print There are significant differences and choices among cameras and lenses. Camera and lens selection is dependent upon your requirements. Indoor or outdoor, day or night, area to be viewed, environmental conditions, etc. Cameras can cost from hundred to thousands of dollars and lenses can cost from $20 to several hundred. You can think of CCTV cameras in the same terms of traditional cameras where similarly camera body and lenses can cost from a few dollars to thousands. BACK TO TOP Can I use my existing cameras? Can I use my existing cameras?  Print The simple answer is 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. Can I view and record, real time/real-motion video on each and every camera? Can I view and record, real time/real-motion video on each and every camera?  Print The short answer is remotely it is highly unlikely, because the bandwidth is usually not large enough to accommodate real-motion video on a real-time basis. To view and record locally is possible on very few DVR systems, and depends upon several factors, such as the video capture board architecture and the DVR components. Real-motion viewing and recording for a 4 cameras system only requires 120fps viewing and 120fps recording. For a 16 camera system you would require 480fps viewing and 480fps recording. The problem comes in on storage of real-time/real motion video as it consumes a massive amount of hard drive space, which makes it expensive and impractical in many cases. BACK TO TOP Do I need any special power requirements for the DVR? Do I need any special power requirements for the DVR?  Print DVR’s are low power consumption devices. Remember, they are in essence a PC. It is recommended that you attach a battery back up to the DVR to protect the hardware against power spikes, reductions or outages. Do I still need my VCR if I purchase a DVR? Do I still need my VCR if I purchase a DVR?  Print 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 as the DVR at the same time. How come DVR manufacturer say their product records 30 frames per second (fps) yet it almost looks like still frames? How come DVR manufacturer say their product records 30 frames per second (fps) yet it almost looks like still frames?  Print The vast majority of DVR manufacturers describe a system in terms of "shared frame rate" which is somewhat misleading. What that means is a 30fps system is 30 frames per second over the entire number of cameras being displayed. Therefore, a 16 camera system sharing 30 frames may yield less than 2 images per second. How come when I view a DVR remotely over the Internet the pictures don't have the same quality or speed as when I view it at the DVR location? How come when I view a DVR remotely over the Internet the pictures don't have the same quality or speed as when I view it at the DVR location?  Print The answer is bandwidth. When you are viewing the DVR locally you are transmitting right from the DVR to your monitor without having to send the images over a network and worry about throughput. Throughput is the amount of data transferred from one place to another in a specified amount of time. The lower the throughput, the slower the transmission. How come when I view only a single camera on a 30fps DVR it still does not look like real-time/real motion? How come when I view only a single camera on a 30fps DVR it still does not look like real-time/real motion?  Print What the manufacturers often fail to tell you is that a 30fps video capture board is the "maximum" frame rate that the video will display. The maximum frame rate is what can be achieved prior to the introduction of other important criteria such as hardware and software processing and video compression and network connection speeds; either of which attributes to the degradation of the capture rate. A 30 fps capture board may lose as much as 20% of its capacity through software compression. How come when I view some websites on the Internet with video they seem to have no robotic motions and clear crisp pictures? How come when I view some websites on the Internet with video they seem to have no robotic motions and clear crisp pictures?  Print Because the video is “streamed” meaning it is aggregated and then delivered on a delayed basis. Again, there is a difference between real time and real motion. How many days of recording can I expect the DVR to store? How many days of recording can I expect the DVR to store?  Print 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! How many frames does it take to give a real motion look? How many frames does it take to give a real motion look?  Print Industry standards typically speak of 30 images per second as real motion video. Think of frames per second in terms of how a cartoon is made with cells or even think of the projector in a movie theater where multiple frames pass in front of the lamp to give the appearance of "real motion." What are real-time images? What are real-time images?  Print Real time images are those images that are being transmitted as they happen, not to be confused with real motion. Unfortunately, the words real time and real motion are used synonymously within the industry. Just because something is real-time does not mean it is real motion. What does a DVR look like? What does a DVR look like?  Print There are principally two different profiles to DVR's. One looks like and acts like a VCR with the same mechanical buttons and On-Screen menus and the other resembling a PC which operates with a keyboard and mouse. For the most part DVR's are the size of VCR's and PC's although with different configurations they can be designed significantly larger or smaller. What is a DVR? What is a DVR?  Print A (DVR) Digital Video Recorder is in simplistic form, a PC which acts like a VCR in that it has the ability to record and playback video images. The DVR takes the feed from a camera and records it into a digital format on a storage device which is most commonly the hard drive. BACK TO TOP What is meant by frame rate? What is meant by frame rate?  Print The frame rate is number of images that are being displayed or recorded over a specific period of time. Typically frames per second or "fps" is the specification most often used. Remember frame rate record and frame rate display are two different items. Just because it displays in real-time doesn't necessarily mean its capable of recording in real-time. What is real motion? What is real motion?  Print Real motion is video that when viewed looks natural and has no herky-jerky motions of any kind whatsoever. Don't be confused by real motion vs. near real motion or real time. Will a 60fps, 120fps or 240fps video capture board run faster on a single camera than a 30fps video capture board? Will a 60fps, 120fps or 240fps video capture board run faster on a single camera than a 30fps video capture board?  Print The architecture of most video capture boards is such that regardless of the total frame rate of the entire video capture board you typically do not exceed 30fps per individual channel, since there is usually only one "chipset" dedicated to that channel. The purpose of higher frame rate video capture boards is the ability to view playback at higher frame rates over multiple channels. For example on a 240fps video capture board you would view 8 cameras at an average maximum rate of 30fps, whereas on a 30fps capture board the same would be less than 4fps over each of the 8 channels.