Posts Tagged ‘ D1’



Frame Rate vs Resolution in Security DVRs – Which is More Important

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Wednesday, May 21st, 2014

When configuring a DVR a very common question is what is the difference between frame rate and resolution and which is more important to have at a higher rate? Of course my answer is it depends… Both are very important but, depending on what you want to use the cameras for is which is more important than the other.

Now to begin you really need to understand what frame rate is. We will take a trip back in time to the 1800’s when cameras were first invented. They only took one picture at a time. The mechanism and film were designed that way. It was a physical limitation for decades. It was tedious and horribly long with the extra processing steps. You had to have fairly dangerous chemicals to actually develop the pictures. To take a picture, people had to stand as perfectly still as possible, because the camera’s shutter speed was so slow and the film need exposure times of ten minutes to an hour depending on the film. As film paper became more sensitive to light it reacted faster, so shutter speeds eventually had to be faster. I remember in the 1980’s the hot thing was Kodak High speed film. What set them apart from everybody else for a few years was Kodak figured out a way to get the film paper extremely sensitive. Coupled with cameras that had extremely fast shutter speeds Kodak figured out to how to take out the blur you may get when objects are moving. The pictures coming out of the Olympics that year were amazing there were no blur and the images extremely crisp. The faster shutter speed means a camera can take more pictures per second. Better film allowed for this by being more responsive to less light. A fact that is not well known by people is that the faster the shutter speed the less light comes in the iris which will create dim images.

Resolution is a separate aspect of the image compared to frame rate. CIF is 320 X 240 pixels. 2CIF is 720 X 240 pixels. 2CIF is a wider image than CIF depending on the need is if you would pick the wider shot or standard CIF. VGA is 640 X 480 pixels. D1 is 720 X 480 pixels. As image processing has improved the pixels have increased. With more pixels the colors become more vibrant and the images more clear. To better understand the clarity parts pixels are a very tiny piece of the puzzle known as your picture. The more pixels you can get the smaller the piece gets to represent that part of the picture. The down side is that this increases the need for better hardware to handle the increased load of imaging, which of course drives the price higher. That said the saying, “you get what you pay for”, could not be truer with DVR systems.

Resolution Comparisons

Now that we understand what both frame rate and resolution really are we can determine which is more important per the application. A few months ago I was helping a customer that had a DVR-EL4120ME. This DVR is capable of all the analog resolutions and the D1 at 7 frame rate but CIF at 30 frames per second. . I will say “John” was using this system to monitor a manufacturing process. The issue he was running into was that he was getting blurry images so he called his tech support GURU Daniel (that’s me). He goes on to describe what he is doing and the images he is getting. I logged into his system to see what he described. His process was happening so fast that he was not really getting an image of what he wanted, so I asked what is more important the resolution or frame rate. John said, “Gee I really don’t know. I thought resolution but with the images I’m getting I need help.” I told him no problem I have the knowledge to get it right. Instead of running the DVR at D1 and 7 frames per second, let’s adjust the system to CIF at 30 frames per second. POOF!!! Just like that the conveyor belt that was carrying some electronic device to be soldered could be seen. It was not about seeing exactly what was being soldered but making sure the robotic arm was hitting the part in time as it passed by. In minutes I was able to take John from not being that satisfied of a customer to being ecstatic about his equipment.

An example of the resolution being more important than frame rate is in monitoring your cash register. In many if not all retail environments keeping a close eye on the money is important. Typically people are not moving at warp speed so they do not look like a blur on camera. Giving way to frames per second while boosting resolution. Being able to make out the print on the one hundred, twenty, ten, five, and one dollar bills is important. People make mistakes on both sides of the register. The clerk gave the wrong change, the customer paid with the wrong bill etc. Now all of a sudden being able to make out the print is a big deal, so you know without a doubt who gave what to who.

Cash register

I can tell you having a customer have a meltdown at the main register is really not good so, as a manager you need a way to quickly defuse the situation before it carries over to other customers. Having your DVR configured to the highest resolution lets you see the 10, the 20, the 50, and 100 dollar bills. You can go back to where the DVR is setup, review the footage and know with confidence what happened or who made the mistake. Also, you can show the customer in real time “who” made the mistake.

Now you know the difference between resolution to frame rate and in which applications makes either feature more important. Should you run into a scenario when you are not able to compromise, IP cameras typically are the way to go. They support the mega pixel resolutions which are considerable higher than analog as well as 30 frame rate per second.

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Security DVR Recording Resolutions

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Friday, March 19th, 2010

You’re in the market for a security surveillance system for your home or your business. What is the one most important component of that system? The Digital Video Recorder, or DVR, is the single most important component. And the most important aspect of choosing a DVR is the recording resolution.

In manufacturing a DVR, the recording resolution is a balancing act between being able to actually see what’s being recorded and having the storage space to store the video. The better the resolution, the better the images look, but the more space it takes to store it, and the beefier the processor it takes to record it. Manufacturers try to offer that ideal balance between being able to actually have usable recorded footage for evidence of an event if needed, being able to process the enormous amounts of data involved while recording it at a usable resolution, and not running out of recording room to store events. How the manufacturers succeed at this is what you need to evaluate when shopping for DVRs. Budget will be a huge consideration here, since the units that juggle these factors in the most optimum way are, of course, the most expensive. Putting together the optimum system which takes into account all your needs, including your budget, and gives you recordings from all DVRs that can actually be used as evidence takes a bit of knowledge and the help of a qualified reputable professional.

When referring to recording resolution the industry usually uses either a variant of CIF, which is 360 x 240 pixel resolution, or D1, which is 720 x 480 pixel resolution. There is a distinction that needs to be addressed here. Each DVR has a recording resolution and a live video resolution. The live video is always going to be clearer, so when you are evaluating DVR units you really need to know how the recorded video will look, since that will be your actionable evidence in the event of a security problem. D1 is currently the highest resolution used for recording, but most standalone DVRs are not able to record in D1 in realtime, which is 30 frames per second (fps) on all the channels at the same time, though some of the new units coming out are starting to improve on that.

The strength and capacity of the processor that is running the DVR will determine how high a resolution can be set for recording. The memory in the unit is also a big factor. Most processors can’t yet record at a realtime resolution, though some of the newer units that are beginning to show up in the marketplace are hitting 4CIF recording in real time on all channels, which is a 704 x 480 pixel resolution. The current average for a DVR is a CIF recording resolution, which is 360 x 240 pixels in real time at 30 fps.

When looking at the specifications, the three things you need to consider together are the recording resolution, the frame rate, and the recording speed. Of the three, the recording resolution carries the most weight in a carefully considered purchasing decision. If there is a security event, you want to be able to clearly identify the face of the person involved, and if the resolution doesn’t allow this, it’s useless. A 640 x 480 recording resolution is the minimum recording resolution which will easily allow this. 720 x 480 has the same quality but in a wider screened aspect ratio to allow viewing on the typical widescreen computer or tv monitor. 1600 x 1200 is ideal for viewing from an actionable standpoint, but the speed, storage and processing needed to maintain this recording resolution make the cost prohibitive for all but the most deep pocket organizations.

When putting together a budget system, the best way to approach it is to choose a better resolution for key points of security, ie near the front door and the cash register, while choosing lesser resolutions for areas which would be more likely to be monitored in realtime but where recording resolution is a bit less critical, and would simply be support footage when combined with the higher resolution footage from the other areas, not an ideal approach, but one which would allow security on a smaller budget.

Whatever your security needs, the help of a qualified and reputable security monitoring specialist will shortcut your efforts enormously. Juggling all the factors involved in the purchase, including the recording resolution needed for actionable evidence, is key to the overall success of your security efforts.

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Basics of Facial Capture and Facial Recognition

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Sunday, January 31st, 2010

It is likely that if you get a security camera system, that you will want to be able to identify an intruder that has been captured on security camera footage. This process is called facial capture. Some people also call it facial recognition although they are really two different processes. Facial capture means to get enough usable details to be able to identify the person of interest by comparing facial features. It doesn’t mean the security cameras will identify the person, only that enough detail has been captured that he can be identified. Facial recognition actually refers to analytic software that can compare and match captured images of a persons face against another in a database. There are many interesting applications for such a process, but that is an entirely separate article.

Getting proper facial capture is an important process to understand because what good are your security cameras if you cannot identify the person of interest in the video? Proper identification requires at least 25% of the video image to be occupied by the face. This means that you really need to use a dedicated camera for this process. Begin the installation by finding an ideal spot to capture the face. Usually an entrance or exit would be ideal, but maybe there is a room entrance to something valuable. Once you have found the perfect spot to capture the face details, decide on the type of camera you will use for this process. It is best to use a good quality day/night security camera with a vari-focal lens rather than an infrared camera. Infrared cameras will be taking video in black and white in low light and this could make identifying the intruder more difficult. Since you will be using a good low light camera, make sure there is at least a little bit of ambient lighting. A night light, motion light or something of the like will be fine. Mount the camera close enough to the capture point so that at least 25% of the video (preferably much more) is the subjects face. Make sure to accommodate for people of different heights. Next, mount a second camera in a corner, or somewhere else in the room to provide you with a good overview. Now you have one cameras that is used to only capture facial details and a second camera that is providing the general overview of what is going on in the room. Make sure that the channel that the facial capture camera is on is set to record at the highest resolution possible. A D1 resolution image will be 4 times larger than a CIF resolution image and therefore will provide you with 4 times more detail. Use the higher resolution setting even if the frame rate has to be reduced. The overview camera can be set at CIF resolution rather than D1.

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The Relationship Between The Camera TVL And The Resolution Of The DVR

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Saturday, August 8th, 2009

Here is a very common question. How many TVL should the camera have to best use the resolution of my DVR? This is one of the most misunderstood relationships in CCTV. The resolution that the DVR records in refers to the SIZE of the image being recorded. So CIF resolution (360×240) and 4CIF resolution (704×480) refer to how large the image actually is. 4CIF is an image that is 4 times larger than CIF.

TVL refers to the Horizontal lines of resolution the camera can display in. This will determine the amount of detail you may see within a certain size image (CIF, 2CIF, 4CIF). When selecting the right camera, keep in mind that the resolution being recorded and the resolution being displayed are usually different. In most cases a DVR will display live video at 4CIF (704×480) or D1 (720×480) resolution, but be recording in a lower resolution like CIF (360×240). Though a live 4CIF display of video will benefit from a 520TVL camera, the recorded image in CIF will not see the difference between a 520TVL camera and a 420TVL camera. So in essence you will only benefit from the live view, not the recorded image.

You will notice that the maximum benefit for a cameras horizontal resolution when recording in 4CIF is actually around 520TVL. Also, notice when recording in CIF resolution a 420TVL camera and a 520TVL camera will look exactly the same in the recorded image if recorded in CIF, but the 520TVL camera will display an enhanced image when recording at 4CIF. This also applies to the live video since it is usually displayed at 4 CIF.

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