Understanding a DVR

What are the major components of a DVR?  This is a diagram of a typical security DVR where you will see the major components starting with the CPU, the compression chip, video encoder and decoder and various sub systems.

DVR standards

The market demand for the best,  fastest and highest quality products push us to continuously develop new and better products.  From the old analog tape based video recorders, the industry standard is now digital video recorders, storing compressed TV quality videos (CIF) at 30 frames per second.  Compression standards have likewise improved over the years, starting with Motion JPEG, then MPEG-4 and now H.264 (also known as MPEG-4 part 10).    Positioning one's product above this standard, at the lowest possible price, is the sweet spot for most manufacturers.  Some products sell just on low price alone and totally forget about quality and performance, while some offer the best performance and quality at prohibitive prices.  What is the sweet spot in positioning?  What is the minimum standard?  What is the best price? 

In my opinion, a decent DVR should have the following features:

• Real-time recording (30 frames per second - Note: Movies run at 24 frames per second) on all cameras for at least CIF size
• MPEG-4 compression
• Recording capability of up to D1 size (better known as DVD quality)
• Network capability (This includes video streaming thru LAN or the internet, remote setup and remote viewing)
• At least triplex operation (Simultaneous operation for recording, search and playback and live view)

Some ultra cheap designs are available in the market but are lacking in some basic features, which goes to show that there is no such thing as "free lunch :)".  What are the possible downside to missing out some of the basic features?

• Missing out important frames due to frame rate limitations.  Imagine split second action that results to damaged property, missing goods or worse, lost lives.  You don't want your video evidence to leave whodunit questions unanswered.

• Why compression?  Yes, storage is cheap, but it shouldn't be a reason why you should waste money on extra storage.   Uncompressed video takes a huge amount of storage space, regardless of whether you're storing it on a hard drive, DVD or digital tape. To imagine how much space is required, consider that a typical uncompressed still frame of video, at the quality most of us are used to viewing, requires just under one megabyte to store. Video typically plays at 30 frames per second. This means that your typical uncompressed video might occupy 27 megabytes per second to store. Do a little more math, and you'll soon discover that the new 80 gigabyte hard drive that came with your computer will only store about 50 minutes of raw, uncompressed video. Do one more calculation and you'll see that a DVD disc (at 4.5GB) can hold less than three minutes. Clearly, we need some form of digital compression to reduce that file size.  The second issue is so closely related to the first that it's really the same problem viewed from another angle. Imagine you have an uncompressed VHS-quality video file sitting on a hard drive, ready to play. In order to provide smooth playback, your hard drive would have to dump data to your computer at a sustained 27 megabytes per second (or, as an engineer would think: 216 megabits per second [27 x 8 bits/byte]). Storage systems are available that can hit these speeds, but they're very expensive. Now consider that you want to deliver that same video to the masses, via the Internet. Whatever technology you use, the speed of that technology (bandwidth) would have to match that 27 megabytes per second, without fail.  
• D1 capability is needed if you want that extra resolution to positively identify objects or people which otherwise would have been unrecognizable.  It's better to have a snapshot of a recognizable face rather than a barely recognizable blob, especially at a distance.

• Network capability?  Remote monitoring and remote setup capabilities add a factor of more than 100 to the useability and convenience of using a DVR.  Imagine, visiting each and every DVR, especially for multi-site installations.  
• Multiplex operation?  This is the most overlooked feature in DVRs.  You don't want recording to stop, just because somebody is viewing via the network or somebody is adding a user to the DVR.

Building a DVR

How do we build a DVR from scratch?   Here is a mini-guided tour to our R&D facility.  

The process starts with a list of needed specifications or features.  From these requirements, two teams will collaborate in the design and production of the DVR, namely hardware and software.  

Depending on the requirement, hardware will design the motherboard only or including the case.  A block diagram is the first order of business to based on all the spec requirement.  Following the block diagram would be a schematic diagram (see left illustration).  The whole process takes around ten (10) working days or less to complete.

     Sample schematic diagram

After the schematics, the printed circuit board (PCB) will be designed based on the schematic diagram.  The process takes around 2 days to complete.    For the casing, the mechanical team will produce the mock up prior to producing the engineering sample.

PCB board design

Mechanical

After each and every stage, a quality control staff checks and monitors the process and output as per established company standards.  Next process is PCB production.

The finished PCBs will be tested and a few samples will undergo surface mount device (SMD) assembly.

 

After assembly completion, the finished board is tested for defects.  The few samples produced will be used for the prototype and subsequent engineering samples for further testing.  

Part of the finished engineering samples will then be turned over to software for testing and driver and application development.

After completing the driver and applications, the finished product will undergo extensive product testing prior to the release of the commercial version. This will include useability testing, aging test, feature and function testing.

Some of our sample products are shown below:

Video Management System

Video Management System 

How to Design Video Surveillance Solutions 

Video management systems are the hub of video surveillance solutions, accepting video from cameras, storing the video and managing distribution of video to viewers. 

There are 4 fundamental options in video management systems. Most organizations choose 1 of the 4. However, as companies may have multiple types when they transition between one and another. 

DVRs are purpose built computers that combine software, hardware and video storage all in one. By definition, they only accept analog camera feeds. Almost all DVRs today support remote viewing over the Internet. DVRs are very simple to install but they significantly limit your flexibility in expansion and hardware changes. DVRs are still today the most common option amongst professional buyers. However, DVRs have definitely fallen out of favor and the trend is to move to one of the 3 categories below. 

HDVRs or hybrid DVRs are DVRs that support IP cameras. They have all the functionality of a DVR listed above plus they add support for IP and megapixel cameras. Most DVRs can be software upgraded to become HDVRs. Such upgrades are certainly a significant trend and is 

attractive because of the low migration cost (supports analog and IP cameras directly). Learn more about the value and issues in selecting HDVRs. 

NVRs are like DVRs in all ways except for camera support. Whereas a DVR only supports analog cameras, an NVR only supports IP cameras. To support analog cameras with an NVR, an encoder must be used. 

IP Video Surveillance Software is a software application, like Word or Excel. Unlike DVRs or NVRs, IP Video Surveillance Software does not come with any hardware or storage. The user must load and set up the PC/Server for the software. This provides much greater freedom 

and potentially lower cost than using DVR/NVR appliances. However, it comes with significant more complexity and time to set up and optimize the system. IP Video Surveillance Software is the hottest trend in video management systems currently and is the most frequent choice for very large camera counts (hundreds or more). 

From IPvideomarket.info

Our first venture

What could be a more duller topic than a CCTV surveillance system?  It's a product that you buy to secure your home, office or any other property.  You buy one, install it and use it.   At first, you spend hours watching it.  Later on you learn that it is probably a good activity to do if you want to beat insomnia.  After a few days, when excitement wanes off, you start to forget about it.  This stuff is pure boring, the average security guard assigned to watch over surveillance systems probably falls asleep more often in front of the live view screen and would not probably pass any lucidity test if one is given especially in the wee hours of the morning. A camera, a video recorder, a monitor is what comprises your average surveillance system and yes, we chose to enter into this very boring business.  

We are not into cameras or monitors, we are into DVRs. Ask the average Joe about a DVR and he would probably say Tivo.  Yes, Tivo was once exciting stuff, you can record your favorite shows, suspend it, resume it, go back to any part of the show, view past shows at the press of a button.  Again, we are not into this exciting stuff, but yes, we can do what a regular Tivo can do plus more!  We do not record TV or cable shows, what we do is watch over what matters most to you, your loved ones, your business, your wealth and your property.  The shows we record are shows of your life or your company's life.  

Security Digital Video Recorders or DVRs, replaced tape based recorders that keep watch over protected areas, but unlike tape recorders, DVRs are more versatile and generally possess some intelligence.  But again, these devices are condemned to be largely unknown by their very nature.  They watch over people, they are usually hidden and would be better if kept secret.

Rewind to the year 2004, developing a DVR seems simple enough! You have established brands out there in the market.  You have an exponentially growing market (due to heightened security awareness, the growth of the internet and falling CCTV prices) and you have the technology and the brainpower, or at least one thought you had it.  Let's aim for number one was the clarion call for the development team.  "Yes we can" was the motto, and so started our journey.  A quixotic charge into the windmills or sure-footed optimism, this is our story.