Posts Tagged ‘ h.264 ’

Camera Surveillance System Features

Monday, September 27th, 2010

If you are looking for a digital video security and surveillance system, you should be aware of the more common camera security system features. Recent advances in digital video camera technology, digital video processing technology, and digital video storage capacities have provided an abundance of useful features and options.

Today’s camera security system features allow the user to have a complete standalone system, a system that can work using a personal computer to replace some of the components of the system (usually resulting in a less expensive system), or a system that can be remotely viewed and controlled via the internet. In addition, most contemporary security camera systems are component systems; that is, the individual parts of the system can be mixed and matched without regard to type or manufacturer with relative ease so the user can create a custom designed system to suit their needs.

Today a typical digital video camera security system features one to several cameras, a processor/Digital Video Recorder or DVR, and a monitor. Let’s examine the camera security system features by looking at the two main components; digital video cameras and processor/DVRs.

Digital Video Cameras
These cameras have a variety of options or features including:
• Specifically made for indoor or outdoor use
• Wireless technology, eliminating the need for a video transmission cable
• Powered by rechargeable batteries (this feature combined with wireless transmission technology makes these cameras truly wireless)
• Light Sensitive Day/Night vision that can produce high quality video images in very low light conditions
• Night vision infrared that can produce high quality black and white video images in total darkness
• Audio recording
• Pan-Tilt-Zoom (PTZ) functions-combined with software or circuit programming these cameras can “track” or “follow” objects
• Motion activated-these cameras do not begin capturing images until a motion detector senses movement
• IP (Internet Protocol) Ready-these cameras have their own built in server and can be networked using the internet
• Hidden or Disguised Covert Cameras-these cameras are so small they can be easily hidden in other objects or the cameras are built already embedded or disguised within other objects

The processor/DVR handles several tasks and is the “brain” of the system. The processor handles the digital video signals sent by the cameras and uses a COmpression/DECompression or CODEC utility to make the digital video files easier to handle. It may also handle other functions like motion detection or PTZ controls. Finally, the DVR is equivalent to a personal computer’s hard disk drive. It stores the digital video files for archiving or later use.

One of the main features of this unit is the number of channels or cameras it can handle at once. Most units offer 4, 8, or 16 channel capability.

Camera security system features for the processors used today offer a variety of different CODEC utilities. There are many other choices for CODEC utilities includingH.264, MPG1 H.26 to MPG4, MOV, and DIV to name a few.

The DVR’s main feature is its storage capacity. Currently DVRs can be purchased that have storage capacities ranging from Gigabytes to Terabytes. As computer hard drive technology increases, storage capacity seems to increase and price usually decreases.

The processor/DVR unit is much like the case of a desktop computer. In addition to the features already mentioned these units may have additional bays or slots to add additional PCI cards or hardware. Common optional features of this type include CD/DVD writers or Flash Card writers that can copy the digital video files from the DVR to more portable media. This is useful for providing the video to police, insurance agencies, etc. or simply for archiving.

Another camera security system feature for the processor/DVR is a computer PCI card that works as a processor/DVR or utilizes a typical personal computer as the processor/DVR. This feature is great for residences because it normally reduces the cost of the system considerably.

As you can see, there are many different camera security system features existing today. This should give you a good working knowledge of the most common features that are available for your use and that will allow you to design your own custom component system.


Security DVR Compression Methods

Friday, March 19th, 2010

Security camera methods used to capture, transmit, and store data have greatly improved in a relatively short period of time. In order to discuss the security camera compression methods used with digital video recorders (DVRs), we need to have an understanding about how and what compression is and what methods are used to store security data.

Security cameras basically take digital pictures just like a standard digital camera. Although cameras vary by construction, the concept is basically the same for each type. A sensor takes a “picture” and instead of using film, creates a binary or digital file of the picture and transmits it to the storage media. A “still” picture is basically one picture or frame while motion-video is the same as a still picture, but there are several pictures taken in rapid succession, generally up to 30 pictures per second. The higher the quality (the more “fluid”) of motion video, the greater the frame rate up to 30 frames per second (FPS).

The problem with digital video is the incredibly large size of the files. A good quality “snapshot” may take up to 500 Kilobytes (KB) to 1 Megabyte (MB) of file space. Therefore, a motion video at a frame rate of 30 FPS could take up to 30 MB for just one second of monitoring.

Up until just a few years ago, the digital file was usually stored on digital tape media, such as a standard VHS tape. Some units used continuous loop tapes that just recorded over previous material after a period of time. Other units may have used standard VHS tapes and automatically rewound the tape to re-record over again, or owners may have had to insert a new tape each time the current tape reached the end.

Technological advances in the computer industry, especially those pertaining to storage technology and file compression have had tremendous benefits for the security camera industry. Now, the most common unit for storing is the DVR. Instead of saving image files to video or digital tape, images are stored as computer files on a hard disk drive, similar to the ones found in personal computers.

Computer (and likewise DVR) hard drives have various storage capacities. Less than 10 years ago, 250 GB hard drives were extremely expensive and rare. Based on a 30 FPS uncompressed video using 1 MG per frame, the hard drive would have a capacity of approximately 8333 seconds or 2 1/3 hours. This type of storage and technology made DVR storage prohibitive for security camera use.

However there was an exception. If the file size of the frame could be reduced in size, then more frames could be stored per unit of storage space on a hard disk. Reducing the size of the digital file is called compression, and is usually accomplished by some sort of mathematical computation called an algorithm. Typical compression file formats for still pictures include JPEG, GIF, and PNG. Each has a special set of mathematical instructions that determine how the file can be compressed in size. Typical compression file formats for digital video include JPEG2000, MPEG, and the newer H.264. Video compression formats are called CODECs for COmpression/DECompression which refers to the process the file goes through to be stored and when retrieved to be viewed. Unfortunately, hard drive storage capacity and file compression formats did not develop overnight or at a synchronous rate.

By current standards it is not unusual for personal computers to have 750 GB hard drives or larger and H.264 compression technology wasn’t really used in the security camera industry until about 2007-2008. The following list should give you an idea of the capabilities of the three popular compression formats used most often in surveillance cameras.

Using a DVR with a hard drive capacity of 250 GBs, at a frame rate of 30 fps with a screen resolution or size of 720 x 480 the following compression rates yield:

• JPEG2000 can record for approximately 20 hours
• MPEG4 can record for approximately 68 hours
• H.264 can record for approximately 120 hours

These formats are available in most DVRs today with the H.264 being the newest and the yielding the highest performance.

There is one other item that needs to be mentioned concerning DVR compression methods. A DVR not only stores the digital video files but it generally has a central processing unit or CPU, like a personal computer, which processes the CODEC to create the file. High frame rates and high compression rates places a heavy load on the processor, and can actually inhibit performance if the processor’s speed is not fast enough. To compensate for this, separate processing boards may be purchased that are added to the DVR to alleviate the load on the CPU to ultimately provide high performance surveillance video.