DVR Card Technology

Digital Video Recording (DVR) is the latest in video recording technology. DVR uses computerized data storage to archive video information in a standardized compressed digital format that can be replayed in a variety of devices including other computers, as well as DVD players and more.

DVR Cards, also known as digital video capture cards, are PCI devices added to a computer to enable the capture of video information. There are a wide variety of capture cards on the market today, however, most are designed for one of two specific applications; digital video surveillance, and home entertainment. While our Professional DVR Cards can be adapted for use in home entertainment (recording video from cable, tv, or satellite), their intended purpose is to be used as a remote video surveillance device.

DVR Card Classification

DVR cards are generally classified by 3 distinct characteristics; frame rate, number of ports or channels, and compression type.

Frame Rate is the number of frames per second the card is capable of viewing and/or recording. Some cards will be rated at a different frame rate for viewing and recording. The frame rate a card is rated for is the maximum amount of frames per second the card is capable of in the given mode. That maximum number is distributed evenly among the number of ports or cameras the card has connected to it.

For example, if a DVR card is rated as 120 Frames / 4 Ports would be able to operate at 30 Frames per Second, per camera. Another example would be a 480 Frame / 32 Port DVR card, would operate at 15 Frames per Second, per camera (with all cameras enabled/in use).

Each DVR capture card differs based on the way it processes video information for storage.

Some DVR cards use a compression method called Software Compression, which means that the video data is deflated by the computer's CPU using a set of instructions provided by the DVR card software. This process can be slow and demanding on the computer's system resources as the information has to travel farther inside the system, and be handled by more parts of the computer before it is sent to the hard disk drive for storage.

Other digital video capture cards utilize a compression method referred to as Hardware Compression. Hardware compression utilizes special components on the DVR card itself to compress the video information, and stores it directly onto the hard disk drive from the card. This compression method is faster, and less demanding on the rest of the computer since all the work is done by the DVR card.

In either case, the set of instructions by which the video information is compressed/stored can vary. This set of instructions is a standardized method of compression/decompression known as a CODEC (COmpressor/DECompressor). Our DVS™ DVR Cards utilize an MPEG-4 video compression codec.
With older generation capture cards, hardware compression often provided superior results than software compression, in terms of video quality and speed. Over the last couple of years, however, advancements in hardware and software design have leveled the playing field between hardware and software compression. Now the type of digital video capture card is more a matter of personal preference than a complicated decision when it comes to compression type.