The Basics of Video Capture Hardware
Video capture hardware refers to the physical device used for converting an analog or digital DVI, VGA, or video signal into a digital format that is readable by a computer. Typically, video capture hardware consists of a frame grabber that “converts” the video input and sends it over the USB, Ethernet, or PCI Express bus. This article will cover all three types of these devices and weigh their benefits and disadvantages.
USB video grabbers are small external devices that plug into the USB port on the capture computer. Generally speaking, they work with Windows, Mac, and Linux machines and accept VGA and DVI inputs. The advantage to using a USB-based frame grabber is that they are compact, easily transportable, and easy to switch between different computers, and work with desktop as well as laptop machines.
Ethernet frame grabbers, similar to their USB counterparts, are also external yet generally larger in size. They use the common RJ45 port for connection and, since the introduction of Gigabit Ethernet, are able to capture video at much higher frame rates than USB grabbers. Furthermore, Ethernet frame grabbers can be installed in a remote location on the network and accessed remotely or through the Internet, which makes them ideal for lecture recording or conference broadcasting applications. Ethernet frame grabbers can also be accessed locally, through a direct crossover RJ45 network connection.
PCI Express-based grabbers are internal devices that occupy the PCIe slot on desktop machines. Unlike the VGA grabber types outlined above, they are not transportable and do not function remotely. Generally speaking, there is no reason to choose a PCIe-based device over an external frame grabber. However, PCI-Express based grabbers are often used in custom applications where they are integrated into a PC.
Network based video capture devices such as the VGA2Ethernet provide extremely high capture rates, are able to acquire VGA and DVI video streams, and can also capture audio. They are also compatible with virtually any computer and can be remotely accessed if needed. No other type of frame grabber provides such an expansive feature set. For this reason, if you are choosing video capture hardware, a network-based solution would be most appropriate.