Choosing the right VGA frame grabber or DVI frame grabber could be a difficult task considering the fact that many have similar features and specifications. This guide will review everything needed to get one started and will offer advice and comparisons related to the many VGA grabber offerings out there.

PCI or USB?

Most frame grabbers available today are PCI or PCI Express-based internal capture cards. What this means is that, in order to use a PCI-based grabber, one needs a desktop computer with an available PCI slot in order to install and operate that device. This is perfect for those that have a dedicated PC that will be used for the VGA capture, as well as the space to keep that PC. Keep in mind that hauling a PC from place to place can become a rather tedious task if your VGA source is mobile.

USB frame grabbers, on the other hand, are portable and can be used with any computer with an available USB port. Because USB grabbers are as small as a small stack of credit cards, these devices can be easily moved around between different sources and, due to their small size, tend to be easier to integrate into existing systems. Another advantage that the USB grabbers have over the PCI devices is the fact that laptops or other small computers may be used with the USB devices. What's more, the computer that the images are being captured to does not need to be modified. With the correct frame grabber driver, the USB-based devices are simply "plug and play".

There are simply many situations where a PCI grabber cannot be used due to its size restrictions and other implicatations. A PCI card requires installation within a PC, something which may void the warranty of many computer manufacturers, such as Dell or Lenovo. As well, it is very important to note the fact that many computer systems, such as military or industrial devices, do not have the space available to add another dedicated desktop-style computer in order to record the VGA output. VGA2USB, on the other hand, is small, lightweight, connects to any open USB port, and works with virtually every single modern operating system. This makes the VGA2USB external frame grabber a much more appealing choice to bulky, internal, and PCI-based devices.

The following manufacturers produce PCI-based frame grabbers: EMS Imaging, Foresight Imaging, Ncast, PixelSmart, Unigraf.

To date, Epiphan Systems is the sole producer of external USB based frame grabbers.

Specifications

In order to choose the correct device for one's needs, the specifications of both the VGA source and the VGA grabber must be matched. First of all, the type of source must be established (VGA or DVI) and, if the source is a DVI signal, a grabber of DVI signals is required. Then, the resolution and capture rate requirements must be established. The output resolution of the VGA source must be supported by the frame grabber. A frame grabber that has a maximum allowed resolution of 1280 x 1024 will not be able to capture a 1600 x 1200 signal. The desired capture rate (frame rate) must also be considered. Low capture rates (<15fps) are ideal for applications such as recording PowerPoint presentations from a projector, recording from a radar with very little movement, and other applications with very little movement. High capture rates (>40fps) are needed to record output from sources with a lot of movement, such as from ultrasound devices, high definition video, military equipment, etc.

Epiphan Systems' VGA2USB LR and DVI2USB Duo are the frame grabbers with the highest resolution ranges and capture rates. The Ncast DCC 3.1 is the highest resolution and frame rate PCI-based capture card, but still has lower specifications than similar offerings from Epiphan Systems.

Other manufacturers offer rather low resolutions compared to the 2048 x 2048 maximum size that the external VGA2USB can handle. Pixelsmart's frame grabbers have a maximum resolution of 1280 x 1024, while Unigraf's high-end frame grabber as well as Foresight Imaging's devices only support up to 1600 x 1200 resolution. The capture rate for all PCI-based manufacturers is also lower than Epiphan Systems' USB-based devices, which can transport a maximum of 330 megapixels per second.

Conclusion

Even though a larger number of manufacturers produce PCI-based frame grabbers, VGA to USB technology from Epiphan Systems is much more modern, cost-effective, and easier to work with. Epiphan also produces the only line of frame grabbers that are compatible with Windows, Linux, and Mac OS X PCs. What's more, Epiphan's devices are the easiest to integrate into existing systems due to their small size, portability, high specifications, and security.

Overall, a VGA grabber from Epiphan Systems would be the preferred choice for anyone who requires the best overall quality and a product from a reputable manufacturer that has been in the business for years.

Check this resource for the detailed list of specs for many high end VGA and DVI frame grabbers.