The hardware configuration of the Epiphan DVI2PCIe card deserves a closer look. Its design is unusual for a mass product since it features a field programmable gate array (FPGA).
We can remind you that early video capture devices that used to work with analog signal were based on analog-to-digital converters, which was enough to ensure acceptable quality at SD resolutions. But now that digital video capture is the No.1 priority, such solutions are a poor choice, especially at HD resolutions. As a matter of fact, there are entry-level digital capture devices available on the market. They first convert video signal into analog format, then use the old methods to capture it, but the result is hardly acceptable. That’s why Epiphan and other manufacturers who position their products as top-end professional solutions employ all-digital conversion that guarantees there’s no quality loss or distortions.
The Epiphan DVI2PCIe is based on an FPGA chip Xilinx Spartan-6 XC6SLX45 which is programmed every time the driver is initialized. Thus, the driver is no less important than the card itself. By today’s standards, the Spartan-6 is a rather simple FPGA, yet it is quite capable of doing all necessary transformation of digital signal and of transmitting the last captured frame into the computer’s system memory via DMA. All connectivity is based on separate specialized chips: the Gennum GN4124 is responsible for PCI Express whereas the Silicon Image Vastlane Sil7181, for receiving input signal from the digital DVI interface. Additionally the card carries 128 megabytes of DDR3 SDRAM which serves for buffering the data stream from the FPGA.
The last component of the DVI2PCIe card we want to note is the Intersil ISL98001 chip, which is the single analog component in this circuit. It supports the analog input interfaces and performs analog-to-digital conversion if the input signal is not digital but comes from VGA or some other analog source.
The DVI2PCIe features a set of diagnostic LEDs placed in such a way that they are visible even inside a computer case. The card uses them to inform the user about its status: if it is ready to capture video or is already doing it.
By the way, the DVI2PCIe doesn’t dissipate much heat, so all of its components do without any heatsinks, even though the chips may get a little hot at work.
The design of the card may not seem too complex, but Epiphan's knowhow is in the driver and specialized software. It is the software components that configure the operating algorithms of the FPGA, Therefore such top-end digital video capture products can only be developed by companies who have a strong team of programmers.