Using Dual-Link DVI to Capture 144fps Sources


DVI, a video display interface developed by the DDWG (Digital Display Working Group), is used for high-speed transmission of digital signals to display devices. The DVI interface standard includes three variants: DVI-A for analog signals, DVI-D for digital signals, and DVI-I for both. DVI-D and DVI-I themselves each support two modes: Single-Link or Dual-Link. Physically, a different number of interface pins are used (18 pins for single-link and 24 pins for dual-link), and the transmission bandwidth of dual-link DVI is twice that of single-link DVI.

Classification Chart of DVI

Based on TMDS technology, DVI can encode 8 data bits (for each primary color signal in R, G, B) into 10 bits (2 bits for control data and 8 bits for video data). The maximum pixel transmission rate of a single TMDS channel is 165MHz, so the maximum transmission bandwidth of single-link DVI (with three TMDS channels) is 165MHz×3×10bit=4.95Gbps, which can transmit 1080p60 signals, but is not enough for 4K signals. However, dual-link DVI provides a maximum pixel transmission rate up to 330MHz for a maximum transmission bandwidth of 9.9Gbps, which is twice that of single-link DVI. It can easily transmit 4Kp30 signals, or achieve a frame rate of 144fps at 1920x1080 resolution.

This is critical in some specific industries. For example, in the security industry, the output signal of security inspection machines may be 120fps or higher, and such machines usually have a DVI output interface. In other applications, users not only need to display sources but also may need to compress and stream video images to a central control room. Typical hardware encoders neither support this high frame rate nor have an appropriate interface, so such users must use capture cards and computers in their solution. Magewell's Pro Capture DVI 4K is ideal for these use cases. This product is equipped with a PCIe 2.0 x4 host connection, supporting both single-link and dual-link DVI. It provides compatibility with the special signals output by devices like these security inspection machines, and can capture these signals into the host computer at 1920x1080 144fps.