Key Information About PCI Express x4 Video Capture Cards

A video capture card connects to an external video source, including video cameras, DVD players, gaming systems, or broadcast television. These also allow you to capture and record video games, live television, and other video signals on your computer. If you are using an analog device, then some cards can also convert an analog signal into a digital signal.

What interface does a video capture card use?

A video capture card may use one or more of the following interfaces:

  • Serial digital interface: SDI, a digital standard, is commonly used in professional settings like television stations and production companies. Professional companies use SDI due to its long range and high bit rates, both of which can vary based on a number of factors. Standard-definition video at a bit rate of 270 megabits per second can be transmitted at a maximum of 980 feet. High-definition bitrates have a maximum length of 330 feet. Both 1080p and 2160p at 60 frames per second are supported.
  • HDMI: HDMI is the standard digital interface for most consumer products, including DVD players, Blu-ray players, and televisions. HDMI can transmit video at a variety of different resolutions and refresh rates. 8K resolution is supported as of HDMI version 2.1.
  • DVI: The DVI standard includes analog only DVI-A, digital-only DVI-D, and digital and analog DVI-D. Although less commonly used in television sets and DVD players, DVI can transmit video at various resolutions up to 3840x2400.
  • Composite: An analog standard that is carried across a single channel.
  • Component: An analog standard that breaks the video up into different components.
  • S-Video: An analog standard for standard-definition video. It has improved image quality over composite, but the color resolution is lower than component.
How does a video capture card connect to a computer?

Video capture cards will fit into an empty expansion slot in your computer and connect to the motherboard through a PCI Express interface, also known as PCIe or PCI-e, much like a graphics card. There are a few different factors that affect the data transfer rate of the interface. One factor is the version of the PCIe standard you are using. There are four versions of PCIe, although only three are commonly available in mainstream personal computers. Each subsequent version of PCI Express has higher data transfer rates than the one before it, and later versions are also backward-compatible with previous versions. The second major factor is the number of data lanes. A PCIe interface can consist of anywhere between one to 32 different lanes, which multiply the data throughput of the data transmitted through the PCI Express interface. If the base rate is 250MB per second, then an x4 interface will have an actual transfer rate of 1GB per second.

Can video capture cards stream video over the internet?

This depends on what capture card you own. If you want to stream video from a gaming system, then the manufacturer should note what consoles or systems their card is compatible with. The Sony PlayStation 4, Microsoft Xbox One, and Nintendo Switch are supported by specific cards.