A capture card or digitizer card is a device that using certain interfaces (HDMI, USB, S-Video, etc.) to save it to a PC using various compression algorithms (usually MPEG 1/2/4, H.264, or H.265). Modern capture cards often support more than one standard. In this article, we will tell you how do capture cards work, and answer the question do you need a capture card to stream.
What does a capture card do? With this device, you can not only convert analog video to digital but also vice versa.
If you want to connect a camera to a PC that does not have HDMI inputs (not to be confused with HDMI outputs) to convert an analog signal to digital (or vice versa), you should use a capture card. It will serve as an interface between these devices. The capture card must be connected to both the computer and the camera to realize the digitization of the image. The result is saved on the computer.
How to use a capture card?
According to the method of connection to the computer, capture cards can be divided into internal and external ones. Internal cards are inserted directly into one of the PCI Express slots (or PCI for legacy devices) of the computer’s motherboard while external cards are connected via supported external connectors (USB, Thunderbolt, etc.). Some external capture cards do not require any connection to the computer at all. Their operating principle is the same; the difference lies in the conditions of use.
How to set up a capture card
Due to the PCI Express bus, internal capture cards are faster than external ones, but they can only be used in conjunction with a PC. On the other hand, external capture cards allow to connect to a wider list of devices, but their performance can be insufficient to work with high-resolution video (especially important for cards that do not support modern high-speed USB 3.0+ or Thunderbolt interfaces).
Also, capture cards can support hardware encoding of the video stream in real-time. These models are more expensive because they can digitize video data quickly enough without using the resources of the CPU.
Video capture cards without hardware encoding support digitize video without compression. They are often equipped with a TV receiver. This type of card is much cheaper than the first and performs transcoding using the resources of the CPU.
How to choose a capture card?
First, you need to determine the requirements for the device. If portability is required, it is worth choosing an external card. In this case, you should take into account that the data transfer rate may be insufficient if you use an obsolete USB 2.0 connector for its connection.
If the size of the received files is important, then the best choice would be a capture card that supports hardware encoding. It is also efficient when working with portable devices because they often have processors that do not run as efficiently as their desktop counterparts. If you are going to process video later or are using a powerful PC, you can do it with an uncompressed card.
It is very essential for videoconferencing that the signal from the camera is transmitted without delays for real-time digitizing. That is why it is preferable to use professional hardware capture cards capable of high quality digitizing including Full HD video stream for such purposes.
After we’ve figured out what a capture card is for, let’s look at some example cards.
AVerMedia EZMaker USB SDK C039P
AVerMedia EZMaker USB SDK is the most budget-friendly capture device in our selection. S-Video and composite inputs are supported as interfaces. The feature of this device is support for AVerMedia EZMaker USB SDK API.
AVerMedia Live Gamer 4K GC573
This solution is positioned primarily for streaming. The device is a board that is mounted in a free PCI-E slot of the motherboard. To protect the electronic components, the board is covered with a removable metal cover with ventilation holes. It supports 4K resolution, HDR processing, H.264 and H.265 encoding, and up to 240 fps in FullHD mode.
AVerMedia ExtremeCap UVC BU110
AVerMedia ExtremeCap UVC BU110 is an external USB 3.0 HDMI converter that allows you to send video to Android mobile devices or laptops for capturing and streaming video. It supports USB 3.0 connection and [email protected] video.
AVerMedia EzRecorder 530 CR530
The AVerMedia EzRecorder 530 CR530 is an external video capture device that supports hardware H.264 compression and FullHD recording. It doesn’t require a PC connection, thanks to the built-in 2.5″ HDD/SSD slot and USB 2.0 connector on the side of the device for connecting external drives. The optimal device for telemedicine applications that can work without a computer connection and is easy to install and use.