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Video Capture Dongles Buyers' Guide

tagsSwitcher Matrix

Any event captured by the camera can be easily streamed in real time. There are countless technical options, from encoders mounted on the camera (or even inside the camera) to dedicated stand-alone devices. One of the most popular production settings is a laptop running a video mixer, such as


, Or

By connecting the capture dongle to the camera, the dongle is inexpensive and can access titles, transition effects, and special effects, thereby adding a professional touch. 

You already have a laptop and software. Now you need a dongle. The price of the dongle ranges from around US$40 to over US$700. This buyer's guide will help guide your buying decision. Please note that the listed products are only representative products and not exhaustive; if your company's products should be used with the listed products, please add the product as a note to the online version of this article. 

The first thing to consider is whether the machine is connected to a camera/output device and a laptop. Of course, from the source, you need to input to match your camera, which usually means SDI or HDMI. If you want to broadcast from another device (such as a computer), it is best to use a dongle that supports VGA or DVI input, although it is best to get the signal through the network device interface (NDI) or similar protocols like vMix and Wirecast. Both support. 

There are two main connectors on the computer side, USB and Thunderbolt. So let's start a quick review of USB and Thunderbolt connections and connectors. For ease of understanding, please understand that most current capture dongles try to transfer uncompressed video to a computer. In the case of 1080p 30fps, the bit rate is about 1.5Gbps, which is twice the 60p that gamers want to capture. 4K video is 4 times that of the two, so 4K30p is about 6Gbps, and 4K60p is about 12Gbps. 

When using USB, remember that this standard was created to connect and power peripheral devices such as keyboards, mice, printers, scanners, etc. in 

 (From Wikipedia) You will see speeds and connectors from USB 1.0 to USB4. The maximum speed is 480Mbps, and USB 2.0 obviously cannot transmit uncompressed video, which is why all USB 2.0 capture dongles use H.264 compression to transmit video to laptops. Even at a speed of 5Gbps, USB 3.0 can only transmit one uncompressed 1080p60 stream, although it may be able to handle two uncompressed 1080p 30 streams. 

When considering both USB and Thunderbolt, please understand that this connector is different from the standard and related performance. Therefore, if you see the Type C connector at the bottom of the picture, it may be connected to USB 2.0, 3.0, 3.1, 3.2, or USB 4, although USB 2.0 is unlikely. How do you know which USB standard your computer supports? Check "Device Manager" on Windows and "System Information" on Mac. 

Also, keep in mind that connecting to a faster port will not increase the speed of the USB device. Although you can connect a USB 2.0 capture device to the USB 3.0 connector, the transfer speed is still USB 2.0. In addition, although multiple dongles can be connected to different USB ports on the laptop, if the devices are on the same USB bus, the bus can still be swamped. Therefore, before purchasing multiple dongles, please check to make sure that the notebook computer has two USB buses accessible. 

Please understand that even if your notebook computer has two separate USB 3.0 buses, it may not have enough RAM or CPU to mix incoming feeds. In this case, please consider connecting the camera to an inexpensive switcher, such as

And run the output feed to the capture dongle. You can switch cameras on the switcher, preserving bus bandwidth and CPU cycles, and you can still add titles, panels, and other content to the selected feed through the hybrid software. 

In the case of designing USB to connect to peripheral devices, Thunderbolt is designed to some extent to replace the Mac MiniDisplay port with a device that can be used as both a display controller and a high-speed bus interface. Technically speaking, Thunderbolt combines PCI Express and DisplayPort standards into a single connection, so its connection speed is much faster than USB. 

As you can see 

, Thunderbolt 1 debuted at a speed of 10Gbps, and Thunderbolt 2 doubled by merging two channels into one connection. Thunderbolt 3 can transmit 40Gbps, but this may be limited by cable length and type (see CNET's excellent article, "USB Type-C and Thunderbolt 3: One port, connect all ports to limit cable connections", Located at

Connection speed

10 Gbit/sec

20 Gbit /. (2 channels)

40 Gbit/s when using 0.5 m cable


Mini DisplayPort

Type C connector

Support other signals

Show off

Display and USB 3.0

Like USB, the standard is different from the connector. Thunderbolt 1 and 2 use MiniDisplay Port connectors, while Thunderbolt 3 uses the same Type C connector as USB 2.0+. Even more confusing is that every Thunderbolt 3 port also supports USB 3 or 3.1, although this is not the case. Not all USB 3.0 Type-C connectors support Thunderbolt. You will see this in Figure 3, which shows the four Thunderbolt 3 ports on the new MacBook Pro, which provide charging, display, Thunderbolt connections, and USB 3.1 Gen 2 connections. 

Although Thunderbolt is faster, USB 3.0 enjoys an advantage that Thunderbolt cannot share-the USB Video Class Standard (UVC), which simplifies installation and hardware configuration on Windows, Mac, and Linux computers. If your USB capture dongle is UVC compatible, and most advanced products are compatible, you can start the dongle and make it run without installing any drivers, and you can run in various programs without configuring the hardware. Therefore, if you want to use the capture dongle and camera as a webcam, Skype will know how to configure the software. If you want to broadcast live in vMix or Wirecast, the same as above. In contrast, when using a Thunderbolt capture device, you must install a device-specific driver, and in some cases, it is difficult to get the driver up and running. 

Now that we have covered the connection between the camera and the computer, let us determine some features to consider when evaluating options. Then we look back at the Thunderbolt and USB 3.0 capture dongles to be considered. 

If you use the dongle for mission-critical applications, please check the support options. Most low-cost manufacturers don’t provide phone support, and while knowledge bases and forums are useful, it’s much better to have knowledgeable technicians where you can talk on the phone, and live chat comes next. For example, Ephipan provides telephone and live chat support, as well as email support and community forums, from 8:30-5:00 EST Monday through Friday. 

When discussing hardware functions, consider whether the signal loop-through function can be used for monitoring or local display. Some devices also provide additional audio input to supplement the camera input and/or headphone jack, which are valuable features for some products. You should also verify that the device is powered by the connector cable to ensure that you do not need to carry another power adapter with you to participate in the event. 

Obviously, if you are buying a USB 3.0 capture product, you should check UVC compatibility. That is, some producers may need to manually control the input resolution, aspect ratio or color space or similar parameter functions. Therefore, some vendors provide software utilities that can perform these adjustments and facilitate firmware updates and other maintenance operations. If you are an adjuster, please check the availability of the program. 

If you know which software video mixer you plan to use, please check its support forum for information on compatibility and reliability before purchasing any hardware dongle. Reviews on Amazon and B&H often contain comments on these issues, and these comments are also valuable. 

USB dongles range from thumbnail-sized plastic devices to solid metal housings the size of a deck of cards. If you use this device for a single non-portable application, plastic may be good. If you want to throw your equipment into your toolkit and participate in multiple events, the solid metal housing may bring benefits in the short term. Devices connected through embedded connectors can save cables, but these connections may be fragile and may break if they are stressed during activities. 

In this regard, when checking the reviews of B&H and Amazon, please pay attention to the comments about the stability of the operation and the temperature rise during normal operation. Excessive heat can cause product failure and make the equipment difficult to use during the event and immediately upon packaging. 

With this as a background, let us identify some candidates, starting with Thunderbolt. One of the lowest cost Thunderbolt 3 products is

Supports SDI and analog video input with SDI and HDMI output (BHPhotovideo is $495, with a rating of 4.5 with 10 reviews). Blackmagic's UltraStudio 4K Mini ($995 on Amazon, a five-star single) supports up to 4K SDI and HDMI input and output through Thunderbolt 3 and USB 3.1 connectors. 

If you are looking for a multi-input Thunderbolt device, check out AJA’s IO 4K Plus, which has 4 SDI inputs and 1 HDMI input with SDI and HDMI output for monitoring (BHPhotovideo costs $2,295 with 2 Five-star reviews). Another option for Thunderbolt is to connect the Thunderbolt expansion case to the notebook computer via the THunderbolt 3 connector. These expansion chassis support one or more PCI Express cards, which are generally cheaper than multi-input external Thunderbolt capture devices. 

Although there are many manufacturers of USB-based capture dongles, the two most familiar are Epiphan and Magewell. Both offer Full HD and 4K products with HDMI, SDI and DVI inputs. You can see the function table of Epiphan's series

And information about Magewell's USB Capture Plus series

. Both produce high-quality products for professional streaming applications; you should choose the best product for you using the conditions specified above. 

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