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Choosing a Capture Card for Multicamera Live Production

To choose the best capture card for mixing live events with PC-based software, you should pursue multi-part analysis. In this article, I'll get you up to speed on what features to look for, but you're going to have to carry the load on the critical subjective items.

Warranty and Support

Warranties for most products in this class range from 1–3 years; while three years sounds much better, the reality of hardware components is that most failures occur early, and otherwise the products tend to live forever. More important than warranty period is the availability of technical support, which you’ll likely need during the install process, and then later should a failure occur. Not all vendors offer U.S. local phone support, which is a big negative in my view.

Try to ascertain if the company will hot-swap for defective products under warranty, and send you a replacement product without first receiving your unit, which will accelerate your receiving the replacement by 2–5 days. Most will, but some require a credit card for the service.

As mentioned earlier in this article, be sure to check user forums and similar venues to see how quickly the company responds to user issues and feature requests. A vibrant forum and user community speaks well for the vendors and the viability of their products. The diversity of video capture programs, host computers, and use cases ensures that problems will always appear; it’s not the problem that’s significant but how quickly the vendor moves to resolve it. Finally, no matter where you actually buy the products you’re considering, check reviews on B&H and Amazon before pulling the trigger.

With this, let’s move to issues to consider for external and internal products.

External Products

If you’re fortunate enough to have both USB 3.0 and Thunderbolt ports available, USB 3.0 should suffice for up to two HD streams, particularly if you throttle the input down to 720p before inputting that into your video mixing software. Most solutions are single input, though Magewell has an interesting product called the XI200XUSB that supports two HDMI, VGA, or component inputs. If you need more than two inputs from a single port, however, Thunderbolt is a better solution.

If you’re buying a capture product for a USB 3.0 port, note that there are two classes of products: UVC (for USB video class) products that install on Windows, Mac, and Linux computers without a driver; and products that require a driver. Essentially, the tradeoff is simplicity versus configurability. The first class works well if you’re capturing standard signals like HD-SDI or HDMI, but if you’re capturing non-standard signals like VGA input from a notebook, or a feed from a document camera, you may need the configurability offered by a driver-based product to customize the feed. In essence, this is the difference between Epiphan’s (Figure 5, below), a UVC device that costs $349; and the DVI2USB 3.0, which includes drivers and costs $699.

Figure 5. The Epipan, a simple-to-use UVC USB dongle with DVI, HDMI, or DVI input

As capture devices go, USB seems to be the most finicky connection, so perform extra due diligence on user forums and Amazon and B&H before buying any USB product.

Internal Products

There are a number of considerations unique to internal cards which I’ll run through quickly.

First, make sure any card that you consider can fit into your computer, which is a particular issue if you’re buying a small case for portability. Some small cases require half-height cards; if you’re working with one, you should know that AJA has a line of cards on their developer program which comes in full and half-height models.

Beyond height, keep in mind that your computer will have multiple PCI Express slots which can be 1-, 4-, 8-, and 16-lane slots. Capture cards are built for these different slots, with single input cards usually having one lane, with higher-density cards now requiring up to eight lanes, with 16-lane capture cards coming. As you would expect, single-lane cards can fit in any slot, but 8-lane cards can only fit into 8- or 16-lane slots. If you’re buying a high-density capture card, make sure you have an open slot to insert it into.

Finally, if you don’t take great pleasure from crawling behind your computer to connect and disconnect audio and video cables, consider choosing a capture card with a breakout box, like all KONA capture cards from AJA. The knees on your jeans, and the back of your head—two frequent casualties of connecting cables behind computers on your floor—will definitely thank you.

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Don't think of Thunderbolt as an external connector like USB; think of it as another PCI Express expansion slot that you can access without opening your computer. You can choose external Thunderbolt capture devices, or you can purchase an external Thunderbolt expansion chassis and install internal PCIe cards in the chassis.
This article explains what features to look for when choosing a capture card to incorporate into your live switching and streaming workflow.