Capture · Record · Stream · Encode · Decode| Feature | HDMI | SDI (3G) | SDI (12G) |
|---|---|---|---|
| Max Resolution | 4K at 60 fps (HDMI 2.0) | 1080p at 60 fps | 4K at 60 fps |
| Cable Length | About 10 m passive; longer with active cables | 100 m or more | Shorter than 3G; tens of metres |
| Connector | Push-fit, no lock | BNC, locking | BNC, locking |
| Typical Use | Mirrorless and DSLR cameras, PTZ cameras, laptops | Broadcast and studio cameras | 4K broadcast cameras |
| Audio | Up to 8 channels embedded | Up to 16 channels embedded | Up to 16 channels embedded |
| Connection | Source and display negotiate (EDID) | One-way signal, no negotiation | One-way signal, no negotiation |
When to choose HDMI capture
Choose HDMI if your sources are consumer or prosumer devices: DSLR and mirrorless cameras, PTZ cameras, camcorders, games consoles and laptops. HDMI is on almost everything, the cables are inexpensive, and it works well for runs of up to about 10 metres. For Zoom, Teams, OBS, vMix or lecture capture with sources like these, HDMI is usually the right choice.
When to choose SDI capture
Choose SDI if you work with broadcast cameras: studio, news and outside broadcast cameras. SDI uses locking BNC connectors, so a cable cannot be knocked out during a live programme. It also runs much further on ordinary coaxial cable. As an example, the Pro Capture SDI card equalises cable of up to 150 metres at 3G-SDI and 190 metres at HD-SDI. SDI is the standard in broadcast infrastructure. If your camera has a BNC output labelled SDI, you need SDI capture.
Magewell capture cards — by signal type
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Choose SDI when your cameras or production equipment already output SDI, when cable runs are longer than about 10 metres, when you are working with existing SDI infrastructure, or when you need locking BNC connectors that cannot be pulled out by accident. HDMI is the better choice for laptops, consumer and prosumer cameras, and short cable runs.
Yes. The simplest way is to fit or connect one device per source: several Magewell capture cards work side by side in one computer, so an HDMI card and an SDI card can run together. The Pro Capture AIO accepts both SDI and HDMI on one PCIe card (HDMI through its supplied breakout cable), which suits a system that has to accept either type, but it captures one input at a time. The Ultra Encode AIO, a standalone encoder, takes HDMI and SDI together and can encode either one or combine both as picture-in-picture or side-by-side.
Yes. SDI carries embedded audio alongside the video, up to 16 channels in the SDI signal. Magewell SDI capture devices accept up to 8 of those embedded channels, and the USB Capture SDI Gen 2 and SDI 4K Plus deliver two of them to your software. In most cases that means no separate audio cable. If your SDI source carries no audio, some models add an analogue input: the USB Capture SDI 4K Plus has a 3.5 mm line input, and the Pro Capture AIO takes analogue stereo through its breakout cable.
It depends on the model. Magewell SDI capture devices cover SD-SDI (ST 259), HD-SDI (ST 292) and 3G-SDI (ST 425), and some add 6G-SDI and 12G-SDI. The Pro Capture SDI and USB Capture SDI Gen 2 go up to 3G-SDI, which is 1080p at 60 fps. The USB Capture SDI 4K Plus adds 6G-SDI for 4K at up to 30 fps. The USB Capture SDI 4K Pro and Pro Capture SDI 4K Plus have 12G-SDI inputs. Check the specification of the model you are considering.