Choosing a 3G-SDI to HDMI converter

The short answer

A 3G-SDI to HDMI converter takes the video and embedded audio from a camera's SDI output and turns it into an HDMI signal. That HDMI signal can then feed a USB capture device, a monitor or a switcher, so the camera can work as a webcam for calls, streaming or recording. When choosing one, check five things: the converter accepts the exact format your camera sends, it supports the 3G-SDI mapping your camera uses, it handles the audio channels you need, it has the outputs you need, and it can be powered reliably where you will use it.

Here is how this relates to microphones. A converter does not contain a microphone and does not change how a microphone captures sound. It only matters for audio when a microphone is plugged into the camera, because that sound travels inside the SDI signal. A separate USB or interface-connected microphone plugged straight into the computer never passes through the converter.

First, confirm you need SDI to HDMI

Most consumer DSLR and mirrorless cameras output HDMI only. SDI outputs are mainly found on cinema, camcorder and broadcast cameras. If your camera has only an HDMI port, this converter is not the right part. You can connect HDMI directly to an HDMI capture device. You would only need an HDMI to SDI converter if you want to run a long cable before converting back.

Also consider whether you need a converter at all. Some capture devices accept SDI directly. If you are buying both a capture device and a converter, an SDI-input capture device can remove one box, one power supply and one connection from the chain.

What to check before buying

• Direction: Products sold as SDI to HDMI, HDMI to SDI and bidirectional look similar. Confirm the input is SDI and the output is HDMI.
• SDI rates supported: 3G-SDI covers formats up to 1080p at 50, 59.94 and 60 frames per second. Most 3G converters also accept HD-SDI and SD-SDI, but check the specification sheet. A 3G converter will not accept 4K over a single 6G or 12G link.
• Level A and Level B: 3G-SDI 1080p50/60 can be sent as Level A or Level B. Some converters accept only Level A. If your camera lets you choose, note which one it uses and confirm the converter supports it.
• Frame formats: Check that your camera's output format and frame rate appear on the converter's supported list. Pay particular attention to interlaced formats and 1080PsF, which some downstream HDMI devices handle poorly.
• Pass-through or scaling: Many converters pass the format through unchanged. Your HDMI capture device or monitor must then accept that format. Converters with a built-in scaler or frame-rate conversion cost more, but they can fix mismatches.
• SDI loop-through: A second SDI output lets you send the same feed to a recorder or monitor while the HDMI output goes to the computer.
• Power: Converters may run from USB power, a DC adapter or both. A locking or secure power connection lowers the risk of an accidental disconnect during a live session.
• Cabling: Use 75-ohm BNC coaxial cable rated for 3G-SDI. Usable cable length depends on cable quality and the converter's equalizer, so check the manufacturer's stated figure.

Audio handling: where microphone choices come in

HD and 3G-SDI can carry many channels of embedded audio. HDMI capture devices and the apps that use them often read only the first stereo pair. If your microphone is connected to the camera, check which SDI channels the converter passes to HDMI. Some converters let you choose which channel pair to output. Others always send a fixed pair.

• If the microphone is plugged into the camera: Its audio stays in sync with the video through the converter. Confirm the converter embeds the right channels in the HDMI output and that your capture device passes them to the computer.
• If you want to use the camera's audio separately: Look for analog or digital audio de-embedding outputs. These let you send the SDI audio to a mixer or audio interface.
• If the microphone connects directly to the computer: The converter has no effect on its audio. Any delay between picture and sound has to be corrected in your streaming or recording software, usually with an audio delay or sync offset setting.
• If the HDMI output feeds a monitor with speakers: You are only hearing playback. This tells you the audio is present in the signal. It tells you nothing about the microphone's capture quality.

Latency and reliability

Pass-through converters usually add little delay. Units that scale or convert frame rates may add more. Manufacturers do not always publish latency figures. If lip sync matters, test the full chain of camera, converter, capture device and software with your own setup. Don't assume one figure applies to every combination.

Gaps in this guide

No verified evidence on specific converter models was available for this guide. That means no prices, availability, specifications, latency measurements or independent test results. The checklist above is based on general SDI and HDMI principles, not on tested products. Before buying, confirm supported formats, Level B support, audio channel handling and power requirements on the manufacturer's current specification sheet. Treat the manufacturer's stated figures as claims, not as independently tested performance.