How to Choose an SDI Video Switcher for Multiple Cameras

An SDI video switcher takes several camera feeds over coaxial cable and lets you cut, mix or route them to one program output. Choosing the right one is mostly about matching its inputs, formats and outputs to the cameras and destinations you already have. Settle your requirements first, then compare specifications, then narrow the options with a checklist.

Start with the intended use

Describe the job in one sentence before looking at models. For example: live-stream a three-camera panel, record each camera separately for editing, feed a screen in the room, or send the program into a video call. Then answer the questions below. Each answer becomes a line in your requirements.

• How many cameras you need now, and how many you expect to add later.
• Other capture sources to switch, such as a presentation computer, a playback device or a remote caller.
• Which outputs each camera has: SDI, HDMI or both.
• The resolution and frame rate the cameras will run at, and whether they can all be set to the same one.
• The cable distance from each camera to the switching position.
• Where the program signal goes: a streaming platform, a recorder, a video call app, a local display or another system.
• Who operates the switcher: one person at a hardware panel, or an operator using software on a computer.
• Where microphones connect, and whether audio travels embedded in the camera SDI signals.

SDI is usually chosen for its locking BNC connectors and for cable runs longer than HDMI typically handles. The practical maximum length depends on the cable and the SDI data rate, so check the cable and switcher specifications rather than assuming a distance. If every camera sits next to the switcher, an HDMI model may be enough.

Features that matter

SDI standard and resolution

SDI comes in generations defined by data rate. HD-SDI covers 720p and 1080i. 3G-SDI adds 1080p at 50 and 60 frames per second. 6G-SDI and 12G-SDI carry Ultra HD, with 12G-SDI supporting Ultra HD up to 60 frames per second on a single cable. A product described only as an HD SDI video switcher may not accept a 1080p60 camera, so confirm the exact standard supported on every input and output.

Input count and format handling

Many switchers require all inputs to match the program resolution and frame rate. Others include per-input scaling or format conversion that accepts mixed sources. If your cameras cannot all be set identically, or you plan to add a computer, look for input conversion in the specifications. Also check whether the advertised input count includes HDMI inputs, and how many are actually SDI.

Synchronisation

Clean cuts depend on synchronised inputs. Some switchers have a frame synchroniser on each input; others expect cameras locked to a shared reference signal through a genlock input. Check which approach the switcher uses and whether your cameras support genlock. Frame synchronisation can add video latency, which may require an audio delay to keep lips and sound aligned.

Outputs and monitoring

Count every destination that needs a signal at the same time: recorder, encoder, display, confidence monitor and camera return feeds. Check the number of program and auxiliary outputs, whether auxiliary outputs can carry any source, and whether a multiview output shows all inputs plus preview and program on one screen.

Audio

Check whether the switcher reads audio embedded in SDI inputs, how many external analog or digital audio inputs it has, and whether it can embed the program mix into its SDI outputs. Useful mixer functions include per-input level control, audio follow video and adjustable delay. Verify channel counts in the specifications for your setup.

Recording and streaming

Some switchers include a streaming encoder, program recording or isolated recording of each input. If you need these, confirm the recording format, codec, available bitrate settings, supported storage media and which streaming protocols are supported. A published bitrate is a setting, not a quality result, so judge image quality at your own settings. For video calls, some models offer a USB output that a computer treats as a webcam; without it, you need a separate SDI capture device.

Control and tally

Decide whether the operator needs physical buttons, software control or both. Tally lights tell presenters and camera operators which camera is live; switchers deliver tally through contact closures, network protocols or, with some camera systems, over the SDI return feed. Confirm that the tally method works with your specific cameras.

Check compatibility

• Cable: use 75-ohm coaxial cable with BNC connectors rated for the SDI standard you will run, especially for 12G-SDI.
• Camera settings: confirm each camera can output the chosen resolution and frame rate over SDI, and can output a clean feed without menus or overlays.
• HDMI cameras: plan an HDMI-to-SDI converter and power for each one if the switcher has no matching HDMI inputs.
• Computer: check that control software, drivers and any USB webcam output support your operating system version and the apps you use.
• Capture: if the switcher has no USB or streaming output, choose an SDI capture device supported by your operating system and streaming or call software.
• Power: check whether the supply is internal or external, whether the connector locks, and whether a redundant or battery power option exists for your venue.
• Mounting: check rack size, desktop footprint and whether the unit uses cooling fans if the room must stay quiet.
• Firmware: some features depend on firmware version, so read the current release notes.

If the switcher connects to streaming accounts or a vendor app, check in the vendor documentation where stream keys, account details and recordings are stored, rather than assuming they stay on the device.

Build a shortlist

Turn your answers into a requirements sheet and compare each candidate against it line by line. Drop any model that misses a hard requirement, then compare the remaining options on the nice-to-have items.

• Inputs: enough SDI inputs for all cameras and other sources, plus at least one spare.
• Format: supports your resolution and frame rate on every input and output, or converts mismatched inputs.
• Sync: frame synchronisers on inputs, or a genlock option your cameras support.
• Outputs: enough program and auxiliary outputs, plus multiview if you need it.
• Audio: the embedded and external inputs you need, with delay adjustment.
• Recording and streaming: built in or handled by external devices, with recording format, encoding options and storage confirmed.
• Control: a panel or software that suits your operator, running on your operating system.
• Tally and camera return: confirmed with your camera models.
• Power and mounting: suitable for your venue.
• Support: current firmware, available manuals and acceptable warranty terms.

Before committing, try the shortlisted video switcher with SDI from your actual cameras if possible. Run your intended format, record a short program, check cuts between every input, confirm audio stays in sync and open the recorded file on the computer you will edit or upload from. Check the return policy in case something on the list fails in practice.