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HDMI vs SDI for live production

By OneProGear · Published · Updated

Use HDMI for short runs at the desk and into an ATEM Mini. Move to SDI once cables run past about 15 m or leave the room. 3G-SDI carries up to 1080p60; 12G-SDI carries 4K at 60 fps. Add converters only where the camera and switcher disagree.

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  1. HDMI: great on the desk, risky over distance

    HDMI is a consumer connector. The plug holds by friction, many sources add HDCP copy protection, and ordinary copper HDMI is not designed for long runs. On a desk, it is the right cable.

    The Rode HDMI Cable is HDMI 2.0, in 1.5 m and 3 m lengths. That is plenty for 1080p60 or 4K at 30 fps, but not 4K at 120 fps. The SmallRig Ultra-Slim 4K HDMI cable is 1 m. The Atomos 4K60 locking HDMI cable is short (28 cm) and made for a monitor.

    Past about 10–15 m, copper HDMI starts dropping out, showing sparkles or refusing 4K. For longer runs, a fibre-optic HDMI cable like the Rode Fibre-Optic HDMI (10 m, up to 8K60 or 4K120) helps. Many fibre cables work in one direction only, so check the source and display labels.

    About HDCP: Blackmagic converters will not accept copy-protected HDMI. A camera's clean output is fine; a laptop playing a streaming app often is not.

  2. SDI: locking connectors built for distance

    SDI uses a BNC connector: you push it on and twist to lock, so it cannot be pulled out by accident. Good converters also reclock the signal, which cleans it up so it survives the next long cable run.

    SDI comes in speeds that match the format:

    • 3G-SDI carries up to 1080p60. The Blackmagic Micro Converter BiDirectional SDI/HDMI 3G handles this on USB-C power.
    • 6G-SDI carries 4K up to about 30 fps. See the Mini Converter HDMI to SDI 6G and SDI to HDMI 6G, which need 12–18 V DC.
    • 12G-SDI carries 4K at 60 fps. The Micro Converter BiDirectional SDI/HDMI 12G handles every speed up to 12G and passes Blackmagic camera control and tally (the on-air light).

    The ATEM Television Studio HD8 takes SDI at HD speeds only, so it will not accept 12G 4K. The short Hollyland SDI cables (50 cm and 1 m) are jumpers. For a 15–50 m run, look for 75 ohm BNC cable rated for your speed.

  3. When HDMI is the whole system

    If every camera is within about 5 m of the switcher and you work in 1080p60, you can stay on HDMI and skip converters. Use a locking HDMI cable if your camera has a locking socket.

    The ATEM Mini Pro has 4 HDMI inputs, converts mismatched formats on every input, streams over Ethernet and works as a USB-C webcam. The ATEM Mini Extreme has 8 HDMI inputs and 2 HDMI outputs. A simple church setup might run an Atomos A-Eye PTZ camera into an ATEM Mini Pro over HDMI.

    Desk capture devices, such as the Atomos Nexus, Rode Streamer X and Blackmagic Intensity Pro 4K, are HDMI by design. The Intensity Pro 4K takes HDMI up to 4K at 30 fps inside a desktop PC.

    Stay on HDMI when the cable does not leave the room and the switcher already has HDMI inputs.

  4. When SDI is the system

    Move to SDI when cables run past about 15 m, when the switcher sits in a rack in another room, or when the switcher only has BNC inputs.

    A larger church setup might put a Blackmagic Micro Converter BiDirectional 12G at each PTZ camera, so the rack receives SDI, and switch on the ATEM Television Studio HD8. A 4K60 HDMI signal from a PTZ will not survive a 25 m copper run to the booth. A 3G-SDI 1080p60 signal will.

    Watch for format mismatches. If your camera sends 4K60 over HDMI and your switcher is HD-only SDI, you have two problems. The converter must be 12G to accept 4K60, and the HD8 will not switch 4K anyway. Either set the camera to 1080p60 and stay in HD, or choose a 4K switcher. Match the switcher to the camera, or convert once.

  5. Pick converters by format

    Converters are there to fix a format mismatch, so buy only what the signal needs:

    • Everything in HD: the Micro Converter BiDirectional SDI/HDMI 3G.
    • Any link carrying 4K at 60 fps: the Micro Converter BiDirectional SDI/HDMI 12G.
    • Adding analogue or digital audio into the SDI signal: the Mini Converter HDMI to SDI 6G, powered by a 12 V adapter.
    • Extra picture processing a micro converter cannot do: the Teranex Mini HDMI to SDI 12G.

    Power matters. Micro converters run on USB-C (around 5 V). Do not rely on a 10 m USB cable for power; put a powered USB supply next to the converter. Mini converters need 12–18 V DC.

    If your cameras are Blackmagic, the bidirectional micro converters also carry camera control and tally, which a generic HDMI-to-SDI box will not.

  6. Camera outputs are not equal

    Check what each output on your camera can really send. The Atomos A-Eye 4K-12X and 4K-20X PTZ cameras output 4K at 60 fps over HDMI, but their 3G-SDI output tops out at 1080p60. The 4K picture is only on HDMI (and over the network via NDI). If you take SDI from these cameras, you are working in HD. Plan the switcher around that, or stay on HDMI or NDI for 4K.

    Cables work the same way. A 3G-SDI cable will carry HD fine but may fail with a 12G signal. That is how you end up with perfect 1080p60 and a mystery 4K dropout.

    In short: use HDMI at the desk and for HD switchers within a few metres. Use SDI when the cable leaves the room. Convert once, at the camera or at the rack, to the format your switcher actually accepts.

What you need

  • The video format you actually switch (1080p60, 4K at 30 fps or 4K at 60 fps)
  • The longest cable run from camera to switcher, in metres
  • A switcher whose inputs match that format (HDMI on the ATEM Mini range, SDI on the ATEM Television Studio HD8)
  • Converters only where the camera and switcher disagree
  • Cables rated for the signal (HDMI 2.0 or 2.1; 3G-SDI or 12G-SDI)

HDMI is the socket you find on cameras, monitors and the ATEM Mini. SDI is the socket on broadcast switchers and long cable runs. Both carry the same kind of picture, but they fail in different ways. Choose by cable length, how securely the connector locks, and the video format, not by which one sounds more professional.

HDMI: great on the desk, risky over distance

HDMI is a consumer connector. The plug holds by friction, many sources add HDCP copy protection, and ordinary copper HDMI is not designed for long runs. On a desk, it is the right cable.

The Rode HDMI Cable is HDMI 2.0, in 1.5 m and 3 m lengths. That is plenty for 1080p60 or 4K at 30 fps, but not 4K at 120 fps. The SmallRig Ultra-Slim 4K HDMI cable is 1 m. The Atomos 4K60 locking HDMI cable is short (28 cm) and made for a monitor.

Past about 10–15 m, copper HDMI starts dropping out, showing sparkles or refusing 4K. For longer runs, a fibre-optic HDMI cable like the Rode Fibre-Optic HDMI (10 m, up to 8K60 or 4K120) helps. Many fibre cables work in one direction only, so check the source and display labels.

About HDCP: Blackmagic converters will not accept copy-protected HDMI. A camera's clean output is fine; a laptop playing a streaming app often is not.

SDI: locking connectors built for distance

SDI uses a BNC connector: you push it on and twist to lock, so it cannot be pulled out by accident. Good converters also reclock the signal, which cleans it up so it survives the next long cable run.

SDI comes in speeds that match the format:

  • 3G-SDI carries up to 1080p60. The Blackmagic Micro Converter BiDirectional SDI/HDMI 3G handles this on USB-C power.
  • 6G-SDI carries 4K up to about 30 fps. See the Mini Converter HDMI to SDI 6G and SDI to HDMI 6G, which need 12–18 V DC.
  • 12G-SDI carries 4K at 60 fps. The Micro Converter BiDirectional SDI/HDMI 12G handles every speed up to 12G and passes Blackmagic camera control and tally (the on-air light).

The ATEM Television Studio HD8 takes SDI at HD speeds only, so it will not accept 12G 4K. The short Hollyland SDI cables (50 cm and 1 m) are jumpers. For a 15–50 m run, look for 75 ohm BNC cable rated for your speed.

When HDMI is the whole system

If every camera is within about 5 m of the switcher and you work in 1080p60, you can stay on HDMI and skip converters. Use a locking HDMI cable if your camera has a locking socket.

The ATEM Mini Pro has 4 HDMI inputs, converts mismatched formats on every input, streams over Ethernet and works as a USB-C webcam. The ATEM Mini Extreme has 8 HDMI inputs and 2 HDMI outputs. A simple church setup might run an Atomos A-Eye PTZ camera into an ATEM Mini Pro over HDMI.

Desk capture devices, such as the Atomos Nexus, Rode Streamer X and Blackmagic Intensity Pro 4K, are HDMI by design. The Intensity Pro 4K takes HDMI up to 4K at 30 fps inside a desktop PC.

Stay on HDMI when the cable does not leave the room and the switcher already has HDMI inputs.

When SDI is the system

Move to SDI when cables run past about 15 m, when the switcher sits in a rack in another room, or when the switcher only has BNC inputs.

A larger church setup might put a Blackmagic Micro Converter BiDirectional 12G at each PTZ camera, so the rack receives SDI, and switch on the ATEM Television Studio HD8. A 4K60 HDMI signal from a PTZ will not survive a 25 m copper run to the booth. A 3G-SDI 1080p60 signal will.

Watch for format mismatches. If your camera sends 4K60 over HDMI and your switcher is HD-only SDI, you have two problems. The converter must be 12G to accept 4K60, and the HD8 will not switch 4K anyway. Either set the camera to 1080p60 and stay in HD, or choose a 4K switcher. Match the switcher to the camera, or convert once.

Pick converters by format

Converters are there to fix a format mismatch, so buy only what the signal needs:

  • Everything in HD: the Micro Converter BiDirectional SDI/HDMI 3G.
  • Any link carrying 4K at 60 fps: the Micro Converter BiDirectional SDI/HDMI 12G.
  • Adding analogue or digital audio into the SDI signal: the Mini Converter HDMI to SDI 6G, powered by a 12 V adapter.
  • Extra picture processing a micro converter cannot do: the Teranex Mini HDMI to SDI 12G.

Power matters. Micro converters run on USB-C (around 5 V). Do not rely on a 10 m USB cable for power; put a powered USB supply next to the converter. Mini converters need 12–18 V DC.

If your cameras are Blackmagic, the bidirectional micro converters also carry camera control and tally, which a generic HDMI-to-SDI box will not.

Camera outputs are not equal

Check what each output on your camera can really send. The Atomos A-Eye 4K-12X and 4K-20X PTZ cameras output 4K at 60 fps over HDMI, but their 3G-SDI output tops out at 1080p60. The 4K picture is only on HDMI (and over the network via NDI). If you take SDI from these cameras, you are working in HD. Plan the switcher around that, or stay on HDMI or NDI for 4K.

Cables work the same way. A 3G-SDI cable will carry HD fine but may fail with a 12G signal. That is how you end up with perfect 1080p60 and a mystery 4K dropout.

In short: use HDMI at the desk and for HD switchers within a few metres. Use SDI when the cable leaves the room. Convert once, at the camera or at the rack, to the format your switcher actually accepts.

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