BK-21 Overview And Use Cases

What Is the BK-21?

The OREI BK-21 is an 8K 2x1 HDMI switch designed to connect two HDMI source devices to one TV, monitor, or projector.

It is useful when your display has limited HDMI inputs, but you want to connect two devices such as a gaming console, Blu-ray player, streaming device, PC, cable box, or media player.

The BK-21 supports HDMI 2.1, HDCP 2.3, with a video bandwidth of 48Gbps, and video resolutions up to 8K@60Hz and 4K@120Hz. It also supports HDR10+, Dolby Vision, HLG, VRR, ALLM, and FVA, making it suitable for high-resolution gaming and media setups.

The BK-21 can be switched manually using the button on top of the unit and also supports automatic switching based on HDMI signal detection.

IMPORTANT — BK-21 Is NOT a Seamless HDMI Switch

The BK-21 is not a seamless switch.

This means that when you switch from one HDMI input to the other, the display will usually show a black screen for a moment while the HDMI signal reconnects.

This is normal. The TV or monitor needs time to detect the new HDMI signal, complete the handshake, and display the image again.

In most setups, the black screen may last a second or two. In some cases, it may take longer depending on:

• The TV or monitor being used
• The resolution and refresh rate
• The HDMI cable quality
• The source device
• Whether 8K@60Hz, 4K@120Hz, HDR, VRR, or Dolby Vision is being used

This product switches between HDMI sources, but it does not provide instant or zero-delay switching.

IMPORTANT — Auto Switching Depends on HDMI 5V Signal Detection

The BK-21 supports auto switching, but it works by detecting the 5V signal coming from the connected HDMI source device.

In simple terms, the switch looks for which HDMI source appears to be “active.”

If one source is connected and then another source is plugged in or powered on, the BK-21 can automatically switch to the newly detected source.

However, many modern streaming devices do not fully turn off. Devices such as Apple TV, Fire TV Stick, Google Chromecast, Roku, and similar media players often go into standby mode instead of shutting down completely. Even in standby, they may continue sending a 5V signal through HDMI.

Because of this, the BK-21 may still detect that device as active, even when the customer thinks it is “off.”

For example:

If you have an Apple TV connected to Input 1 and a PlayStation 5 connected to Input 2, the BK-21 may switch to Apple TV when the PS5 is turned off because the Apple TV is still sending HDMI signal.

But when you later turn the PS5 back on, the switch may not automatically switch away from Apple TV because the Apple TV never fully stopped sending its HDMI 5V signal.

In this type of setup, manual switching using the button on the BK-21 is needed.

Ports and Panel Layout

Step-by-Step Setup

1. Connect your first HDMI source device to HDMI IN 1 on the BK-21.
2. Connect your second HDMI source device to HDMI IN 2 on the BK-21.
3. Connect the HDMI OUT port on the BK-21 to your TV, monitor, or projector.
4. Turn on your display and HDMI source devices.
5. Press the switch button on top of the BK-21 to manually switch between Input 1 and Input 2.
6. Connect the included Micro USB power cable to a USB power adapter to power the device.
7. To enable or disable auto switching, press and hold the switch button.
8. If auto switching does not work as expected with streaming devices, use the button to switch manually.

HDMI Cable Requirement — Critical

For 8K@60Hz, 8K@30Hz, or 4K@120Hz, use Ultra High-Speed Certified HDMI 2.1 cables under 15 feet.

Understanding Manual and Auto Switching

The BK-21 can switch between the two HDMI inputs in two ways.

Manual switching is done by pressing the button on top of the unit. This is the most reliable option when both connected devices remain active or in standby mode.

Auto switching works by detecting HDMI signal activity. It can be helpful when a new source is connected or when a source fully powers on/off.

However, auto switching may not work as expected with devices that stay active in standby mode, such as Apple TV, Fire TV Stick, Chromecast, Roku, and some game consoles or set-top boxes.

If the switch does not automatically change to the input you want, press the button manually.

What Source Devices Is the BK-21 Compatible With?

The OREI BK-21 is compatible with HDMI source devices such as:

• PlayStation 5
• Xbox Series X/S
• Apple TV
• Fire TV Stick
• Roku
• Google Chromecast
• Blu-ray players
• Cable boxes
• Satellite boxes
• Gaming PCs
• Laptops with HDMI output
• Media players

For 8K@60Hz or 4K@120Hz, the source device, HDMI cable, and display must all support the required HDMI 2.1 bandwidth.

What Displays Is the BK-21 Compatible With?

The BK-21 is compatible with HDMI displays such as:

• TVs
• Monitors
• Projectors
• Gaming displays
• 8K displays
• 4K@120Hz displays

The final resolution and refresh rate will depend on the source device, display, HDMI cables, and video settings.

Frequently Asked Questions

Q: What is the OREI BK-21 used for?
A: The BK-21 is used to connect two HDMI source devices to one TV, monitor, or projector and switch between them.

Q: Is the BK-21 a seamless switch?
A: No. The BK-21 is not a seamless switch. When switching inputs, the display will usually go black for a second or two while the HDMI signal reconnects.

Q: Why do I see a black screen when switching inputs?
A: This is normal. The display needs time to detect the new HDMI signal and complete the HDMI handshake. The delay may be longer depending on the display, source device, resolution, refresh rate, and HDMI cables.

Q: Does auto switching work with Apple TV, Fire TV Stick, Chromecast, or Roku?
A: Auto switching may not work consistently with these devices because they often stay in standby mode and continue sending a 5V HDMI signal. The BK-21 may still detect them as active even when they appear to be off.

Q: Why does the switch stay on Apple TV even when I turn on my PS5?
A: Apple TV may still be sending a 5V HDMI signal while in standby. Since the BK-21 still sees Apple TV as active, it may not automatically switch to the PS5. Use the button on the BK-21 to switch manually. This also applies to other devices like the Fire TV Stick, Roku Stick, Chromecast, etc.

Q: How does auto switching work on the BK-21?
A: Auto switching works by detecting the 5V signal from HDMI source devices. When a new active source is detected, the switch may automatically change to that input.

Q: How do I turn auto switching on or off?
A: Press and hold the switch button to turn auto switching on or off.

Q: Do I need to connect the Micro USB power cable?
A: Yes, the Micro USB power cable is needed to power the device.