Q: tv4 intermittent flickering with airplay

Hello there, Bengt.

It sounds like you're having issues with AirPlay from two different computers. The following Knowledge Base article offers up some great information to review:

Use AirPlay to display video from your Mac on an HDTV

Get help

If you don't see the AirPlay icon  , make sure that your Apple TV is awake and meets the system requirements.

If you don't see your Apple TV in the AirPlay menu, make sure that your Mac and Apple TV meet the system requirements, and your Apple TV software is up to date. Also check your firewall settings:

1. Choose Apple menu > System Preferences, click Security & Privacy, then click the Firewall tab.
2. Click the lock icon, then enter an administrator name and password.
3. Click Firewall Options.
4. Deselect the option “Block all incoming connections.”
5. Select the option “Automatically allow signed software to receive incoming connections.”

If your desktop doesn't look good on your HDTV, your HDTV might be applying picture-quality enhancements that aren't best for computer images. Check your HDTV manual for information about how to adjust your HDTV settings for use with a computer. Your HDTV might offer a more suitable viewing mode, such as computer mode or game mode. Also try adjusting HDTV settings such as sharpness, detail enhancement, and noise reduction.

If you're mirroring your display and the image doesn't fit your HDTV screen, you can adjust the desktop size for the best picture. Click the AirPlay icon, then choose an option under "Match Desktop Size To." If you match desktop size to your Apple TV, the image fills the HDTV screen but might not look as good on your Mac display. Learn about overscan and underscan and what you can do to correct it. 

If AirPlay disconnects by itself, your wireless network might be too busy or have too much wireless interference to maintain the AirPlay connection. Learn how to troubleshoot Wi-Fi connectivity issues. The manual of your network router might have additional suggestions for maintaining a strong and fast connection with your devices.

Requirements for using AirPlay

If you go to Apple menu > System Preferences, click Displays, and don't see the option to "Show mirroring options in the menu bar when available," your Mac doesn't meet these requirements.

Minimum requirements if your Mac and Apple TV are on the same network:

• Apple TV (2nd generation or later) with the latest Apple TV software
• For mirroring your display or extending your desktop, any of the following Mac computers with OS X Mountain Lion v10.8 or later: 
   
  • iMac (Mid 2011 or later)
   
  • Mac mini (Mid 2011 or later)
   
  • MacBook (Early 2015 or later)
   
  • MacBook Air (Mid 2011 or later)
   
  • MacBook Pro (Early 2011 or later)
   
  • Mac Pro (Late 2013 or later)

Minimum requirements for peer-to-peer AirPlay, which lets visitors quickly and easily connect their Mac or iOS device to your Apple TV without gaining passwords and connecting to the Wi-Fi network:

• Apple TV (3rd generation rev A, model A1469 or later) with the latest Apple TV software
• A Mac (2012 or later) with OS X Yosemite v10.10 or later

Thanks for reaching out to Apple Support Communities.

Kind regards.