Apple TV doesn't stream via Quicktime

I would have hoped that Subler would fix ‘stubborn’ MP4 files and make them more compliant, as it has routinely done for me.

Can you give some details: duration (under ~10 hours is not special), file size (under 4GB is not special), video codec (e.g. H.264 or H.265), resolution, etc. Full report would be most helpful.

Did you film this yourself? With what equipment (camera)?

Did you get this from someone else, who may not have had Apple TV compatibility in mind?

Would you mind making a conversion (re-encode) to make it more compatible?

It is important that the video specs are within the limits as stated in the technical specifications (Video Formats), and AirPlay may impose further limits.

Can you test if it happens with just that one file, and do other .mp4 files play fine over AirPlay from QuickTime Player?

• If other files play fine, then one movie file has to be altered to fix it.
• If all movie files won’t play using AirPlay, then possibly your system software or settings files need tweaking.

Perhaps there is something glitchy or otherwise unexpected in the file that QuickTime can deal with, but the Apple TV player can’t. If that is the case, then mirroring (=re-encoding the screen) would work while ‘basic’ AirPlay wouldn’t.

Try remuxing the file using Subler (opening, saving as new file with optimizing) to create a more compatible file.