Software to horizonally flip (not rotate) OSX's monitor output?

For display reasons we've got a setup where a user watches videos on a MacBook via a mirror. Of course, this works okay for videos normally, but the user would like to be able to do more than watch videos, including play some games and read comics and the like.

Since the user views the display though a mirror (there are disability issues around this - I'm aware it's a relatively odd question) obviously the text is backwards. Is it possible to horizonally flip OS X's output? Either to the main screen or a external monitor? At the moment it looks like two mirrors is going to be the only solution and that's going to be tricky to arrange.

To be clear - I'm trying to flip horizontally, not rotate by 180 degrees. So the Apple menu is in the top right and the spotlight Notification Center are top left.

Please indicate/edit and OS version requirements in your answer.

Solution 1:

I realize how old this is, but the answer is VLC player. I have an El Capitan Macbook 13". Open VLC, then Window - Video Effects - Geometry - Transform. From there you can rotate 90/180/270, flip horizontally or vertically, magnify, clone etc. Perfect if you have a p/w locked no remote garage sale projector like mine.

Solution 2:

It looks like Open Broadcaster Softare (OBS) can do this. https://obsproject.com/

I haven't tried it in production yet. In my testing environment I have three displays. I use a Display Capture source with input from my laptop screen. I run whatever I need on the teleprompter there. I use a 24" HDMI monitor as my primary display for managing OBS, audio apps, etc. I use a VGA 32" monitor for the teleprompter. I tell OBS to send my output to the "projector" via the miniDisplay->VGA adapter. Add Transform -> Flip Horizontal, and voila! My laptop screen is displayed to the 32" monitor with a horizontal flip. (It's mirrored and it's mirrored. :) )

I'm not actually broadcasting anything with OBS. I'm just using its Flip Horizontal filter to artificially mirror my laptop display to the teleprompter display. CPU usage by OBS is relatively low, since it's not having to broadcast anything It's ONLY mirroring the display.

Solution 3:

SwitchResX (paid) provides the exact functionality your are looking for. It allows you to horizontally flip the display output.

This mirror image feature is hidden in the current version because it no longer works consistently across all new macs. You can option-click the menu icon to see all the hidden features, including this one