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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.

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    I have the same issue, I need to flip primary display on my MacBook pro not just rotate, but flip horizontally, has anyone find a solution? I know it is supported by graphics card by default as you can do it on windows or linux machine using either Nvidia or Ati control panel, however those addons are not available on Osx...
    – user52412
    Jul 1, 2013 at 8:45
  • This is valuable during lockdown when having dance classes over Zoom! Apr 19, 2020 at 16:48

4 Answers 4

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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.

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  • Anyone know how to get subtitle (e.g. .srt files) to flip in VLC as well? This tip worked for the video image, but my overlaid subs were still unflipped.
    – tomh
    Aug 12, 2016 at 18:29
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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.

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  • I use OBS already and this might be a nice, if slightly awkward solution. Thank you.
    – Joe
    Jul 10, 2020 at 19:02
  • I'm using it in production this weekend, and it's working very well. Oddly, it doesn't include the menu bar, so it's stretching the screen ever so slightly even though it says it isn't. Thus the font looks a little off. I'll attempt to adjust the transform... but for the most part, it is working beautifully. :)
    – Mike P.
    Jul 11, 2020 at 20:18
  • This seems like a very interesting solution. However, if you try to share this screen during a video call, it would appear as reversed to the audience. Is that accurate?
    – Jay
    Jun 2, 2021 at 21:22
  • I've never tried to share the third screen. It's identical to the second monitor, so I would share that one, not the flipped one. The ONLY purpose for the 32" monitor is to use as a flipped image of the 24" monitor for the teleprompter. I can't think of a reason to attempt to share that screen.
    – Mike P.
    Jun 3, 2021 at 22:13
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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

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    I couldn't see a flip option to SwitchResX so I contacted the author, who replied quickly to say that he's hidden this feature 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.
    – Jon Topper
    Jul 20, 2020 at 8:44
  • @JonTopper Thanks for sharing the info. You may want to edit this information into the answer.
    – Nimesh Neema
    Jul 20, 2020 at 9:00
  • I installed the said application. Went into the hidden menu. Indeed the options for various mirror flips of the screen are there. NONE work. The best the app does in that respect is to just rotate the screen 90/180/270 deg while flipping the mouse movement only. You can imaging how how confusing this is. Further, there is no means for clean uninstall and removal of this s/w. Beware! Once it hooks in it will stay on your computer. This is quite bad, given its intermittent and random way of operating. Feb 21, 2021 at 15:48
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There is a free macOS utility from Teleprompter Mirror that will horizontally flip any selected window of a macOS app.

Unfortunately it significantly reduces the frame rate as it is continuously capturing window contents and drawing the flipped version over it. Tested on a macBook pro 13" (model 2017 with T1 chip) and latest macOS Monterey 12 Beta. The result fps is about 5 fps, not enough to watch videos but quite enough for presentations over Zoom and such.

Link to web page: mac Mirror flip utility

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