iPhone landscape video rotated 90 degrees in Photos

[Easttime]

Hi, I can't figure out (a) what I did wrong and (b) whether I can fix this video. I've shot lots of videos on my iPhones. This time, the video shows up in Photos (iOS and Mac OS) rotated 90 degrees. I tried a couple of test videos since, holding the iPhone "upright" and "upside down" and both are normal. I tried rotating the video on my Mac using Photos, but that option is greyed out. Any thoughts?

Update: I finally figured out how to use iMovie to rotate the video. Still haven't sorted out why the video was rotated in the first place.

 

[malofx]

Sounds like Rotation Lock is activated.

 

[v0lume4]

I second @malofx. The phone thought it was in portrait orientation even though you had it turned sideways to record a video. (Side note -- I though that orientation lock didn't activate for the camera? I don't know.)

Anyway, you can rotate and re-export the video in a video editing software. MAYBE iMovie for iOS but I don't think it has a "rotate video" feature.