Why phone videos end up sideways
A phone's camera sensor always records in landscape. When you hold the phone upright, it doesn't turn the pixels, it stores a small rotation flag that tells players to turn the picture when they show it.
Things go wrong when the phone guesses the orientation incorrectly (common if you start recording with the phone lying flat), or when an app ignores the flag. Fixing it means either correcting the flag or turning the pixels themselves, and this tool can do both.
Re-encode or Fast?
Re-encode decodes every frame, turns it and compresses it again as an H.264 MP4. The finished file has no rotation flag left to misread, so it looks right in every player, editor and upload form. It takes about as long as the video plays, often less, and uses a bitrate matched to your original so the picture keeps its look.
Fast rewrites only the rotation flag and copies the video stream untouched. It takes seconds, loses nothing and keeps the file's format, but it only works for MP4 and MOV files, and a few apps and websites still ignore the flag. Mirroring can't be stored as a dependable flag, so a mirrored or flipped video is always re-encoded.
Mirror, flip and turn: what's the difference?
- Mirror swaps left and right, like looking in a mirror. It fixes selfie-camera clips where writing appears backwards.
- Flip turns the picture upside down across its middle, so the top becomes the bottom, useful for footage from a camera mounted upside down.
- Turning 180° also puts the picture upside down, but without reversing left and right. Mirror plus Flip together equals a 180° turn.
After rotating
A video that's now upright often needs a new frame as well. Crop it to cut away edges, or resize it for TikTok, Reels and Shorts to place it in a 9:16 frame with a blurred background. To keep just the good part, trim it.