Fix a sideways or mirrored phone video
Updated November 3, 2026
The clip looks fine on the phone and arrives lying on its side in an e-mail, on a TV or in a video editor. Nothing is broken: the phone recorded the pixels sideways and wrote a note in the file saying turn this when you play it. Some players read the note and some ignore it.
The fix is to turn the picture so that every player agrees, and, for a front-camera clip, to undo the mirror image the phone kept. Rotate video and Flip video do both in the browser, and Compress video makes the result lighter for sending.
Why it plays sideways
A phone's camera sensor is mounted landscape. When you film upright, most phones save the frames as they come off the sensor, sideways, and add an orientation flag to the MP4 that tells the player to rotate by 90 degrees. Phones, browsers and VLC obey it; some desktop players, TVs, editors and web sites do not, and show the raw frames.
That also explains why the same file looks different in different places and why the thumbnail can be upright while the video is not. There is no wrong copy to find: the one file carries both the sideways pixels and the instruction.
Rotate it in the browser
Open Rotate video, drop the clip and pick 90° right, 90° left or 180° under Quarter turn. On an MP4 the tool can write the orientation flag, which is instant and keeps every pixel, but that only helps where the flag is already honoured. For a file that must look right everywhere, tick Re-encode: the pixels themselves are turned and written anew, so there is no flag left to ignore.
Re-encoding means the whole clip is decoded and encoded again on your device, at a bitrate that follows the source's own. It takes a while, roughly as long as the clip on a laptop and longer on a phone, and the file size changes a little either way. WebM and MKV have no flag that players follow, so they are always re-encoded.
Mirrored selfie videos
Front cameras show you a mirror while recording, and some phones save the clip that way: text on a T-shirt reads backwards and your parting is on the wrong side. Flip video with Horizontal swaps left and right so the clip shows what others see. It is always re-encoded, because most players ignore a mirror mark.
A clip that is both sideways and mirrored takes two passes: rotate first, then hand the result to Flip video with Continue with. Vertical turns the picture upside down, and Both equals a half turn.
Check it, then share it
Play the result in the browser and, if you can, in the program that showed it wrong; a rotated clip that looks right in the player you already trusted proves nothing. Check the first and the last seconds, where a cut or a frozen frame would show. Then run it through Compress video if it is going by chat or mail: a re-encoded clip is about as big as the original, and 720p at Medium makes it a fraction of that, with the sound kept unless you tick Remove audio.
Tips
- The flag route is fine for a clip that goes to another phone or to a browser; re-encode for a TV, a projector or an editing program.
- Hold the phone landscape when filming anything that will be watched on a screen wider than it is tall.
- Straightening a tilted horizon is the same tool: type a small angle such as 2° and the frame grows to fit.
- Keep the original; a re-encoded copy is a copy.
Questions
- Does rotating lose quality?
- Written as a flag, nothing changes in the picture. Re-encoded, the picture is compressed again at about the source's bitrate; the difference is hard to see, and the sound is copied as it is.
- Why does my video still play sideways after rotating?
- The flag was written and your player ignores it. Run it again with Re-encode ticked.
- Can I rotate only part of the video?
- No; the whole clip turns. Trim video first if only a part is needed.
- Is the video uploaded?
- No. The clip is read in pieces and encoded by the browser's own encoders on your device.