MP4/MOV Rotate

Rotate phone videos from the Windows Explorer right-click menu, the same way Windows lets you rotate photos.

Right-click one or more .mp4 files and choose MP4 Rotate -> Rotate left / Rotate right / Rotate 180. Also works with iPhone/QuickTime .mov, .m4v and .3gp videos: the menu is named after the type you right-click (MOV Rotate, M4V Rotate, ...), or Video Rotate for a mix.

Written by Justin Nelson with help from Claude Code for the JustinNelsonsProjects YouTube channel. More projects at JustinNelsonsProjects.com.

Features

• Lossless and instant. Nothing is re-encoded. The video's rotation is stored as a small transformation matrix in the MP4/MOV container, and MP4/MOV Rotate rewrites only those 36 bytes per video track, in place. A 5 GB 4K video rotates as fast as a 5 MB one.
• Works with H.264 and HEVC (H.265) alike, since the rotation lives in the container, not the video stream. Built and tested with videos from a Samsung Galaxy S24, an iPhone 4S and two dashcams.
• MP4, MOV, M4V and 3GP. These all share the same ISO/QuickTime file structure (MP4 grew out of Apple's QuickTime format), so the same lossless edit works for all of them.
• Windows 11 main context menu (not just "Show more options"), with light/dark-mode icons. On Windows 10 the commands appear in the classic context menu.
• Multiple files at once. Select several videos and rotate them in one go.
• Explorer thumbnails update right after rotating.
• No .NET runtime or Visual C++ redistributable required. The tool is a single native exe.

Install

Download the installer from the Releases page and run it. Setup installs for all users and offers to restart Windows Explorer at the end; Windows 11 only loads new context menu commands when Explorer starts. (Your taskbar and desktop disappear for a moment while it restarts. That's normal.)

Command line

mp4rotate.exe can also be used directly:

mp4rotate left  <file> [file...]    rotate 90 degrees counter-clockwise
mp4rotate right <file> [file...]    rotate 90 degrees clockwise
mp4rotate 180   <file> [file...]    rotate 180 degrees
mp4rotate info  <file> [file...]    show the current rotation, change nothing

It's a windowless program (so Explorer never flashes a console window). In PowerShell, pipe it to Out-String to wait for its output, e.g. mp4rotate info video.mp4 | Out-String.

How it works

Every MP4/MOV track has a track header box (moov/trak/tkhd) containing a 3x3 matrix that tells players how to transform the video when displaying it. Phones don't actually record portrait video sideways; they record in the sensor's orientation and set this matrix. MP4/MOV Rotate:

1. Walks the top-level boxes to find moov, skipping the (huge) mdat media data without reading it.
2. Finds every video track (hdlr type vide) and reads its current rotation from the matrix.
3. Writes the new rotation matrix back over the old one. File size and everything else stay unchanged.

The Windows 11 menu is an IExplorerCommand shell extension (shell/) registered through a sparse MSIX package (package/), which is what gives third-party commands a place in the new menu.

Building from source

Requirements:

• Visual Studio 2022 with the Desktop development with C++ workload
• .NET 9 SDK
• Windows 10/11 SDK (for makeappx.exe)
• Inno Setup 5.5.9

Then run:

build.cmd           (signed build; needs a SignTool named "AzureSign" configured in Inno Setup)
build.cmd NOSIGN    (unsigned build)

The installer is written to installer\Output.

If you fork this: Windows only registers the context-menu package if mp4rotate.msix is signed by a certificate the PC trusts, and the Publisher in package\AppxManifest.xml must exactly match that certificate's subject. Change the Publisher to your own certificate's subject and set up your own SignTool. An unsigned build installs fine, but the Windows 11 menu won't appear.

Project layout

Path	What it is
Program.cs	mp4rotate.exe: the MP4 rotation itself, plus package registration and Explorer restart helpers
shell/	mp4rotate_shell.dll: the Explorer context menu (C++ IExplorerCommand)
package/	Sparse MSIX package manifest and logos
installer/	Inno Setup script and artwork
tools/	Scripts that generate the icons

Contributing

This project is published as-is for viewers and anyone curious how it works. Pull requests are not accepted, but you're welcome to fork it and make it your own under the terms of the GPL-3.0 license.

License

GPL-3.0. Copyright (c) 2026 Justin Nelson / JRN Enterprise Inc.