Video Rotation Tool - Rotate & Flip Videos Online

Unlike phone cameras and many "rotate" tools that only flip a rotation flag in the MP4 container metadata (the rotate=90 tag) and leave the actual pixels untouched, this tool burns the orientation directly into the frames. It runs ffmpeg.wasm (@ffmpeg/core 0.12.6) entirely in your browser and applies real FFmpeg video filters: 90 CW maps to transpose=1, 270 CCW to transpose=2, 180 to a chained transpose=2,transpose=2, while "Flip H" and "Flip V" add hflip and vflip to the filter chain. Because the pixels themselves are rewritten, the corrected orientation survives in every player and editor instead of appearing sideways wherever the metadata flag is ignored.

Applying a transform re-encodes the video with libx264 using -preset ultrafast and -crf 23 (a visually near-lossless quality target), with -threads 0 to use all available cores and -movflags +faststart so the output is web-streamable. The audio track is stream-copied with -c:a copy, so it is never re-encoded and stays bit-for-bit identical; only the video is touched. The trade-off is that any rotation or flip costs one generation of H.264 re-encoding, and the download keeps your original container extension (the file is saved as name_rotated.ext). FFmpeg loads its multi-threaded core (core-mt 0.12.6) when SharedArrayBuffer is available and silently falls back to a single-threaded build otherwise, so nothing leaves your machine.

The editor shows a side-by-side Original vs Transformed preview using a live CSS transform, and reports both the source resolution and the computed output resolution in the corners. A 90 or 270 rotation swaps width and height, so a 1920x1080 clip becomes 1080x1920 in the preview readout and in the rendered file. Beyond the manual 90° CW / 90° CCW / 180° / Flip H / Flip V buttons, there are four one-click presets (Portrait → Landscape = 90, Landscape → Portrait = 270, Selfie Fix = horizontal mirror only, Fix Upside Down = 180) and keyboard shortcuts: R rotates clockwise, Shift+R counter-clockwise, H and V flip, Space plays/pauses, and Esc resets the transform. Rotations accumulate modulo 360, and the Apply & Download button stays disabled until at least one transform is selected.