1Upload the MP4 videos that came out the wrong way round.
2Pick a quarter turn or a half turn, or type an arbitrary angle and choose a colour for the corners it will expose.
3Apply the rotation; the frames and the container display matrix are reconciled, so every player agrees on which way is up.
4Download the rotated MP4 file.
Rotate MP4 FAQ
How does Rotate MP4 turn the file?
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Concretely, a rotation flag is written into the container where the target supports one, which needs no re-encode at all; where it does not, the frames are transposed and the stream is re-encoded once. Quarter turns and half turns are the common case and take the cheapest path available for the format.
Can I rotate by an arbitrary angle, not just 90 degrees?
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Yes, though the two are different operations underneath. A multiple of 90 degrees rearranges existing data; any other angle has to rebuild the grid and fill the corners, so it costs a resample and usually wants a background colour choosing.
Does the format decide whether rotation is lossless?
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It does. MP4 is the safest delivery container: H.264 video with AAC audio plays on effectively every phone, browser and TV without a codec pack. That property is exactly what determines whether a quarter turn is free or costs a re-encode.
Anything specific to MP4 I should know?
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Yes — MP4 keeps its index in a moov atom, so a stream-copy edit is near-instant and the result still seeks properly in a browser. It is the kind of thing that explains why a file looks right in one application and wrong in another.
Why does my clip play upright on my phone but sideways on a computer?
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Because the turn is recorded as a display matrix in the container rather than baked into the picture, and not every player reads it. Rotating here reconciles the two — the frames and the matrix end up agreeing, so the clip is upright in a browser, an editor and a TV alike.
Can I rotate a whole batch in one go?
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Yes. The same rotation is applied to every clip you upload, which is the practical fix for a set of phone recordings that all came in the wrong way round.
What can I upload to Rotate MP4?
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MP4, MOV, MKV, WebM, AVI, WMV, FLV, 3GP, M4V, MPEG and MPG. The container and codec are probed before anything runs, so a mixed batch is handled correctly per file rather than assumed to be uniform.
Is there a file size limit on Rotate MP4?
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Yes: free accounts process video up to 1 GiB per file, by far the most generous cap on the site; ffmpeg with x264, x265 and libvpx does the work, which is the same toolchain behind most desktop video software. Video is the one family where the cap is high enough that upload time, not the limit, is what you will actually notice.
Will Rotate MP4 lower the quality of my MP4 videos?
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It depends on whether the job needs a re-encode. Operations that only touch the container or the timeline are done as a stream copy and the picture is bit-identical to the source. Anything that has to redraw frames goes through x264/x265 at a quality level you set, where CRF 23 is visually transparent on most footage.
Can I run Rotate MP4 on several MP4 videos at once?
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Yes. Uploads queue in parallel, which matters more here than anywhere else because video jobs are minutes rather than seconds. Free accounts run one file at a time; a pass lifts that.
What happens to audio, subtitle and chapter tracks?
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They are carried across. Multi-track audio, embedded subtitle tracks and chapter markers survive wherever the target container can represent them — that is the main thing that separates a proper job from a naive re-encode that silently keeps only track one.
Does Rotate MP4 cost anything?
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No. Rotate MP4 is free without an account, and the output carries no watermark, no corner logo and no intro card. Uploaded video is deleted from the workers shortly after the job completes.
