Convert · runs on your device

Convert M4V to MP4 in your browser

M4V and MP4 are structurally the same format, so this conversion is a container rewrite: seconds of work, no re-encoding, and a file that is pixel-identical to the source.

Nothing is uploaded

Drop video files here

M4V

Choose video files to convert

Output format

Plays on effectively every browser, phone, TV and editor when it holds H.264 and AAC.

Video codec

The universal baseline. Hardware decoding exists on essentially every device sold since 2010.

How to size the output

A constant quality target. File sizes vary with how demanding the footage is.

Quality — 10 of 10

Resolution limit

Files smaller than the limit are left alone. Capping usually looks better than lowering the bitrate.

Frame rate

Audio

Fast rewrapCopy streams without re-encoding when the codecs already fit

Lossless and near-instant when it applies. It cannot reduce file size, so turn it off if you need a smaller file.

Apple introduced .m4v so iTunes could flag video files that might carry FairPlay DRM. Underneath, an M4V is an MP4: the same ISO base media structure, normally holding H.264 video with AAC audio. Nothing about the video data needs to change to make it an MP4.

That makes this the fastest conversion on the site. Video Mender reads the track layout, writes a standard MP4 container around the existing streams and hands the file back. Nothing is decoded, so nothing can be degraded, and the output is the same size as the input.

The one genuine failure case is DRM. If the M4V came from the iTunes Store with FairPlay protection, no converter can open it — that is what the protection is for. Video Mender detects the condition and marks the file unsupported instead of producing something broken.

What this actually does to your file

Rewrap or re-encode

Rewrap is the normal and expected path for every DRM-free M4V, since MP4 accepts exactly the codecs M4V uses. A re-encode is only needed if you also change resolution, frame rate or codec.

Quality

Zero quality change on the rewrap path, because no frame is ever decoded. Quality only enters the picture if you deliberately turn fast rewrap off.

FairPlay-protected M4V files from the iTunes Store cannot be converted by any tool, including this one.
Chapter markers and iTunes metadata such as artwork are not carried across.
The MP4 is the same size as the M4V. This route changes the container, not the file size.

How to use this page

Add your M4V files.
Confirm each shows the "Fast rewrap" badge.
Press Start; the queue should finish almost immediately.
Download the MP4 files individually or as one ZIP.

Where the result plays

Checked against the containers and codecs this page produces, stated conservatively.

Target	Works	Detail
Windows and Android	Yes	MP4 is recognised everywhere; .m4v often needs an explicit "open with".
Browsers	Yes	MP4 plays inline. M4V support depends on the browser guessing the type correctly.
Video editors	Yes	Some editors filter their file picker by extension and simply will not show .m4v files.
Apple devices	Yes	Both formats already work; converting is for everything outside the Apple ecosystem.

The formats involved

Format	Read	Write	What it is
M4V	Yes	Yes	Apple's MP4 variant used by iTunes. Byte-for-byte it is an MP4; the extension exists so iTunes can flag optional FairPlay DRM.
MP4	Yes	Yes	The MPEG-4 Part 14 container. It is a wrapper, not a codec — an MP4 usually holds H.264 or HEVC video with AAC audio.
MOV	Yes	Yes	Apple QuickTime. Structurally a close cousin of MP4, which is why MOV files can often be rewrapped to MP4 with no re-encode.
MKV	Yes	Yes	Matroska. The most permissive common container: it will carry almost any codec, plus multiple audio tracks, chapters and subtitles.

Tested limits

Real ceilings measured on real devices, not a marketing claim of unlimited.

Limit	Desktop	iPhone / iPad	Why
File size — rewrap	1.3 GiB	384 MiB	Rewrapping never decodes a frame, so it tolerates far larger files.
File size — re-encode	1.0 GiB	256 MiB	Decoding holds uncompressed frames in memory, which is the real constraint.
Clip length — re-encode	4:00:00	30:00	Beyond this, progress reporting and memory behaviour stop being dependable.
Resolution — re-encode	4096 × 2160	1920 × 1080	A 4K frame is about 12 MB decoded, before the encoder allocates anything.

If something goes wrong

The file is marked unsupported.

It is DRM-protected. Files bought from the iTunes Store with FairPlay cannot be decoded by third-party software, and no setting here changes that.

My cover artwork disappeared.

iTunes-specific metadata is not transferred by the rewrap. The video and audio are intact; only the tags are gone.

Why is the MP4 the same size?

Because it holds the same compressed data. A rewrap changes the wrapper, not the contents — that is what makes it lossless and instant.

Your video never leaves this device

This is a structural property of the application, not a policy we ask you to take on trust. There is no upload endpoint, no API route and no server action anywhere in the codebase, so there is nowhere for a video to be sent even by mistake.

Conversion runs in WebAssembly inside this browser tab. The engine is served from this domain and loaded only when you start a job.
The Content-Security-Policy restricts network connections to this origin, so the page is not permitted to contact a third party at all.
Nothing is stored. Close the tab and every queued file and finished output is gone — which is also why you should download results before you leave.
There are no accounts and no AI. Anonymous page views are counted — which page, roughly what country, what kind of device — and nothing whatsoever about your files.

The repository contains a test that fails the build if any media byte is passed to fetch, XMLHttpRequest, sendBeacon or a WebSocket. See the privacy page for how that is verified.

Questions

What is the difference between M4V and MP4?

In practice, the extension and Apple’s optional DRM flag. The container structure and the codecs inside are the same, which is why the conversion is a rewrite rather than a re-encode.

Can I just rename the file to .mp4?

Often that works, because the bytes are already MP4-compatible. It fails when the M4V declares an Apple-specific brand that strict players reject, and a real rewrap fixes the declaration properly.

Does this remove DRM?

No. DRM-protected files fail at the decode stage and are reported as unsupported. Removing protection is not something this tool does.

Is the quality affected?

Not at all on the rewrap path. The compressed video stream is copied without being decoded, so the output is bit-for-bit equivalent in picture terms.

Can I convert a batch of M4V files?

Yes, and it is fast. Rewrapping is cheap enough that large batches finish in the time it takes to read this answer.