Convert M4V to MP4

M4V is the extension Apple used for iTunes Store video, and store purchases carry FairPlay encryption. An encrypted file cannot be decoded by a browser, so this conversion stops before it starts and reports that nothing in the file could be converted. That message means the file is locked, not that it is damaged.

Where the file came from is the test. Bought or rented from the iTunes Store or the Apple TV app: protected, and it stays inside Apple’s apps. Exported from QuickTime, iMovie, Final Cut or Compressor, produced by a camera, or downloaded from a course platform: not protected, and it converts like any other video. Nothing on this page removes protection, and any site claiming otherwise is asking you to upload a film to find out.

An unprotected M4V is an ISO MPEG-4 file — the same container as MP4, with the same H.264 and AAC inside. A great deal of software refuses it purely because of the extension: upload forms with a fixed list of accepted types, older Windows applications, some Android players, and anything that checks the name instead of the contents.

For all of those, changing the extension in Finder or Explorer fixes the problem instantly and touches not one byte of the video. It takes less time than reading this paragraph and it costs nothing, which makes it the right first move. If the file still will not play afterwards, the extension was never the problem and the next section is.

The common case is HEVC. Recent Apple hardware records and exports HEVC by default because it halves the file size, and plenty of televisions, budget media boxes and older Android phones have no HEVC decoder at all. The file plays perfectly on the Mac it came from and is rejected everywhere else, which looks like a format problem and is a codec problem.

This conversion always writes H.264 at High profile with AAC audio, whatever the source held. That is the combination that has been decoded in hardware by essentially every device made in the last twenty years, and converting to it is the thing that actually fixes a television saying "unsupported file".

One generation of quality. The video is decoded and encoded again rather than copied across, so some detail is given up even at the highest setting. On a file that came out of a camera or an editor this is barely visible; on a file that has already been converted once by somebody else it compounds.

The practical rule is to convert once, from the best copy you have, and keep the M4V. It costs storage and nothing else, and if the MP4 later turns out to be the wrong resolution or the wrong quality band, you want to be re-encoding the original rather than the copy.

Editing software is the other common refusal, and it is usually stricter than a player: an application may open a file for playback and still decline to place it on a timeline, most often because of HEVC or because of a variable frame rate from a screen recorder.

Converting to H.264 solves the first. It does not solve the second: no frame rate is imposed here, so a variable-rate screen recording keeps its original timing and an editor that refused it may refuse it again. Use the high quality band for this — the file is about to be cut, graded and exported again, and every generation you protect at the input shows up at the output.

This is the failure that confuses people most, and it is worth knowing before converting rather than after. A track in AC-3, E-AC-3, DTS or TrueHD is dropped, and on this video-to-video conversion that means the picture converts fine and the result plays silent. It is not a broken file and not a setting you missed.

It is a common case, and it shows up specifically on rips from a disc or a broadcast, which is where that kind of audio lives. Checking first costs a minute: open the file in a player that lists its tracks — VLC does — and look at the audio codec. If it is one of those four, there is no shortcut here and the audio needs re-encoding with a desktop tool first.

Chapter marks and embedded subtitle tracks are dropped. On a feature film or a recorded lecture series that is a genuine loss, and it is especially likely on an M4V, since Apple’s container is commonly used with chapters.

The workable answer is a sidecar subtitle file with the same base name as the MP4, in the same folder, which players and media servers pick up on their own. If the subtitle only exists inside the M4V, extract it with a local tool before converting — afterward it is nowhere.

If the destination is a phone, a tablet or a slow home network, the resolution control is where the saving is. Halving the width and height quarters the pixel count, and a 4K file on a device with a 1080p screen is spending storage and bandwidth on detail the screen cannot show.

The control only ever reduces. Asking for more than the source has is ignored on purpose: upscaling produces a larger file containing exactly the detail that was already in the smaller one. Combine a resolution reduction with the balanced quality band and a large recording usually lands at a fraction of its original size with nothing visibly lost on the target screen.

This runs inside the browser tab on your own processor, and the file is never sent anywhere. For this pair that matters more than usual, because the M4V files people convert are frequently personal: home video off a Mac, a recorded family event, a course somebody paid for, footage from a phone.

It is also simply faster. On a hosted converter, several hundred megabytes has to go up before any work starts and come back down afterwards, and on a domestic connection the upload alone normally takes longer than this entire conversion. There is no queue, no account and no daily count; the free tier accepts files up to 100 MB.

Keep both, at least until the MP4 has done the job it was made for. The M4V is the better copy and the one to convert from again if the resolution turns out wrong; the MP4 is the one that plays on the television. Deleting the source immediately after a lossy conversion is the single most common way a video gets quietly worse over a few years.

If storage forces a choice, keep whichever came directly out of the camera or the editor. A delivery file is replaceable by converting the master again; a master is not replaceable by anything.