Convert M4V to M4A

An M4V is an MPEG-4 file with Apple’s extension on it. An M4A is an MPEG-4 file with a different extension, used by Apple since iTunes 4 in 2003 so that a double-click opens a music player rather than a video player. Both of them hold AAC. Structurally, the difference between the file you have and the file you want is that one of them has a video track and the other does not.

That is unusual. Most audio extractions cross between families — Opus out of a Matroska box, AAC into a raw stream, samples into RIFF — and something has to be translated. Here nothing has to be translated at all, which is why the next section is the one that matters.

In principle the compressed AAC frames could be lifted out of the M4V and written straight into the M4A: no decoder, no encoder, no loss, and the whole job finished in about the time it takes to copy the file. The underlying library supports exactly that.

This page does not take it. Every lossy target here offers a quality band, and requesting a bitrate is precisely what disqualifies the direct copy — so the audio is decoded to samples and compressed again, spending one real generation. On a lecture nobody will hear it. On a music video or a concert recording it is measurable, and it is entirely avoidable.

This site has a second route to the same file, and on this pair it is the better one. The Extract audio tool discards the video track and writes an M4A without asking for a bitrate, which is the condition under which the original AAC packets are carried over rather than re-encoded.

The practical rule is short. If the soundtrack is music — a concert film, a music video, a recorded performance — use the tool and keep the original encode. If it is speech and you want a smaller file than the source’s bitrate would give, use this conversion and set the band deliberately, because then the second pass is buying you something.

The extension is what decides which application claims the file, and that decision has consequences beyond which icon appears. Audio in a music library gets a place in a playlist, a position in an album, syncing to a watch, playback with the screen off and continuation over CarPlay. Video does not get any of those, no matter how little picture it contains.

That is the real reason this conversion exists on Apple hardware specifically. A recorded talk left as an M4V lives in a video app, stops when the screen locks and cannot be queued behind anything. The same audio as an M4A behaves like every other track on the device — which is what somebody who wants to listen on a walk is actually asking for.

The container accepts Apple Lossless as well as AAC, and nothing in the extension distinguishes them. An M4A ripped from a CD by iTunes in lossless mode and an M4A bought from a store are the same kind of file holding fundamentally different audio, which is where most of the confusion about the format comes from.

What this conversion writes is always AAC. There is no ALAC encoder available to a web page, so a lossless copy of an M4V soundtrack is not something this pair can produce — and it would be a strange thing to want, since the source was lossy AAC to begin with. If lossless storage is the goal rather than Apple compatibility, FLAC is the honest target and its own page explains what that does and does not buy.

Long-form spoken material is the strongest case for this pair. A course module, a conference recording, a narrated documentary — all of them are more useful as audio, and Apple’s Books app handles long audio better than its music app does, remembering where you stopped. It recognises audiobooks by the .m4b extension, and renaming a finished .m4a to .m4b is the usual way in; nothing inside the file changes.

What will not come along is the chapter marks. Apple-delivered video carries them more often than most sources, and they do not survive into the audio file, so a lecture series that was navigable by section arrives as one continuous run. If the divisions matter, converting each section separately gives you tracks you can actually skip between.

Nearly all of it. On a recorded talk at any normal resolution the video track accounts for the overwhelming majority of the bytes, and removing it is where the size drop comes from rather than from anything happening to the sound. An hour of video measured in gigabytes becomes an hour of audio measured in tens of megabytes.

The quality band then moves that figure by roughly a factor of two in each direction. Balanced is right for speech and for anything that will be listened to once; the high band is worth its extra size only where there is music, because this is already a second encode and a lean one has nothing in reserve. If neither answer appeals, that is the signal to use the Extract audio tool and keep the bitrate the M4V already had.

FairPlay encryption covers the whole file, not just the picture. A film or a series episode bought or rented from the iTunes Store or the Apple TV app cannot be decoded in a browser, so the conversion stops before it starts and reports that nothing in the file could be converted.

Where the file came from is the reliable test, and the M4V to MP4 page sets it out in full rather than repeating it here. In short: bought means locked; exported, recorded or downloaded from a course platform means it converts like anything else.

Decoding and encoding both happen inside the browser tab, using the AAC support the machine already has for playing the file. Nothing carrying the video is sent anywhere and there is no account. The free tier takes files up to 100 MB, which for a lecture or an episode segment is usually enough and for a feature is not.

That local arrangement is what makes this workable on the phone that has the recording. The awkward part of the problem is normally geography — the M4V is on the iPad, and the obvious fix involves a computer and two transfers. This page runs in mobile Safari, so the file goes from Files to Music without leaving the device in between.