Convert M4V to FLAC

FLAC is genuinely lossless and here it losslessly preserves an approximation. The AAC in the M4V analysed the sound, decided what a listener would not notice and discarded it, permanently, before the file ever reached you. Encoding the result as FLAC keeps every remaining sample exactly and adds nothing.

That is worth stating before the disk space is spent, because the word "lossless" sitting in a library is misleading to whoever reads it in five years. A FLAC made from a delivery encode is a faithful copy of a compressed recording, and labelling it as such at the time is the difference between an archive and a set of files nobody can interpret.

Apple built its own lossless codec, ALAC, and its software is arranged around it. FLAC came from Josh Coalson in 2001, moved to Xiph.Org in 2003 and became the standard everywhere else — the registry lists Audacity, foobar2000 and VLC as the software that reads it, and iTunes is conspicuously not among them while it is listed against M4A.

So this conversion is a move between ecosystems as much as between codecs. That is fine if the collection is already outside Apple’s, on a NAS or in a music manager that reads everything. It is an odd choice if the destination is the same Music app the M4V is sitting next to, where the file will need an extra player to open at all.

There is an argument specific to this source, and it inverts the usual advice. The M4V holds AAC packets that somebody encoded once, deliberately, at a chosen bitrate. The Extract audio tool on this site writes an M4A without requesting a bitrate, which is the condition under which those packets are carried across untouched — no decoder, no encoder, no second opinion about the audio.

A FLAC, by contrast, is a lossless recording of what this browser’s AAC decoder produced. That is a good copy of a decode rather than the delivered bitstream itself, and it is several times larger. For preserving what was distributed, the packet copy is the more faithful artefact; for feeding tools that only read lossless formats, the FLAC is the one that opens.

The registry records FLAC as carrying up to eight channels. A 5.1 mix is six and a 7.1 mix is eight, so both fit, and a film or concert soundtrack keeps its channel layout rather than being folded into stereo.

That is the concrete reason to pick FLAC over MP3 for material where the mix is part of the work. MPEG-2 Part 3 did specify a multichannel MP3 and nothing in practice writes one: LAME encodes stereo, players expect stereo, and a surround mix has to be folded down to get there. If the M4V is a live recording, a documentary with a designed mix or a music video mastered in surround, this is one of the few places the larger file buys something specific rather than something theoretical.

Most M4V files are people talking, and for people talking a FLAC is storage spent on nothing anyone will ever hear. The exception is the category where the soundtrack is the point: a filmed performance, a music video, a recital somebody in the family played at, a live set that was never released separately.

For those the audio is the part with a future and the picture is incidental, which reverses the usual weighting. It is also the case where the second consideration above bites hardest, because a music soundtrack is exactly where a decode-and-re-encode is measurable — and where the packet copy, if it is available to you, is the better first move.

VLC, Audacity and foobar2000 read FLAC as a matter of course, as do media servers, most Linux desktops and every serious music manager. Android has handled it natively for years. What is missing is the obvious one: Apple’s own applications, which is a real inconvenience when the source file arrived through them.

Plan for it rather than discovering it. If the archive will be browsed from a phone, install a player that reads FLAC before converting a hundred files; if it will only ever be read by a server or a script, none of this matters. An archive nobody can open is a backup, and a backup is a different thing from a collection.

Expect a multiple rather than a fraction. FLAC typically lands between 40 and 60 per cent of the equivalent uncompressed audio, with speech at the efficient end, and the M4V’s AAC soundtrack was a small fraction of that to begin with. A recording that occupied tens of megabytes as delivered audio occupies hundreds as FLAC.

The other number is on the input side and it is the one that stops people: the free tier accepts files up to 100 MB, and long-form M4V material is usually far above it. Trimming the piece worth keeping in QuickTime Player before converting is both the workaround and, more often than not, the correct archival decision — a collection of the parts that matter beats a shelf of complete files nobody indexes.

Anything bought or rented from the iTunes Store or the Apple TV app carries FairPlay encryption, so the audio cannot be decoded in a browser and the conversion reports that nothing in the file could be converted. No tool here removes protection, and archiving purchased media was never what this pair is for.

What it is for is material somebody made or was given: a Compressor export, a camera recording, a course download, a video from a family archive. The M4V to MP4 page explains how to tell the two apart quickly, which is worth doing once across a shelf rather than file by file.

Up to a hundred files can be converted in one pass, each with its own progress, downloading together as a ZIP. The encoding runs in the tab on your own processor, so a large batch is limited by the machine rather than by an allowance, and nothing carrying the audio is transmitted at any point.

For preservation work that is the sensible arrangement rather than a talking point. The recordings people convert to FLAC are the ones with the longest expected life and the least tolerance for being handled carelessly, and routing a decade of them through an unfamiliar server is a poor opening move in a plan that is meant to last decades more.