Compress an M4V file

M4V is an MP4 with a different extension

Both are the ISO Base Media File Format: the same box structure, the same moov and mdat atoms, the same H.264 and AAC inside. Apple introduced the extension so that iTunes could distinguish video from the .m4a audio files sharing the same format, and so that macOS could route double-clicks to the right application. It is a filing decision, not a technical one.

FFmpeg does not treat it as a separate format at all. The demuxer that reads it is the same one that reads MP4, MOV, M4A and 3GP, which is why nothing on this page needs to be qualified: whatever a tool can do with an MP4 it can do with an M4V, with one exception covered below.

Before you compress anything, try renaming it

If your problem is that a player, a website or an upload form will not accept the file, change the extension from .m4v to .mp4 and try again. Nothing inside the file changes, no bytes are rewritten, and it takes a second. A large share of M4V complaints are software refusing an extension it does not recognise while being perfectly capable of playing the contents.

It does not always work, and the failures are informative. If renaming does not help, either the file is DRM-protected, or the video inside is HEVC rather than H.264 and the thing you are handing it to cannot decode HEVC — the same problem iPhone recordings have. The second one this tool fixes, by re-encoding to H.264.

If you would rather not rename files by hand, Remux with MP4 as the output does the same job properly: it rewrites the container, copies the video stream untouched, and finishes in seconds without decoding a frame.

The exception is FairPlay, and there is no way round it

Films and television bought or rented from the iTunes Store arrive as M4V files protected with FairPlay, Apple's DRM. The video track is encrypted, and the key lives in Apple's account system rather than in the file. FFmpeg will report that the stream is encrypted and stop, and that is where it ends. This tool will not decrypt it, no browser-based tool will, and pointing you at one that claims to would be dishonest.

Telling the two apart is easy enough. A protected file plays in the Apple TV app on a machine signed into the account that bought it and nowhere else, including in VLC. An unprotected M4V — anything you exported yourself from Final Cut, iMovie, Compressor or HandBrake — plays everywhere, and everything else on this page applies to it.

When an M4V is genuinely worth compressing

The files people actually need to shrink are exports rather than purchases. Final Cut and Compressor write M4V at delivery presets that are generous by design, iMovie's share options do the same, and anything ripped from your own discs with HandBrake's Apple presets lands here too. Those are ordinary oversized MP4 files and the advice on the MP4 page applies unchanged: resolution first, then bitrate.

Movie-style M4V files carry things a plain MP4 usually does not, and they do not survive the conversion. Chapter markers, subtitle tracks, alternate language audio and a 5.1 AC-3 track alongside the stereo AAC are all common, and this tool takes one video stream and one audio stream and discards the rest — the same caveat that applies to MKV files. If those tracks matter, use a desktop tool.

Settings for an M4V

If the file only needs to play somewhere, remux to MP4 or rename it, and stop. Neither costs you anything.

If it needs to be smaller, output MP4 with Best compression, and set the resolution to what it will actually be watched at rather than leaving it on original. Target-size mode also works on M4V, which sets it apart from the other legacy formats on this site — browsers open MP4-family files, so the tool can read the clip length and show you a bitrate budget before it encodes. If it does report that it cannot read the length, the extension is confusing your browser rather than the file being unusual, and renaming it to .mp4 before dropping it in will clear that up. Then pick a ceiling and let the bitrate be solved.

M4V compression questions

Compressing to a size limit instead?

If what brought you here is a number rather than the fact that it is a M4V file, start from the ceiling instead. Each of these opens the compressor with that target already set, ready for your M4V:

• 5 MB
• 8 MB
• 10 MB
• 16 MB
• 20 MB
• 25 MB
• 50 MB
• 100 MB
• 200 MB
• 500 MB

Other formats

• Compress MP4 The universal container. Usually already H.264, so the gains come from bitrate and resolution.
• Compress MOV iPhone and QuickTime recordings. Frequently HEVC or ProRes, and frequently huge.
• Compress MKV Long recordings, rips and archives. Big enough that upload-based tools often refuse them.
• Compress WebM Already efficient — so the realistic gains are smaller, and worth understanding first.
• Compress AVI Legacy codecs, dramatic savings. Read in, MP4 out.
• Compress WMV Old Windows exports. Nothing plays them now, and remuxing is not an option.
• Compress FLV A dead container, often with a perfectly modern video inside. Try remux first.
• Compress MTS / M2TS AVCHD camcorder footage. Enormous, usually interlaced, and split into 2 GB pieces.

The formats reference puts M4V beside the other containers and shows which codec combinations play where.