MOV - Apple QuickTime Movie

MOV is the QuickTime movie format, introduced by Apple in 1991 with the first version of QuickTime. It was one of the earliest formats able to hold synchronised video, audio and other timed data in a single file, and it was so well designed that MPEG later adopted it as the starting point for the ISO Base Media File Format, the foundation MP4 stands on. That history matters for a practical reason: a MOV and an MP4 are structurally close cousins. MOV is still the native recording format of iPhones and iPads, and the working format of Apple's editing programs, so most people meet it either straight off a phone or on the way out of an editor.

How a MOV file is put together

MOV is a container: the box, not the compression. The picture and sound inside are compressed by a codec, and which codec you find says a lot about where the file came from. Video from a modern iPhone is usually H.264 or HEVC with AAC audio, both lossy. Files that came out of an editing suite are often ProRes, a codec designed to survive repeated editing and re-saving with very little visible loss, at the price of much larger files. MOV can also hold an alpha channel for transparency and a separate timecode track, which is why it stays popular in professional work.

The internal structure is a tree of blocks Apple calls atoms, each labelled with four characters. moov is the index of the whole movie, mdat holds the media itself, and each track gets its own sub-tree with a header and a set of tables that map time onto byte positions. Because the index is separate from the data, a MOV can reference media without duplicating it, and cutting a clip can be a matter of rewriting tables rather than re-compressing pictures.

What metadata a MOV file carries

MOV metadata is stored in atoms, and a phone recording is one of the richest video files you will look at.

• The movie header holds creation and modification dates. QuickTime counts them in seconds from the first of January 1904, so a badly written file sometimes shows a date in that year.
• Track headers give dimensions, duration, a language code and a transformation matrix that records rotation, which is how a phone marks a clip filmed in portrait.
• A user data atom holds classic QuickTime tags whose names start with a copyright sign: title, author, artist, comment, copyright, description and the software that wrote the file.
• Apple devices add their own set of keys covering the camera make, the camera model, the iOS version, a creation date that includes the time zone, and the recording location as latitude and longitude.
• An iPhone clip usually also carries a timed metadata track, a hidden stream that records sensor readings alongside the picture rather than once for the whole file.
• Software from Adobe may add an XMP packet, a structured text block repeating title, creator, copyright and edit history.

The camera make, the model, the software version, the time zone and the coordinates are all personal information. Together they say where you were, when, and what you were holding. Those are the fields to strip before a clip filmed on your own phone goes anywhere public.

When to use MOV instead of MP4

Keep MOV while you are working: it is the format Apple's tools are happiest with, it carries ProRes, transparency and timecode, and it survives an editing round trip better than a heavily compressed delivery file. Convert to MP4 when you are finished and the file has to travel, because MP4 plays on more devices and browsers with less argument. When both use H.264 or HEVC the conversion can be a straight remux, which changes the wrapper and leaves the picture untouched.