MP4 vs MOV

MP4 was standardised in 2001 directly from Apple’s QuickTime file format. The internal structure is the same idea — a tree of boxes describing tracks, timing and sample positions — and a great deal of the specification is shared word for word.

Which means a MOV and an MP4 containing H.264 video and AAC audio are, in practice, the same file with a different four-character brand written near the front. A desktop tool told to copy the streams — `ffmpeg -c copy` is the usual one — moves them across in about a second and leaves the picture bit-for-bit identical. The converter this page links to is not that tool: it decodes and encodes again, which costs time and one generation and is also what turns an HEVC recording into something Windows will play.

Everything a production workflow needs and a delivery format has no use for. ProRes, Apple’s editing codec, which is very large, very fast to scrub and largely confined to MOV. An alpha channel, so a graphic can be rendered with real transparency. Timecode tracks, which is how footage from several cameras is lined up. Multiple audio tracks with proper channel labelling.

MP4 can technically hold some of this and in practice tools do not expect it there. If a file needs to carry any of it, it is a MOV, and that is the entire reason the format still exists rather than having been retired into MP4.

MP4 is the most widely accepted video file there is: televisions, phones, browsers, editors, presentation software, car systems, digital signage, upload forms. It is the safe answer whenever the destination is unknown.

MOV is entirely at home on Apple hardware and increasingly fine elsewhere — VLC plays it, Windows plays common ones, editors accept it. Where it fails is upload forms and older or embedded devices, which check the extension and refuse. A MOV holding ProRes fails much more widely, because there the codec really is the problem rather than the container.

An iPhone records MOV. That is why the format turns up on machines that have never seen a Mac, and why the usual question is how to get it into something that will accept it.

For anything shot on a phone the video inside is already H.264 or HEVC, so the container change itself asks nothing of the picture. What costs you is the tool. A desktop tool that copies the streams finishes in seconds and alters nothing; the browser converter this page links to decodes the video and encodes it again as H.264, which takes time proportional to the length of the clip and spends one lossy generation — and is also the reason an HEVC recording comes back playable on a Windows machine.

The related trap is HEVC. Recent iPhones record it by default, and while the container converts trivially, older software may still refuse the codec. Setting the camera to "Most Compatible" records H.264 instead, which avoids the question at the source.

Edit in MOV when the footage is MOV, especially with ProRes: scrubbing is dramatically faster than with a delivery codec, because ProRes is designed to be decoded a frame at a time rather than in long compressed sequences. The files are enormous and that is the trade being made.

Deliver in MP4, always. Nobody watching a finished video benefits from the container it was cut in, and every awkward playback conversation disappears. Keeping the MOV masters and exporting MP4 for distribution is the arrangement every editing workflow converges on.

Nearly every complaint of this shape is about the codec rather than the container. Two things travel inside MOV files that Windows often cannot decode without help: ProRes, which comes out of professional editing, and HEVC, which is what recent iPhones record by default in their space-saving mode.

Renaming the file changes nothing, because the container was never the problem. Converting it re-encodes to H.264 and produces a file that plays anywhere, at the price of one lossy generation. The alternative, if the file came from your own iPhone, is to switch the camera to Most Compatible before recording rather than converting afterwards.

A minute of 4K at 60 frames a second is roughly 400 megabytes in the space-saving HEVC mode and roughly double that in the compatible H.264 mode. The container makes no difference to either figure — the same footage in MP4 and in MOV is the same size, because the video data inside is identical.

This is worth stating because the two settings on the phone change both things at once and are easy to read as one choice. Most Compatible produces H.264 in a MOV that plays anywhere and takes twice the room; High Efficiency produces HEVC that halves the room and is what Windows machines then struggle to open. The container is not the variable in either case.

Neither container. Size is a function of the codec, the bitrate, the resolution and the frame rate, and a MOV and an MP4 carrying the same H.264 stream differ by a few kilobytes of header.

When somebody reports a MOV being five times larger, the codec is different — usually ProRes, which is meant to be large, or an older intra-frame codec from a camera. Converting the container will not change that. Re-encoding to H.264 will, and that is a different operation with a different cost.

Keep the original, whichever it is. A camera or phone original has been through one encode; every copy after that is a generation down unless it was rewrapped rather than re-encoded.

Then hold MP4 as the copy you share, upload and hand to people, and keep MOV only where its extras are actually in use — ProRes masters, anything with an alpha channel, multi-camera footage with timecode. For an ordinary video of a family occasion, MOV offers nothing MP4 does not, and MP4 will open on more of the devices it is going to be watched on.