Compress a MOV file

Why iPhone and QuickTime files are so large

A phone recording video has a different objective from a compressor. It has milliseconds per frame to make encoding decisions, it is running on a battery, and it is capturing something unrepeatable — so it errs heavily towards spending bits. A minute of 4K at 60 fps off a recent iPhone routinely lands around 400 MB, which is not a mistake; it is the camera protecting the footage.

QuickTime screen recordings on a Mac are large for a different reason: they capture at the display's native resolution, which on a Retina panel is far more pixels than the content needs, and they do not compress aggressively while recording because doing so would cost CPU that the thing being recorded needs.

The largest MOV files of all come out of editing software. ProRes is an intermediate codec designed for editing rather than delivery — it barely compresses at all on purpose, so that every frame can be decoded independently and colour grading has room to work. A ProRes master is routinely a hundred times the size of the H.264 export made from it.

HEVC, and the compatibility problem it creates

Recent iPhones default to recording HEVC — also called H.265 — rather than H.264, because it reaches similar quality at a meaningfully lower bitrate. That is good for the phone's storage and bad for everyone you send the file to: HEVC decoding is not universal, and Android devices, older machines and a lot of web software will either refuse the file or play audio over a black frame.

Compressing to MP4 here re-encodes the video to H.264, which solves the compatibility problem as a side effect of solving the size problem. The file gets smaller and it also starts playing on hardware that could not open it before. This is usually the right move for anything you are sending to someone else. Apple publishes its own storage figures per recording mode, and they explain most of the size.

Note the direction of the trade: H.264 is less efficient than HEVC, so the same visual quality needs a higher bitrate. If you are only archiving for yourself on Apple hardware, you have two decent options — leave the file as it is and re-encode nothing, or set the codec to H.265 and shrink it while keeping the generation it was shot in. The second is far slower in a browser tab than the H.264 route, and the output is tagged hvc1 so QuickTime and Safari will open it. How much H.265 actually saves.

MOV to MP4 without re-encoding

MP4 was standardised from the QuickTime file format, which is why the two containers are structurally so close. If your MOV already holds H.264 video and AAC audio — true of most iPhone recordings from before the HEVC switch, and of most H.264 exports — you can convert it to MP4 by rewriting the wrapper alone.

That is what Remux does. It finishes in seconds regardless of how long the video is, and it loses precisely nothing, because no pixel is decoded or re-encoded. What it does not do is make the file smaller. Use it when the problem is "this will not play here" and use the compression modes when the problem is "this is too big".

Settings for a MOV

Output to MP4. Set the resolution deliberately rather than leaving it on original: 4K phone footage almost never needs to stay 4K, and dropping to 1080p removes three quarters of the pixels before the encoder even starts, which is a larger saving than any bitrate setting will give you.

If you are sending the clip somewhere with a limit — 16 MB for WhatsApp, 25 MB for email — use target-size mode and let the bitrate be solved for you.

MOV compression questions

Compressing to a size limit instead?

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

• 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 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 M4V Apple's MP4 under another name. Renaming it often solves the whole problem.
• Compress MTS / M2TS AVCHD camcorder footage. Enormous, usually interlaced, and split into 2 GB pieces.

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