Video
Converting a MOV video to MP4: when it is instant, and when it must be re-encoded
Videos shot on an iPhone, or exported from QuickTime and iMovie, have the .mov extension. They play fine on a Mac, but sometimes cause trouble elsewhere: an online form that rejects them, a TV that refuses to open them, Windows software that shows a black picture. MP4 almost always solves these problems. Depending on what your file contains, though, the conversion can be instant and completely lossless, or require real re-encoding work.
MOV and MP4: close cousins
MOV is the QuickTime container format created by Apple; MP4 was standardised from it. The two therefore have a very similar structure, and can carry the same codecs, that is, the same ways of compressing picture and sound. The difference is mainly compatibility: MP4 is an ISO standard recognised by virtually every device, program and website, whereas MOV remains tied to the Apple ecosystem.
If the idea of containers and codecs is unfamiliar, our guide on containers and codecs explains it in detail. The key point here: what matters is not just the extension, but the video codec inside the file.
Case 1: an H.264 MOV, the instant conversion
If the video is encoded in H.264, the most widespread codec, FileXvert does not need to re-encode it: it copies the video track as it is into an MP4 container. This operation, called remuxing, takes a few seconds even for a long file, and the picture quality is strictly identical to the original.
This is the case for iPhone videos recorded in Most Compatible mode, Android devices and most consumer cameras. FileXvert detects the codec automatically: there is nothing to set, as long as you do not ask for size reduction or a resolution change, both of which require re-encoding.
Case 2: an H.265 MOV, re-encoding required
Since 2017, iPhones record by default in H.265, also called HEVC (the High Efficiency setting). This codec compresses better than H.264, but many devices, browsers and programs cannot decode it. Simple remuxing would therefore not be enough: the resulting MP4 would have the same playback problems.
In this case, FileXvert re-encodes the video to H.264. It takes longer, since every frame is decoded and then recompressed by your own device, and it introduces a slight loss that is hard to notice in normal playback. The resulting file plays everywhere.
What we measured
To illustrate both paths, we converted an 89-second smartphone video, shot in 1080p at 60 frames per second, in H.264 with uncompressed (PCM) sound, 261.3 MB to begin with.
| Conversion | Size | Picture |
|---|---|---|
| Remux MOV → MP4 (automatic) | 247.1 MB | Identical to the original |
| H.264 re-encode, no reduction | 181.5 MB | SSIM 0.977: difference hard to notice in normal playback |
| Re-encode, balanced reduction | 77.5 MB | SSIM 0.955: loss of fine detail visible on a paused frame |
| Re-encode, smallest size (720p) | 16.8 MB | 720p, SSIM 0.868: clear loss in full screen, fine on a phone |
Remuxing still shrinks the file by 14 MB: the uncompressed sound is converted to AAC, the standard audio format of MP4. If your only goal is to make the video playable, it is the best option. If you also need to make it lighter, balanced reduction divides the size by more than three here.
The steps, and the checks
Drop the MOV file on the conversion page, choose MP4, then prepare the converter and start the conversion. Before deleting anything, check the result:
- Open the MP4 and skim through the beginning, middle and end.
- Check lip sync on a passage where someone is speaking.
- Check the orientation: a video shot in portrait should stay in portrait.
- Test the file on the target device or service.
- Keep the original MOV, at least until the MP4 has been approved.
The free plan accepts files up to 100 MB. For a long video like the one we measured, you need either the Premium plan (up to 2 GB) or to trim the video on your phone beforehand.
Avoiding the problem at the source
If you often share iPhone videos with people using other devices, you can change the recording format: in Settings, under Camera then Formats, the Most Compatible option records in H.264. Files will be somewhat larger, but will convert to MP4 instantly, or even play directly. Conversely, keep High Efficiency if storage space on your phone is your priority.