Understand a media file's format before converting it
A media file has two layers: the container — named by the extension, like .mp4 — and the codec, the way the picture and sound are packed inside it, like H.264. A device refuses a file when it cannot read one of those layers, and knowing which one it is saves pointless conversions.
Reviewed 9 Nov 2026
Who it suits
- A photo or video from one device will not open or play on another device
- A TV, computer or app says the format is not supported
- You are about to convert a file and want to convert it to the right thing, once
Who it doesn’t suit
- The file is damaged, or was only partly copied across — a format change cannot repair it
- The file is copy-protected (for example a purchased film); conversion cannot and should not remove that protection
Start guided mode or read all 6 steps below — guided mode is never mandatory.
Before you start
Preparation
- Make a spare copy of the file to experiment with — this method never converts your only original.
- Note which device refused the file and, if it showed one, the exact message it gave.
▲ Caution — possible effects
- Converting creates a new file and can reduce picture or sound quality; the original is unchanged as long as you keep it, as this method insists.
- Installing codec extensions on a computer changes what that computer can play, for all apps, not just one file.
⬢ Stop if…
- Convert a copy, never your only original — if a conversion goes wrong, the original must still exist.
- Stop if the file is protected content. A format change will not legitimately remove that protection.
Original sources
- Upload HEIF and HEVC photos and videos to OneDrive — Microsoft Support (Official documentation — accessed 9 Nov 2026)
- Back up photos & videos — file types that can be backed up — Google Photos Help (Official documentation — accessed 9 Nov 2026)
- Photos app error: 'Can't view this file type' (HEIF and HEVC) — Microsoft Support (Official documentation — accessed 9 Nov 2026)
Steps
Read the extension first
Find the letters after the dot in the file name — .mp4, .mov, .heic, .mkv. That is the container: the box the media travels in. On Windows, right-click the file → Properties shows its 'Type of file'; on Android, the Files app's details show the type.
Understand the second layer: the codec
Inside the box, the video is stored using a codec such as H.264 or H.265 (also called HEVC). Two files can both be .mp4 yet use different codecs — which is why one .mp4 plays on a device and another does not.
Know the most widely supported combination
An MP4 file with H.264 video is the most widely supported combination across phones, computers, TVs and browsers. If you do need to convert a video for sharing, that is the target to choose. Google Photos' own backup list includes .mp4 video and .jpg/.heic photos.
Expect HEIC and HEVC caveats
Photos from iPhones are often HEIC and their videos HEVC — Microsoft notes these are the default formats on most Apple devices. Many Windows PCs cannot open them out of the box: Microsoft describes installing the HEIF and HEVC extensions, having files converted automatically when they are re-imported or emailed, or viewing them through OneDrive as the options.
Check the format details before changing anything
A quick way to check: open the file's properties or details and look for format and codec information (on Windows, Properties → Details shows the video and audio codecs for many media files). Write down both the container and the codec — that pair of facts tells you whether a conversion can help at all.
Convert only a copy, then test it
Use a converter you trust to make a copy in MP4 with H.264, keep the original untouched, and test the copy on the very device that refused the first file. If the copy plays, send the copy — and keep the original as your master version.
How to check success
Finishing the steps is not the same as fixing the problem. You are done if these practical checks pass:
- Check: Can you state the file's container (its extension) and, where your device shows it, its codec?
- Check: Does a converted copy in MP4/H.264 play on the device that refused the original?
- Check: Is your original file still safely stored, unconverted?
If it fails
- If even an MP4/H.264 copy will not play, the file itself may be damaged or only partly copied. Copy it again from the source device, compare its size with the original — the related method shows how to check a file's size and format — and try once more before suspecting the playing device. Related method: Check a file's size and format before you change anything ›
Evidence, review and results
- Source
- Official documentation
- Testing
- Not team-tested
- Reports
- No reviewed results yet — be the first to record yours.
An official source means the maker documents this procedure — it does not mean our team has run it, and one person’s success is not a guarantee for everyone. Public counts appear only when reviewed reports exist; none are published yet.
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About this method
Change note: First published version. Where one team did the writing, reviewing and (when done) testing, the same name appears in each role — we say so rather than invent separate people.