NUT File Format (.nut)
A NUT file is a general-purpose media container created inside the FFmpeg and MPlayer projects, built as a simple, open, patent-free alternative to AVI and similar formats, and able to wrap any codec those tools support.
NUT at a glance#
| Full name | NUT open container |
|---|---|
| File extension | .nut |
| Category | Video Files |
| Developer | FFmpeg and MPlayer projects |
| Compression | Varies from file to file |
| FileFlip support | FileFlip reads and writes this format |
What a .nut file can hold#
These are the things a NUT file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Embedded metadata | Yes |
|---|---|
| Audio | Yes |
| Video | Yes |
| Streaming | Yes |
Strengths and limitations of NUT#
What NUT does well
- The container spec itself is open and unencumbered by patents, unlike AVI-era formats it was meant to replace
- Frame headers are designed to resync after corruption, so a damaged file does not necessarily take the rest of the stream down with it
Where NUT falls short
- Almost nothing outside FFmpeg, MPlayer and players built on their libraries reads or writes NUT
- It never displaced Matroska as the flexible-container format people actually reach for, so support stayed limited to its own ecosystem
- No professional editing software, phone or streaming platform accepts NUT as an input or delivery format
NUT is worth using only inside an FFmpeg-based pipeline, such as a test harness or a tool chain that already standardises on it.
Convert NUT to MP4 or MKV for anything that needs to open outside FFmpeg or a player built on its libraries, since almost no other software recognises the container.
How to open a .nut file#
A .nut file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts NUT into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | ffplay, mpv |
| macOS | ffplay, mpv |
| Linux | ffplay, mpv, Xine |
| Web | FileFlip |
NUT questions people ask#
What opens a NUT file?
ffplay and mpv both open NUT files directly, since both are built on FFmpeg's own libavformat library, which is where the NUT container comes from. Outside that ecosystem, support is essentially nonexistent.
Why would a file be in NUT instead of MP4 or MKV?
NUT usually turns up as the output of an FFmpeg-based tool or test pipeline rather than something a person chose deliberately, since it was designed as an open, patent-free container within the FFmpeg and MPlayer projects. Matroska ended up filling the same role for everyone else.
Is NUT related to Matroska or AVI?
NUT was designed around the same time as Matroska and for a similar reason, as a flexible, open alternative to AVI's limitations, but the two are independent formats with no shared structure. Matroska is the one that ended up widely adopted; NUT stayed inside the FFmpeg and MPlayer projects that built it.
Converting NUT files#
Convert NUT to another format
Convert another format to NUT
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.