DUK File

What are DUK files and how to open them

Are you having problems opening a DUK file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your DUK files.

What is a DUK file?

A .DUK file is a Duck Corporation TrueMotion 1 Video file.

Duck Corporation TrueMotion 1 Video File is a legacy video file format created using the TrueMotion 1 (also called TrueMotion S) codec by The Duck Corporation (later On2 Technologies). It was designed for full-motion video content such as cut-scenes in mid-1990s PC and Sega Saturn games. It stores motion video data in a proprietary compressed format rather than raw frames. Bitberry File Opener is known to read these files.

These files are typically written during game development or during production of multimedia content using TrueMotion 1 as the codec. After creation, they are decoded by players or video tools that support TrueMotion 1 (for example via FFmpeg's "truemotion1" decoder) to be viewed or converted into more modern video formats. Because TrueMotion 1 files often live inside AVI containers or other game-archive packages, extracting and decoding is usually required before playback.

Technically, TrueMotion 1 uses interframe differencing and differential pulse-code modulation, compressing pixels using small delta predictors with block-based coding. Only 16-bit RGB formats (RGB555 or RGB565) are reliably decoded in most implementations; 24-bit color support is limited or unsupported. Headers are encoded with a small encryption/obfuscation: the first byte encodes header length via a rotate-left by 5 then mask operation, and each following byte is XORed with the next to extract real header fields.

How to open DUK files

We have identified one DUK opener that is compatible with this specific type of DUK file.

Programs that open Duck Corporation TrueMotion 1 Video files

Last updated: August 6, 2026

Various apps that use files with this extension

These apps are known to open certain types of DUK files. Remember, different programs may use DUK files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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