CNM File

What are CNM files and how to open them

Are you having problems opening a CNM 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 CNM files.

What is a CNM file?

CNM files have multiple uses, and Arxel Video is one of them. Read more about the other uses further down the page.

Arxel Video

Arxel Video files store cutscene video and associated audio data used in the adventure game Ring: The Legend of the Nibelungen and its sequel Faust: The Seven Games of the Soul, created by Arxel Tribe. These files serve as game assets: video playback in the game engine uses them to present story sequences, rather than for general video editing.

The format is a bespoke container defined by Arxel Tribe that wraps both video and optional PCM audio. Video frames are stored in a tiled image format with interleaved tiles and support for versioned encoding schemes. Version 1 encodes each frame independently while version 2 introduces keyframe groups and interframe prediction to improve compression. Audio is represented as raw PCM from one or more tracks where present.

These files start with an ASCII signature "CNM UNR\0" at the start of a file.

How to open CNM files

Important: Different programs may use files with the CNM file extension for different purposes, so unless you are sure which format your CNM file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested three different CNM openers which you will find listed below.

Last updated: August 31, 2026

All known file formats using extension .CNM

While Arxel Video is a popular type of CNM-file, we know of 2 different uses of the .CNM file extension. Different software may use files with the same extension for different types of data.

CNM Video

CNM Video is a multimedia container format created by the game company Arxel Tribe for use in their adventure game Ring: The Legend of the Nibelungen. It stores both video and audio streams in a single file, where the video is divided into frames compressed in tiles and audio is stored as raw PCM. CI2 is a later version of this format with modified compression methods.

Files in this format begin with a specific header identifying how many frames are present, the dimensions of the video, and how many audio tracks and channels the audio has. Video frames are stored either as full images or as tiles that are delta-coded (differences from previous tiles), and in version 2 frames are arranged in small groups with keyframes and interframes for compression. Audio is uncompressed PCM data prefixed by size values.

The file begins with the ASCII signature CNM UNR and includes a table of frame offsets so that the player knows where to find each video or audio frame. Version-specific magic numbers and frame-type codes indicate whether a chunk is audio, image, tile data, or motion vector data, allowing a decoder to parse and display the content correctly.

Various apps that use files with this extension

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

Help us help others

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