.DM File Extension

A DM file is a file that has been copy-protected by Sony Ericsson DRM Packager or another Symbian OS mobile phone DRM app. Most often, DM files contain a ringtone or other audio clip. However, some DM files contain a digitally-signed mobile app. DM files can be installed only on an authorized cell phone.

The Nokia Ovi Store is a notable source of DM files. Typically, the Ovi Store downloads and installs DM files in the background, so users will never encounter them. However, users sometimes download DM files manually, using an app like the Ovi-Store add-on for the Opera web browser, and save them to their computers. Users can then install these DM files using Nokia Ovi Suite.

For example, users might encounter DM files saved with the .SIS.DM and .SISX.DM extensions. These files are copy-protected .SIS and .SISX files, which often contain apps downloaded from the Nokia Ovi Store.

Sony Ericsson phones also use audio files and apps saved as DM files. Both types of phones use Symbian OS, so the DM files they use are similar.

You can open SIS.DM and SISX.DM files with SISContents (Windows), a tool that allows you to unpack Symbian OS SIS packages. Before doing so, you must:

1. Open the file in a hex editor and delete its first four lines of text.
2. Rename the file to use the .sis or .sisx extension.

You can attempt to open other DM files in a similar manner (by deleting the files' first four lines of text, renaming them to remove the .dm extension, and opening them in an appropriate program).

A DM file is an encrypted file created by the Gallery app included with select LG mobile phones, such as the G4 and G5. It contains a video or image that a user has encrypted to prevent the content from being viewed by other users. DM files can be viewed only using the LG Gallery app, by opening the file and providing the correct PIN number or fingerprint.

LG users may create DM files when opening an image or video, such as a .JPG, .GIF, or .MOV file, in the Gallery app. While viewing the image, the user can tap Lock in the top-right menu and set a PIN number to protect the file.

DM files are meant to be opened in the Gallery app of the LG phone that created them, using the PIN or fingerprint used to lock the file.

However, if your LG phone dies and you manage to retrieve your DM files, you may be able to open them on another LG phone. Doing so requires transferring your DM files to your computer, creating a new locked image or video on your new phone, and then transferring your old DM files to your new phone (placing them alongside the new locked picture/video). For more information on this workaround, refer to the November 11, 2016 and December 11, 2016 posts in this XDA forum thread.

A DM file is a code file used by BYOND Dream Maker, a free online multiplayer game creation platform. It contains code written in BYOND's DM programming language. DM files are included within BYOND Dream Maker projects; Dream Maker compiles a project's DM file(s) to produce a working video game.

Build Your Own Net Dream, better known as BYOND, is a game development engine that can be used to create, play, and publish multiplayer video games. To do so, developers download BYOND and use BYOND Dream Maker to write their games in the program's unique DM programming language. Developers save a game's code within DM files, which Dream Maker uses to compile all the code within a project and run the developer's game.

A BYOND Dream Maker project can include any number of DM files. Simple games might consist of just one DM file, while complex games might consist of multiple DM files that define only certain aspects of a game.

You should open a DM file in BYOND Dream Maker (Windows, Linux), as it contains language-specific tools that will help you edit the DM code contained within the file. However, because DM files are plain text files, you can also open and edit them in any text editor if needed.