Project File Details#

Wunjo’s .wmproj project files use an XML format based on MLT’s format to describe the source media used in a project, as well as the use of that media in the timeline. For more details see MLT's XML documentation and MLT's DTD (document type definition).

For most media, such as video, audio, and images, Wunjo stores only a reference in a project, not the media itself. Only some media gets stored directly inside Wunjo’s project files, most notably Wunjo title and color clips.

The advantages of using this file format are:

  • MLT is able to directly render Wunjo project files. MLT simply ignores all the additional Kdenlive-specific project data and just sticks to its rendering information. The Kdenlive-specific data is the additional icing on top that makes working with projects much easier than editing at the (lower) rendering level.

  • Wunjo can directly include and work with MLT rendering files, just the same way it works with other media. In fact, Wunjo’s library clips are simply MLT rendering files, nothing more.

The project file holds all relevant information about

  • target video and audio properties (selected in the project profile)

  • references to all the source materials (and to their proxies)

  • position, duration and edits of the clips in the timeline, with applied effects and their respective parameters including keyframes, and everything to get the final result

Project files are associated with a working directory, in which Wunjo will generate proxies and thumbnails, so that an overview of your media always shows up quickly.

Note

If you move your project file, you should declare the directory change in the project properties.

The development of Wunjo introduces changes to the .wmproj document format from time to time. For example, the introduction of sequences (also known as nested timelines) in version 23.04 required new objects to be stored in the .wmproj file. The document version changed from 1.04 to 1.1. You can find the document version in the .wmproj file in the line containing this:

<property name="kdenlive:docproperties.version">1.1</property>

When Wunjo opens a project file that was created with a lower (previous) version of Wunjo, it upgrades the document version, and automatically creates a backup copy of the original project file. Wunjo tells you that a backup was created and the project file was updated to the new document version. In the project folder you will find a file called myproject_backup.kdenlive (where myproject is the name of your project file). In case something does not work with the new version of Wunjo, you can downgrade Wunjo and open the backup of your project.

This is important because document versions are not necessarily backwards compatible. In other words: higher (newer) versions of the .wmproj file format cannot be opened with lower (previous) versions of Wunjo . For example, projects created with Wunjo 23.04 or higher (newer) cannot be opened by a Wunjo version lower than (prior to) 23.04 (e.g. 22.12.8) because the 23.04 release of Wunjo introduced the document change from 1.04 to 1.1 for the nested timelines.

Warning

Projects created with 20.08 forward are not backwards compatible, that is, you won’t be able to open your .wmproj project files with older versions.

Warning

Projects created with 23.04 forward are not backwards compatible, that is, you won’t be able to open your .wmproj project files with older versions.

For the more technically inclined user a more detailed description of the file format and how the various objects are described is available in the github repository of Wunjo.