Even the latest version of Microsoft Video Maker supports the previously used MSWMM format and thus can import these files and work with it. Using the File ► Save movie function is then possible to export only the audio from the projects as M4A.
Convert Microsoft Windows Movie Maker project to MPEG-4 compressed audio.
We found 2 software records in the database related to .mswmm to .m4a file format conversion.
Microsoft Windows software - convert mswmm to m4a on Windows
A proprietary video editor for Microsoft Windows
Convert from mswmm file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned mswmm to m4a. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A video editing software distributed with Microsoft Windows