<p>This has been puzzling me for many months because I've never had trouble with m4a files on my windows 7 machines but a friend with 3 windows 7 machines available can never get m4a files to work, despite loading VLC. So we have to convert to mp3 which always work for her.</p><p>My question is, would the audio editor Audacity, which is installed on all my machines but none of hers, explain this difference? It hadn't occured to me until reading this thread, particularly the remark made later about codec packs, that OpenLP might be able to pick and use something that Audacity installs but I have been stumped for a long time trying to think of differences between her machines and mine. Would the FFmpeg import library, which Audacity needs for WMA files, be necessary as well, or is it just Audacity? (I'm not lazy, but would prefer not to appear to be just 'trying things out at random' on someone else's machine.)</p><p>Many thanks</p>