Gstreamer reported that MP3 or MP4 Is not supported in this media player
First off, of course mp3 and mp4 are generally supported by Parole, but you need the relevant gstreamer-plugins. Did you install those? Other than that, please always include the version-number of Parole and the distribution you're using (as a minimum requirement) – the bugreport isn't very helpful without that information. Thanks!
I'm having a similar problem, I think ... Using 0.5.2 and the new 0.5.3, ubuntu 13.04, when first opening a file (tested with mkv), I've had a message telling it needed DTS decoder to read the file, with possibility to install, but it froze parole so I had to force-close it. Same thing with AAC when opening a mkv file requiring such codec. After this, when I reopen the same files, there's no problem/messages at all. Of course, all needed plugins are already installed ...
I'd attribute both issues to gstreamer frankly. Does this still happen with 0.6?
This is likely a problem with the gstreamer plugins installer. As we won't rewrite this feature to work properly the solution is to install the needed gstreamer plugins through the package manager (and hopefully distributors will set the recommends of parole accordingly, so the most needed plugins come with installing parole).