I know other file managers, like the LXDE one, can be set up to make thumbnail previews using an executable defined in a settings file. As you can see above the command line utility "sox" can be made to generate a waveform image from a sound file. This can be used for a preview. The way LXDE does it is defined in an Open Desktop standard which is not official but has been taken on by some WM's. Use of the sox executable binary is defined in thumbnailer definition file. I could just load up the LXDE file manager in KDE, but I wonder if there is a way of doing this in Dolphin ? I am not a developer but I have built basic C++ applications before (very simple) and done scripting in BASH and Javascript, however I think coding a preview plugin is a bit beyond my capabilities at the moment. I think that what would be nice is to code a preview plugin with a config dialog that allows the user to define a CLI command the result of which is passed to the plugin and rendered as a preview. I think I've seen some developers claim this is some kind of security risk, but with appropriate warnings the user should be left to make the final decision. There are so many utils out there these days, C++, Python and all the rest that can be used to make natty previews and send info back about files. Many don't have libraries, making it difficult to develop a C++ plugin directly. So I can see a good case here for writing a general purpose plugin for this that would allow waveform previews and many other preview types to be generated from a user defined CLI command line.