PM123 Plug-in Developer's Guide

Developing PM123 Plug-ins

PM123 1.2 supports four kinds of plug-ins: visual, decoder, output and filter. Visual plug-ins are used to peek at the data currently being heard (or not) by the user through the output plug-in and visually produce data from it back to the user. Decoder plug-ins are used to decode different types of files, tracks or streams the user can play. Output plug-ins is the final destination of the decoded data. It can be rerouted to a sound card, to the hard disk or anywhere else appropriate. The data is in standard PCM format. Filter plug-ins are chained between the decoder and the output plug-in to modify the PCM data before getting to the output plug-in.

Visual plug-in interface has not been changed since version 1.0, eventhough they could be ameliorated in the future. Currently, Visual plug-ins allow the creation of internal or external windows and they can tap into PM123 in several ways: they can retrieve currently playing samples, control PM123 and so on. Plug-ins are Dynamic Linked Libraries, DLLs, which PM123 loads on use. Note that visual plug-ins cannot be loaded via PM123's Properties dialog because they are skin specific. They can of course be loaded when loading a new skin.

plugin.h contains the necessary structures for all pm123 plug-ins. A plug-in must have a function that identifies it as a plug-in:

    int _System plugin_query(PPLUGIN_QUERYPARAM param);

The plug-in will then have to fill the variables in the param structure, for example:

     param->type         = PLUGIN_VISUAL; /* Identify the plug-in as
visual plug-in. Types can be ORred to include multiple plug-in types in
the same DLL. */

     param->author       = "Matti Meikäläinen";
      /* Author of the plug-in */

     param->desc         = "Example plug-in";
      /* A short description of the plug-in */

     param->configurable = TRUE;
      /* Toggles plug-in configurability via PM123 Properties dialog */

If you set param->configurable = TRUE, configuration dialog should appear when PM123 calls

     int _System plugin_configure(HWND hwnd, HMODULE module);

where hwnd is the notebook window so that you can "lock" your window on it if you want and where module can be used to load a resource from your DLL

Visual plug-ins should deinitialize and destroy their windows and free allocated memory when receiving a

     int _System plugin_deinit(int unload);

It can also be used to save settings in your INI file for other sort of plug-ins.

Developing PM123 Plug-ins

Now, which type of plug-in to you want to program?