Forte identifies all plugins by a unique identifier called a CLSID.  The CLSID of a plugin can be found in the plugins.xml cache file and it looks something like {305B2033-9E2D-4FF1-A6D4-6930EC21AB26} but is different for each plugin.

CLSIDs were originally a unique identifier for DirectX (and DirectShow) plugins.  For VST plugins, Forte created a CLSID by hashing together the plugin’s VST ID value with the plugin’s DLL name and combining the result with a standard fragment of CLSID {xxxxxxxx-9E2D-4FF1-A6D4-6930EC21AB26}.

This has always worked well except that many plugin vendors deliver the 32 bit and 64 bit plugins with the same VST ID but using different DLL filenames.  This unfortunately results in different generated CLSIDs.  For instance, the CLSID generated by 32 bit Forte uses the 32 bit DLL plugin name and the 64 bit uses the other DLL plugins name, resulting in different CLSIDs, which if not accounted for makes it impossible to load some rack files built in 32 bit Forte into 64 bit Forte.

Plugin Cache (plugins.xml and plugins64.xml)

Forte keeps track of discovered VST plugins in a “cache” file called plugins.xml (for 32 bit) and plugins64.xml (for 64 bit).  The Forte installer will attempt to migrate the Forte 2 plugins.xml cache file if it is available and a Forte version doesn’t already exist.  This means that in most upgrades from Forte 2 or 3 (32 bit) to 64 bit, a 32 bit plugins.xml file will be available to 64 bit Forte as well as its own plugins64.xml.

Forte 64 bit will load its plugins64.xml cache normally, but will also scan the “alternate” plugins.xml file for information about potential substitutions.  If you load a 32 bit rack file into Forte 64 and it doesn’t have a particular CLSID (because that CLSID was generated in 32 bit Forte), it will replace the plugin with the 64 bit version of the VST plugin if it shares the same VST ID.

For this feature to work, a 32 bit plugins.xml file must be available in the same location as plugins64.xml.

When installing 64 bit Forte, make sure you either select the option to migrate Forte 2 data, which will copy the plugins.xml from the Forte 2installation folder to the new Forte folder.  Alternately, you may copy the plugins.xml file into the Forte installation folder manually.