The h-mixr.prm file is the Audio Mixer plugin for Adobe Premiere from Adobe Systems Incorporated.  Adobe’s video editing program is called Adobe Premiere, and plugins to this application usually have an extension of prm.  Third party software creators make some extensions for Premiere and Adobe that includes a number of them as part of their product.  The Audio Mixer is one of the plugins that was included in Adobe Premiere 6.0.  This file is used in the editing and creation of sound files included with a video.

A program is made up of multiple files on a machine.  Some files are only used every once in a while, and other files are needed for every function.  Plugins tend to be tools that aren’t constantly needed and are put into different files, so they don’t load every time the program starts, slowing it down.

To keep track of these files, Windows has a database called the registry that has entries for every file that belongs to every installed program.  If you get a registry error, you may need to clean your registry with ZookaWare PC Cleaner, which guarantees 100% fix of all registry errors on your computer.