Many raster processing libraries, including RasterFrames and Rasterio build on top of the GDAL library.  The following excerpt from GDAL's documentation describes what this library does:

GDAL is a translator library for raster and vector geospatial data formats that is released under an X/MIT style Open Source License by the Open Source Geospatial Foundation. As a library, it presents a single raster abstract data model and single vector abstract data model to the calling application for all supported formats. It also comes with a variety of useful command line utilities for data translation and processing.

Learn more on the GDAL website.