Windows multimedia XML file
PRX files contain XML data referring to the audio and video codecs to be used, bit rates, and language. PRX files are used as a template for video formats used when creating a multimedia project. PRX files are referenced by Windows Media Player, Windows Live Movie Maker and Windows Media Encoder. PRX files can be edited by Windows Media profile editor which is bundled with the Windows Media Encoder installation.
Learn more about .PRX files:
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