Users often encounter file extensions such as .epv , .evo , or .dav when dealing with digital video recorders (DVRs), security cameras, or legacy high-definition media. These formats are designed to compress video efficiently or encrypt it for security purposes, preventing standard players like Windows Media Player or QuickTime from reading the data. The "EPV" extension is frequently associated with specific surveillance hardware or, in some cases, confused with the format used in HD DVD technologies.