An MPEG-4 video file format from Apple that supports digital rights management (DRM). Copy-protected video content from Apple's iTunes store uses M4V, and many non-Apple media players support the format. The audio part of an M4V file is Dolby Digital AC-3, and audio-only MPEG-4 files use an M4A file extension.M4V files are Apple's copy-protected version of the MP4 format. If the content is not copy protected, the file extension on M4V videos can be changed to MP4 for older media players that do not support M4V. See MP4 and MPEG.