Is a video format similar to MP4. The difference between the formats is their developers and protection. Apple company, has developed a format that has provided DRM-lock for M4V. Video files in this format are downloaded from iTunes.
this is open lossless codecs, developed under the Ogg project. Lately it’s become quite popular: many users wishing to store audio with original quality choose FLAC. This is partly in connection with the fact that codecs uses IDv1 and IDv3 tags - this allows a user to sort an audio collection according to one’s particular tastes, changing the original metadata of the tracks.