Files with the .BDM extension contain drive information – particularly the contents of a file located in a specified AVHCD recording catalog.

These files are created by AVHCD recordings and placed in the AVCHD / BDMV catalog on a storage unit. The files are usually named index.Bdm or movieobj.Bdm and generated on drives other than optical drives, such as hard drives or pen drives. Optical drives usually contain equivalent BDMV files.