The major difference between the two formats is that a PMCD master is the physical disc, where as a DDPi master is a file, that can be burnt onto a DVD, sent via the internet, or backed up onto a hard drive. We recommend the DDPi format because a DDPi can be backed up onto multiple hard drives, so with this format you will only ever need to pay for one master. With a PMCD master, the master is a physical item and if it is lost or damaged you will need another.