Patent ID: 8015295

Claim:
A communication system, comprising: a communication device; and a reproduction device configured to carry out data communication with said communication device, said reproduction device including a first storage unit configured to store content data items, and a first communication unit configured to communicate with said communication device, and said communication device including a second storage unit configured to store content data items, a second communication unit configured to communicate with said first communication unit, and a priority ranking determination unit configured to obtain a first list of content data items stored in said first storage unit and additional priority ranking information associated with each item of content data in the first list via the first and second communication units, obtain a second list of content data items stored in said second storage unit and additional priority ranking information associated with each item of content data in the second list, and determine an individual priority ranking of each item of content data in a content data group including both the content data items of the first list and the content data items of the second list, based on a priority ranking criteria and the additional priority ranking information associated with each item of content data in the first and second lists, wherein said communication device further includes a difference extraction unit configured to extract content data items from said second storage unit to be transferred to said reproduction device, based upon the individual priority ranking of each item of content data in the content data group.