may move the screen of the interface of the corresponding time shifting instance pressing the return button may close the time shifting setting interface pressing a stop button not shown may close a corresponding interface of the time shifting instance subsequently the other interface of the time shifting instance may be enlarged to a full screen fig5 is a schematic diagram illustrating an interaction between a user interface module and a file managing module according to an exemplary embodiment the file managing module 130 is a core module in an exemplary embodiment each time shifting instance may interact with the file managing module 130 through the user interface module 140 the file managing module 130 may differentiate time shifting instances using a corresponding label thereof the file managing module 130 sets a physical disk fragment as a smallest management unit adds functions such as delete merge establish etc regarding disk fragments to a file system driver the file managing module 130 may also link all the disk fragments by using a disk fragment list and match a data offset in a file with the absolute offset of the key frame the file managing module 130 provides an interface to interact with other modules obtains real time bit rate data from the bit.