The present disclosure relates to a file generation device and method, and a content playback device, enabling efficient access to arbitrary subsamples within a sample. Information for acquiring arbitrary subsamples (tiles) is disposed not by extending the sidx and the ssix, but by defining a separate box, a general subsegment index box (gsix), after the sidx and the ssix at the beginning of the segment file. The present disclosure may be applied to a content playback system equipped with a content server and a content playback device, for example.