A recorded data processing method includes calculating, for each of N (N is a natural number of three or more) recorded data pairs each formed by two pieces of recorded data that are adjacent to each other when N pieces of recorded data each representing a recording target including at least one of audio or an image are arranged cyclically, a time difference between time signals representing temporal changes of the recording target in the two respective pieces of recorded data of the recorded data pair. It is also evaluated whether or not the N pieces of recorded data include recorded data having no relation according to a total value of N time differences calculated for the N recorded data pairs.

A plurality of kinds of LPCM signals/compression digital audio signals is switched to one another in transmission, thereby enabling audio reproduction to be satisfactorily carried out. A digital audio signal is transmitted to an external apparatus through a predetermined transmission path. Information associated with the digital audio signal to be next transmitted is added to the digital audio signal which is currently being transmitted. For example, first metadata exhibiting a transmission frequency of the digital audio signal, and second metadata exhibiting a data type of the digital audio signal are contained in the information.

The invention, as shown by the system in FIG. 2, relates to a client-side content tracking system of media files, e.g. digital music files. Audio trackingor indeed multimedia trackingis shifted to a client-side perspective, with the client tasked with establishing use of a selected source audio track by trackingand then reporting uplink to the serverat least one of: entry and exit points associated with playing of at least one of said musical sections in the identified source audio track, and how the identified source audio track was used, performed or manipulated at the client device. Server functionality is designed, having regard to the reported tracking data and its link to a unique identifier to permit the media file (e.g. source audio track) to be selected and/or identified, to store or relaypossibly in the context of a subscription service and billing regime for content usetracking data related to use of at least a portion of the source audio track at or by the client device. In the context of audio, reporting of use at a client device can, in turn, cause streaming of related multi-media content from a third-party database to the client device. For music, reporting of entry and end points into and out of sections of complete audio tracks can coincide with musically seamless audio transitions between sections.