Abstract: A data processing system. A storage medium stores an audio data stream comprising a plurality of samples. A seek unit seeks through the audio data stream to determine a file offset of a target sample. A playback controller controls playback of the audio data stream. The playback controller is assigned an execution priority higher than the seek unit, and the seek unit and the playback controller operates according to their assigned execution priority.

Abstract: Data processing methods and systems for accessing a target sample in a media data stream. The media data stream has a plurality of samples and corresponding sample information recorded in at least one entry, wherein the sample information for a predetermined number of the entries is calculated and the calculated result is stored in at least one cache entry. Target sample information corresponding to the target sample is provided. One of the cache entries is located by comparing the target sample information with the calculated result of respective cache entries. After locating the cache entry, the target sample from the entries is located corresponding to the located cache entry.