ВОСПРОИЗВЕДЕНИЕ СИГНАЛА С ИЗМЕНЯЕМЫМИ СКОРОСТЬЮ ИНАПРАВЛЕНИЕМ ВОСПРОИЗВЕДЕНИЯ

摘要

A trick play signal is derived from a stored, and typically encrypted video stream. The video stream comprises data representing a series of I frames and P or B frames encoded at a variable bit rate, the I-frames being decodable independent of any other frame, decoding of the P or B frames requiring reference to other frames. Selected segments of data are retrieved from the video stream. Each segment corresponds to a part of data from the stream with a selected length. Distances between successive retrieved segments are selected dependent on a trick play speed. A trick play video signal is generated that comprises an earliest first frame from each respective segment. Stream specific properties of the stream are determined that are indicative of a rate at which the I-frames occur in the stream. The selected length for use in said selective retrieving is computed from the properties that have been determined, so that on the basis of the properties the segments of said selected length are predicted to include data representing at least one whole first frame at least on average.