| 摘要 |
<p>A stream of video data is normally played in forward direction. Units of control word information required to decrypt successive segments of the stream are supplied synchronized to the stream. During reverse mode replay sections of the stream are replayed in reverse order. The units of control word information are resynchronized relative to supply of video information. Crossing of boundaries between segments during reverse mode replay triggers supply of selected units. The units are selected so that they contain the control word needed to decrypt a first segment that is normally previous to a second segment that ends at the boundary. Generally, this is a unit that normally starts to be supplied just before or after the start of the first segment.</p> |
