| 摘要 |
A data processing apparatus ( 800 ) has an input ( 810 ) for receiving a first and second sequence of frame-based A/V data. A processor ( 830 ) edits the two sequences forming a third combined sequence. So-called "I-frames" are intra-coded, without reference to any other frame of the sequence. "P-frames" are coded with reference to one prior reference frame, and "B-frames" are coded with reference to one prior and one subsequent reference frame. The referential coding of a frame is based on motion vectors in the frame indicating similar macro blocks in the frame referred to. The processor identifies frames in the first sequence up to and including a first edit point and frames in the second sequence starting at a second edit point that have lost a reference frame. The processor ( 830 ) re-encodes each identified B-frames into a corresponding re-encoded frame by deriving motion vectors of the re-encoded frame solely from motion vectors of the original B-frame.
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