TRANSCODING OF VIDEO DATA STREAMS

摘要

MPEG video bitstreams comprising a mixture of I-, P- and B-pictures are transcoded for transfer between apparatuses (110 and 112), using an intermediate bitstream format which comprise essentially I-pictures. Additional information (122) is inserted into the intermediate bitstream in user data fields, to identify which pictures were I-pictures in the original bitstream, and which were not. When transcoding again to IPB format (126), loss of picture quality can be minimised using this knowledge of the original video bitstream structure, in particular by encoding as I-pictures those pictures which were encoded as I-pictures in the original bitstream.