公开(公告)号：EP0963657B1

公开(公告)日：2002-11-27

申请号：EP98907045.3

申请日：1998-02-25

申请人： BRITISH BROADCASTING CORPORATION ,  SNELL & WILCOX LIMITED

发明人： WERNER, Oliver Hartwig ,  WELLS, Nicholas Dominic ,  KNEE, Michael James

IPC分类号： H04N7/30

CPC分类号： H04N19/40 ,  H04N19/124 ,  H04N19/126 ,  H04N19/13 ,  H04N19/147 ,  H04N19/186 ,  H04N19/19 ,  H04N19/60 ,  H04N19/61 ,  H04N19/91

公开(公告)号：EP0963657A1

公开(公告)日：1999-12-15

申请号：EP98907045.0

申请日：1998-02-25

申请人： BRITISH BROADCASTING CORPORATION ,  SNELL & WILCOX LIMITED

发明人： WERNER, Oliver Hartwig ,  WELLS, Nicholas Dominic ,  KNEE, Michael James

IPC分类号： G06T9 ,  H04N7

CPC分类号： H04N19/40 ,  H04N19/124 ,  H04N19/126 ,  H04N19/13 ,  H04N19/147 ,  H04N19/186 ,  H04N19/19 ,  H04N19/60 ,  H04N19/61 ,  H04N19/91

摘要： In compression encoding of a digital signal, such as MPEG2, transform coefficients are quantised with the lower bound of each interval being controlled by a parameter μ. In the MPEG2 reference coder, for example, μ=0.75. Because the quantised coefficients are variable length coded, improved quality or reduced bit rates can be achieved by controlling μ so as to vary dynamically the bound of each interval with respect to the associated representation level. The parameter μ can vary with coefficient amplitude, with frequency, with quantisation step size. In a transcoding operation, μ can also vary with parameters in the initial coding operation.