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ISO/IEC 14496-3:2005(E)
where n is the split vector number, m is the index of the candidate split vector , sp is the starting LSP order of the nth
split vector and dim is the dimension of the n-th split vector. (lsp_tbl[][][] is shown in Annex 2.E)
Table 2.A.1 — Starting order and dimension of the first stage LSP vector
Split vector number: n Starting LSP order: sp Dimension of the vector: dim
0 0 10
In the second stage, above-mentioned two quantization methods, which are two-split vector quantizer, are applied
respectively. Total quantization errors in the second stage are calculated for all combinations of the first stage
candidates and the second stage candidates and the one which has the minimum error is selected. As a result,
indices of the first stage are determined and corresponding indices and signs for the second stage are stored in
LSP2 and LSP3. The flag which indicates the selected quantization method is also stored in LSP4. The
quantization error in the second stage err2_total is given by:
VQ without interframe prediction:
err2_ total = err2[ 0] + err2[
1]
{ }
dim−1
2
[ ] ( [ ] [ ] [ ][ ][ ] ) [ ]
err2 n = ∑ lsp_res sp + i −sign n ⋅d_ tbl n m i ⋅ w sp + i n = 01 ,
i = 0
[ + ] = [ + ] − [ + ]
lsp_res sp i lsp sp i lsp_ first sp i
where lsp_first[] is the quantized LSP vector of the first stage, n is the split vector number, m is the index of the
candidate split vector , sp is the starting LSP order of the n-th split vector and dim is the dimension of the n-th split
vector. (d_tbl[][][] is shown in Annex 2.E.)
VQ with interframe prediction:
err2_ total = err2[ 0] + err2[
1]
{ }
dim−1
2
[ ] ( [ ] [ ] [ ][ ][ ] ) [ ]
err2 n = ∑ lsp_ pres sp + i −sign n ⋅pd_tbl n m i ⋅ w sp + i n = 01 ,
i=
0
[ + ] = [ + ] −
{ ( 1 −ratio_ predict ) ⋅ lsp_ first[ sp + i] + ratio_ predict ⋅ lsp_ previous[ sp + i]
}
lsp_ pres sp i lsp sp i
where lsp_first[] is the quantized LSP vector of the first stage, n is the split vector number, m is the index of the
candidate split vector , sp is the starting LSP order of the n-th split vector, dim is the dimension of the n-th split
vector and ratio_predict = 0.7. (pd_tbl[][][] is shown in Annex 2.E.)
Table 2.A.2 — Starting order and dimension of the second stage LSP vector
Split vector number: n Starting LSP order: sp Dimension of the vector: dim
0 0 5
1 5 5
© ISO/IEC 2005 — All rights reserved 63