Annex G 16
kbit/s fixed point specification
G.1 Introduction
G.1.1 General philosophy
G.1.2 Numerical representation
G.1.3 Arithmetic operations
G.2 Algorithmic changes
G.2.1 Changes in the backward vector gain
adapter (block 20)
G.2.2 Changes in the Levinson-Durbin recursion
modules
G.3 Pseudo-code for other modules of Recommendation G.728
G.3.1 Block 4 Pseudo-code for weighting
filter
G.3.2 Blockzir Pseudo-code for synthesis and
perceptual weighting filters during zero‑input response computation
G.3.3 Blocks
9 and 10 Pseudo-code for synthesis and perceptual weighting filter memory
updates
G.3.4 Block 11 VQ target vector computation
G.3.5 Block 12 Impulse response vector
calculation
G.3.6 Block 13 Time-reversed convolution
G.3.7 Block 14 Shape codevector convolution
and energy calculation
G.3.8 Block 16 VQ target vector normalization
G.3.9 Block 17 VQ search error calculator and
best codebook index selector
G.3.10 Block 19 Excitation VQ codebook and
block 21 Gain scaling unit
G.3.11 Block 32 Decoder synthesis filter
G.3.12 Block 36 Pseudo-code for hybrid windowing module
G.3.13 Block 38 Weighting filter coefficient
calculator
G.3.14 Block 43 Hybrid windowing module
G.3.15 Block 45 Bandwidth expansion module
G.3.16 Block 46 Log-gain linear prediction
G.3.17 Block 49 Hybrid window module for
synthesis filter
G.3.18 HWMCORE Core of hybrid window module
G.3.19 Block 51 Bandwidth expansion module
G.3.20 Blocks 71 and 72 Long-term and
short-term postfilters
G.3.21 Blocks 73 and 74 Sum of absolute value
calculators
G.3.22 Block 75 Scaling factor calculator
G.3.23 Block 76 First-order lowpass filter and
block 77 Output gain scaling unit
G.3.24 Block 81 10th order LPC inverse filter
G.3.25 Block 82 Pitch period extraction module
G.3.26 Block 83
Pitch predictor tap calculator
G.3.27 Block 84 Long-term postfilter
coefficient calculator
G.3.28 Block 85 Short-term postfilter
coefficient calculator
G.4 LD-CELP internal variable representations
G.5 Log-gain tables for gain and shape codebook vectors
G.6 Integer values of gain codebook related arrays
G.7 Encoder and decoder main program pseudo-codes