1 Introduction and
references
1.1 Introduction
1.2 References
2 Outline of LD-CELP
2.1 LD-CELP encoder
2.2 LD-CELP decoder
3 LD-CELP (encoder principles)
3.1 Input PCM format
conversion
3.2 Vector buffer
3.3 Adapter for perceptual
weighting filter
3.4 Perceptual weighting
filter
3.5 Synthesis filter
3.6 VQ target vector
computation
3.7 Backward synthesis filter adapter
3.8 Backward vector gain
adapter
3.9 Codebook search module
3.10 Simulated decoder
3.11 Synchronization and
in-band signalling
4 LD-CELP decoder principles
4.1 Excitation VQ codebook
4.2 Gain scaling unit
4.3 Synthesis filter
4.4 Backward vector gain
adapter
4.5 Backward synthesis
filter adapter
4.6 Postfilter
4.7 Postfilter adapter
4.8 Output PCM format
conversion
5 Computational details
5.1 Description of basic
coder parameters
5.2 Description of
internal variables
5.3 Input PCM format
conversion (block 1)
5.4 Vector buffer (block
2)
5.5 Adapter for perceptual
weighting filter (block 3, Figure 4-a)
5.6 Backward synthesis
filter adapter (block 23, Figure 5)
5.7 Backward vector gain
adapter (block 20, Figure 6)
5.8 Perceptual weighting
filter
5.9 Computation of
zero-input response vector
5.10 VQ target vector
computation
5.11 Codebook search module
(block 24)
5.12 Simulated decoder
(block 8)
5.13 Filter memory update
for blocks 9 and 10
5.14 Decoder (Figure 3)
Annex A – Hybrid window functions for various LPC analyses in
LD-CELP
A.1 Hybrid window for the
synthesis filter
A.2 Hybrid window for the
log-gain predictor
A.3 Hybrid window for the
perceptual weighting filter
Annex B – Excitation shape and gain codebook tables
Annex C – Values for bandwidth broadcasting
Annex D – Coefficients of the 1 kHz lowpass elliptic filter
used in pitch period extraction module (block 82)
Annex E – Time scheduling the sequence of computations
Annex F – Alphabetical list of abbreviations used in this
Recommendation
Annex G – 16 kbit/s fixed point specification
G.1 Introduction
G.2 Algorithmic changes
G.3 Pseudo-code for other
modules of ITU-T G.728
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
Annex H – Variable bit rate LD-CELP operation mainly for DCME
at rates less than 16 kbit/s
H.1 Introduction
H.2 Principles of
operation
H.3 Modifications for 12.8
kbit/s operation
H.4 Modifications for 9.6
kbit/s operation
Annex I – Frame or packet loss concealment for the LD-CELP
decoder
I.1 Scope
I.2 Normative
references
I.3 Introduction
I.4 Principles
of operation
I.5 Pseudo-code for frame erasure concealment
I.6 Additional coder parameters and variables
Annex J – Variable bit-rate operation of LD-CELP mainly for
voiceband-data applications in DCME
J.1 Scope
J.2 Normative
references
Page
J.3 Overview
J.4 Algorithm description
Appendix I – Programs and test sequences for implementation
verification of the algorithm of the ITU-T G.728 16 kbit/s LD-CELP speech
coder
I.1 General
I.2 Test
configurations
I.3 Verification
programs
I.4 Test
sequences
I.5 Verification
tools distribution
Appendix II – Speech performance
II.1 Introduction
II.2 Speech performance
II.3 Performance with
non-speech signals
II.4 Artificial voice
signals
Appendix III – Values used for scaling ETPAST during frame
erasures
Bibliography