Content for TS 46.010 Word version: 18.0.0
3 Functional description of the RPE-LTP codec
4 Codec homing
5 Computational details of the RPE-LTP codec
6 Digital test sequences
A Codec performance
B Test sequence disks
$ Change History
3 Functional description of the RPE-LTP codec p. 13
3.1 Functional description of the RPE-LTP encoder p. 13
3.1.1 Offset compensation p. 14
3.1.2 Pre-emphasis p. 14
3.1.3 Segmentation p. 14
3.1.4 Autocorrelation p. 15
3.1.5 Schur Recursion p. 15
3.1.6 Transformation of reflection coefficients to Log.-Area Ratios p. 15
3.1.7 Quantization and coding of Log.-Area Ratios p. 15
3.1.8 Decoding of the quantized Log.-Area Ratios p. 16
3.1.9 Interpolation of Log.-Area Ratios p. 16
3.1.10 Transformation of Log.-Area Ratios into reflection coefficients p. 16
3.1.11 Short term analysis filtering p. 16
3.1.12 Sub-segmentation p. 17
3.1.13 Calculation of the LTP parameters p. 17
3.1.14 Coding/Decoding of the LTP lags p. 17
3.1.15 Coding/Decoding of the LTP gains p. 18
3.1.16 Long term analysis filtering p. 18
3.1.17 Long term synthesis filtering p. 18
3.1.18 Weighting Filter p. 19
3.1.19 Adaptive sample rate decimation by RPE grid selection p. 19
3.1.20 APCM quantization of the selected RPE sequence p. 19
3.1.21 APCM inverse quantization p. 20
3.1.22 RPE grid positioning p. 21
3.2 Decoder p. 21
4 Codec homing p. 25
4.1 Functional description p. 25
4.2 Definitions p. 25
4.3 Encoder homing p. 26
4.4 Decoder homing p. 26
4.5 Encoder home state p. 27
4.6 Decoder home state p. 27
5 Computational details of the RPE-LTP codec p. 27
5.1 Data representation and arithmetic operations p. 27
5.2 Fixed point implementation of the RPE-LTP coder p. 29
5.2.0 Scaling of the input variable p. 30
5.2.1 Downscaling of the input signal p. 30
5.2.2 Offset compensation p. 30
5.2.3 Pre-emphasis p. 30
5.2.4 Autocorrelation p. 31
5.2.5 Computation of the reflection coefficients p. 31
5.2.6 Transformation of reflection coefficients to Log.-Area Ratios p. 32
5.2.7 Quantization and coding of the Log.-Area Ratios p. 33
5.2.8 Decoding of the coded Log.-Area Ratios p. 33
5.2.9 Computation of the quantized reflection coefficients p. 34
5.2.9.1 Interpolation of the LARpp[1..8] to get the LARp[1..8] p. 34
5.2.9.2 Computation of the rp[1..8] from the interpolated LARp[1..8] p. 34
5.2.10 Short term analysis filtering p. 34
5.2.11 Calculation of the LTP parameters p. 35
5.2.12 Long term analysis filtering p. 36
5.2.13 Weighting filter p. 36
5.2.14 RPE grid selection p. 37
5.2.15 APCM quantization of the selected RPE sequence p. 37
5.2.16 APCM inverse quantization p. 38
5.2.17 RPE grid positioning p. 39
5.2.18 Update of the reconstructed short term residual signal dp[-120..-1] p. 39
5.3 Fixed point implementation of the RPE-LTP decoder p. 39
5.3.1 RPE decoding clause p. 39
5.3.2 Long term synthesis filtering p. 40
5.3.3 Computation of the decoded reflection coefficients p. 40
5.3.4 Short term synthesis filtering clause p. 40
5.3.5 De-emphasis filtering p. 41
5.3.6 Upscaling of the output signal p. 41
5.3.7 Truncation of the output variable p. 41
5.4 Tables used in the fixed point implementation of the RPE-LTP coder and decoder p. 42
6 Digital test sequences p. 43
6.1 Input and output signals p. 44
6.2 Configuration for the application of the test sequences p. 44
6.3 Test sequences p. 45
A Codec performance p. 53
A.1 Performance of the RPE-LTP p. 53
A.1.1 Introduction p. 53
A.1.2 Speech performance p. 53
A.1.2.1 Single encoding p. 53
A.1.2.2 Speech performance when interconnected with coding systems on an analogue basis p. 54
A.1.3 Non-speech performance p. 55
A.1.3.1 Performance with single sine waves p. 55
A.1.3.2 Performance with DTMF tones p. 55
A.1.3.3 Performance with information tones p. 55
A.1.3.4 Performance with voice-band data p. 55
A.1.4 Delay p. 55
A.1.5 Bibliography p. 57
A.2 Subjective relevance of the speech coder output bits p. 57
A.3 Format for test sequence distribution p. 59
B Test sequence disks p. 62
$ Change History p. 63
