1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
|
/*
* LSP computing for ACELP-based codecs
*
* Copyright (c) 2008 Vladimir Voroshilov
*
* This file is part of Libav.
*
* Libav is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* Libav is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with Libav; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#ifndef AVCODEC_LSP_H
#define AVCODEC_LSP_H
#include <stdint.h>
/**
(I.F) means fixed-point value with F fractional and I integer bits
*/
/**
* @brief ensure a minimum distance between LSFs
* @param[in,out] lsfq LSF to check and adjust
* @param lsfq_min_distance minimum distance between LSFs
* @param lsfq_min minimum allowed LSF value
* @param lsfq_max maximum allowed LSF value
* @param lp_order LP filter order
*/
void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order);
/**
* Adjust the quantized LSFs so they are increasing and not too close.
*
* This step is not mentioned in the AMR spec but is in the reference C decoder.
* Omitting this step creates audible distortion on the sinusoidal sweep
* test vectors in 3GPP TS 26.074.
*
* @param[in,out] lsf LSFs in Hertz
* @param min_spacing minimum distance between two consecutive lsf values
* @param size size of the lsf vector
*/
void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size);
/**
* @brief Convert LSF to LSP
* @param[out] lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
* @param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
* @param lp_order LP filter order
*
* @remark It is safe to pass the same array into the lsf and lsp parameters.
*/
void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order);
/**
* Floating point version of ff_acelp_lsf2lsp()
*/
void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order);
/**
* @brief LSP to LP conversion (3.2.6 of G.729)
* @param[out] lp decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
* @param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
* @param lp_half_order LP filter order, divided by 2
*/
void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order);
/**
* LSP to LP conversion (5.2.4 of AMR-WB)
*/
void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order);
/**
* @brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
* @param[out] lp_1st decoded LP coefficients for first subframe (-0x8000 <= (3.12) < 0x8000)
* @param[out] lp_2nd decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
* @param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
* @param lsp_prev LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000)
* @param lp_order LP filter order
*/
void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order);
#define MAX_LP_HALF_ORDER 10
#define MAX_LP_ORDER (2*MAX_LP_HALF_ORDER)
/**
* Reconstruct LPC coefficients from the line spectral pair frequencies.
*
* @param lsp line spectral pairs in cosine domain
* @param lpc linear predictive coding coefficients
* @param lp_half_order half the number of the amount of LPCs to be
* reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER
*
* @note buffers should have a minimux size of 2*lp_half_order elements.
*
* TIA/EIA/IS-733 2.4.3.3.5
*/
void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order);
/**
* Sort values in ascending order.
*
* @note O(n) if data already sorted, O(n^2) - otherwise
*/
void ff_sort_nearly_sorted_floats(float *vals, int len);
/**
* Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients
* needed for LSP to LPC conversion.
* We only need to calculate the 6 first elements of the polynomial.
*
* @param lsp line spectral pairs in cosine domain
* @param[out] f polynomial input/output as a vector
*
* TIA/EIA/IS-733 2.4.3.3.5-1/2
*/
void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order);
#endif /* AVCODEC_LSP_H */
|
