FFmpeg coverage


Directory: ../../../ffmpeg/
File: src/libavcodec/lpc.h
Date: 2022-11-28 23:49:43
Exec Total Coverage
Lines: 42 43 97.7%
Branches: 30 36 83.3%

Line Branch Exec Source
1 /*
2 * LPC utility code
3 * Copyright (c) 2006 Justin Ruggles <justin.ruggles@gmail.com>
4 *
5 * This file is part of FFmpeg.
6 *
7 * FFmpeg is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * FFmpeg is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 * Lesser General Public License for more details.
16 *
17 * You should have received a copy of the GNU Lesser General Public
18 * License along with FFmpeg; if not, write to the Free Software
19 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20 */
21
22 #ifndef AVCODEC_LPC_H
23 #define AVCODEC_LPC_H
24
25 #include <stdint.h>
26 #include <stddef.h>
27 #include "libavutil/avassert.h"
28 #include "libavutil/lls.h"
29 #include "aac_defines.h"
30
31 #define ORDER_METHOD_EST 0
32 #define ORDER_METHOD_2LEVEL 1
33 #define ORDER_METHOD_4LEVEL 2
34 #define ORDER_METHOD_8LEVEL 3
35 #define ORDER_METHOD_SEARCH 4
36 #define ORDER_METHOD_LOG 5
37
38 #define MIN_LPC_ORDER 1
39 #define MAX_LPC_ORDER 32
40
41 /**
42 * LPC analysis type
43 */
44 enum FFLPCType {
45 FF_LPC_TYPE_DEFAULT = -1, ///< use the codec default LPC type
46 FF_LPC_TYPE_NONE = 0, ///< do not use LPC prediction or use all zero coefficients
47 FF_LPC_TYPE_FIXED = 1, ///< fixed LPC coefficients
48 FF_LPC_TYPE_LEVINSON = 2, ///< Levinson-Durbin recursion
49 FF_LPC_TYPE_CHOLESKY = 3, ///< Cholesky factorization
50 FF_LPC_TYPE_NB , ///< Not part of ABI
51 };
52
53 typedef struct LPCContext {
54 int blocksize;
55 int max_order;
56 enum FFLPCType lpc_type;
57 double *windowed_buffer;
58 double *windowed_samples;
59
60 /**
61 * Apply a Welch window to an array of input samples.
62 * The output samples have the same scale as the input, but are in double
63 * sample format.
64 * @param data input samples
65 * @param len number of input samples
66 * @param w_data output samples
67 */
68 void (*lpc_apply_welch_window)(const int32_t *data, ptrdiff_t len,
69 double *w_data);
70 /**
71 * Perform autocorrelation on input samples with delay of 0 to lag.
72 * @param data input samples.
73 * constraints: no alignment needed, but must have at
74 * least lag*sizeof(double) valid bytes preceding it, and
75 * size must be at least (len+1)*sizeof(double) if data is
76 * 16-byte aligned or (len+2)*sizeof(double) if data is
77 * unaligned.
78 * @param len number of input samples to process
79 * @param lag maximum delay to calculate
80 * @param autoc output autocorrelation coefficients.
81 * constraints: array size must be at least lag+1.
82 */
83 void (*lpc_compute_autocorr)(const double *data, ptrdiff_t len, int lag,
84 double *autoc);
85
86 // TODO: these should be allocated to reduce ABI compatibility issues
87 LLSModel lls_models[2];
88 } LPCContext;
89
90
91 /**
92 * Calculate LPC coefficients for multiple orders
93 */
94 int ff_lpc_calc_coefs(LPCContext *s,
95 const int32_t *samples, int blocksize, int min_order,
96 int max_order, int precision,
97 int32_t coefs[][MAX_LPC_ORDER], int *shift,
98 enum FFLPCType lpc_type, int lpc_passes,
99 int omethod, int min_shift, int max_shift, int zero_shift);
100
101 int ff_lpc_calc_ref_coefs(LPCContext *s,
102 const int32_t *samples, int order, double *ref);
103
104 double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
105 int order, double *ref);
106
107 /**
108 * Initialize LPCContext.
109 */
110 int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
111 enum FFLPCType lpc_type);
112 void ff_lpc_init_x86(LPCContext *s);
113
114 /**
115 * Uninitialize LPCContext.
116 */
117 void ff_lpc_end(LPCContext *s);
118
119 #if USE_FIXED
120 typedef int LPC_TYPE;
121 typedef unsigned LPC_TYPE_U;
122 #else
123 #ifdef LPC_USE_DOUBLE
124 typedef double LPC_TYPE;
125 typedef double LPC_TYPE_U;
126 #else
127 typedef float LPC_TYPE;
128 typedef float LPC_TYPE_U;
129 #endif
130 #endif // USE_FIXED
131
132 /**
133 * Schur recursion.
134 * Produces reflection coefficients from autocorrelation data.
135 */
136 2147 static inline void compute_ref_coefs(const LPC_TYPE *autoc, int max_order,
137 LPC_TYPE *ref, LPC_TYPE *error)
138 {
139 int i, j;
140 LPC_TYPE err;
141 LPC_TYPE gen0[MAX_LPC_ORDER], gen1[MAX_LPC_ORDER];
142
143
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26431 for (i = 0; i < max_order; i++)
144 24284 gen0[i] = gen1[i] = autoc[i + 1];
145
146 2147 err = autoc[0];
147
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2147 ref[0] = -gen1[0] / ((USE_FIXED || err) ? err : 1);
148 2147 err += gen1[0] * ref[0];
149
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2147 if (error)
150 2147 error[0] = err;
151
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24284 for (i = 1; i < max_order; i++) {
152
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150519 for (j = 0; j < max_order - i; j++) {
153 128382 gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j];
154 128382 gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j];
155 }
156
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22137 ref[i] = -gen1[0] / ((USE_FIXED || err) ? err : 1);
157 22137 err += gen1[0] * ref[i];
158
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22137 if (error)
159 22137 error[i] = err;
160 }
161 2147 }
162
163 /**
164 * Levinson-Durbin recursion.
165 * Produce LPC coefficients from autocorrelation data.
166 */
167 37708 static inline int AAC_RENAME(compute_lpc_coefs)(const LPC_TYPE *autoc, int max_order,
168 LPC_TYPE *lpc, int lpc_stride, int fail,
169 int normalize)
170 {
171 int i, j;
172 37708 LPC_TYPE err = 0;
173 37708 LPC_TYPE *lpc_last = lpc;
174
175 av_assert2(normalize || !fail);
176
177
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37708 if (normalize)
178 28767 err = *autoc++;
179
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37708 if (fail && (autoc[max_order - 1] == 0 || err <= 0))
181 4 return -1;
182
183
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644922 for(i=0; i<max_order; i++) {
184 607218 LPC_TYPE r = AAC_SRA_R(-autoc[i], 5);
185
186
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607218 if (normalize) {
187
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7881021 for(j=0; j<i; j++)
188 7332671 r -= lpc_last[j] * autoc[i-j-1];
189
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548350 if (err)
191 548350 r /= err;
192 548350 err *= FIXR(1.0) - (r * r);
193 }
194
195 607218 lpc[i] = r;
196
197
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4536239 for(j=0; j < (i+1)>>1; j++) {
198 3929021 LPC_TYPE f = lpc_last[ j];
199 3929021 LPC_TYPE b = lpc_last[i-1-j];
200 3929021 lpc[ j] = f + (LPC_TYPE_U)AAC_MUL26(r, b);
201 3929021 lpc[i-1-j] = b + (LPC_TYPE_U)AAC_MUL26(r, f);
202 }
203
204
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607218 if (fail && err < 0)
205 return -1;
206
207 607218 lpc_last = lpc;
208 607218 lpc += lpc_stride;
209 }
210
211 37704 return 0;
212 }
213
214 #endif /* AVCODEC_LPC_H */
215