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>
29
30 #define ORDER_METHOD_EST 0
31 #define ORDER_METHOD_2LEVEL 1
32 #define ORDER_METHOD_4LEVEL 2
33 #define ORDER_METHOD_8LEVEL 3
34 #define ORDER_METHOD_SEARCH 4
35 #define ORDER_METHOD_LOG 5
36
37 #define MIN_LPC_ORDER 1
38 #define MAX_LPC_ORDER 32
39
40 /**
41 * LPC analysis type
42 */
50 };
51
58
59 /**
60 * Apply a Welch window to an array of input samples.
61 * The output samples have the same scale as the input, but are in double
62 * sample format.
63 * @param data input samples
64 * @param len number of input samples
65 * @param w_data output samples
66 */
68 double *w_data);
69 /**
70 * Perform autocorrelation on input samples with delay of 0 to lag.
71 * @param data input samples.
72 * constraints: no alignment needed, but must have at
73 * least lag*sizeof(double) valid bytes preceding it, and
74 * size must be at least (len+1)*sizeof(double) if data is
75 * 16-byte aligned or (len+2)*sizeof(double) if data is
76 * unaligned.
77 * @param len number of input samples to process
78 * @param lag maximum delay to calculate
79 * @param autoc output autocorrelation coefficients.
80 * constraints: array size must be at least lag+1.
81 */
83 double *autoc);
84
85 // TODO: these should be allocated to reduce ABI compatibility issues
88
89
90 /**
91 * Calculate LPC coefficients for multiple orders
92 */
94 const int32_t *samples,
int blocksize,
int min_order,
95 int max_order, int precision,
98 int omethod, int min_shift, int max_shift, int zero_shift);
99
101 const int32_t *samples,
int order,
double *
ref);
102
104 int order,
double *
ref);
105
106 /**
107 * Initialize LPCContext.
108 */
112
113 /**
114 * Uninitialize LPCContext.
115 */
117
118 #if USE_FIXED
121 #else
122 #ifdef LPC_USE_DOUBLE
125 #else
128 #endif
129 #endif // USE_FIXED
130
131 /**
132 * Schur recursion.
133 * Produces reflection coefficients from autocorrelation data.
134 */
137 {
138 int i, j;
141
142 for (i = 0; i < max_order; i++)
143 gen0[i] = gen1[i] = autoc[i + 1];
144
145 err = autoc[0];
146 ref[0] = -gen1[0] / err;
147 err += gen1[0] * ref[0];
148 if (error)
149 error[0] = err;
150 for (i = 1; i < max_order; i++) {
151 for (j = 0; j < max_order - i; j++) {
152 gen1[j] = gen1[j + 1] + ref[i - 1] * gen0[j];
153 gen0[j] = gen1[j + 1] * ref[i - 1] + gen0[j];
154 }
155 ref[i] = -gen1[0] / err;
156 err += gen1[0] * ref[i];
157 if (error)
158 error[i] = err;
159 }
160 }
161
162 /**
163 * Levinson-Durbin recursion.
164 * Produce LPC coefficients from autocorrelation data.
165 */
168 int normalize)
169 {
170 int i, j;
173
175
176 if (normalize)
177 err = *autoc++;
178
179 if (
fail && (autoc[max_order - 1] == 0 || err <= 0))
180 return -1;
181
182 for(i=0; i<max_order; i++) {
184
185 if (normalize) {
186 for(j=0; j<i; j++)
187 r -= lpc_last[j] * autoc[i-j-1];
188
189 r /= err;
190 err *=
FIXR(1.0) - (r *
r);
191 }
192
194
195 for(j=0; j < (i+1)>>1; j++) {
200 }
201
203 return -1;
204
205 lpc_last = lpc;
206 lpc += lpc_stride;
207 }
208
209 return 0;
210 }
211
212 #endif /* AVCODEC_LPC_H */
static int shift(int a, int b)
Linear least squares model.
ptrdiff_t const GLvoid * data
static void compute_ref_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *ref, LPC_TYPE *error)
Schur recursion.
#define av_assert2(cond)
assert() equivalent, that does lie in speed critical code.
do not use LPC prediction or use all zero coefficients
simple assert() macros that are a bit more flexible than ISO C assert().
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
int ff_lpc_calc_coefs(LPCContext *s, const int32_t *samples, int blocksize, int min_order, int max_order, int precision, int32_t coefs[][MAX_LPC_ORDER], int *shift, enum FFLPCType lpc_type, int lpc_passes, int omethod, int min_shift, int max_shift, int zero_shift)
Calculate LPC coefficients for multiple orders.
typedef void(APIENTRY *FF_PFNGLACTIVETEXTUREPROC)(GLenum texture)
int ff_lpc_init(LPCContext *s, int blocksize, int max_order, enum FFLPCType lpc_type)
Initialize LPCContext.
static int AAC_RENAME() compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize)
Levinson-Durbin recursion.
static void error(const char *err)
void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
Levinson-Durbin recursion.
use the codec default LPC type
double * windowed_samples
FFLPCType
LPC analysis type.
static int ref[MAX_W *MAX_W]
void(* lpc_compute_autocorr)(const double *data, int len, int lag, double *autoc)
Perform autocorrelation on input samples with delay of 0 to lag.
double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len, int order, double *ref)
void(* lpc_apply_welch_window)(const int32_t *data, int len, double *w_data)
Apply a Welch window to an array of input samples.
void ff_lpc_init_x86(LPCContext *s)