FFmpeg
lpc.h
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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/lls.h"
28 
29 #define ORDER_METHOD_EST 0
30 #define ORDER_METHOD_2LEVEL 1
31 #define ORDER_METHOD_4LEVEL 2
32 #define ORDER_METHOD_8LEVEL 3
33 #define ORDER_METHOD_SEARCH 4
34 #define ORDER_METHOD_LOG 5
35 
36 #define MIN_LPC_ORDER 1
37 #define MAX_LPC_ORDER 32
38 
39 /**
40  * LPC analysis type
41  */
42 enum FFLPCType {
43  FF_LPC_TYPE_DEFAULT = -1, ///< use the codec default LPC type
44  FF_LPC_TYPE_NONE = 0, ///< do not use LPC prediction or use all zero coefficients
45  FF_LPC_TYPE_FIXED = 1, ///< fixed LPC coefficients
46  FF_LPC_TYPE_LEVINSON = 2, ///< Levinson-Durbin recursion
47  FF_LPC_TYPE_CHOLESKY = 3, ///< Cholesky factorization
48  FF_LPC_TYPE_NB , ///< Not part of ABI
49 };
50 
51 typedef struct LPCContext {
52  int blocksize;
53  int max_order;
55  double *windowed_buffer;
57 
58  /**
59  * Apply a Welch window to an array of input samples.
60  * The output samples have the same scale as the input, but are in double
61  * sample format.
62  * @param data input samples
63  * @param len number of input samples
64  * @param w_data output samples
65  */
66  void (*lpc_apply_welch_window)(const int32_t *data, ptrdiff_t len,
67  double *w_data);
68  /**
69  * Perform autocorrelation on input samples with delay of 0 to lag.
70  * @param data input samples.
71  * constraints: no alignment needed, but must have at
72  * least lag*sizeof(double) valid bytes preceding it, and
73  * size must be at least (len+1)*sizeof(double) if data is
74  * 16-byte aligned or (len+2)*sizeof(double) if data is
75  * unaligned.
76  * @param len number of input samples to process
77  * @param lag maximum delay to calculate
78  * @param autoc output autocorrelation coefficients.
79  * constraints: array size must be at least lag+1.
80  */
81  void (*lpc_compute_autocorr)(const double *data, ptrdiff_t len, int lag,
82  double *autoc);
83 
84  // TODO: these should be allocated to reduce ABI compatibility issues
86 } LPCContext;
87 
88 
89 /**
90  * Calculate LPC coefficients for multiple orders
91  */
93  const int32_t *samples, int blocksize, int min_order,
94  int max_order, int precision,
95  int32_t coefs[][MAX_LPC_ORDER], int *shift,
96  enum FFLPCType lpc_type, int lpc_passes,
97  int omethod, int min_shift, int max_shift, int zero_shift);
98 
100  const int32_t *samples, int order, double *ref);
101 
102 double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len,
103  int order, double *ref);
104 
105 /**
106  * Initialize LPCContext.
107  */
108 int ff_lpc_init(LPCContext *s, int blocksize, int max_order,
109  enum FFLPCType lpc_type);
112 
113 /**
114  * Uninitialize LPCContext.
115  */
116 void ff_lpc_end(LPCContext *s);
117 
118 #endif /* AVCODEC_LPC_H */
LLSModel
Linear least squares model.
Definition: lls.h:37
FFLPCType
FFLPCType
LPC analysis type.
Definition: lpc.h:42
LPCContext::lpc_apply_welch_window
void(* lpc_apply_welch_window)(const int32_t *data, ptrdiff_t len, double *w_data)
Apply a Welch window to an array of input samples.
Definition: lpc.h:66
ff_lpc_end
void ff_lpc_end(LPCContext *s)
Uninitialize LPCContext.
Definition: lpc.c:366
FF_LPC_TYPE_CHOLESKY
@ FF_LPC_TYPE_CHOLESKY
Cholesky factorization.
Definition: lpc.h:47
data
const char data[16]
Definition: mxf.c:148
LPCContext::windowed_buffer
double * windowed_buffer
Definition: lpc.h:55
LPCContext
Definition: lpc.h:51
ff_lpc_init
int ff_lpc_init(LPCContext *s, int blocksize, int max_order, enum FFLPCType lpc_type)
Initialize LPCContext.
Definition: lpc.c:341
FF_LPC_TYPE_DEFAULT
@ FF_LPC_TYPE_DEFAULT
use the codec default LPC type
Definition: lpc.h:43
s
#define s(width, name)
Definition: cbs_vp9.c:198
LPCContext::lpc_type
enum FFLPCType lpc_type
Definition: lpc.h:54
lls.h
LPCContext::lls_models
LLSModel lls_models[2]
Definition: lpc.h:85
ff_lpc_calc_ref_coefs_f
double ff_lpc_calc_ref_coefs_f(LPCContext *s, const float *samples, int len, int order, double *ref)
Definition: lpc.c:210
LPCContext::max_order
int max_order
Definition: lpc.h:53
ff_lpc_calc_ref_coefs
int ff_lpc_calc_ref_coefs(LPCContext *s, const int32_t *samples, int order, double *ref)
Definition: lpc.c:198
LPCContext::blocksize
int blocksize
Definition: lpc.h:52
LPCContext::lpc_compute_autocorr
void(* lpc_compute_autocorr)(const double *data, ptrdiff_t len, int lag, double *autoc)
Perform autocorrelation on input samples with delay of 0 to lag.
Definition: lpc.h:81
ff_lpc_calc_coefs
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.
Definition: lpc.c:239
shift
static int shift(int a, int b)
Definition: bonk.c:261
FF_LPC_TYPE_NB
@ FF_LPC_TYPE_NB
Not part of ABI.
Definition: lpc.h:48
MAX_LPC_ORDER
#define MAX_LPC_ORDER
Definition: lpc.h:37
ff_lpc_init_x86
void ff_lpc_init_x86(LPCContext *s)
Definition: lpc_init.c:106
LPCContext::windowed_samples
double * windowed_samples
Definition: lpc.h:56
len
int len
Definition: vorbis_enc_data.h:426
ff_lpc_init_riscv
void ff_lpc_init_riscv(LPCContext *s)
Definition: lpc_init.c:31
ref
static int ref[MAX_W *MAX_W]
Definition: jpeg2000dwt.c:112
samples
Filter the word “frame” indicates either a video frame or a group of audio samples
Definition: filter_design.txt:8
int32_t
int32_t
Definition: audioconvert.c:56
FF_LPC_TYPE_NONE
@ FF_LPC_TYPE_NONE
do not use LPC prediction or use all zero coefficients
Definition: lpc.h:44
FF_LPC_TYPE_LEVINSON
@ FF_LPC_TYPE_LEVINSON
Levinson-Durbin recursion.
Definition: lpc.h:46
FF_LPC_TYPE_FIXED
@ FF_LPC_TYPE_FIXED
fixed LPC coefficients
Definition: lpc.h:45