FFmpeg: libavcodec/lpc_functions.h Source File

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lpc_functions.h

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1 /*

2 * LPC utility functions

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 */

22 #ifndef AVCODEC_LPC_FUNCTIONS_H

23 #define AVCODEC_LPC_FUNCTIONS_H

25 #include "libavutil/avassert.h"

27 #ifndef LPC_USE_FIXED

28 #define LPC_USE_FIXED 0

29 #endif

31 #if LPC_USE_FIXED

32 typedef int LPC_TYPE;

33 typedef unsigned LPC_TYPE_U;

34 #else

35 #ifndef LPC_SRA_R

36 #define LPC_SRA_R(x, y) (x)

37 #define LPC_MUL26(x, y) ((x) * (y))

38 #define LPC_FIXR(x) ((float)(x))

39 #endif

41 #ifdef LPC_USE_DOUBLE

42 typedef double LPC_TYPE;

43 typedef double LPC_TYPE_U;

44 #else

45 typedef float LPC_TYPE;

46 typedef float LPC_TYPE_U;

47 #endif

48 #endif // USE_FIXED

50 /**

51 * Levinson-Durbin recursion.

52 * Produce LPC coefficients from autocorrelation data.

53 */

54 static inline int compute_lpc_coefs(const LPC_TYPE *autoc, int i, int max_order,

55 LPC_TYPE *lpc, int lpc_stride, int fail,

56 int normalize, LPC_TYPE *err_ptr)

57 {

58 LPC_TYPE err = 0;

59 LPC_TYPE *lpc_last = lpc;

61 av_assert2(normalize || !fail);

63 if (normalize) {

64 if (i == 0)

65 err = *autoc++;

66 else {

67 err = *err_ptr;

68 }

69 }

71 if (fail && (autoc[max_order - 1] == 0 || err <= 0))

72 return -1;

74 for( ; i < max_order; i++) {

75 LPC_TYPE r = LPC_SRA_R(-autoc[i], 5);

77 if (normalize) {

78 for(int j = 0; j < i; j++)

79 r -= lpc_last[j] * autoc[i-j-1];

81 if (err)

82 r /= err;

83 err *= LPC_FIXR(1.0) - (r * r);

84 }

86 lpc[i] = r;

88 for(int j = 0; j < (i + 1) >> 1; j++) {

89 LPC_TYPE f = lpc_last[ j];

90 LPC_TYPE b = lpc_last[i-1-j];

91 lpc[ j] = f + (LPC_TYPE_U)LPC_MUL26(r, b);

92 lpc[i-1-j] = b + (LPC_TYPE_U)LPC_MUL26(r, f);

93 }

95 if (fail && err < 0)

96 return -1;

98 lpc_last = lpc;

99 lpc += lpc_stride;

100 }

101

102 if (err_ptr)

103 *err_ptr = err;

104

105 return 0;

106 }

107

108 #endif /* AVCODEC_LPC_FUNCTIONS_H */

const char * r

Definition: vf_curves.c:127

#define b

Definition: input.c:42

fail

#define fail()

Definition: checkasm.h:206

avassert.h

LPC_MUL26

#define LPC_MUL26(x, y)

Definition: lpc_functions.h:37

Definition: af_crystalizer.c:122

normalize

Definition: normalize.py:1

av_assert2

#define av_assert2(cond)

assert() equivalent, that does lie in speed critical code.

Definition: avassert.h:68

#define i(width, name, range_min, range_max)

Definition: cbs_h2645.c:256

compute_lpc_coefs

static int compute_lpc_coefs(const LPC_TYPE *autoc, int i, int max_order, LPC_TYPE *lpc, int lpc_stride, int fail, int normalize, LPC_TYPE *err_ptr)

Levinson-Durbin recursion.

Definition: lpc_functions.h:54

LPC_TYPE_U

float LPC_TYPE_U

Definition: lpc_functions.h:46

LPC_TYPE

float LPC_TYPE

Definition: lpc_functions.h:45

LPC_FIXR

#define LPC_FIXR(x)

Definition: lpc_functions.h:38

LPC_SRA_R

#define LPC_SRA_R(x, y)

Definition: lpc_functions.h:36

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