| Line | Branch | Exec | Source |
|---|---|---|---|
| 1 | /* | ||
| 2 | * LPC utility functions | ||
| 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_FUNCTIONS_H | ||
| 23 | #define AVCODEC_LPC_FUNCTIONS_H | ||
| 24 | |||
| 25 | #include "libavutil/avassert.h" | ||
| 26 | |||
| 27 | #ifndef LPC_USE_FIXED | ||
| 28 | #define LPC_USE_FIXED 0 | ||
| 29 | #endif | ||
| 30 | |||
| 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 | ||
| 40 | |||
| 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 | ||
| 49 | |||
| 50 | /** | ||
| 51 | * Levinson-Durbin recursion. | ||
| 52 | * Produce LPC coefficients from autocorrelation data. | ||
| 53 | */ | ||
| 54 | 38180 | static inline int compute_lpc_coefs(const LPC_TYPE *autoc, int max_order, | |
| 55 | LPC_TYPE *lpc, int lpc_stride, int fail, | ||
| 56 | int normalize) | ||
| 57 | { | ||
| 58 | 38180 | LPC_TYPE err = 0; | |
| 59 | 38180 | LPC_TYPE *lpc_last = lpc; | |
| 60 | |||
| 61 | av_assert2(normalize || !fail); | ||
| 62 | |||
| 63 |
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38180 | if (normalize) |
| 64 | 29215 | err = *autoc++; | |
| 65 | |||
| 66 |
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38180 | if (fail && (autoc[max_order - 1] == 0 || err <= 0)) |
| 67 | 4 | return -1; | |
| 68 | |||
| 69 |
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649170 | for(int i = 0; i < max_order; i++) { |
| 70 | 610994 | LPC_TYPE r = LPC_SRA_R(-autoc[i], 5); | |
| 71 | |||
| 72 |
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610994 | if (normalize) { |
| 73 |
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7897149 | for(int j = 0; j < i; j++) |
| 74 | 7345215 | r -= lpc_last[j] * autoc[i-j-1]; | |
| 75 | |||
| 76 |
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551934 | if (err) |
| 77 | 551934 | r /= err; | |
| 78 | 551934 | err *= LPC_FIXR(1.0) - (r * r); | |
| 79 | } | ||
| 80 | |||
| 81 | 610994 | lpc[i] = r; | |
| 82 | |||
| 83 |
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4547599 | for(int j = 0; j < (i + 1) >> 1; j++) { |
| 84 | 3936605 | LPC_TYPE f = lpc_last[ j]; | |
| 85 | 3936605 | LPC_TYPE b = lpc_last[i-1-j]; | |
| 86 | 3936605 | lpc[ j] = f + (LPC_TYPE_U)LPC_MUL26(r, b); | |
| 87 | 3936605 | lpc[i-1-j] = b + (LPC_TYPE_U)LPC_MUL26(r, f); | |
| 88 | } | ||
| 89 | |||
| 90 |
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610994 | if (fail && err < 0) |
| 91 | ✗ | return -1; | |
| 92 | |||
| 93 | 610994 | lpc_last = lpc; | |
| 94 | 610994 | lpc += lpc_stride; | |
| 95 | } | ||
| 96 | |||
| 97 | 38176 | return 0; | |
| 98 | } | ||
| 99 | |||
| 100 | #endif /* AVCODEC_LPC_FUNCTIONS_H */ | ||
| 101 |