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| 4349 | Serge | 1 | /* |
| 2 | * LSP computing for ACELP-based codecs |
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| 3 | * |
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| 4 | * Copyright (c) 2008 Vladimir Voroshilov |
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| 5 | * |
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| 6 | * This file is part of FFmpeg. |
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| 7 | * |
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| 8 | * FFmpeg is free software; you can redistribute it and/or |
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| 9 | * modify it under the terms of the GNU Lesser General Public |
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| 10 | * License as published by the Free Software Foundation; either |
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| 11 | * version 2.1 of the License, or (at your option) any later version. |
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| 12 | * |
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| 13 | * FFmpeg is distributed in the hope that it will be useful, |
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| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
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| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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| 16 | * Lesser General Public License for more details. |
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| 17 | * |
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| 18 | * You should have received a copy of the GNU Lesser General Public |
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| 19 | * License along with FFmpeg; if not, write to the Free Software |
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| 20 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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| 21 | */ |
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| 22 | |||
| 23 | #ifndef AVCODEC_LSP_H |
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| 24 | #define AVCODEC_LSP_H |
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| 25 | |||
| 26 | #include |
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| 27 | |||
| 28 | /** |
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| 29 | (I.F) means fixed-point value with F fractional and I integer bits |
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| 30 | */ |
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| 31 | |||
| 32 | /** |
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| 33 | * @brief ensure a minimum distance between LSFs |
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| 34 | * @param[in,out] lsfq LSF to check and adjust |
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| 35 | * @param lsfq_min_distance minimum distance between LSFs |
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| 36 | * @param lsfq_min minimum allowed LSF value |
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| 37 | * @param lsfq_max maximum allowed LSF value |
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| 38 | * @param lp_order LP filter order |
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| 39 | */ |
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| 40 | void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order); |
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| 41 | |||
| 42 | /** |
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| 43 | * Adjust the quantized LSFs so they are increasing and not too close. |
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| 44 | * |
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| 45 | * This step is not mentioned in the AMR spec but is in the reference C decoder. |
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| 46 | * Omitting this step creates audible distortion on the sinusoidal sweep |
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| 47 | * test vectors in 3GPP TS 26.074. |
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| 48 | * |
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| 49 | * @param[in,out] lsf LSFs in Hertz |
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| 50 | * @param min_spacing minimum distance between two consecutive lsf values |
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| 51 | * @param size size of the lsf vector |
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| 52 | */ |
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| 53 | void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size); |
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| 54 | |||
| 55 | /** |
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| 56 | * @brief Convert LSF to LSP |
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| 57 | * @param[out] lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000) |
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| 58 | * @param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI) |
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| 59 | * @param lp_order LP filter order |
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| 60 | * |
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| 61 | * @remark It is safe to pass the same array into the lsf and lsp parameters. |
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| 62 | */ |
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| 63 | void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order); |
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| 64 | |||
| 65 | /** |
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| 66 | * Floating point version of ff_acelp_lsf2lsp() |
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| 67 | */ |
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| 68 | void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order); |
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| 69 | |||
| 70 | /** |
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| 71 | * @brief LSP to LP conversion (3.2.6 of G.729) |
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| 72 | * @param[out] lp decoded LP coefficients (-0x8000 <= (3.12) < 0x8000) |
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| 73 | * @param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000) |
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| 74 | * @param lp_half_order LP filter order, divided by 2 |
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| 75 | */ |
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| 76 | void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order); |
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| 77 | |||
| 78 | /** |
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| 79 | * LSP to LP conversion (5.2.4 of AMR-WB) |
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| 80 | */ |
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| 81 | void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order); |
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| 82 | |||
| 83 | /** |
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| 84 | * @brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729) |
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| 85 | * @param[out] lp_1st decoded LP coefficients for first subframe (-0x8000 <= (3.12) < 0x8000) |
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| 86 | * @param[out] lp_2nd decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000) |
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| 87 | * @param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000) |
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| 88 | * @param lsp_prev LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000) |
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| 89 | * @param lp_order LP filter order |
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| 90 | */ |
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| 91 | void ff_acelp_lp_decode(int16_t* lp_1st, int16_t* lp_2nd, const int16_t* lsp_2nd, const int16_t* lsp_prev, int lp_order); |
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| 92 | |||
| 93 | |||
| 94 | #define MAX_LP_HALF_ORDER 10 |
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| 95 | #define MAX_LP_ORDER (2*MAX_LP_HALF_ORDER) |
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| 96 | |||
| 97 | /** |
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| 98 | * Reconstruct LPC coefficients from the line spectral pair frequencies. |
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| 99 | * |
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| 100 | * @param lsp line spectral pairs in cosine domain |
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| 101 | * @param lpc linear predictive coding coefficients |
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| 102 | * @param lp_half_order half the number of the amount of LPCs to be |
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| 103 | * reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER |
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| 104 | * |
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| 105 | * @note buffers should have a minimux size of 2*lp_half_order elements. |
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| 106 | * |
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| 107 | * TIA/EIA/IS-733 2.4.3.3.5 |
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| 108 | */ |
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| 109 | void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order); |
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| 110 | |||
| 111 | /** |
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| 112 | * Sort values in ascending order. |
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| 113 | * |
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| 114 | * @note O(n) if data already sorted, O(n^2) - otherwise |
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| 115 | */ |
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| 116 | void ff_sort_nearly_sorted_floats(float *vals, int len); |
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| 117 | |||
| 118 | /** |
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| 119 | * Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients |
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| 120 | * needed for LSP to LPC conversion. |
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| 121 | * We only need to calculate the 6 first elements of the polynomial. |
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| 122 | * |
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| 123 | * @param lsp line spectral pairs in cosine domain |
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| 124 | * @param[out] f polynomial input/output as a vector |
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| 125 | * |
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| 126 | * TIA/EIA/IS-733 2.4.3.3.5-1/2 |
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| 127 | */ |
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| 128 | void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order); |
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| 129 | |||
| 130 | #endif /* AVCODEC_LSP_H */ |