apps/codecs/libwmavoice/lsp.h

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