libavcodec/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 lsfq [in/out] 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  * \brief Convert LSF to LSP
  44  * \param lsp [out] LSP coefficients (-0x8000 <= (0.15) < 0x8000)
  45  * \param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
  46  * \param lp_order LP filter order
  47  *
  48  * \remark It is safe to pass the same array into the lsf and lsp parameters.
  49  */
  50 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order);
  51
  52 /**
  53  * \brief LSP to LP conversion (3.2.6 of G.729)
  54  * \param lp [out] decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
  55  * \param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
  56  * \param lp_half_order LP filter order, divided by 2
  57  */
  58 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order);
  59
  60 /**
  61  * \brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
  62  * \param lp_1st [out] decoded LP coefficients for first subframe (-0x8000 <= (3.12) < 0x8000)
  63  * \param lp_2nd [out] decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
  64  * \param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
  65  * \param lsp_prev LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000)
  66  * \param lp_order LP filter order
  67  */
  68 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);
  69
  70 /**
  71  * Reconstructs LPC coefficients from the line spectral pair frequencies.
  72  *
  73  * @param lsp line spectral pairs in cosine domain
  74  * @param lpc linear predictive coding coefficients
  75  *
  76  * TIA/EIA/IS-733 2.4.3.3.5
  77  */
  78 void ff_acelp_lspd2lpc(const double *lsp, float *lpc);
  79
  80 #endif /* AVCODEC_LSP_H */