/*
  * LSP computing for ACELP-based codecs
  *
  * Copyright (c) 2008 Vladimir Voroshilov
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 

 #ifndef AVCODEC_LSP_H
 #define AVCODEC_LSP_H

 
 #include <stdint.h>
 

 /**
   (I.F) means fixed-point value with F fractional and I integer bits
 */
 
 /**

  * @brief ensure a minimum distance between LSFs
  * @param[in,out] lsfq LSF to check and adjust
  * @param lsfq_min_distance minimum distance between LSFs
  * @param lsfq_min minimum allowed LSF value
  * @param lsfq_max maximum allowed LSF value
  * @param lp_order LP filter order

  */

 void ff_acelp_reorder_lsf(int16_t* lsfq, int lsfq_min_distance, int lsfq_min, int lsfq_max, int lp_order);

 
 /**

  * Adjust the quantized LSFs so they are increasing and not too close.
  *
  * This step is not mentioned in the AMR spec but is in the reference C decoder.
  * Omitting this step creates audible distortion on the sinusoidal sweep
  * test vectors in 3GPP TS 26.074.
  *

  * @param[in,out] lsf    LSFs in Hertz

  * @param min_spacing    minimum distance between two consecutive lsf values

  * @param size           size of the lsf vector

  */

 void ff_set_min_dist_lsf(float *lsf, double min_spacing, int size);

 
 /**

  * @brief Convert LSF to LSP
  * @param[out] lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
  * @param lsf normalized LSF coefficients (0 <= (2.13) < 0x2000 * PI)
  * @param lp_order LP filter order

  *

  * @remark It is safe to pass the same array into the lsf and lsp parameters.

  */

 void ff_acelp_lsf2lsp(int16_t *lsp, const int16_t *lsf, int lp_order);

 
 /**

  * Floating point version of ff_acelp_lsf2lsp()
  */
 void ff_acelp_lsf2lspd(double *lsp, const float *lsf, int lp_order);
 
 /**

  * @brief LSP to LP conversion (3.2.6 of G.729)
  * @param[out] lp decoded LP coefficients (-0x8000 <= (3.12) < 0x8000)
  * @param lsp LSP coefficients (-0x8000 <= (0.15) < 0x8000)
  * @param lp_half_order LP filter order, divided by 2

  */

 void ff_acelp_lsp2lpc(int16_t* lp, const int16_t* lsp, int lp_half_order);

 
 /**

  * LSP to LP conversion (5.2.4 of AMR-WB)
  */
 void ff_amrwb_lsp2lpc(const double *lsp, float *lp, int lp_order);
 
 /**

  * @brief Interpolate LSP for the first subframe and convert LSP -> LP for both subframes (3.2.5 and 3.2.6 of G.729)
  * @param[out] lp_1st decoded LP coefficients for first subframe  (-0x8000 <= (3.12) < 0x8000)
  * @param[out] lp_2nd decoded LP coefficients for second subframe (-0x8000 <= (3.12) < 0x8000)
  * @param lsp_2nd LSP coefficients of the second subframe (-0x8000 <= (0.15) < 0x8000)
  * @param lsp_prev LSP coefficients from the second subframe of the previous frame (-0x8000 <= (0.15) < 0x8000)
  * @param lp_order LP filter order

  */

 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);

 #define MAX_LP_HALF_ORDER 10

 #define MAX_LP_ORDER      (2*MAX_LP_HALF_ORDER)

 /**

  * Reconstruct LPC coefficients from the line spectral pair frequencies.

  *
  * @param lsp line spectral pairs in cosine domain
  * @param lpc linear predictive coding coefficients

  * @param lp_half_order half the number of the amount of LPCs to be
  *        reconstructed, need to be smaller or equal to MAX_LP_HALF_ORDER

  *

  * @note buffers should have a minimux size of 2*lp_half_order elements.
  *

  * TIA/EIA/IS-733 2.4.3.3.5
  */

 void ff_acelp_lspd2lpc(const double *lsp, float *lpc, int lp_half_order);

 /**
  * Sort values in ascending order.
  *
  * @note O(n) if data already sorted, O(n^2) - otherwise
  */
 void ff_sort_nearly_sorted_floats(float *vals, int len);
 

 /**

  * Compute the Pa / (1 + z(-1)) or Qa / (1 - z(-1)) coefficients

  * needed for LSP to LPC conversion.
  * We only need to calculate the 6 first elements of the polynomial.
  *
  * @param lsp line spectral pairs in cosine domain

  * @param[out] f polynomial input/output as a vector

  *
  * TIA/EIA/IS-733 2.4.3.3.5-1/2
  */
 void ff_lsp2polyf(const double *lsp, double *f, int lp_half_order);
 

 #endif /* AVCODEC_LSP_H */