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FFmpeg/libavcodec/lsp.h

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  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 */