FreeCalypso > hg > gsm-codec-lib
view libtwamr/enc_lag3.c @ 464:fa0652115168
libtwamr: add amr_dhf_subst_efr2()
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Sun, 12 May 2024 21:36:26 +0000 |
parents | 0349de7c45b7 |
children |
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/* ******************************************************************************** * * GSM AMR-NB speech codec R98 Version 7.6.0 December 12, 2001 * R99 Version 3.3.0 * REL-4 Version 4.1.0 * ******************************************************************************** * * File : enc_lag3.c * Purpose : Encoding of fractional pitch lag with 1/3 resolution. * ******************************************************************************** */ /* ******************************************************************************** * MODULE INCLUDE FILE AND VERSION ID ******************************************************************************** */ #include "namespace.h" #include "enc_lag3.h" /* ******************************************************************************** * INCLUDE FILES ******************************************************************************** */ #include "typedef.h" #include "basic_op.h" #include "no_count.h" #include "cnst.h" /* ******************************************************************************** * PUBLIC PROGRAM CODE ******************************************************************************** */ /************************************************************************* * * FUNCTION: Enc_lag3 * * PURPOSE: Encoding of fractional pitch lag with 1/3 resolution. * * DESCRIPTION: * First and third subframes: * -------------------------- * The pitch range is divided as follows: * 19 1/3 to 84 2/3 resolution 1/3 * 85 to 143 resolution 1 * * The period is encoded with 8 bits. * For the range with fractions: * index = (T-19)*3 + frac - 1; * where T=[19..85] and frac=[-1,0,1] * and for the integer only range * index = (T - 85) + 197; where T=[86..143] * * Second and fourth subframes: * ---------------------------- * For the 2nd and 4th subframes a resolution of 1/3 is always used, * and the search range is relative to the lag in previous subframe. * If t0 is the lag in the previous subframe then * t_min=t0-5 and t_max=t0+4 and the range is given by * t_min - 2/3 to t_max + 2/3 * * The period in the 2nd (and 4th) subframe is encoded with 5 bits: * index = (T-(t_min-1))*3 + frac - 1; * where T=[t_min-1..t_max+1] * *************************************************************************/ Word16 Enc_lag3( /* o : Return index of encoding */ Word16 T0, /* i : Pitch delay */ Word16 T0_frac, /* i : Fractional pitch delay */ Word16 T0_prev, /* i : Integer pitch delay of last subframe */ Word16 T0_min, /* i : minimum of search range */ Word16 T0_max, /* i : maximum of search range */ Word16 delta_flag, /* i : Flag for 1st (or 3rd) subframe */ Word16 flag4 /* i : Flag for encoding with 4 bits */ ) { Word16 index, i, tmp_ind, uplag; Word16 tmp_lag; test (); if (delta_flag == 0) { /* if 1st or 3rd subframe */ /* encode pitch delay (with fraction) */ test (); if (sub (T0, 85) <= 0) { /* index = T0*3 - 58 + T0_frac */ i = add (add (T0, T0), T0); index = add (sub (i, 58), T0_frac); } else { index = add (T0, 112); } } else { /* if second or fourth subframe */ test (); if (flag4 == 0) { /* 'normal' encoding: either with 5 or 6 bit resolution */ /* index = 3*(T0 - T0_min) + 2 + T0_frac */ i = sub (T0, T0_min); i = add (add (i, i), i); index = add (add (i, 2), T0_frac); } else { /* encoding with 4 bit resolution */ tmp_lag = T0_prev; move16 (); test (); if ( sub( sub(tmp_lag, T0_min), 5) > 0) tmp_lag = add (T0_min, 5); test (); if ( sub( sub(T0_max, tmp_lag), 4) > 0) tmp_lag = sub (T0_max, 4); uplag = add (add (add (T0, T0), T0), T0_frac); i = sub (tmp_lag, 2); tmp_ind = add (add (i, i), i); test (); if (sub (tmp_ind, uplag) >= 0) { index = add (sub (T0, tmp_lag), 5); } else { i = add (tmp_lag, 1); i = add (add (i, i), i); test (); if (sub (i, uplag) > 0) { index = add ( sub (uplag, tmp_ind), 3); } else { index = add (sub (T0, tmp_lag), 11); } } } /* end if (encoding with 4 bit resolution) */ } /* end if (second of fourth subframe) */ return index; }