calc_en.h

arm音频编解码库

/*
********************************************************************************
*
*      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             : calc_en.h
*      Purpose          : calculation of energy coefficients for quantizers
*
********************************************************************************
*/
#ifndef calc_en_h
#define calc_en_h "$Id $"
 
/*
********************************************************************************
*                         INCLUDE FILES
********************************************************************************
*/
#include "typedef.h"
#include "mode.h"

/*
********************************************************************************
*                         DECLARATION OF PROTOTYPES
********************************************************************************
*/

/*************************************************************************
 *
 * FUNCTION: calc_unfilt_energies
 *
 * PURPOSE:  calculation of several energy coefficients for unfiltered
 *           excitation signals and the LTP coding gain
 *
 *       frac_en[0]*2^exp_en[0] = <res res>   // LP residual energy
 *       frac_en[1]*2^exp_en[1] = <exc exc>   // LTP residual energy
 *       frac_en[2]*2^exp_en[2] = <exc code>  // LTP/CB innovation dot product
 *       frac_en[3]*2^exp_en[3] = <lres lres> // LTP residual energy
 *                                            // (lres = res - gain_pit*exc)
 *       ltpg = log2(LP_res_en / LTP_res_en)
 *
 *************************************************************************/
void
calc_unfilt_energies(
    Word16 res[],     /* i  : LP residual,                               Q0  */
    Word16 exc[],     /* i  : LTP excitation (unfiltered),               Q0  */
    Word16 code[],    /* i  : CB innovation (unfiltered),                Q13 */
    Word16 gain_pit,  /* i  : pitch gain,                                Q14 */
    Word16 L_subfr,   /* i  : Subframe length                                */

    Word16 frac_en[], /* o  : energy coefficients (3), fraction part,    Q15 */
    Word16 exp_en[],  /* o  : energy coefficients (3), exponent part,    Q0  */
    Word16 *ltpg      /* o  : LTP coding gain (log2()),                  Q13 */
);

/*************************************************************************
 *
 * FUNCTION: calc_filt_energies
 *
 * PURPOSE:  calculation of several energy coefficients for filtered
 *           excitation signals
 *
 *     Compute coefficients need for the quantization and the optimum
 *     codebook gain gcu (for MR475 only).
 *
 *      coeff[0] =    y1 y1
 *      coeff[1] = -2 xn y1
 *      coeff[2] =    y2 y2
 *      coeff[3] = -2 xn y2
 *      coeff[4] =  2 y1 y2
 *
 *
 *      gcu = <xn2, y2> / <y2, y2> (0 if <xn2, y2> <= 0)
 *
 *     Product <y1 y1> and <xn y1> have been computed in G_pitch() and
 *     are in vector g_coeff[].
 *
 *************************************************************************/
void
calc_filt_energies(
    enum Mode mode,     /* i  : coder mode                                   */
    Word16 xn[],        /* i  : LTP target vector,                       Q0  */
    Word16 xn2[],       /* i  : CB target vector,                        Q0  */
    Word16 y1[],        /* i  : Adaptive codebook,                       Q0  */
    Word16 Y2[],        /* i  : Filtered innovative vector,              Q12 */
    Word16 g_coeff[],   /* i  : Correlations <xn y1> <y1 y1>                 */
                        /*      computed in G_pitch()                        */

    Word16 frac_coeff[],/* o  : energy coefficients (5), fraction part,  Q15 */
    Word16 exp_coeff[], /* o  : energy coefficients (5), exponent part,  Q0  */
    Word16 *cod_gain_frac,/* o: optimum codebook gain (fraction part),   Q15 */
    Word16 *cod_gain_exp  /* o: optimum codebook gain (exponent part),   Q0  */
);

/*************************************************************************
 *
 * FUNCTION: calc_target_energy
 *
 * PURPOSE:  calculation of target energy
 *
 *      en = <xn, xn>
 *
 *************************************************************************/
void
calc_target_energy(
    Word16 xn[],     /* i: LTP target vector,                       Q0  */
    Word16 *en_exp,  /* o: optimum codebook gain (exponent part),   Q0  */
    Word16 *en_frac  /* o: optimum codebook gain (fraction part),   Q15 */
);
#endif