www.pudn.com > AVS_M_ver10.rar > d_gain2p.c
/*
***********************************************************************
* COPYRIGHT AND WARRANTY INFORMATION
*
* Copyright 2007 Audio Video Coding Standard, Part ¢ú
*
* This software module was developed by AVS Audio sub-group
*
* DISCLAIMER OF WARRANTY
*
* These software programs are available to the users without any
* license fee or royalty on an "as is" basis. The AVS disclaims
* any and all warranties, whether express, implied, or statutory,
* including any implied warranties of merchantability or of fitness
* for a particular purpose. In no event shall the contributors or
* the AVS be liable for any incidental, punitive, or consequential
* damages of any kind whatsoever arising from the use of this program.
*
* This disclaimer of warranty extends to the user of this program
* and user's customers, employees, agents, transferees, successors,
* and assigns.
*
* The AVS does not represent or warrant that the program furnished
* hereunder are free of infringement of any third-party patents.
* Commercial implementations of AVS, including shareware, may be
* subject to royalty fees to patent holders. Information regarding
* the AVS patent policy is available from the AVS Web site at
* http://www.avs.org.cn
*
* THIS IS NOT A GRANT OF PATENT RIGHTS - SEE THE AVS PATENT POLICY.
************************************************************************
*/
/*-------------------------------------------------------------------*
* procedure d_gain2_plus *
* ~~~~~~~~~~~~~~~~~~~~~~ *
* Decoding of pitch and codebook gains (see q_gain2_plus.c) *
*-------------------------------------------------------------------*
* input arguments: *
* *
* indice :Quantization index *
* code[] :Innovative code vector *
* lcode :Subframe size *
* bfi :Bad frame indicator *
* *
* output arguments: *
* *
* gain_pit :Quantized pitch gain *
* gain_code :Quantized codeebook gain *
* *
* Global variables defining quantizer (in qua_gns.h) *
* *
* t_qua_gain[] :Table of gain quantizers *
* nb_qua_gain :Nombre de quantization levels *
* *
*-------------------------------------------------------------------*/
#include <math.h>
#include <float.h>
#include <stdlib.h>
#include "../include/amr_plus.h"
float d_gain2_plus( /* (o) : 'correction factor' */
int index, /* (i) : index of quantizer */
float code[], /* (i) : Innovative code vector */
int lcode, /* (i) : Subframe size */
float *gain_pit, /* (o) : Quantized pitch gain */
float *gain_code, /* (o) : Quantized codebook gain */
int bfi, /* (i) : Bad frame indicato */
float mean_ener, /* (i) : mean_ener defined in open-loop (2 bits) */
float *past_gpit, /* (i) : past gain of pitch */
float *past_gcode)/* (i/o): past gain of code */
{
int i;
float ener_code, gcode0;
const float *t_qua_gain;
float ener_inov, gcode_inov;
t_qua_gain = E_ROM_qua_gain7b;
ener_inov = 0.01f;
for(i=0; i<lcode; i++) {
ener_inov += code[i] * code[i];
}
gcode_inov = (float)(1.0 / sqrt(ener_inov / (float)lcode));
/*----------------- Test erasure ---------------*/
if (bfi != 0)
{
if (*past_gpit > 0.95f) {
*past_gpit = 0.95f;
}
if (*past_gpit < 0.5f) {
*past_gpit = 0.5f;
}
*gain_pit = *past_gpit;
*past_gpit *= 0.95f;
*past_gcode *= (1.4f - *past_gpit);
*gain_code = *past_gcode * gcode_inov;
return *past_gcode;
}
/*-------------- Decode gains ---------------*/
/* innovation energy (without gain) */
ener_code = 0.01F;
for(i=0; i<lcode; i++) {
ener_code += code[i] * code[i];
}
ener_code = (float)(10.0 * log10(ener_code /(float)lcode));
/* predicted codebook gain */
/* mean energy quantized with 2 bits : 18, 30, 42 or 54 dB */
gcode0 = mean_ener - ener_code;
gcode0 = (float)pow(10.0,gcode0/20.0); /* predicted gain */
*gain_pit = t_qua_gain[index*2];
*gain_code = t_qua_gain[index*2+1] * gcode0;
/* update bad frame handler */
*past_gpit = *gain_pit;
*past_gcode = *gain_code/gcode_inov;
return t_qua_gain[index*2+1];
}