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GAINPRED.C
资源名称：G711-729.rar [点击查看]
上传用户：meifeng08
上传日期：2013-06-18
资源大小：5304k
文件大小：8k
源码类别：
语音压缩
开发平台：
C/C++
- /*
- ITU-T G.729A Speech Coder ANSI-C Source Code
- Version 1.1 Last modified: September 1996
- Copyright (c) 1996,
- AT&T, France Telecom, NTT, Universite de Sherbrooke
- All rights reserved.
- */
- /*---------------------------------------------------------------------------*
- * Gain_predict() : make gcode0(exp_gcode0) *
- * Gain_update() : update table of past quantized energies. *
- * Gain_update_erasure() : update table of past quantized energies. *
- * (frame erasure) *
- * This function is used both Coder and Decoder. *
- *---------------------------------------------------------------------------*/
- #include "typedef.h"
- #include "basic_op.h"
- #include "ld8a.h"
- #include "tab_ld8a.h"
- #include "oper_32b.h"
- /*---------------------------------------------------------------------------*
- * Function Gain_predict *
- * ~~~~~~~~~~~~~~~~~~~~~~ *
- * MA prediction is performed on the innovation energy (in dB with mean *
- * removed). *
- *---------------------------------------------------------------------------*/
- void Gain_predict(
- Word16 past_qua_en[], /* (i) Q10 :Past quantized energies */
- Word16 code[], /* (i) Q13 :Innovative vector. */
- Word16 L_subfr, /* (i) :Subframe length. */
- Word16 *gcode0, /* (o) Qxx :Predicted codebook gain */
- Word16 *exp_gcode0 /* (o) :Q-Format(gcode0) */
- )
- {
- Word16 i, exp, frac;
- Word32 L_tmp;
- /*-------------------------------*
- * Energy coming from code *
- *-------------------------------*/
- L_tmp = 0;
- for(i=0; i<L_subfr; i++)
- L_tmp = L_mac(L_tmp, code[i], code[i]);
- /*-----------------------------------------------------------------*
- * Compute: means_ener - 10log10(ener_code/ L_sufr) *
- * Note: mean_ener change from 36 dB to 30 dB because input/2 *
- * *
- * = 30.0 - 10 log10( ener_code / lcode) + 10log10(2^27) *
- * !!ener_code in Q27!! *
- * = 30.0 - 3.0103 * log2(ener_code) + 10log10(40) + 10log10(2^27) *
- * = 30.0 - 3.0103 * log2(ener_code) + 16.02 + 81.278 *
- * = 127.298 - 3.0103 * log2(ener_code) *
- *-----------------------------------------------------------------*/
- Log2(L_tmp, &exp, &frac); /* Q27->Q0 ^Q0 ^Q15 */
- L_tmp = Mpy_32_16(exp, frac, -24660); /* Q0 Q15 Q13 -> ^Q14 */
- /* hi:Q0+Q13+1 */
- /* lo:Q15+Q13-15+1 */
- /* -24660[Q13]=-3.0103 */
- L_tmp = L_mac(L_tmp, 32588, 32); /* 32588*32[Q14]=127.298 */
- /*-----------------------------------------------------------------*
- * Compute gcode0. *
- * = Sum(i=0,3) pred[i]*past_qua_en[i] - ener_code + mean_ener *
- *-----------------------------------------------------------------*/
- L_tmp = L_shl(L_tmp, 10); /* From Q14 to Q24 */
- for(i=0; i<4; i++)
- L_tmp = L_mac(L_tmp, pred[i], past_qua_en[i]); /* Q13*Q10 ->Q24 */
- *gcode0 = extract_h(L_tmp); /* From Q24 to Q8 */
- /*-----------------------------------------------------------------*
- * gcode0 = pow(10.0, gcode0/20) *
- * = pow(2, 3.3219*gcode0/20) *
- * = pow(2, 0.166*gcode0) *
- *-----------------------------------------------------------------*/
- L_tmp = L_mult(*gcode0, 5439); /* *0.166 in Q15, result in Q24*/
- L_tmp = L_shr(L_tmp, 8); /* From Q24 to Q16 */
- L_Extract(L_tmp, &exp, &frac); /* Extract exponent of gcode0 */
- *gcode0 = extract_l(Pow2(14, frac)); /* Put 14 as exponent so that */
- /* output of Pow2() will be: */
- /* 16768 < Pow2() <= 32767 */
- *exp_gcode0 = sub(14,exp);
- }
- /*---------------------------------------------------------------------------*
- * Function Gain_update *
- * ~~~~~~~~~~~~~~~~~~~~~~ *
- * update table of past quantized energies *
- *---------------------------------------------------------------------------*/
- void Gain_update(
- Word16 past_qua_en[], /* (io) Q10 :Past quantized energies */
- Word32 L_gbk12 /* (i) Q13 : gbk1[indice1][1]+gbk2[indice2][1] */
- )
- {
- Word16 i, tmp;
- Word16 exp, frac;
- Word32 L_acc;
- for(i=3; i>0; i--){
- past_qua_en[i] = past_qua_en[i-1]; /* Q10 */
- }
- /*----------------------------------------------------------------------*
- * -- past_qua_en[0] = 20*log10(gbk1[index1][1]+gbk2[index2][1]); -- *
- * 2 * 10 log10( gbk1[index1][1]+gbk2[index2][1] ) *
- * = 2 * 3.0103 log2( gbk1[index1][1]+gbk2[index2][1] ) *
- * = 2 * 3.0103 log2( gbk1[index1][1]+gbk2[index2][1] ) *
- * 24660:Q12(6.0205) *
- *----------------------------------------------------------------------*/
- Log2( L_gbk12, &exp, &frac ); /* L_gbk12:Q13 */
- L_acc = L_Comp( sub(exp,13), frac); /* L_acc:Q16 */
- tmp = extract_h( L_shl( L_acc,13 ) ); /* tmp:Q13 */
- past_qua_en[0] = mult( tmp, 24660 ); /* past_qua_en[]:Q10 */
- }
- /*---------------------------------------------------------------------------*
- * Function Gain_update_erasure *
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ *
- * update table of past quantized energies (frame erasure) *
- *---------------------------------------------------------------------------*
- * av_pred_en = 0.0; *
- * for (i = 0; i < 4; i++) *
- * av_pred_en += past_qua_en[i]; *
- * av_pred_en = av_pred_en*0.25 - 4.0; *
- * if (av_pred_en < -14.0) av_pred_en = -14.0; *
- *---------------------------------------------------------------------------*/
- void Gain_update_erasure(
- Word16 past_qua_en[] /* (i) Q10 :Past quantized energies */
- )
- {
- Word16 i, av_pred_en;
- Word32 L_tmp;
- L_tmp = 0; /* Q10 */
- for(i=0; i<4; i++)
- L_tmp = L_add( L_tmp, L_deposit_l( past_qua_en[i] ) );
- av_pred_en = extract_l( L_shr( L_tmp, 2 ) );
- av_pred_en = sub( av_pred_en, 4096 ); /* Q10 */
- if( sub(av_pred_en, -14336) < 0 ){
- av_pred_en = -14336; /* 14336:14[Q10] */
- }
- for(i=3; i>0; i--){
- past_qua_en[i] = past_qua_en[i-1];
- }
- past_qua_en[0] = av_pred_en;
- }
