www.pudn.com > p_voice.rar > DECOD2.C
/*
**
** File: "decod2.c"
**
** Description: Top-level source code for G.723.1 dual-rate decoder
**
** Functions: Init_Decod()
** Decod()
**
**
*/
/*
ITU-T G.723.1 Floating Point Speech Coder ANSI C Source Code. Version 5.1F
Original fixed-point code copyright (c) 1995,
AudioCodes, DSP Group, France Telecom, Universite de Sherbrooke.
All rights reserved.
Floating-point code copyright (c) 1995,
Intel Corporation and France Telecom (CNET).
All rights reserved.
*/
#include
#include
#include
#include "typedef2.h"
#include "cst2.h"
#include "tab2.h"
#include "lbccode2.h"
#include "decod2.h"
#include "util2.h"
#include "lpc2.h"
#include "lsp2.h"
#include "exc2.h"
#include "deccng2.h"
/*
The following structure contains all the static decoder
variables.
*/
DECSTATDEF DecStat;
/*
**
** Function: Init_Decod()
**
** Description: Initializes non-zero state variables
** for the decoder.
**
** Links to text: Section 3.11
**
** Arguments: None
**
** Outputs: None
**
** Return value: None
**
*/
void Init_Decod(void)
{
int i;
/* Initialize decoder data structure with zeros */
memset(&DecStat,0,sizeof(DECSTATDEF));
/* Initialize the previously decoded LSP vector to the DC vector */
for (i = 0; i < LpcOrder; i++)
DecStat.PrevLsp[i] = LspDcTable[i];
DecStat.Gain = (FLOAT)1.0;
}
/*
**
** Function: Decod()
**
** Description: Implements G.723.1 dual-rate decoder for a frame
** of speech
**
** Links to text: Section 3
**
** Arguments:
**
** FLOAT *DataBuff Empty buffer
** Word16 Vinp[] Encoded frame (22/26 bytes)
**
** Outputs:
**
** FLOAT DataBuff[] Decoded frame (480 bytes)
**
** Return value:
**
** Flag Always True
**
*/
Flag Decod(FLOAT *DataBuff, char *Vinp, Word16 Crc)
{
int i, j, g;
FLOAT Senr;
FLOAT QntLpc[SubFrames*LpcOrder];
FLOAT AcbkCont[SubFrLen];
FLOAT LspVect[LpcOrder];
FLOAT Temp[PitchMax+Frame];
FLOAT *Dpnt;
LINEDEF Line;
PFDEF Pf[SubFrames];
Word16 Ftyp;
/*
* Decode the packed bitstream for the frame. (Text: Section 4;
* pars of sectio,d 2.17, 2.18)
*/
Line = Line_Unpk(Vinp, &Ftyp, Crc);
if (Line.Crc != (Word16) 0) {
if(DecCng.PastFtyp == 1)
Ftyp = 1; /* active */
else
Ftyp = 0; /* untransmitted */
}
if (Ftyp != 1) {
/* Silence frame : do noise generation */
Dec_Cng(Ftyp, &Line, DataBuff, QntLpc);
}
else {
/*
* Update the frame erasure count (Text: Section 3.10)
*/
if (Line.Crc != 0)
DecStat.Ecount++;
else
DecStat.Ecount = 0;
if (DecStat.Ecount > ErrMaxNum)
DecStat.Ecount = ErrMaxNum;
/*
* Decode the LSP vector for subframe 3. (Text: Section 3.2)
*/
Lsp_Inq(LspVect, DecStat.PrevLsp, Line.LspId, Line.Crc);
/*
* Interpolate the LSP vectors for subframes 0--2. Convert the
* LSP vectors to LPC coefficients. (Text: Section 3.3)
*/
Lsp_Int(QntLpc, LspVect, DecStat.PrevLsp);
/* Copy the LSP vector for the next frame */
for ( i = 0 ; i < LpcOrder ; i ++ )
DecStat.PrevLsp[i] = LspVect[i];
/*
* In case of no erasure, update the interpolation gain memory.
* Otherwise compute the interpolation gain (Text: Section 3.10)
*/
if (DecStat.Ecount == 0) {
g = (Line.Sfs[SubFrames-2].Mamp + Line.Sfs[SubFrames-1].Mamp) >> 1;
DecStat.InterGain = FcbkGainTable[g];
}
else
DecStat.InterGain = DecStat.InterGain*(FLOAT)0.75;
/*
* Generate the excitation for the frame
*/
for (i = 0; i < PitchMax; i++)
Temp[i] = DecStat.PrevExc[i];
Dpnt = &Temp[PitchMax];
if (DecStat.Ecount == 0) {
for (i = 0; i < SubFrames; i++) {
/* Generate the fixed codebook excitation for a
subframe. (Text: Section 3.5) */
Fcbk_Unpk(Dpnt, Line.Sfs[i], Line.Olp[i>>1], i);
/* Generate the adaptive codebook excitation for a
subframe. (Text: Section 3.4) */
Decod_Acbk(AcbkCont, &Temp[SubFrLen*i], Line.Olp[i>>1],
Line.Sfs[i].AcLg, Line.Sfs[i].AcGn);
/* Add the adaptive and fixed codebook contributions to
generate the total excitation. */
for (j = 0; j < SubFrLen; j++)
Dpnt[j] = Dpnt[j] + AcbkCont[j];
Dpnt += SubFrLen;
}
/* Save the excitation */
for (j = 0; j < Frame; j++)
DataBuff[j] = Temp[PitchMax+j];
/* Compute interpolation index. (Text: Section 3.10) */
/* Use DecCng.SidGain to store */
/* excitation energy estimation */
DecStat.InterIndx = Comp_Info(Temp, Line.Olp[SubFrames/2-1],
&DecCng.SidGain);
/* Compute pitch post filter coefficients. (Text: Section 3.6) */
if (UsePf)
for (i = 0; i < SubFrames; i++)
Pf[i] = Comp_Lpf(Temp, Line.Olp[i>>1], i);
/* Reload the original excitation */
for (j = 0; j < PitchMax; j++)
Temp[j] = DecStat.PrevExc[j];
for (j = 0; j < Frame; j++)
Temp[PitchMax+j] = DataBuff[j];
/* Clip newly generated samples in Temp array */
for (j = 0; j < Frame; j++) {
if (Temp[PitchMax+j] < (FLOAT)-32767.5)
Temp[PitchMax+j] = (FLOAT)-32768.0;
else if (Temp[PitchMax+j] > (FLOAT)32766.5)
Temp[PitchMax+j] = (FLOAT)32767.0;
}
/* Perform pitch post filtering for the frame. (Text: Section
3.6) */
if (UsePf)
for (i = 0; i < SubFrames; i++)
Filt_Lpf(DataBuff, Temp, Pf[i], i);
/* Save Lsps --> LspSid */
for (i=0; i < LpcOrder; i++)
DecCng.LspSid[i] = DecStat.PrevLsp[i];
}
else {
/* If a frame erasure has occurred, regenerate the
signal for the frame. (Text: Section 3.10) */
Regen(DataBuff, Temp, DecStat.InterIndx, DecStat.InterGain,
DecStat.Ecount, &DecStat.Rseed);
}
/* Update the previous excitation for the next frame */
for (j = 0; j < PitchMax; j++)
DecStat.PrevExc[j] = Temp[Frame+j];
/* Resets random generator for CNG */
DecCng.RandSeed = 12345;
}
/* Save Ftyp information for next frame */
DecCng.PastFtyp = Ftyp;
/*
* Synthesize the speech for the frame
*/
Dpnt = DataBuff;
for (i = 0; i < SubFrames; i++) {
/* Compute the synthesized speech signal for a subframe.
* (Text: Section 3.7)
*/
Synt(Dpnt, &QntLpc[i*LpcOrder]);
if (UsePf) {
/* Do the formant post filter. (Text: Section 3.8) */
Senr = Spf( Dpnt, &QntLpc[i*LpcOrder] ) ;
/* Do the gain scaling unit. (Text: Section 3.9) */
Scale(Dpnt, Senr);
}
Dpnt += SubFrLen;
}
return (Flag) True;
}