www.pudn.com > G711-729.rar > DECOD.C
/*
**
** File: "decod.c"
**
** Description: Top-level source code for G.723 dual-rate decoder
**
** Functions: Init_Decod()
** Decod()
**
**
*/
/*
ITU-T G.723 Speech Coder ANSI-C Source Code Version 5.00
copyright (c) 1995, AudioCodes, DSP Group, France Telecom,
Universite de Sherbrooke. All rights reserved.
*/
#include
#include
#include
#include "typedef.h"
#include "basop.h"
#include "cst_lbc.h"
#include "tab_lbc.h"
#include "lbccodec.h"
#include "decod.h"
#include "util_lbc.h"
#include "lpc.h"
#include "lsp.h"
#include "exc_lbc.h"
#include "dec_cng.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( )
{
int i ;
/* Initialize encoder 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] ;
/* Initialize the gain scaling unit memory to a constant */
DecStat.Gain = (Word16) 0x1000 ;
return;
}
/*
**
** Function: Decod()
**
** Description: Implements G.723 dual-rate decoder for a frame
** of speech
**
** Links to text: Section 3
**
** Arguments:
**
** Word16 *DataBuff Empty buffer
** Word16 Vinp[] Encoded frame (22/26 bytes)
**
** Outputs:
**
** Word16 DataBuff[] Decoded frame (480 bytes)
**
** Return value:
**
** Flag Always True
**
*/
Flag Decod( Word16 *DataBuff, char *Vinp, Word16 Crc )
{
int i,j ;
Word32 Senr ;
Word16 QntLpc[SubFrames*LpcOrder] ;
Word16 AcbkCont[SubFrLen] ;
Word16 LspVect[LpcOrder] ;
Word16 Temp[PitchMax+Frame] ;
Word16 *Dpnt ;
LINEDEF Line ;
PFDEF Pf[SubFrames] ;
Word16 Ftyp;
/*
* Decode the packed bitstream for the frame. (Text: Section 4;
* pars of sections 2.17, 2.18)
*/
Line = Line_Unpk( Vinp, &Ftyp, Crc ) ;
/*
* Update the frame erasure count (Text: Section 3.10)
*/
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 != (Word16) 0 )
DecStat.Ecount = add( DecStat.Ecount, (Word16) 1 ) ;
else
DecStat.Ecount = (Word16) 0 ;
if ( DecStat.Ecount > (Word16) ErrMaxNum )
DecStat.Ecount = (Word16) 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 == (Word16) 0 ) {
DecStat.InterGain = add( Line.Sfs[SubFrames-2].Mamp,
Line.Sfs[SubFrames-1].Mamp ) ;
DecStat.InterGain = shr( DecStat.InterGain, (Word16) 1 ) ;
DecStat.InterGain = FcbkGainTable[DecStat.InterGain] ;
}
else
DecStat.InterGain = mult_r( DecStat.InterGain, (Word16) 0x6000 ) ;
/*
* Generate the excitation for the frame
*/
for ( i = 0 ; i < PitchMax ; i ++ )
Temp[i] = DecStat.PrevExc[i] ;
Dpnt = &Temp[PitchMax] ;
if ( DecStat.Ecount == (Word16) 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], (Word16) 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] = shl( Dpnt[j], (Word16) 1 ) ;
Dpnt[j] = add( 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 and DecCng.CurGain to store */
/* excitation energy estimation */
DecStat.InterIndx = Comp_Info( Temp, Line.Olp[SubFrames/2-1],
&DecCng.SidGain, &DecCng.CurGain ) ;
/* 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], (Word16) 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] ;
/* 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], (Word16) 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 ;
}