www.gusucode.com > VC++ 视频采集与压缩、音频采集、加扰和解绕-源码程序 > VC++ 视频采集与压缩、音频采集、加扰和解绕-源码程序/code/VideoNet_src/decoder/GetBlk.cpp
//Download by http://www.NewXing.com
////////////////////////////////////////////////////////////////////////////
//
//
// Project : VideoNet version 1.1.
// Description : Peer to Peer Video Conferencing over the LAN.
// Author : Nagareshwar Y Talekar ( nsry2002@yahoo.co.in)
// Date : 15-6-2004.
//
// This is the modified version of tmndecode (H.263 decoder)
// written by Karl & Robert.It was in ANSI C. I have converted into C++
// so that it can be integrated into any windows application. I have
// removed some of the files which had display and file storing
// functions.I have removed the unnecessary code and also added some
// new files..
// Original library dealt with files. Input & Output , both were files.
// I have done some major changes so that it can be used for real time
// decoding process. Now one can use this library for decoding H263 frames.
//
//
// File description :
// Name : GetBlk.cpp
//
/////////////////////////////////////////////////////////////////////////////
/************************************************************************
*
* getblk.c, DCT block decoding for tmndecode (H.263 decoder)
* Copyright (C) 1996 Telenor R&D, Norway
* Karl Olav Lillevold <Karl.Lillevold@nta.no>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* Karl Olav Lillevold <Karl.Lillevold@nta.no>
* Telenor Research and Development
* P.O.Box 83 tel.: +47 63 84 84 00
* N-2007 Kjeller, Norway fax.: +47 63 81 00 76
*
* Robert Danielsen e-mail: Robert.Danielsen@nta.no
* Telenor Research and Development www: http://www.nta.no/brukere/DVC/
* P.O.Box 83 tel.: +47 63 84 84 00
* N-2007 Kjeller, Norway fax.: +47 63 81 00 76
*
************************************************************************/
/*
* based on mpeg2decode, (C) 1994, MPEG Software Simulation Group
* and mpeg2play, (C) 1994 Stefan Eckart
* <stefan@lis.e-technik.tu-muenchen.de>
*
*/
#include "GetBlk.h"
void getblock(int comp,int mode)
{
int val, i, j, sign;
unsigned int code;
VLCtabI *tab;
short *bp;
int run, last, level, QP;
short *qval;
bp = ld->block[comp];
/* decode AC coefficients */
for (i=(mode==0); ; i++) {
code = showbits(12);
if (code>=512)
tab = &DCT3Dtab0[(code>>5)-16];
else if (code>=128)
tab = &DCT3Dtab1[(code>>2)-32];
else if (code>=8)
tab = &DCT3Dtab2[(code>>0)-8];
else {
if (!quiet)
fputs("invalid Huffman code in getblock()\n",dlog);
fault = 1;
return;
}
flushbits(tab->len);
run = (tab->val >> 4) & 255;
level = tab->val & 15;
last = (tab->val >> 12) & 1;
if (trace) {
fputs(" (",dlog);
printbits(code,12,tab->len);
}
if (tab->val==ESCAPE) { /* escape */
if (trace) {
putchar(' ');
printbits(showbits(1),1,1);
}
last = getbits1();
if (trace) {
putchar(' ');
printbits(showbits(6),6,6);
}
i += run = getbits(6);
if (trace) {
putchar(' ');
printbits(showbits(8),8,8);
}
level = getbits(8);
if ((sign = (level>=128)))
val = 256 - level;
else
val = level;
}
else {
i+= run;
val = level;
sign = getbits(1);
//if (trace)
// printf("%d",sign);
}
if (i >= 64)
{
if (!quiet)
fputs("DCT coeff index (i) out of bounds\n",dlog);
fault = 1;
return;
}
//if (trace)
// fputs("): %d/%d\n",run,sign ? -val : val);
j = zig_zag_scan[i];
qval = &bp[j];
if (comp >= 6)
QP = mmax (1, mmin( 31, ( bquant_tab[bquant] * quant ) >> 2 ));
else
QP = quant;
/* TMN3 dequantization */
if ((QP % 2) == 1)
*qval = ( sign ? -(QP * (2* val+1)) : QP * (2* val+1) );
else
*qval = ( sign ? -(QP * (2* val+1)-1): QP * (2* val+1)-1 );
if (last) { /* That's it */
if (trace)
fputs("last\n",dlog);
return;
}
}
}
/*********************************************************************
*
* Name: get_sac_block
*
* Description: Decodes blocks of Arithmetic Encoded DCT Coeffs.
* and performs Run Length Decoding and Coefficient
* Dequantisation.
*
* Input: Picture block type and number.
*
* Returns: Nothing.
*
* Side Effects:
*
* Author: Wayne Ellis <ellis_w_wayne@bt-web.bt.co.uk>
*
*********************************************************************/
void get_sac_block(int comp, int ptype)
{
int position=0;
int TCOEF_index, symbol_word;
int last=0, QP, i, j;
short *qval, *bp;
RunCoef DCTcoef;
bp = ld->block[comp];
i = (ptype==0);
while (!last) { /* while there are DCT coefficients remaining */
position++; /* coefficient counter relates to Coeff. model */
TCOEF_index = DecodeTCoef(position, !ptype);
if (TCOEF_index == ESCAPE_INDEX) { /* ESCAPE code encountered */
DCTcoef = Decode_Escape_Char(!ptype, &last);
if (trace)
fputs("ESC: ",dlog);
}
else {
symbol_word = tcoeftab[TCOEF_index];
DCTcoef = vlc_word_decode(symbol_word,&last);
}
/*if (trace) {
printf("val: %d, run: %d, sign: %d, last: %d\n",
DCTcoef.val, DCTcoef.run, DCTcoef.sign, last);
}
*/
i += DCTcoef.run;
j = zig_zag_scan[i];
qval = &bp[j];
i++;
if (comp >= 6)
QP = mmax (1, mmin( 31, ( bquant_tab[bquant] * quant ) >> 2 ));
else
QP = quant;
if ((QP % 2) == 1)
*qval = ( (DCTcoef.sign) ? -(QP * (2* (DCTcoef.val)+1)) :
QP * (2* (DCTcoef.val)+1) );
else
*qval = ( (DCTcoef.sign) ? -(QP * (2* (DCTcoef.val)+1)-1):
QP * (2* (DCTcoef.val)+1)-1 );
}
return;
}
/*********************************************************************
*
* Name: vlc_word_decode
*
* Description: Fills Decoder FIFO after a fixed word length
* string has been detected.
*
* Input: Symbol to be decoded, last data flag.
*
* Returns: Decoded Symbol via the structure DCTcoeff.
*
* Side Effects: Updates last flag.
*
* Author: Wayne Ellis <ellis_w_wayne@bt-web.bt.co.uk>
*
*********************************************************************/
RunCoef vlc_word_decode(int symbol_word, int *last)
{
int sign_index;
RunCoef DCTcoef;
*last = (symbol_word >> 12) & 01;
DCTcoef.run = (symbol_word >> 4) & 255;
DCTcoef.val = (symbol_word) & 15;
sign_index = decode_a_symbol(cumf_SIGN);
DCTcoef.sign = signtab[sign_index];
return (DCTcoef);
}
/*********************************************************************
*
* Name: Decode_Escape_Char
*
* Description: Decodes all components for a Symbol when an
* ESCAPE character has been detected.
*
* Input: Picture Type and last data flag.
*
* Returns: Decoded Symbol via the structure DCTcoeff.
*
* Side Effects: Modifies last data flag.
*
* Author: Wayne Ellis <ellis_w_wayne@bt-web.bt.co.uk>
*
*********************************************************************/
RunCoef Decode_Escape_Char(int intra, int *last)
{
int last_index, run, run_index, level, level_index;
RunCoef DCTcoef;
if (intra) {
last_index = decode_a_symbol(cumf_LAST_intra);
*last = last_intratab[last_index];
}
else {
last_index = decode_a_symbol(cumf_LAST);
*last = lasttab[last_index];
}
if (intra)
run_index = decode_a_symbol(cumf_RUN_intra);
else
run_index = decode_a_symbol(cumf_RUN);
run = runtab[run_index];
/*$if (mrun) run|=64;$*/
DCTcoef.run = run;
if (intra)
level_index = decode_a_symbol(cumf_LEVEL_intra);
else
level_index = decode_a_symbol(cumf_LEVEL);
//if (trace)
// printf("level_idx: %d ",level_index);
level = leveltab[level_index];
if (level >128)
level -=256;
if (level < 0) {
DCTcoef.sign = 1;
DCTcoef.val = abs(level);
}
else {
DCTcoef.sign = 0;
DCTcoef.val = level;
}
return (DCTcoef);
}
/*********************************************************************
*
* Name: DecodeTCoef
*
* Description: Decodes a.c DCT Coefficients using the
* relevant arithmetic decoding model.
*
* Input: DCT Coeff count and Picture Type.
*
* Returns: Index to LUT
*
* Side Effects: None
*
* Author: Wayne Ellis <ellis_w_wayne@bt-web.bt.co.uk>
*
*********************************************************************/
int DecodeTCoef(int position, int intra)
{
int index;
switch (position) {
case 1:
{
if (intra)
index = decode_a_symbol(cumf_TCOEF1_intra);
else
index = decode_a_symbol(cumf_TCOEF1);
break;
}
case 2:
{
if (intra)
index = decode_a_symbol(cumf_TCOEF2_intra);
else
index = decode_a_symbol(cumf_TCOEF2);
break;
}
case 3:
{
if (intra)
index = decode_a_symbol(cumf_TCOEF3_intra);
else
index = decode_a_symbol(cumf_TCOEF3);
break;
}
default:
{
if (intra)
index = decode_a_symbol(cumf_TCOEFr_intra);
else
index = decode_a_symbol(cumf_TCOEFr);
break;
}
}
return (index);
}