h263dec.c

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/* ***** BEGIN LICENSE BLOCK *****
 * Source last modified: $Id: h263dec.c,v 1.3.34.1 2004/07/09 01:56:22 hubbe Exp $
 * 
 * Portions Copyright (c) 1995-2004 RealNetworks, Inc. All Rights Reserved.
 * 
 * The contents of this file, and the files included with this file,
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 * http://www.helixcommunity.org/content/rpsl unless you have licensed
 * the file under the current version of the RealNetworks Community
 * Source License (the "RCSL") available at
 * http://www.helixcommunity.org/content/rcsl, in which case the RCSL
 * will apply. You may also obtain the license terms directly from
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 * to this file, the RCSL.  Please see the applicable RPSL or RCSL for
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 * 
 * This file is part of the Helix DNA Technology. RealNetworks is the
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#include "dllindex.h"
#include "h261defs.h"
#include "vldstate.h"
#include "vldtabs.h"
#include "h261func.h"
#include "vldecode.h"       /* set the proper pragmas for VLDecode          */
#include "h263plus.h"

//#include <stdio.h>
//#include <stdlib.h>
//#define BS_ERR_MSG(a)   a   // Generate messages on bitstream error (i.e., illegal 
                            // bitstream syntax) to simplify debugging
#define BS_ERR_MSG(a)       // Suppress error messages 

//#define CHECKSYM(a)     a     // Check symbol types to verify decoder state tables
#define CHECKSYM(a)             // Don't check symbol types

////////////  Static function declarations  ////////////
//  initPBtabs - Initialize tables for Bquant and mvB/mvF
static void initPBtabs( PICTURE_DESCR * pic );
//  decMvd - Decode "num" motion vectors
static int  decMvd( BS_PTR * bs,    // Bitstream pointer; updated by this routine
                    int * maxBits,  // max bits to decode; updated by this routine
                    int num,        // number of motion vectors to decode
                    S8  x[],        // hor. components decoded by this routine
                    S8  y[]         // vert. components decoded by this routine
                    );
// getMvComp - Compute mv component in H.263 decoder
static int getMvComp( int pred, S8 diff, int unrestrictedMv );
//  dec263blocks - Decode block layer for a macroblock
static int  dec263blocks(   BS_PTR * bs,    // Bitstream pointer; updated by this routine
                            int * maxBits,  // max bits to decode; updated by this routine
                            int cbp,        // Coded Block Pattern
                            int intraFlag,  // 0: INTER block, otherwise INTRA
                            int advancedIntraMode, // 0: off else on
                            BLOCK_DESCR block[6],   // block descriptors generated by this routine
                            SYMBOL sym[],   // array for symbols generated by this routine
                            int maxsym      // size of sym[] array
                            );
//  parseSymbols - Create block descriptor and merge ESC-RUN and ESC-LEVEL symbols
//  Return number of symbols
static int parseSymbols( SYMBOL insym[],        // Input symbols
                        int nsym,               // # input symbols
                        SYMBOL outsym[]         // output symbols
                        );



//  DecPicLayer263 - Decode H.263 Picture Layer information
extern int  DecPicLayer263( BS_PTR * bs, int nbits, PICTURE_DESCR * pic,
                            GOB_DESCR * gob, int * decPtype )
{
    int     gn, tr, ptype, quant, pei, pspare, cpm;
#ifdef DO_H263_PLUS
    int eptype=0;
#endif
    // Decode GN
    if (FLDecSymbol( bs, 5, &nbits, &gn )  !=  OK)  return( OUT_OF_BITS );
    if (gn != 0)  return( H261_ERROR );     // GN=0 for Picture Start Code
    // Decode TR
    if (FLDecSymbol( bs, 8, &nbits, &tr )  !=  OK)  return( OUT_OF_BITS );
    pic->tr = tr;
    // Decode PTYPE
    if (FLDecSymbol( bs, 13, &nbits, &ptype )  !=  OK)  return( OUT_OF_BITS );

#ifdef DO_H263_PLUS
    if ((ptype & 0xe0) == PTYPE263_EPTYPE) {
        if(FLDecSymbol( bs, 14, &nbits, &eptype )  !=  OK)  return( OUT_OF_BITS );
        // the picture type is in bits 1-3 of EPTYPE, put those bits into bits 6-8 of PTYPE
        ptype &= 0xFFFFFF1F; // clear bits 6-8
        ptype |= (0x3800 & eptype) >> 6; 
    }
#endif

    pic->ptype = ptype;
    *decPtype = ptype;
    pic->splitscreen = ptype & PTYPE263_SPLITSCREEN;
    pic->doccamera = ptype & PTYPE263_DOCCAMERA;
    pic->fp_release = ptype & PTYPE263_FP_RELEASE;
    switch (ptype & 0xe0)
    {
    case PTYPE263_SQCIF:
        pic->format = SQCIF;
        break;
    case PTYPE263_QCIF:
        pic->format = QCIF;
        break;
    case PTYPE263_CIF:
        pic->format = CIF;
        break;
    case PTYPE263_4CIF:
        pic->format = CIF4;
        break;
    case PTYPE263_16CIF:
        pic->format = CIF16;
        break;
    case PTYPE263_RESERVED:
        pic->format = ANYSIZE;
        break;
    default:
        return( H261_ERROR );
        break;
    }
    if ((ptype & 0x800) != 0  || (ptype & 0x1000) == 0) return( H261_ERROR );
    pic->interFrame = ptype & PTYPE263_INTER;
    pic->unrestrictedMv = ptype & PTYPE263_UNRESTRICTED_MV;
    pic->advancedPred = ptype & PTYPE263_ADVANCED_PRED;
    pic->syntax_basedAC = ptype & PTYPE263_SYNTAX_BASED_AC;
    if (pic->syntax_basedAC) {
        BS_ERR_MSG( H261ErrMsg("Syntax-based AC not yet supported"); )
        return( H261_ERROR );
    }
    pic->PBframeMode = (ptype & PTYPE263_PB_FRAME) != 0;

#ifdef DO_H263_PLUS
    // Do PB frame - either orignal or improved mode
    pic->PBframeMode = (ptype & PTYPE263_PB_FRAME) ? 1 : 0;
    if(pic->PBframeMode) {
        if( eptype & EPTYPE263PLUS_IMPROVED_PBFRAME_MODE) {
            pic->PBframeMode = H263PLUS_IMPROVED_PBFRAME_MODE;
        }
    } else {
        if( eptype & EPTYPE263PLUS_IMPROVED_PBFRAME_MODE) {
            return ( H261_ERROR );
        }
    }
    // Are deblocking filters on?
    pic->deblockingFilterMode = eptype & EPTYPE263PLUS_DEBLOCKING_FILTER_MODE;
    // Use advanced intra mode?
    pic->advancedIntraMode = eptype & EPTYPE263PLUS_ADVANCED_INTRA_MODE;
    // Using Reduced-resolution Update mode?
    pic->reducedResUpdate = eptype & EPTYPE263PLUS_REDUCED_RES_UPDATE;
    //if (pic->reducedResUpdate && (!pic->interFrame || pic->PBframeMode)) return( H261_ERROR );
#else
    pic->reducedResUpdate = 0;
#endif

    if(pic->interFrame == 0 && pic->PBframeMode != 0) return( H261_ERROR );
    // Decode PQUANT
    if (FLDecSymbol( bs, 5, &nbits, &quant )  !=  OK)  return( OUT_OF_BITS );
    if (quant < QUANT_MIN  ||  quant > QUANT_MAX)  return( H261_ERROR );
    gob->gquant = quant;
     // Decode CPM (continuous presence multipoint). For now, flag error if not zero.
    if (FLDecSymbol( bs, 1, &nbits, &cpm )  !=  OK)  return( OUT_OF_BITS );
    // if (cpm != 0)  return( H261_ERROR );
    pic->cpm = cpm;     // Save (we may need it?)
    if (pic->PBframeMode) {
        // Decode TRB
        if (FLDecSymbol( bs, 3, &nbits, &tr )  !=  OK)  return( OUT_OF_BITS );
        pic->tempRefBframe = tr;
        // Decode DBQUANT
        if (FLDecSymbol( bs, 2, &nbits, &quant )  !=  OK)  return( OUT_OF_BITS );
        pic->dbQuant = quant;
        initPBtabs( pic );  // Generate lookup tables for Bquant and mvB/mvF
    }
    pic->trPrev = pic->tr;  // Hold on to TR for decoding of next picture
    // Decode PEI
    if (FLDecSymbol( bs, 1, &nbits, &pei )  !=  OK)  return( OUT_OF_BITS );
    pic->peiCount = 0;
    // Decode PSPARE
    while (pei) {   // Loop until PEI=0
        if (pic->peiCount < MAX_PEI_COUNT) {
            FLDecSymbol( bs, 8, &nbits, &pspare );
            pic->pSpare[pic->peiCount] = pspare;
        } else {
            ++bs->byteptr;  // Drop PSPARE on the floor
        }
        ++pic->peiCount;
        if (FLDecSymbol( bs, 1, &nbits, &pei )  !=  OK)  return( OUT_OF_BITS );
    }
    // Indicate that GOB header has no "spares"
    gob->gei = 0;
    gob->num_gspare = 0;
    return( OK );
}


//  InitMvTabs - Initialize tables for mvB/mvF
extern void InitMvTabs( int trD, int trB,
                        int tabMvF[], int tabMvB[]  // [UMV_MIN:UMV_MAX]
                        )
{
    int i;

    // Generate tables for B-picture motion vectors
    trD &= H263_TR_MASK;
    if (trD == 0)  trD = 2; // Avoid divide by 0
    if (trB >= trD)  trB = 0;   // Ensure trB < trD
    for (i = UMV_MIN; i <= UMV_MAX; ++i) {
        tabMvF[i] = (trB * i) / trD;          // Mv using prev. picture
        tabMvB[i] = ((trB - trD) * i) / trD;  // Mv using new P-picture
    }
}


// Tables for B-picture: Bquant and mvF/mvB
static U8   tabBquant[QUANT_MAX-QUANT_MIN+1];
static int  decMvF[UMV_MAX-UMV_MIN+1],  // Mv using prev. picture
            decMvB[UMV_MAX-UMV_MIN+1];  // Mv using new P-picture

//  initPBtabs - Initialize tables for Bquant and mvB/mvF
static void initPBtabs( PICTURE_DESCR * pic )
{
    int i, n;