PeerStreamer

/*

 * MSMPEG4 backend for ffmpeg encoder and decoder

 * Copyright (c) 2001 Fabrice Bellard

 * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>

 *

 * msmpeg4v1 & v2 stuff by Michael Niedermayer <michaelni@gmx.at>

 *

 * This file is part of Libav.

 *

 * Libav is free software; you can redistribute it and/or

 * modify it under the terms of the GNU Lesser General Public

 * License as published by the Free Software Foundation; either

 * version 2.1 of the License, or (at your option) any later version.

 *

 * Libav 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

 * Lesser General Public License for more details.

 *

 * You should have received a copy of the GNU Lesser General Public

 * License along with Libav; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

 */

/**

 * @file

 * MSMPEG4 backend for ffmpeg encoder and decoder.

 */

#include "avcodec.h"

#include "dsputil.h"

#include "mpegvideo.h"

#include "msmpeg4.h"

#include "libavutil/x86_cpu.h"

#include "h263.h"

#include "mpeg4video.h"

/*

 * You can also call this codec : MPEG4 with a twist !

 *

 * TODO:

 *        - (encoding) select best mv table (two choices)

 *        - (encoding) select best vlc/dc table

 */

//#define DEBUG

#define DC_VLC_BITS 9

#define V2_INTRA_CBPC_VLC_BITS 3

#define V2_MB_TYPE_VLC_BITS 7

#define MV_VLC_BITS 9

#define V2_MV_VLC_BITS 9

#define TEX_VLC_BITS 9

#define II_BITRATE 128*1024

#define MBAC_BITRATE 50*1024

#define DEFAULT_INTER_INDEX 3

static uint32_t v2_dc_lum_table[512][2];

static uint32_t v2_dc_chroma_table[512][2];

/* vc1 externs */

extern const uint8_t wmv3_dc_scale_table[32];

#ifdef DEBUG

int frame_count = 0;

#endif

#include "msmpeg4data.h"

#if CONFIG_ENCODERS //strangely gcc includes this even if it is not referenced

static uint8_t rl_length[NB_RL_TABLES][MAX_LEVEL+1][MAX_RUN+1][2];

#endif //CONFIG_ENCODERS

static uint8_t static_rl_table_store[NB_RL_TABLES][2][2*MAX_RUN + MAX_LEVEL + 3];

/* This table is practically identical to the one from h263

 * except that it is inverted. */

static av_cold void init_h263_dc_for_msmpeg4(void)

{

        int level, uni_code, uni_len;

        for(level=-256; level<256; level++){

            int size, v, l;

            /* find number of bits */

            size = 0;

            v = abs(level);

            while (v) {

                v >>= 1;

                    size++;

            }

            if (level < 0)

                l= (-level) ^ ((1 << size) - 1);

            else

                l= level;

            /* luminance h263 */

            uni_code= ff_mpeg4_DCtab_lum[size][0];

            uni_len = ff_mpeg4_DCtab_lum[size][1];

            uni_code ^= (1<<uni_len)-1; //M$ does not like compatibility

            if (size > 0) {

                uni_code<<=size; uni_code|=l;

                uni_len+=size;

                if (size > 8){

                    uni_code<<=1; uni_code|=1;

                    uni_len++;

                }

            }

            v2_dc_lum_table[level+256][0]= uni_code;

            v2_dc_lum_table[level+256][1]= uni_len;

            /* chrominance h263 */

            uni_code= ff_mpeg4_DCtab_chrom[size][0];

            uni_len = ff_mpeg4_DCtab_chrom[size][1];

            uni_code ^= (1<<uni_len)-1; //M$ does not like compatibility

            if (size > 0) {

                uni_code<<=size; uni_code|=l;

                uni_len+=size;

                if (size > 8){

                    uni_code<<=1; uni_code|=1;

                    uni_len++;

                }

            }

            v2_dc_chroma_table[level+256][0]= uni_code;

            v2_dc_chroma_table[level+256][1]= uni_len;

        }

}

static av_cold void common_init(MpegEncContext * s)

{

    static int initialized=0;

    switch(s->msmpeg4_version){

    case 1:

    case 2:

        s->y_dc_scale_table=

        s->c_dc_scale_table= ff_mpeg1_dc_scale_table;

        break;

    case 3:

        if(s->workaround_bugs){

            s->y_dc_scale_table= old_ff_y_dc_scale_table;

            s->c_dc_scale_table= wmv1_c_dc_scale_table;

        } else{

            s->y_dc_scale_table= ff_mpeg4_y_dc_scale_table;

            s->c_dc_scale_table= ff_mpeg4_c_dc_scale_table;

        }

        break;

    case 4:

    case 5:

        s->y_dc_scale_table= wmv1_y_dc_scale_table;

        s->c_dc_scale_table= wmv1_c_dc_scale_table;

        break;

#if CONFIG_VC1_DECODER

    case 6:

        s->y_dc_scale_table= wmv3_dc_scale_table;

        s->c_dc_scale_table= wmv3_dc_scale_table;

        break;

#endif

    }

    if(s->msmpeg4_version>=4){

        ff_init_scantable(s->dsp.idct_permutation, &s->intra_scantable  , wmv1_scantable[1]);

        ff_init_scantable(s->dsp.idct_permutation, &s->intra_h_scantable, wmv1_scantable[2]);

        ff_init_scantable(s->dsp.idct_permutation, &s->intra_v_scantable, wmv1_scantable[3]);

        ff_init_scantable(s->dsp.idct_permutation, &s->inter_scantable  , wmv1_scantable[0]);

    }

    //Note the default tables are set in common_init in mpegvideo.c

    if(!initialized){

        initialized=1;

        init_h263_dc_for_msmpeg4();

    }

}

#if CONFIG_ENCODERS

/* build the table which associate a (x,y) motion vector to a vlc */

static void init_mv_table(MVTable *tab)

{

    int i, x, y;

    tab->table_mv_index = av_malloc(sizeof(uint16_t) * 4096);

    /* mark all entries as not used */

    for(i=0;i<4096;i++)

        tab->table_mv_index[i] = tab->n;

    for(i=0;i<tab->n;i++) {

        x = tab->table_mvx[i];

        y = tab->table_mvy[i];

        tab->table_mv_index[(x << 6) | y] = i;

    }

}

void ff_msmpeg4_code012(PutBitContext *pb, int n)

{

    if (n == 0) {

        put_bits(pb, 1, 0);

    } else {

        put_bits(pb, 1, 1);

        put_bits(pb, 1, (n >= 2));

    }

}

static int get_size_of_code(MpegEncContext * s, RLTable *rl, int last, int run, int level, int intra){

    int size=0;

    int code;

    int run_diff= intra ? 0 : 1;

    code = get_rl_index(rl, last, run, level);

    size+= rl->table_vlc[code][1];

    if (code == rl->n) {

        int level1, run1;

        level1 = level - rl->max_level[last][run];

        if (level1 < 1)

            goto esc2;

        code = get_rl_index(rl, last, run, level1);

        if (code == rl->n) {

            esc2:

            size++;

            if (level > MAX_LEVEL)

                goto esc3;

            run1 = run - rl->max_run[last][level] - run_diff;

            if (run1 < 0)

                goto esc3;

            code = get_rl_index(rl, last, run1, level);

            if (code == rl->n) {

            esc3:

                /* third escape */

                size+=1+1+6+8;

            } else {

                /* second escape */

                size+= 1+1+ rl->table_vlc[code][1];

            }

        } else {

            /* first escape */

            size+= 1+1+ rl->table_vlc[code][1];

        }

    } else {

        size++;

    }

    return size;

}

av_cold void ff_msmpeg4_encode_init(MpegEncContext *s)

{

    static int init_done=0;

    int i;

    common_init(s);

    if(s->msmpeg4_version>=4){

        s->min_qcoeff= -255;

        s->max_qcoeff=  255;

    }

    if (!init_done) {

        /* init various encoding tables */

        init_done = 1;

        init_mv_table(&mv_tables[0]);

        init_mv_table(&mv_tables[1]);

        for(i=0;i<NB_RL_TABLES;i++)

            init_rl(&rl_table[i], static_rl_table_store[i]);

        for(i=0; i<NB_RL_TABLES; i++){

            int level;

            for(level=0; level<=MAX_LEVEL; level++){

                int run;

                for(run=0; run<=MAX_RUN; run++){

                    int last;

                    for(last=0; last<2; last++){

                        rl_length[i][level][run][last]= get_size_of_code(s, &rl_table[  i], last, run, level, 0);

                    }

                }

            }

        }

    }

}

static void find_best_tables(MpegEncContext * s)

{

    int i;

    int best       =-1, best_size       =9999999;

    int chroma_best=-1, best_chroma_size=9999999;

    for(i=0; i<3; i++){

        int level;

        int chroma_size=0;

        int size=0;

        if(i>0){// ;)

            size++;

            chroma_size++;

        }

        for(level=0; level<=MAX_LEVEL; level++){

            int run;

            for(run=0; run<=MAX_RUN; run++){

                int last;

                const int last_size= size + chroma_size;

                for(last=0; last<2; last++){

                    int inter_count       = s->ac_stats[0][0][level][run][last] + s->ac_stats[0][1][level][run][last];

                    int intra_luma_count  = s->ac_stats[1][0][level][run][last];

                    int intra_chroma_count= s->ac_stats[1][1][level][run][last];

                    if(s->pict_type==FF_I_TYPE){

                        size       += intra_luma_count  *rl_length[i  ][level][run][last];

                        chroma_size+= intra_chroma_count*rl_length[i+3][level][run][last];

                    }else{

                        size+=        intra_luma_count  *rl_length[i  ][level][run][last]

                                     +intra_chroma_count*rl_length[i+3][level][run][last]

                                     +inter_count       *rl_length[i+3][level][run][last];

                    }

                }

                if(last_size == size+chroma_size) break;

            }

        }

        if(size<best_size){

            best_size= size;

            best= i;

        }

        if(chroma_size<best_chroma_size){

            best_chroma_size= chroma_size;

            chroma_best= i;

        }

    }

//    printf("type:%d, best:%d, qp:%d, var:%d, mcvar:%d, size:%d //\n",

//           s->pict_type, best, s->qscale, s->mb_var_sum, s->mc_mb_var_sum, best_size);

    if(s->pict_type==FF_P_TYPE) chroma_best= best;

    memset(s->ac_stats, 0, sizeof(int)*(MAX_LEVEL+1)*(MAX_RUN+1)*2*2*2);

    s->rl_table_index       =        best;

    s->rl_chroma_table_index= chroma_best;

    if(s->pict_type != s->last_non_b_pict_type){

        s->rl_table_index= 2;

        if(s->pict_type==FF_I_TYPE)

            s->rl_chroma_table_index= 1;

        else

            s->rl_chroma_table_index= 2;

    }

}

/* write MSMPEG4 compatible frame header */

void msmpeg4_encode_picture_header(MpegEncContext * s, int picture_number)

{

    find_best_tables(s);

    align_put_bits(&s->pb);

    put_bits(&s->pb, 2, s->pict_type - 1);

    put_bits(&s->pb, 5, s->qscale);

    if(s->msmpeg4_version<=2){

        s->rl_table_index = 2;

        s->rl_chroma_table_index = 2;

    }

    s->dc_table_index = 1;

    s->mv_table_index = 1; /* only if P frame */

    s->use_skip_mb_code = 1; /* only if P frame */

    s->per_mb_rl_table = 0;

    if(s->msmpeg4_version==4)

        s->inter_intra_pred= (s->width*s->height < 320*240 && s->bit_rate<=II_BITRATE && s->pict_type==FF_P_TYPE);

//printf("%d %d %d %d %d\n", s->pict_type, s->bit_rate, s->inter_intra_pred, s->width, s->height);

    if (s->pict_type == FF_I_TYPE) {

        s->slice_height= s->mb_height/1;

        put_bits(&s->pb, 5, 0x16 + s->mb_height/s->slice_height);

        if(s->msmpeg4_version==4){

            msmpeg4_encode_ext_header(s);

            if(s->bit_rate>MBAC_BITRATE)

                put_bits(&s->pb, 1, s->per_mb_rl_table);

        }

        if(s->msmpeg4_version>2){

            if(!s->per_mb_rl_table){

                ff_msmpeg4_code012(&s->pb, s->rl_chroma_table_index);

                ff_msmpeg4_code012(&s->pb, s->rl_table_index);

            }

            put_bits(&s->pb, 1, s->dc_table_index);

        }

    } else {

        put_bits(&s->pb, 1, s->use_skip_mb_code);

        if(s->msmpeg4_version==4 && s->bit_rate>MBAC_BITRATE)

            put_bits(&s->pb, 1, s->per_mb_rl_table);

        if(s->msmpeg4_version>2){

            if(!s->per_mb_rl_table)

                ff_msmpeg4_code012(&s->pb, s->rl_table_index);

            put_bits(&s->pb, 1, s->dc_table_index);

            put_bits(&s->pb, 1, s->mv_table_index);

        }

    }

    s->esc3_level_length= 0;

    s->esc3_run_length= 0;

}

void msmpeg4_encode_ext_header(MpegEncContext * s)

{

        put_bits(&s->pb, 5, s->avctx->time_base.den / s->avctx->time_base.num); //yes 29.97 -> 29

        put_bits(&s->pb, 11, FFMIN(s->bit_rate/1024, 2047));

        if(s->msmpeg4_version>=3)

            put_bits(&s->pb, 1, s->flipflop_rounding);

        else

            assert(s->flipflop_rounding==0);

}

#endif //CONFIG_ENCODERS

/* predict coded block */

int ff_msmpeg4_coded_block_pred(MpegEncContext * s, int n, uint8_t **coded_block_ptr)

{

    int xy, wrap, pred, a, b, c;

    xy = s->block_index[n];

    wrap = s->b8_stride;

    /* B C

     * A X

     */

    a = s->coded_block[xy - 1       ];

    b = s->coded_block[xy - 1 - wrap];

    c = s->coded_block[xy     - wrap];

    if (b == c) {

        pred = a;

    } else {

        pred = c;

    }

    /* store value */

    *coded_block_ptr = &s->coded_block[xy];

    return pred;

}

#if CONFIG_ENCODERS

void ff_msmpeg4_encode_motion(MpegEncContext * s,

                                  int mx, int my)

{

    int code;

    MVTable *mv;

    /* modulo encoding */

    /* WARNING : you cannot reach all the MVs even with the modulo

       encoding. This is a somewhat strange compromise they took !!!  */

    if (mx <= -64)

        mx += 64;

    else if (mx >= 64)

        mx -= 64;

    if (my <= -64)

        my += 64;

    else if (my >= 64)

        my -= 64;

    mx += 32;

    my += 32;

#if 0

    if ((unsigned)mx >= 64 ||

        (unsigned)my >= 64)

        av_log(s->avctx, AV_LOG_ERROR, "error mx=%d my=%d\n", mx, my);

#endif

    mv = &mv_tables[s->mv_table_index];

    code = mv->table_mv_index[(mx << 6) | my];

    put_bits(&s->pb,

             mv->table_mv_bits[code],

             mv->table_mv_code[code]);

    if (code == mv->n) {

        /* escape : code literally */

        put_bits(&s->pb, 6, mx);

        put_bits(&s->pb, 6, my);

    }

}

void ff_msmpeg4_handle_slices(MpegEncContext *s){

    if (s->mb_x == 0) {

        if (s->slice_height && (s->mb_y % s->slice_height) == 0) {

            if(s->msmpeg4_version < 4){

                ff_mpeg4_clean_buffers(s);

            }

            s->first_slice_line = 1;

        } else {

            s->first_slice_line = 0;

        }

    }

}

static void msmpeg4v2_encode_motion(MpegEncContext * s, int val)

{

    int range, bit_size, sign, code, bits;

    if (val == 0) {

        /* zero vector */

        code = 0;

        put_bits(&s->pb, mvtab[code][1], mvtab[code][0]);

    } else {

        bit_size = s->f_code - 1;

        range = 1 << bit_size;

        if (val <= -64)

            val += 64;

        else if (val >= 64)

            val -= 64;

        if (val >= 0) {

            sign = 0;

        } else {

            val = -val;

            sign = 1;

        }

        val--;

        code = (val >> bit_size) + 1;

        bits = val & (range - 1);

        put_bits(&s->pb, mvtab[code][1] + 1, (mvtab[code][0] << 1) | sign);

        if (bit_size > 0) {

            put_bits(&s->pb, bit_size, bits);

        }

    }

}

void msmpeg4_encode_mb(MpegEncContext * s,

                       DCTELEM block[6][64],

                       int motion_x, int motion_y)

{

    int cbp, coded_cbp, i;

    int pred_x, pred_y;

    uint8_t *coded_block;

    ff_msmpeg4_handle_slices(s);

    if (!s->mb_intra) {

        /* compute cbp */

        cbp = 0;

        for (i = 0; i < 6; i++) {

            if (s->block_last_index[i] >= 0)

                cbp |= 1 << (5 - i);

        }

        if (s->use_skip_mb_code && (cbp | motion_x | motion_y) == 0) {

            /* skip macroblock */

            put_bits(&s->pb, 1, 1);

            s->last_bits++;

            s->misc_bits++;

            s->skip_count++;

            return;

        }

        if (s->use_skip_mb_code)

            put_bits(&s->pb, 1, 0);     /* mb coded */

        if(s->msmpeg4_version<=2){

            put_bits(&s->pb,

                     v2_mb_type[cbp&3][1],

                     v2_mb_type[cbp&3][0]);

            if((cbp&3) != 3) coded_cbp= cbp ^ 0x3C;

            else             coded_cbp= cbp;

            put_bits(&s->pb,

                     ff_h263_cbpy_tab[coded_cbp>>2][1],

                     ff_h263_cbpy_tab[coded_cbp>>2][0]);

            s->misc_bits += get_bits_diff(s);

            h263_pred_motion(s, 0, 0, &pred_x, &pred_y);

            msmpeg4v2_encode_motion(s, motion_x - pred_x);

            msmpeg4v2_encode_motion(s, motion_y - pred_y);

        }else{

            put_bits(&s->pb,

                     table_mb_non_intra[cbp + 64][1],

                     table_mb_non_intra[cbp + 64][0]);

            s->misc_bits += get_bits_diff(s);

            /* motion vector */

            h263_pred_motion(s, 0, 0, &pred_x, &pred_y);

            ff_msmpeg4_encode_motion(s, motion_x - pred_x,

                                  motion_y - pred_y);

        }

        s->mv_bits += get_bits_diff(s);

        for (i = 0; i < 6; i++) {

            ff_msmpeg4_encode_block(s, block[i], i);

        }

        s->p_tex_bits += get_bits_diff(s);

    } else {

        /* compute cbp */

        cbp = 0;

        coded_cbp = 0;

        for (i = 0; i < 6; i++) {

            int val, pred;

            val = (s->block_last_index[i] >= 1);

            cbp |= val << (5 - i);

            if (i < 4) {

                /* predict value for close blocks only for luma */

                pred = ff_msmpeg4_coded_block_pred(s, i, &coded_block);

                *coded_block = val;

                val = val ^ pred;

            }

            coded_cbp |= val << (5 - i);

        }

#if 0

        if (coded_cbp)

            printf("cbp=%x %x\n", cbp, coded_cbp);

#endif

        if(s->msmpeg4_version<=2){

            if (s->pict_type == FF_I_TYPE) {

                put_bits(&s->pb,

                         v2_intra_cbpc[cbp&3][1], v2_intra_cbpc[cbp&3][0]);

            } else {

                if (s->use_skip_mb_code)

                    put_bits(&s->pb, 1, 0);     /* mb coded */

                put_bits(&s->pb,

                         v2_mb_type[(cbp&3) + 4][1],

                         v2_mb_type[(cbp&3) + 4][0]);

            }

            put_bits(&s->pb, 1, 0);             /* no AC prediction yet */

            put_bits(&s->pb,

                     ff_h263_cbpy_tab[cbp>>2][1],

                     ff_h263_cbpy_tab[cbp>>2][0]);

        }else{

            if (s->pict_type == FF_I_TYPE) {

                put_bits(&s->pb,

                         ff_msmp4_mb_i_table[coded_cbp][1], ff_msmp4_mb_i_table[coded_cbp][0]);

            } else {

                if (s->use_skip_mb_code)

                    put_bits(&s->pb, 1, 0);     /* mb coded */

                put_bits(&s->pb,

                         table_mb_non_intra[cbp][1],

                         table_mb_non_intra[cbp][0]);

            }

            put_bits(&s->pb, 1, 0);             /* no AC prediction yet */

            if(s->inter_intra_pred){

                s->h263_aic_dir=0;

                put_bits(&s->pb, table_inter_intra[s->h263_aic_dir][1], table_inter_intra[s->h263_aic_dir][0]);

            }

        }

        s->misc_bits += get_bits_diff(s);

        for (i = 0; i < 6; i++) {

            ff_msmpeg4_encode_block(s, block[i], i);

        }

        s->i_tex_bits += get_bits_diff(s);

        s->i_count++;

    }

}

#endif //CONFIG_ENCODERS

static inline int msmpeg4v1_pred_dc(MpegEncContext * s, int n,

                                    int32_t **dc_val_ptr)

{

    int i;

    if (n < 4) {

        i= 0;

    } else {

        i= n-3;

    }

    *dc_val_ptr= &s->last_dc[i];

    return s->last_dc[i];

}

static int get_dc(uint8_t *src, int stride, int scale)

{

    int y;

    int sum=0;

    for(y=0; y<8; y++){

        int x;

        for(x=0; x<8; x++){

            sum+=src[x + y*stride];

        }

    }

    return FASTDIV((sum + (scale>>1)), scale);

}

/* dir = 0: left, dir = 1: top prediction */

static inline int msmpeg4_pred_dc(MpegEncContext * s, int n,

                             int16_t **dc_val_ptr, int *dir_ptr)

{

    int a, b, c, wrap, pred, scale;

    int16_t *dc_val;

    /* find prediction */

    if (n < 4) {

        scale = s->y_dc_scale;

    } else {

        scale = s->c_dc_scale;

    }

    wrap = s->block_wrap[n];

    dc_val= s->dc_val[0] + s->block_index[n];

    /* B C

     * A X

     */

    a = dc_val[ - 1];

    b = dc_val[ - 1 - wrap];

    c = dc_val[ - wrap];

    if(s->first_slice_line && (n&2)==0 && s->msmpeg4_version<4){

        b=c=1024;

    }

    /* XXX: the following solution consumes divisions, but it does not

       necessitate to modify mpegvideo.c. The problem comes from the

       fact they decided to store the quantized DC (which would lead

       to problems if Q could vary !) */

#if ARCH_X86 && HAVE_7REGS && HAVE_EBX_AVAILABLE

    __asm__ volatile(

        "movl %3, %%eax         \n\t"

        "shrl $1, %%eax         \n\t"

        "addl %%eax, %2         \n\t"

        "addl %%eax, %1         \n\t"

        "addl %0, %%eax         \n\t"

        "mull %4                \n\t"

        "movl %%edx, %0         \n\t"

        "movl %1, %%eax         \n\t"

        "mull %4                \n\t"

        "movl %%edx, %1         \n\t"

        "movl %2, %%eax         \n\t"

        "mull %4                \n\t"

        "movl %%edx, %2         \n\t"

        : "+b" (a), "+c" (b), "+D" (c)

        : "g" (scale), "S" (ff_inverse[scale])

        : "%eax", "%edx"

    );

#else

    /* #elif ARCH_ALPHA */

    /* Divisions are extremely costly on Alpha; optimize the most

       common case. But they are costly everywhere...

     */

    if (scale == 8) {

        a = (a + (8 >> 1)) / 8;

        b = (b + (8 >> 1)) / 8;

        c = (c + (8 >> 1)) / 8;

    } else {

        a = FASTDIV((a + (scale >> 1)), scale);

        b = FASTDIV((b + (scale >> 1)), scale);

        c = FASTDIV((c + (scale >> 1)), scale);

    }

#endif

    /* XXX: WARNING: they did not choose the same test as MPEG4. This

       is very important ! */

    if(s->msmpeg4_version>3){

        if(s->inter_intra_pred){

            uint8_t *dest;

            int wrap;

            if(n==1){

                pred=a;

                *dir_ptr = 0;

            }else if(n==2){

                pred=c;

                *dir_ptr = 1;

            }else if(n==3){

                if (abs(a - b) < abs(b - c)) {

                    pred = c;

                    *dir_ptr = 1;

                } else {

                    pred = a;

                    *dir_ptr = 0;

                }

            }else{

                if(n<4){

                    wrap= s->linesize;

                    dest= s->current_picture.data[0] + (((n>>1) + 2*s->mb_y) * 8*  wrap ) + ((n&1) + 2*s->mb_x) * 8;

                }else{

                    wrap= s->uvlinesize;

                    dest= s->current_picture.data[n-3] + (s->mb_y * 8 * wrap) + s->mb_x * 8;

                }

                if(s->mb_x==0) a= (1024 + (scale>>1))/scale;

                else           a= get_dc(dest-8, wrap, scale*8);

                if(s->mb_y==0) c= (1024 + (scale>>1))/scale;

                else           c= get_dc(dest-8*wrap, wrap, scale*8);

                if (s->h263_aic_dir==0) {

                    pred= a;

                    *dir_ptr = 0;

                }else if (s->h263_aic_dir==1) {

                    if(n==0){

                        pred= c;

                        *dir_ptr = 1;

                    }else{

                        pred= a;

                        *dir_ptr = 0;

                    }

                }else if (s->h263_aic_dir==2) {

                    if(n==0){

                        pred= a;

                        *dir_ptr = 0;

                    }else{

                        pred= c;

                        *dir_ptr = 1;

                    }

                } else {

                    pred= c;

                    *dir_ptr = 1;

                }

            }

        }else{

            if (abs(a - b) < abs(b - c)) {

                pred = c;

                *dir_ptr = 1;

            } else {

                pred = a;

                *dir_ptr = 0;

            }

        }

    }else{

        if (abs(a - b) <= abs(b - c)) {

            pred = c;

            *dir_ptr = 1;

        } else {

            pred = a;

            *dir_ptr = 0;

        }

    }

    /* update predictor */

    *dc_val_ptr = &dc_val[0];

    return pred;

}

#define DC_MAX 119

static void msmpeg4_encode_dc(MpegEncContext * s, int level, int n, int *dir_ptr)

{

    int sign, code;

    int pred, extquant;

    int extrabits = 0;

    if(s->msmpeg4_version==1){

        int32_t *dc_val;

        pred = msmpeg4v1_pred_dc(s, n, &dc_val);

        /* update predictor */

        *dc_val= level;

    }else{

        int16_t *dc_val;

        pred = msmpeg4_pred_dc(s, n, &dc_val, dir_ptr);

        /* update predictor */

        if (n < 4) {

            *dc_val = level * s->y_dc_scale;

        } else {

            *dc_val = level * s->c_dc_scale;

        }

    }

    /* do the prediction */

    level -= pred;

    if(s->msmpeg4_version<=2){

        if (n < 4) {

            put_bits(&s->pb,

                     v2_dc_lum_table[level+256][1],

                     v2_dc_lum_table[level+256][0]);

        }else{

            put_bits(&s->pb,

                     v2_dc_chroma_table[level+256][1],

                     v2_dc_chroma_table[level+256][0]);

        }

    }else{

        sign = 0;

        if (level < 0) {

            level = -level;

            sign = 1;

        }

        code = level;

        if (code > DC_MAX)

            code = DC_MAX;

        else if( s->msmpeg4_version>=6 ) {

            if( s->qscale == 1 ) {

                extquant = (level + 3) & 0x3;

                code  = ((level+3)>>2);

            } else if( s->qscale == 2 ) {

                extquant = (level + 1) & 0x1;

                code  = ((level+1)>>1);

            }

        }

        if (s->dc_table_index == 0) {

            if (n < 4) {

                put_bits(&s->pb, ff_table0_dc_lum[code][1], ff_table0_dc_lum[code][0]);

            } else {

                put_bits(&s->pb, ff_table0_dc_chroma[code][1], ff_table0_dc_chroma[code][0]);

            }

        } else {

            if (n < 4) {

                put_bits(&s->pb, ff_table1_dc_lum[code][1], ff_table1_dc_lum[code][0]);

            } else {

                put_bits(&s->pb, ff_table1_dc_chroma[code][1], ff_table1_dc_chroma[code][0]);

            }

        }

        if(s->msmpeg4_version>=6 && s->qscale<=2)

            extrabits = 3 - s->qscale;

        if (code == DC_MAX)

            put_bits(&s->pb, 8 + extrabits, level);

        else if(extrabits > 0)//== VC1 && s->qscale<=2

            put_bits(&s->pb, extrabits, extquant);

        if (level != 0) {

            put_bits(&s->pb, 1, sign);

        }

    }

}

/* Encoding of a block. Very similar to MPEG4 except for a different

   escape coding (same as H263) and more vlc tables.

 */

void ff_msmpeg4_encode_block(MpegEncContext * s, DCTELEM * block, int n)

{

    int level, run, last, i, j, last_index;

    int last_non_zero, sign, slevel;

    int code, run_diff, dc_pred_dir;