msmpeg4.c

ffmpeg的完整源代码和作者自己写的文档。不但有在Linux的工程哦

#endif //CONFIG_ENCODERS

/* predict coded block */
static inline int 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;
}

#ifdef CONFIG_ENCODERS

static void 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);
    }
}

static inline void 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;
        }
    }
}

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;

    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,
                     cbpy_tab[coded_cbp>>2][1],
                     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);
            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 = 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 == 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,
                     cbpy_tab[cbp>>2][1],
                     cbpy_tab[cbp>>2][0]);
        }else{
            if (s->pict_type == 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 (defined(ARCH_X86)) && !defined PIC
    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 defined (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;