h263.c

mediastreamer2是开源的网络传输媒体流的库

        put_bits(&s->pb, 5, s->qscale); /* GQUANT */
    }
}

static inline int get_block_rate(MpegEncContext * s, DCTELEM block[64], int block_last_index, uint8_t scantable[64]){
    int last=0;
    int j;
    int rate=0;

    for(j=1; j<=block_last_index; j++){
        const int index= scantable[j];
        int level= block[index];
        if(level){
            level+= 64;
            if((level&(~127)) == 0){
                if(j<block_last_index) rate+= s->intra_ac_vlc_length     [UNI_AC_ENC_INDEX(j-last-1, level)];
                else                   rate+= s->intra_ac_vlc_last_length[UNI_AC_ENC_INDEX(j-last-1, level)];
            }else
                rate += s->ac_esc_length;
            level-= 64;

            last= j;
        }
    }

    return rate;
}

static inline int decide_ac_pred(MpegEncContext * s, DCTELEM block[6][64], int dir[6], uint8_t *st[6], int zigzag_last_index[6])
{
    int score= 0;
    int i, n;
    int8_t * const qscale_table= s->current_picture.qscale_table;

    memcpy(zigzag_last_index, s->block_last_index, sizeof(int)*6);

    for(n=0; n<6; n++){
        int16_t *ac_val, *ac_val1;

        score -= get_block_rate(s, block[n], s->block_last_index[n], s->intra_scantable.permutated);

        ac_val = s->ac_val[0][0] + s->block_index[n] * 16;
        ac_val1= ac_val;
        if(dir[n]){
            const int xy= s->mb_x + s->mb_y*s->mb_stride - s->mb_stride;
            /* top prediction */
            ac_val-= s->block_wrap[n]*16;
            if(s->mb_y==0 || s->qscale == qscale_table[xy] || n==2 || n==3){
                /* same qscale */
                for(i=1; i<8; i++){
                    const int level= block[n][s->dsp.idct_permutation[i   ]];
                    block[n][s->dsp.idct_permutation[i   ]] = level - ac_val[i+8];
                    ac_val1[i  ]=    block[n][s->dsp.idct_permutation[i<<3]];
                    ac_val1[i+8]= level;
                }
            }else{
                /* different qscale, we must rescale */
                for(i=1; i<8; i++){
                    const int level= block[n][s->dsp.idct_permutation[i   ]];
                    block[n][s->dsp.idct_permutation[i   ]] = level - ROUNDED_DIV(ac_val[i + 8]*qscale_table[xy], s->qscale);
                    ac_val1[i  ]=    block[n][s->dsp.idct_permutation[i<<3]];
                    ac_val1[i+8]= level;
                }
            }
            st[n]= s->intra_h_scantable.permutated;
        }else{
            const int xy= s->mb_x-1 + s->mb_y*s->mb_stride;
            /* left prediction */
            ac_val-= 16;
            if(s->mb_x==0 || s->qscale == qscale_table[xy] || n==1 || n==3){
                /* same qscale */
                for(i=1; i<8; i++){
                    const int level= block[n][s->dsp.idct_permutation[i<<3]];
                    block[n][s->dsp.idct_permutation[i<<3]]= level - ac_val[i];
                    ac_val1[i  ]= level;
                    ac_val1[i+8]=    block[n][s->dsp.idct_permutation[i   ]];
                }
            }else{
                /* different qscale, we must rescale */
                for(i=1; i<8; i++){
                    const int level= block[n][s->dsp.idct_permutation[i<<3]];
                    block[n][s->dsp.idct_permutation[i<<3]]= level - ROUNDED_DIV(ac_val[i]*qscale_table[xy], s->qscale);
                    ac_val1[i  ]= level;
                    ac_val1[i+8]=    block[n][s->dsp.idct_permutation[i   ]];
                }
            }
            st[n]= s->intra_v_scantable.permutated;
        }

        for(i=63; i>0; i--) //FIXME optimize
            if(block[n][ st[n][i] ]) break;
        s->block_last_index[n]= i;

        score += get_block_rate(s, block[n], s->block_last_index[n], st[n]);
    }

    return score < 0;
}

static inline void restore_ac_coeffs(MpegEncContext * s, DCTELEM block[6][64], int dir[6], uint8_t *st[6], int zigzag_last_index[6])
{
    int i, n;
    memcpy(s->block_last_index, zigzag_last_index, sizeof(int)*6);

    for(n=0; n<6; n++){
        int16_t *ac_val = s->ac_val[0][0] + s->block_index[n] * 16;

        st[n]= s->intra_scantable.permutated;
        if(dir[n]){
            /* top prediction */
            for(i=1; i<8; i++){
                block[n][s->dsp.idct_permutation[i   ]] = ac_val[i+8];
            }
        }else{
            /* left prediction */
            for(i=1; i<8; i++){
                block[n][s->dsp.idct_permutation[i<<3]]= ac_val[i  ];
            }
        }
    }
}

/**
 * init s->current_picture.qscale_table from s->lambda_table
 */
static void ff_init_qscale_tab(MpegEncContext *s){
    int8_t * const qscale_table= s->current_picture.qscale_table;
    int i;

    for(i=0; i<s->mb_num; i++){
        unsigned int lam= s->lambda_table[ s->mb_index2xy[i] ];
        int qp= (lam*139 + FF_LAMBDA_SCALE*64) >> (FF_LAMBDA_SHIFT + 7);
        qscale_table[ s->mb_index2xy[i] ]= av_clip(qp, s->avctx->qmin, s->avctx->qmax);
    }
}

/**
 * modify qscale so that encoding is acually possible in h263 (limit difference to -2..2)
 */
void ff_clean_h263_qscales(MpegEncContext *s){
    int i;
    int8_t * const qscale_table= s->current_picture.qscale_table;

    ff_init_qscale_tab(s);

    for(i=1; i<s->mb_num; i++){
        if(qscale_table[ s->mb_index2xy[i] ] - qscale_table[ s->mb_index2xy[i-1] ] >2)
            qscale_table[ s->mb_index2xy[i] ]= qscale_table[ s->mb_index2xy[i-1] ]+2;
    }
    for(i=s->mb_num-2; i>=0; i--){
        if(qscale_table[ s->mb_index2xy[i] ] - qscale_table[ s->mb_index2xy[i+1] ] >2)
            qscale_table[ s->mb_index2xy[i] ]= qscale_table[ s->mb_index2xy[i+1] ]+2;
    }

    if(s->codec_id != CODEC_ID_H263P){
        for(i=1; i<s->mb_num; i++){
            int mb_xy= s->mb_index2xy[i];

            if(qscale_table[mb_xy] != qscale_table[s->mb_index2xy[i-1]] && (s->mb_type[mb_xy]&CANDIDATE_MB_TYPE_INTER4V)){
                s->mb_type[mb_xy]|= CANDIDATE_MB_TYPE_INTER;
            }
        }
    }
}

/**
 * modify mb_type & qscale so that encoding is acually possible in mpeg4
 */
void ff_clean_mpeg4_qscales(MpegEncContext *s){
    int i;
    int8_t * const qscale_table= s->current_picture.qscale_table;

    ff_clean_h263_qscales(s);

    if(s->pict_type== B_TYPE){
        int odd=0;
        /* ok, come on, this isn't funny anymore, there's more code for handling this mpeg4 mess than for the actual adaptive quantization */

        for(i=0; i<s->mb_num; i++){
            int mb_xy= s->mb_index2xy[i];
            odd += qscale_table[mb_xy]&1;
        }

        if(2*odd > s->mb_num) odd=1;
        else                  odd=0;

        for(i=0; i<s->mb_num; i++){
            int mb_xy= s->mb_index2xy[i];
            if((qscale_table[mb_xy]&1) != odd)
                qscale_table[mb_xy]++;
            if(qscale_table[mb_xy] > 31)
                qscale_table[mb_xy]= 31;
        }

        for(i=1; i<s->mb_num; i++){
            int mb_xy= s->mb_index2xy[i];
            if(qscale_table[mb_xy] != qscale_table[s->mb_index2xy[i-1]] && (s->mb_type[mb_xy]&CANDIDATE_MB_TYPE_DIRECT)){
                s->mb_type[mb_xy]|= CANDIDATE_MB_TYPE_BIDIR;
            }
        }
    }
}

#endif //CONFIG_ENCODERS

#define tab_size ((signed)(sizeof(s->direct_scale_mv[0])/sizeof(int16_t)))
#define tab_bias (tab_size/2)

void ff_mpeg4_init_direct_mv(MpegEncContext *s){
    int i;
    for(i=0; i<tab_size; i++){
        s->direct_scale_mv[0][i] = (i-tab_bias)*s->pb_time/s->pp_time;
        s->direct_scale_mv[1][i] = (i-tab_bias)*(s->pb_time-s->pp_time)/s->pp_time;
    }
}

static inline void ff_mpeg4_set_one_direct_mv(MpegEncContext *s, int mx, int my, int i){
    int xy= s->block_index[i];
    uint16_t time_pp= s->pp_time;
    uint16_t time_pb= s->pb_time;
    int p_mx, p_my;

    p_mx= s->next_picture.motion_val[0][xy][0];
    if((unsigned)(p_mx + tab_bias) < tab_size){
        s->mv[0][i][0] = s->direct_scale_mv[0][p_mx + tab_bias] + mx;
        s->mv[1][i][0] = mx ? s->mv[0][i][0] - p_mx
                            : s->direct_scale_mv[1][p_mx + tab_bias];
    }else{
        s->mv[0][i][0] = p_mx*time_pb/time_pp + mx;
        s->mv[1][i][0] = mx ? s->mv[0][i][0] - p_mx
                            : p_mx*(time_pb - time_pp)/time_pp;
    }
    p_my= s->next_picture.motion_val[0][xy][1];
    if((unsigned)(p_my + tab_bias) < tab_size){
        s->mv[0][i][1] = s->direct_scale_mv[0][p_my + tab_bias] + my;
        s->mv[1][i][1] = my ? s->mv[0][i][1] - p_my
                            : s->direct_scale_mv[1][p_my + tab_bias];
    }else{
        s->mv[0][i][1] = p_my*time_pb/time_pp + my;
        s->mv[1][i][1] = my ? s->mv[0][i][1] - p_my
                            : p_my*(time_pb - time_pp)/time_pp;
    }
}

#undef tab_size
#undef tab_bias

/**
 *
 * @return the mb_type
 */
int ff_mpeg4_set_direct_mv(MpegEncContext *s, int mx, int my){
    const int mb_index= s->mb_x + s->mb_y*s->mb_stride;
    const int colocated_mb_type= s->next_picture.mb_type[mb_index];
    uint16_t time_pp= s->pp_time;
    uint16_t time_pb= s->pb_time;
    int i;

    //FIXME avoid divides
    // try special case with shifts for 1 and 3 B-frames?

    if(IS_8X8(colocated_mb_type)){
        s->mv_type = MV_TYPE_8X8;
        for(i=0; i<4; i++){
            ff_mpeg4_set_one_direct_mv(s, mx, my, i);
        }
        return MB_TYPE_DIRECT2 | MB_TYPE_8x8 | MB_TYPE_L0L1;
    } else if(IS_INTERLACED(colocated_mb_type)){
        s->mv_type = MV_TYPE_FIELD;
        for(i=0; i<2; i++){
            int field_select= s->next_picture.ref_index[0][s->block_index[2*i]];
            s->field_select[0][i]= field_select;
            s->field_select[1][i]= i;
            if(s->top_field_first){
                time_pp= s->pp_field_time - field_select + i;
                time_pb= s->pb_field_time - field_select + i;
            }else{
                time_pp= s->pp_field_time + field_select - i;
                time_pb= s->pb_field_time + field_select - i;
            }
            s->mv[0][i][0] = s->p_field_mv_table[i][0][mb_index][0]*time_pb/time_pp + mx;
            s->mv[0][i][1] = s->p_field_mv_table[i][0][mb_index][1]*time_pb/time_pp + my;
            s->mv[1][i][0] = mx ? s->mv[0][i][0] - s->p_field_mv_table[i][0][mb_index][0]
                                : s->p_field_mv_table[i][0][mb_index][0]*(time_pb - time_pp)/time_pp;
            s->mv[1][i][1] = my ? s->mv[0][i][1] - s->p_field_mv_table[i][0][mb_index][1]
                                : s->p_field_mv_table[i][0][mb_index][1]*(time_pb - time_pp)/time_pp;
        }
        return MB_TYPE_DIRECT2 | MB_TYPE_16x8 | MB_TYPE_L0L1 | MB_TYPE_INTERLACED;
    }else{
        ff_mpeg4_set_one_direct_mv(s, mx, my, 0);
        s->mv[0][1][0] = s->mv[0][2][0] = s->mv[0][3][0] = s->mv[0][0][0];
        s->mv[0][1][1] = s->mv[0][2][1] = s->mv[0][3][1] = s->mv[0][0][1];
        s->mv[1][1][0] = s->mv[1][2][0] = s->mv[1][3][0] = s->mv[1][0][0];
        s->mv[1][1][1] = s->mv[1][2][1] = s->mv[1][3][1] = s->mv[1][0][1];
        if((s->avctx->workaround_bugs & FF_BUG_DIRECT_BLOCKSIZE) || !s->quarter_sample)
            s->mv_type= MV_TYPE_16X16;
        else
            s->mv_type= MV_TYPE_8X8;
        return MB_TYPE_DIRECT2 | MB_TYPE_16x16 | MB_TYPE_L0L1; //Note see prev line
    }
}

void ff_h263_update_motion_val(MpegEncContext * s){
    const int mb_xy = s->mb_y * s->mb_stride + s->mb_x;
               //FIXME a lot of that is only needed for !low_delay
    const int wrap = s->b8_stride;
    const int xy = s->block_index[0];

    s->current_picture.mbskip_table[mb_xy]= s->mb_skipped;

    if(s->mv_type != MV_TYPE_8X8){
        int motion_x, motion_y;
        if (s->mb_intra) {
            motion_x = 0;
            motion_y = 0;
        } else if (s->mv_type == MV_TYPE_16X16) {
            motion_x = s->mv[0][0][0];
            motion_y = s->mv[0][0][1];
        } else /*if (s->mv_type == MV_TYPE_FIELD)*/ {
            int i;
            motion_x = s->mv[0][0][0] + s->mv[0][1][0];
            motion_y = s->mv[0][0][1] + s->mv[0][1][1];
            motion_x = (motion_x>>1) | (motion_x&1);
            for(i=0; i<2; i++){
                s->p_field_mv_table[i][0][mb_xy][0]= s->mv[0][i][0];
                s->p_field_mv_table[i][0][mb_xy][1]= s->mv[0][i][1];
            }
            s->current_picture.ref_index[0][xy           ]=
            s->current_picture.ref_index[0][xy        + 1]= s->field_select[0][0];
            s->current_picture.ref_index[0][xy + wrap    ]=
            s->current_picture.ref_index[0][xy + wrap + 1]= s->field_select[0][1];
        }

        /* no update if 8X8 because it has been done during parsing */
        s->current_picture.motion_val[0][xy][0] = motion_x;
        s->current_picture.motion_val[0][xy][1] = motion_y;
        s->current_picture.motion_val[0][xy + 1][0] = motion_x;
        s->current_picture.motion_val[0][xy + 1][1] = motion_y;
        s->current_picture.motion_val[0][xy + wrap][0] = motion_x;
        s->current_picture.motion_val[0][xy + wrap][1] = motion_y;
        s->current_picture.motion_val[0][xy + 1 + wrap][0] = motion_x;
        s->current_picture.motion_val[0][xy + 1 + wrap][1] = motion_y;
    }

    if(s->encoding){ //FIXME encoding MUST be cleaned up
        if (s->mv_type == MV_TYPE_8X8)
            s->current_picture.mb_type[mb_xy]= MB_TYPE_L0 | MB_TYPE_8x8;
        else if(s->mb_intra)
            s->current_picture.mb_type[mb_xy]= MB_TYPE_INTRA;
        else
            s->current_picture.mb_type[mb_xy]= MB_TYPE_L0 | MB_TYPE_16x16;
    }
}

#ifdef CONFIG_ENCODERS

static inline int h263_get_motion_length(MpegEncContext * s, int val, int f_code){
    int l, bit_size, code;

    if (val == 0) {
        return mvtab[0][1];
    } else {
        bit_size = f_code - 1;
        /* modulo encoding */
        l= INT_BIT - 6 - bit_size;
        val = (val<<l)>>l;
        val--;
        code = (val >> bit_size) + 1;

        return mvtab[code][1] + 1 + bit_size;
    }
}

static inline void ff_h263_encode_motion_vector(MpegEncContext * s, int x, int y, int f_code){
    if(s->flags2 & CODEC_FLAG2_NO_OUTPUT){
        skip_put_bits(&s->pb,
            h263_get_motion_length(s, x, f_code)
           +h263_get_motion_length(s, y, f_code));
    }else{
        ff_h263_encode_motion(s, x, f_code);
        ff_h263_encode_motion(s, y, f_code);
    }
}