vc1.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

        /* Hopefully this is correct for P frames */
        v->s.mv_table_index = get_bits(gb, 2); //but using ff_vc1_ tables
        v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];
        if (v->dquant)
        {
            av_log(v->s.avctx, AV_LOG_DEBUG, "VOP DQuant info\n");
            vop_dquant_decoding(v);
        }

        v->ttfrm = 0; //FIXME Is that so ?
        if (v->vstransform)
        {
            v->ttmbf = get_bits1(gb);
            if (v->ttmbf)
            {
                v->ttfrm = ff_vc1_ttfrm_to_tt[get_bits(gb, 2)];
            }
        } else {
            v->ttmbf = 1;
            v->ttfrm = TT_8X8;
        }
        break;
    case B_TYPE:
        if(v->postprocflag)
            v->postproc = get_bits1(gb);
        if (v->extended_mv) v->mvrange = get_unary(gb, 0, 3);
        else v->mvrange = 0;
        v->k_x = v->mvrange + 9 + (v->mvrange >> 1); //k_x can be 9 10 12 13
        v->k_y = v->mvrange + 8; //k_y can be 8 9 10 11
        v->range_x = 1 << (v->k_x - 1);
        v->range_y = 1 << (v->k_y - 1);

        if (v->pq < 5) v->tt_index = 0;
        else if(v->pq < 13) v->tt_index = 1;
        else v->tt_index = 2;

        lowquant = (v->pq > 12) ? 0 : 1;
        v->mv_mode = get_bits1(gb) ? MV_PMODE_1MV : MV_PMODE_1MV_HPEL_BILIN;
        v->s.quarter_sample = (v->mv_mode == MV_PMODE_1MV);
        v->s.mspel = v->s.quarter_sample;

        status = bitplane_decoding(v->direct_mb_plane, &v->dmb_is_raw, v);
        if (status < 0) return -1;
        av_log(v->s.avctx, AV_LOG_DEBUG, "MB Direct Type plane encoding: "
               "Imode: %i, Invert: %i\n", status>>1, status&1);
        status = bitplane_decoding(v->s.mbskip_table, &v->skip_is_raw, v);
        if (status < 0) return -1;
        av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
               "Imode: %i, Invert: %i\n", status>>1, status&1);

        v->s.mv_table_index = get_bits(gb, 2);
        v->cbpcy_vlc = &ff_vc1_cbpcy_p_vlc[get_bits(gb, 2)];

        if (v->dquant)
        {
            av_log(v->s.avctx, AV_LOG_DEBUG, "VOP DQuant info\n");
            vop_dquant_decoding(v);
        }

        v->ttfrm = 0;
        if (v->vstransform)
        {
            v->ttmbf = get_bits1(gb);
            if (v->ttmbf)
            {
                v->ttfrm = ff_vc1_ttfrm_to_tt[get_bits(gb, 2)];
            }
        } else {
            v->ttmbf = 1;
            v->ttfrm = TT_8X8;
        }
        break;
    }

    /* AC Syntax */
    v->c_ac_table_index = decode012(gb);
    if (v->s.pict_type == I_TYPE || v->s.pict_type == BI_TYPE)
    {
        v->y_ac_table_index = decode012(gb);
    }
    /* DC Syntax */
    v->s.dc_table_index = get_bits1(gb);
    if ((v->s.pict_type == I_TYPE || v->s.pict_type == BI_TYPE) && v->dquant) {
        av_log(v->s.avctx, AV_LOG_DEBUG, "VOP DQuant info\n");
        vop_dquant_decoding(v);
    }

    v->bi_type = 0;
    if(v->s.pict_type == BI_TYPE) {
        v->s.pict_type = B_TYPE;
        v->bi_type = 1;
    }
    return 0;
}

/***********************************************************************/
/**
 * @defgroup block VC-1 Block-level functions
 * @see 7.1.4, p91 and 8.1.1.7, p(1)04
 * @{
 */

/**
 * @def GET_MQUANT
 * @brief Get macroblock-level quantizer scale
 */
#define GET_MQUANT()                                           \
  if (v->dquantfrm)                                            \
  {                                                            \
    int edges = 0;                                             \
    if (v->dqprofile == DQPROFILE_ALL_MBS)                     \
    {                                                          \
      if (v->dqbilevel)                                        \
      {                                                        \
        mquant = (get_bits1(gb)) ? v->altpq : v->pq;           \
      }                                                        \
      else                                                     \
      {                                                        \
        mqdiff = get_bits(gb, 3);                              \
        if (mqdiff != 7) mquant = v->pq + mqdiff;              \
        else mquant = get_bits(gb, 5);                         \
      }                                                        \
    }                                                          \
    if(v->dqprofile == DQPROFILE_SINGLE_EDGE)                  \
        edges = 1 << v->dqsbedge;                              \
    else if(v->dqprofile == DQPROFILE_DOUBLE_EDGES)            \
        edges = (3 << v->dqsbedge) % 15;                       \
    else if(v->dqprofile == DQPROFILE_FOUR_EDGES)              \
        edges = 15;                                            \
    if((edges&1) && !s->mb_x)                                  \
        mquant = v->altpq;                                     \
    if((edges&2) && s->first_slice_line)                       \
        mquant = v->altpq;                                     \
    if((edges&4) && s->mb_x == (s->mb_width - 1))              \
        mquant = v->altpq;                                     \
    if((edges&8) && s->mb_y == (s->mb_height - 1))             \
        mquant = v->altpq;                                     \
  }

/**
 * @def GET_MVDATA(_dmv_x, _dmv_y)
 * @brief Get MV differentials
 * @see MVDATA decoding from 8.3.5.2, p(1)20
 * @param _dmv_x Horizontal differential for decoded MV
 * @param _dmv_y Vertical differential for decoded MV
 */
#define GET_MVDATA(_dmv_x, _dmv_y)                                  \
  index = 1 + get_vlc2(gb, ff_vc1_mv_diff_vlc[s->mv_table_index].table,\
                       VC1_MV_DIFF_VLC_BITS, 2);                    \
  if (index > 36)                                                   \
  {                                                                 \
    mb_has_coeffs = 1;                                              \
    index -= 37;                                                    \
  }                                                                 \
  else mb_has_coeffs = 0;                                           \
  s->mb_intra = 0;                                                  \
  if (!index) { _dmv_x = _dmv_y = 0; }                              \
  else if (index == 35)                                             \
  {                                                                 \
    _dmv_x = get_bits(gb, v->k_x - 1 + s->quarter_sample);          \
    _dmv_y = get_bits(gb, v->k_y - 1 + s->quarter_sample);          \
  }                                                                 \
  else if (index == 36)                                             \
  {                                                                 \
    _dmv_x = 0;                                                     \
    _dmv_y = 0;                                                     \
    s->mb_intra = 1;                                                \
  }                                                                 \
  else                                                              \
  {                                                                 \
    index1 = index%6;                                               \
    if (!s->quarter_sample && index1 == 5) val = 1;                 \
    else                                   val = 0;                 \
    if(size_table[index1] - val > 0)                                \
        val = get_bits(gb, size_table[index1] - val);               \
    else                                   val = 0;                 \
    sign = 0 - (val&1);                                             \
    _dmv_x = (sign ^ ((val>>1) + offset_table[index1])) - sign;     \
                                                                    \
    index1 = index/6;                                               \
    if (!s->quarter_sample && index1 == 5) val = 1;                 \
    else                                   val = 0;                 \
    if(size_table[index1] - val > 0)                                \
        val = get_bits(gb, size_table[index1] - val);               \
    else                                   val = 0;                 \
    sign = 0 - (val&1);                                             \
    _dmv_y = (sign ^ ((val>>1) + offset_table[index1])) - sign;     \
  }

/** Predict and set motion vector
 */
static inline void vc1_pred_mv(MpegEncContext *s, int n, int dmv_x, int dmv_y, int mv1, int r_x, int r_y, uint8_t* is_intra)
{
    int xy, wrap, off = 0;
    int16_t *A, *B, *C;
    int px, py;
    int sum;

    /* scale MV difference to be quad-pel */
    dmv_x <<= 1 - s->quarter_sample;
    dmv_y <<= 1 - s->quarter_sample;

    wrap = s->b8_stride;
    xy = s->block_index[n];

    if(s->mb_intra){
        s->mv[0][n][0] = s->current_picture.motion_val[0][xy][0] = 0;
        s->mv[0][n][1] = s->current_picture.motion_val[0][xy][1] = 0;
        s->current_picture.motion_val[1][xy][0] = 0;
        s->current_picture.motion_val[1][xy][1] = 0;
        if(mv1) { /* duplicate motion data for 1-MV block */
            s->current_picture.motion_val[0][xy + 1][0] = 0;
            s->current_picture.motion_val[0][xy + 1][1] = 0;
            s->current_picture.motion_val[0][xy + wrap][0] = 0;
            s->current_picture.motion_val[0][xy + wrap][1] = 0;
            s->current_picture.motion_val[0][xy + wrap + 1][0] = 0;
            s->current_picture.motion_val[0][xy + wrap + 1][1] = 0;
            s->current_picture.motion_val[1][xy + 1][0] = 0;
            s->current_picture.motion_val[1][xy + 1][1] = 0;
            s->current_picture.motion_val[1][xy + wrap][0] = 0;
            s->current_picture.motion_val[1][xy + wrap][1] = 0;
            s->current_picture.motion_val[1][xy + wrap + 1][0] = 0;
            s->current_picture.motion_val[1][xy + wrap + 1][1] = 0;
        }
        return;
    }

    C = s->current_picture.motion_val[0][xy - 1];
    A = s->current_picture.motion_val[0][xy - wrap];
    if(mv1)
        off = (s->mb_x == (s->mb_width - 1)) ? -1 : 2;
    else {
        //in 4-MV mode different blocks have different B predictor position
        switch(n){
        case 0:
            off = (s->mb_x > 0) ? -1 : 1;
            break;
        case 1:
            off = (s->mb_x == (s->mb_width - 1)) ? -1 : 1;
            break;
        case 2:
            off = 1;
            break;
        case 3:
            off = -1;
        }
    }
    B = s->current_picture.motion_val[0][xy - wrap + off];

    if(!s->first_slice_line || (n==2 || n==3)) { // predictor A is not out of bounds
        if(s->mb_width == 1) {
            px = A[0];
            py = A[1];
        } else {
            px = mid_pred(A[0], B[0], C[0]);
            py = mid_pred(A[1], B[1], C[1]);
        }
    } else if(s->mb_x || (n==1 || n==3)) { // predictor C is not out of bounds
        px = C[0];
        py = C[1];
    } else {
        px = py = 0;
    }
    /* Pullback MV as specified in 8.3.5.3.4 */
    {
        int qx, qy, X, Y;
        qx = (s->mb_x << 6) + ((n==1 || n==3) ? 32 : 0);
        qy = (s->mb_y << 6) + ((n==2 || n==3) ? 32 : 0);
        X = (s->mb_width << 6) - 4;
        Y = (s->mb_height << 6) - 4;
        if(mv1) {
            if(qx + px < -60) px = -60 - qx;
            if(qy + py < -60) py = -60 - qy;
        } else {
            if(qx + px < -28) px = -28 - qx;
            if(qy + py < -28) py = -28 - qy;
        }
        if(qx + px > X) px = X - qx;
        if(qy + py > Y) py = Y - qy;
    }
    /* Calculate hybrid prediction as specified in 8.3.5.3.5 */
    if((!s->first_slice_line || (n==2 || n==3)) && (s->mb_x || (n==1 || n==3))) {
        if(is_intra[xy - wrap])
            sum = FFABS(px) + FFABS(py);
        else
            sum = FFABS(px - A[0]) + FFABS(py - A[1]);
        if(sum > 32) {
            if(get_bits1(&s->gb)) {
                px = A[0];
                py = A[1];
            } else {
                px = C[0];
                py = C[1];
            }
        } else {
            if(is_intra[xy - 1])
                sum = FFABS(px) + FFABS(py);
            else
                sum = FFABS(px - C[0]) + FFABS(py - C[1]);
            if(sum > 32) {
                if(get_bits1(&s->gb)) {
                    px = A[0];
                    py = A[1];
                } else {
                    px = C[0];
                    py = C[1];
                }
            }
        }
    }
    /* store MV using signed modulus of MV range defined in 4.11 */
    s->mv[0][n][0] = s->current_picture.motion_val[0][xy][0] = ((px + dmv_x + r_x) & ((r_x << 1) - 1)) - r_x;
    s->mv[0][n][1] = s->current_picture.motion_val[0][xy][1] = ((py + dmv_y + r_y) & ((r_y << 1) - 1)) - r_y;
    if(mv1) { /* duplicate motion data for 1-MV block */
        s->current_picture.motion_val[0][xy + 1][0] = s->current_picture.motion_val[0][xy][0];
        s->current_picture.motion_val[0][xy + 1][1] = s->current_picture.motion_val[0][xy][1];
        s->current_picture.motion_val[0][xy + wrap][0] = s->current_picture.motion_val[0][xy][0];
        s->current_picture.motion_val[0][xy + wrap][1] = s->current_picture.motion_val[0][xy][1];
        s->current_picture.motion_val[0][xy + wrap + 1][0] = s->current_picture.motion_val[0][xy][0];
        s->current_picture.motion_val[0][xy + wrap + 1][1] = s->current_picture.motion_val[0][xy][1];
    }
}

/** Motion compensation for direct or interpolated blocks in B-frames
 */
static void vc1_interp_mc(VC1Context *v)
{
    MpegEncContext *s = &v->s;
    DSPContext *dsp = &v->s.dsp;
    uint8_t *srcY, *srcU, *srcV;
    int dxy, uvdxy, mx, my, uvmx, uvmy, src_x, src_y, uvsrc_x, uvsrc_y;

    if(!v->s.next_picture.data[0])return;

    mx = s->mv[1][0][0];
    my = s->mv[1][0][1];
    uvmx = (mx + ((mx & 3) == 3)) >> 1;
    uvmy = (my + ((my & 3) == 3)) >> 1;
    if(v->fastuvmc) {
        uvmx = uvmx + ((uvmx<0)?-(uvmx&1):(uvmx&1));
        uvmy = uvmy + ((uvmy<0)?-(uvmy&1):(uvmy&1));
    }
    srcY = s->next_picture.data[0];
    srcU = s->next_picture.data[1];
    srcV = s->next_picture.data[2];

    src_x = s->mb_x * 16 + (mx >> 2);
    src_y = s->mb_y * 16 + (my >> 2);