vc9.c

ffmpeg源码分析

        else
        {
            if (!v->mv_mode)
            {
                if (get_bits(gb, 1))
                     av_log(v->s.avctx, AV_LOG_ERROR,
                            "mv_mode for highquant B frame was %i\n", v->mv_mode);
            }
            v->mv_mode = 1-v->mv_mode; //To match (pq < 13) mapping
        }
    }

    return 0;
}

/** B and BI frame header decoding, secondary part
 * @see Tables 11+12, p62-65
 * @param v VC9 context
 * @return Status
 * @warning Also handles BI frames
 * @warning To call once all MB arrays are allocated
 * @todo Support Advanced Profile headers
 */
static int decode_b_picture_secondary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int status;

    status = bitplane_decoding(&v->skip_mb_plane, v);
    if (status < 0) return -1;
#if TRACE
    if (v->mv_mode == MV_PMODE_MIXED_MV)
    {
        status = bitplane_decoding(&v->mv_type_mb_plane, v);
        if (status < 0)
            return -1;
#if TRACE
        av_log(v->s.avctx, AV_LOG_DEBUG, "MB MV Type plane encoding: "
               "Imode: %i, Invert: %i\n", status>>1, status&1);
#endif
    }

    //bitplane
    status = bitplane_decoding(&v->direct_mb_plane, v);
    if (status < 0) return -1;
#if TRACE
    av_log(v->s.avctx, AV_LOG_DEBUG, "MB Direct plane encoding: "
           "Imode: %i, Invert: %i\n", status>>1, status&1);
#endif

    av_log(v->s.avctx, AV_LOG_DEBUG, "Skip MB plane encoding: "
           "Imode: %i, Invert: %i\n", status>>1, status&1);
#endif

    /* FIXME: what is actually chosen for B frames ? */
    v->s.mv_table_index = get_bits(gb, 2); //but using vc9_ tables
    v->cbpcy_vlc = &vc9_cbpcy_p_vlc[get_bits(gb, 2)];

    if (v->dquant)
    {
        vop_dquant_decoding(v);
    }

    if (v->vstransform)
    {
        v->ttmbf = get_bits(gb, 1);
        if (v->ttmbf)
        {
            v->ttfrm = get_bits(gb, 2);
            av_log(v->s.avctx, AV_LOG_INFO, "Transform used: %ix%i\n",
                   (v->ttfrm & 2) ? 4 : 8, (v->ttfrm & 1) ? 4 : 8);
        }
    }
    /* Epilog (AC/DC syntax) should be done in caller */
    return 0;
}

/** I frame header decoding, primary part
 * @see Tables 5+7, p53-54 and 55-57
 * @param v VC9 context
 * @return Status
 * @todo Support Advanced Profile headers
 */
static int decode_i_picture_primary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int pqindex;

    /* Prolog common to all frametypes should be done in caller */
    //BF = Buffer Fullness
    if (v->profile < PROFILE_ADVANCED && get_bits(gb, 7))
    {
        av_log(v->s.avctx, AV_LOG_DEBUG, "I BufferFullness not 0\n");
    }

    /* Quantizer stuff */
    pqindex = get_bits(gb, 5);
    if (v->quantizer_mode == QUANT_FRAME_IMPLICIT)
        v->pq = pquant_table[0][pqindex];
    else
    {
        v->pq = pquant_table[v->quantizer_mode-1][pqindex];
    }
    if (pqindex < 9) v->halfpq = get_bits(gb, 1);
    if (v->quantizer_mode == QUANT_FRAME_EXPLICIT)
        v->pquantizer = get_bits(gb, 1);
    av_log(v->s.avctx, AV_LOG_DEBUG, "I frame: QP=%i (+%i/2)\n",
           v->pq, v->halfpq);
    return 0;
}

/** I frame header decoding, secondary part
 * @param v VC9 context
 * @return Status
 * @warning Not called in A/S/C profiles, it seems
 * @todo Support Advanced Profile headers
 */
static int decode_i_picture_secondary_header(VC9Context *v)
{
#if HAS_ADVANCED_PROFILE
    int status;
    if (v->profile == PROFILE_ADVANCED)
    {
        v->s.ac_pred = get_bits(&v->s.gb, 1);
        if (v->postprocflag) v->postproc = get_bits(&v->s.gb, 1);
        /* 7.1.1.34 + 8.5.2 */
        if (v->overlap && v->pq<9)
        {
            v->condover = get_bits(&v->s.gb, 1);
            if (v->condover)
            {
                v->condover = 2+get_bits(&v->s.gb, 1);
                if (v->condover == 3)
                {
                    status = bitplane_decoding(&v->over_flags_plane, v);
                    if (status < 0) return -1;
#  if TRACE
                    av_log(v->s.avctx, AV_LOG_DEBUG, "Overflags plane encoding: "
                           "Imode: %i, Invert: %i\n", status>>1, status&1);
#  endif
                }
            }
        }
    }
#endif

    /* Epilog (AC/DC syntax) should be done in caller */
    return 0;
}

/** P frame header decoding, primary part
 * @see Tables 5+7, p53-54 and 55-57
 * @param v VC9 context
 * @todo Support Advanced Profile headers
 * @return Status
 */
static int decode_p_picture_primary_header(VC9Context *v)
{
    /* INTERFRM, FRMCNT, RANGEREDFRM read in caller */
    GetBitContext *gb = &v->s.gb;
    int lowquant, pqindex;

    pqindex = get_bits(gb, 5);
    if (v->quantizer_mode == QUANT_FRAME_IMPLICIT)
        v->pq = pquant_table[0][pqindex];
    else
    {
        v->pq = pquant_table[v->quantizer_mode-1][pqindex];
    }
    if (pqindex < 9) v->halfpq = get_bits(gb, 1);
    if (v->quantizer_mode == QUANT_FRAME_EXPLICIT)
        v->pquantizer = get_bits(gb, 1);
    av_log(v->s.avctx, AV_LOG_DEBUG, "P Frame: QP=%i (+%i/2)\n",
           v->pq, v->halfpq);
    if (v->extended_mv == 1) v->mvrange = get_prefix(gb, 0, 3);
#if HAS_ADVANCED_PROFILE
    if (v->profile == PROFILE_ADVANCED)
    {
        if (v->postprocflag) v->postproc = get_bits(gb, 1);
    }
    else
#endif
        if (v->multires) v->respic = get_bits(gb, 2);
    lowquant = (v->pquantizer>12) ? 0 : 1;
    v->mv_mode = mv_pmode_table[lowquant][get_prefix(gb, 1, 4)];
    if (v->mv_mode == MV_PMODE_INTENSITY_COMP)
    {
        v->mv_mode2 = mv_pmode_table[lowquant][get_prefix(gb, 1, 3)];
        v->lumscale = get_bits(gb, 6);
        v->lumshift = get_bits(gb, 6);
    }
    return 0;
}

/** P frame header decoding, secondary part
 * @see Tables 5+7, p53-54 and 55-57
 * @param v VC9 context
 * @warning To call once all MB arrays are allocated
 * @return Status
 */
static int decode_p_picture_secondary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int status = 0;
    if ((v->mv_mode == MV_PMODE_INTENSITY_COMP &&
         v->mv_mode2 == MV_PMODE_MIXED_MV)
        || v->mv_mode == MV_PMODE_MIXED_MV)
    {
        status = bitplane_decoding(&v->mv_type_mb_plane, v);
        if (status < 0) return -1;
#if TRACE
        av_log(v->s.avctx, AV_LOG_DEBUG, "MB MV Type plane encoding: "
               "Imode: %i, Invert: %i\n", status>>1, status&1);
#endif
    }

    status = bitplane_decoding(&v->skip_mb_plane, v);
    if (status < 0) return -1;
#if TRACE
    av_log(v->s.avctx, AV_LOG_DEBUG, "MB Skip plane encoding: "
           "Imode: %i, Invert: %i\n", status>>1, status&1);
#endif

    /* Hopefully this is correct for P frames */
    v->s.mv_table_index =get_bits(gb, 2); //but using vc9_ tables
    v->cbpcy_vlc = &vc9_cbpcy_p_vlc[get_bits(gb, 2)];

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

    v->ttfrm = 0; //FIXME Is that so ?
    if (v->vstransform)
    {
        v->ttmbf = get_bits(gb, 1);
        if (v->ttmbf)
        {
            v->ttfrm = get_bits(gb, 2);
            av_log(v->s.avctx, AV_LOG_INFO, "Transform used: %ix%i\n",
                   (v->ttfrm & 2) ? 4 : 8, (v->ttfrm & 1) ? 4 : 8);
        }
    }
    /* Epilog (AC/DC syntax) should be done in caller */
    return 0;
}
/** @} */ //End of group all_frm_hdr


/***********************************************************************/
/**
 * @defgroup std_frame_hdr VC9 Simple/Main Profiles header decoding
 * @brief Part of the frame header decoding belonging to Simple/Main Profiles
 * @warning Only pro/epilog differs between Simple/Main and Advanced =>
 *          check caller
 * @{
 */

/** Frame header decoding, first part, in Simple and Main profiles
 * @see Tables 5+7, p53-54 and 55-57
 * @param v VC9 context
 * @todo FIXME: RANGEREDFRM element not read if BI frame from Table6, P54
 *              However, 7.1.1.8 says "all frame types, for main profiles"
 * @return Status
 */
static int standard_decode_picture_primary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int status = 0;

    if (v->finterpflag) v->interpfrm = get_bits(gb, 1);
    skip_bits(gb, 2); //framecnt unused
    if (v->rangered) v->rangeredfrm = get_bits(gb, 1);
    v->s.pict_type = get_bits(gb, 1);
    if (v->s.avctx->max_b_frames)
    {
        if (!v->s.pict_type)
        {
            if (get_bits(gb, 1)) v->s.pict_type = I_TYPE;
            else v->s.pict_type = B_TYPE;
        }
        else v->s.pict_type = P_TYPE;
    }
    else v->s.pict_type++;

    switch (v->s.pict_type)
    {
    case I_TYPE: status = decode_i_picture_primary_header(v); break;
    case P_TYPE: status = decode_p_picture_primary_header(v); break;
    case BI_TYPE: //Same as B
    case B_TYPE: status = decode_b_picture_primary_header(v); break;
    }

    if (status == FRAME_SKIPPED)
    {
      av_log(v->s.avctx, AV_LOG_INFO, "Skipping frame...\n");
      return status;
    }
    return 0;
}

/** Frame header decoding, secondary part
 * @param v VC9 context
 * @warning To call once all MB arrays are allocated
 * @return Status
 */
static int standard_decode_picture_secondary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int status = 0;

    switch (v->s.pict_type)
    {
    case P_TYPE: status = decode_p_picture_secondary_header(v); break;
    case B_TYPE: status = decode_b_picture_secondary_header(v); break;
    case BI_TYPE:
    case I_TYPE: break; //Nothing needed as it's done in the epilog
    }
    if (status < 0) return FRAME_SKIPPED;

    /* 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 = decode012(gb);

    return 0;
}
/** @} */ //End for group std_frame_hdr

#if HAS_ADVANCED_PROFILE
/***********************************************************************/
/**
 * @defgroup adv_frame_hdr VC9 Advanced Profile header decoding
 * @brief Part of the frame header decoding belonging to Advanced Profiles
 * @warning Only pro/epilog differs between Simple/Main and Advanced =>
 *          check caller
 * @{
 */
/** Frame header decoding, primary part
 * @param v VC9 context
 * @return Status
 */
static int advanced_decode_picture_primary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    static const int type_table[4] = { P_TYPE, B_TYPE, I_TYPE, BI_TYPE };
    int type;

    if (v->interlace)
    {
        v->fcm = get_bits(gb, 1);
        if (v->fcm) v->fcm = 2+get_bits(gb, 1);
    }

    type = get_prefix(gb, 0, 4);
    if (type > 4 || type < 0) return FRAME_SKIPPED;
    v->s.pict_type = type_table[type];
    av_log(v->s.avctx, AV_LOG_INFO, "AP Frame Type: %i\n", v->s.pict_type);

    if (v->tfcntrflag) v->tfcntr = get_bits(gb, 8);
    if (v->broadcast)
    {
        if (!v->interlace) v->rptfrm = get_bits(gb, 2);
        else
        {
            v->tff = get_bits(gb, 1);
            v->rff = get_bits(gb, 1);
        }
    }

    if (v->panscanflag)
    {
#if 0
        for (i=0; i<v->numpanscanwin; i++)
        {
            v->topleftx[i] = get_bits(gb, 16);
            v->toplefty[i] = get_bits(gb, 16);
            v->bottomrightx[i] = get_bits(gb, 16);
            v->bottomrighty[i] = get_bits(gb, 16);
        }
#else
        skip_bits(gb, 16*4*v->numpanscanwin);
#endif
    }
    v->s.no_rounding = !get_bits(gb, 1);
    v->uvsamp = get_bits(gb, 1);
    if (v->finterpflag == 1) v->interpfrm = get_bits(gb, 1);

    switch(v->s.pict_type)
    {
    case I_TYPE: if (decode_i_picture_primary_header(v) < 0) return -1;
    case P_TYPE: if (decode_p_picture_primary_header(v) < 0) return -1;
    case BI_TYPE:
    case B_TYPE: if (decode_b_picture_primary_header(v) < 0) return FRAME_SKIPPED;
    default: return -1;
    }
}

/** Frame header decoding, secondary part
 * @param v VC9 context
 * @return Status
 */
static int advanced_decode_picture_secondary_header(VC9Context *v)
{
    GetBitContext *gb = &v->s.gb;
    int status = 0;

    switch(v->s.pict_type)