/*

 * MPEG-4 decoder / encoder common code

 * Copyright (c) 2000,2001 Fabrice Bellard

 * Copyright (c) 2002-2010 Michael Niedermayer <michaelni@gmx.at>

 *

 * This file is part of FFmpeg.

 *

 * FFmpeg 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.

 *

 * FFmpeg 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 FFmpeg; if not, write to the Free Software

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

 */

#include "mpegutils.h"

#include "mpegvideo.h"

#include "mpeg4video.h"

#include "mpeg4data.h"

int ff_mpeg4_get_video_packet_prefix_length(enum AVPictureType pict_type,

                                            int f_code, int b_code)

{

    switch (pict_type) {

    case AV_PICTURE_TYPE_I:

        return 16;

    case AV_PICTURE_TYPE_P:

    case AV_PICTURE_TYPE_S:

        return f_code + 15;

    case AV_PICTURE_TYPE_B:

        return FFMAX3(f_code, b_code, 2) + 15;

    default:

        return -1;

    }

}

void ff_mpeg4_clean_buffers(MpegEncContext *s)

{

    const int mb_height = s->mb_height;

    int c_wrap, l_wrap, l_xy;

    l_wrap = s->b8_stride;

    l_xy   = (2 * s->mb_y - 1) * l_wrap + s->mb_x * 2 - 1;

    c_wrap = s->mb_stride;

    int u_xy = 2 * mb_height * l_wrap + s->mb_y * c_wrap + s->mb_x - 1;

    int v_xy = u_xy + c_wrap * (mb_height + 1);

    int16_t (*ac_val)[16] = s->ac_val;

    /* clean AC */

    memset(ac_val + l_xy, 0, (l_wrap * 2 + 1) * sizeof(*ac_val));

    memset(ac_val + u_xy, 0, (c_wrap     + 1) * sizeof(*ac_val));

    memset(ac_val + v_xy, 0, (c_wrap     + 1) * sizeof(*ac_val));

    /* clean MV */

    // we can't clear the MVs as they might be needed by a B-frame

    s->last_mv[0][0][0] =

    s->last_mv[0][0][1] =

    s->last_mv[1][0][0] =

    s->last_mv[1][0][1] = 0;

}

#define tab_size ((signed)FF_ARRAY_ELEMS(s->direct_scale_mv[0]))

#define tab_bias (tab_size / 2)

// used by MPEG-4 and rv10 decoder

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_pic.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_pic.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_pic.mb_type[mb_index];

    uint16_t time_pp;

    uint16_t time_pb;

    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_BIDIR_MV;

    } else if (IS_INTERLACED(colocated_mb_type)) {

        s->mv_type = MV_TYPE_FIELD;

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

            int field_select = s->next_pic.ref_index[0][4 * mb_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_BIDIR_MV | 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;

        // Note see prev line

        return MB_TYPE_DIRECT2 | MB_TYPE_16x16 | MB_TYPE_BIDIR_MV;

    }

}