FFmpeg/libavcodec/mpeg4video.c

/*
 * MPEG4 decoder / encoder common code.
 * Copyright (c) 2000,2001 Fabrice Bellard
 * Copyright (c) 2002-2010 Michael Niedermayer <michaelni@gmx.at>
 *
 * This file is part of Libav.
 *
 * Libav 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.
 *
 * Libav 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 Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "mpegvideo.h"
#include "mpeg4video.h"
#include "mpeg4data.h"

uint8_t ff_mpeg4_static_rl_table_store[3][2][2*MAX_RUN + MAX_LEVEL + 3];

int ff_mpeg4_get_video_packet_prefix_length(MpegEncContext *s){
    switch(s->pict_type){
        case AV_PICTURE_TYPE_I:
            return 16;
        case AV_PICTURE_TYPE_P:
        case AV_PICTURE_TYPE_S:
            return s->f_code+15;
        case AV_PICTURE_TYPE_B:
            return FFMAX3(s->f_code, s->b_code, 2) + 15;
        default:
            return -1;
    }
}

void ff_mpeg4_clean_buffers(MpegEncContext *s)
{
    int c_wrap, c_xy, 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;
    c_xy= (s->mb_y-1)*c_wrap + s->mb_x - 1;

#if 0
    /* clean DC */
    memsetw(s->dc_val[0] + l_xy, 1024, l_wrap*2+1);
    memsetw(s->dc_val[1] + c_xy, 1024, c_wrap+1);
    memsetw(s->dc_val[2] + c_xy, 1024, c_wrap+1);
#endif

    /* clean AC */
    memset(s->ac_val[0] + l_xy, 0, (l_wrap*2+1)*16*sizeof(int16_t));
    memset(s->ac_val[1] + c_xy, 0, (c_wrap  +1)*16*sizeof(int16_t));
    memset(s->ac_val[2] + c_xy, 0, (c_wrap  +1)*16*sizeof(int16_t));

    /* clean MV */
    // we can't clear the MVs as they might be needed by a b frame
//    memset(s->motion_val + l_xy, 0, (l_wrap*2+1)*2*sizeof(int16_t));
//    memset(s->motion_val, 0, 2*sizeof(int16_t)*(2 + s->mb_width*2)*(2 + s->mb_height*2));
    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 mpeg4 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_picture.f.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.f.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.f.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_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.f.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_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
    }
}