error_resilience.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

                s->mb_intra=0;
                s->mv_type = MV_TYPE_16X16;
                s->mb_skipped=0;

                s->dsp.clear_blocks(s->block[0]);

                s->mb_x= mb_x;
                s->mb_y= mb_y;
                s->mv[0][0][0]= 0;
                s->mv[0][0][1]= 0;
                decode_mb(s);
            }
        }
        return;
    }

    for(depth=0;; depth++){
        int changed, pass, none_left;

        none_left=1;
        changed=1;
        for(pass=0; (changed || pass<2) && pass<10; pass++){
            int mb_x, mb_y;
int score_sum=0;

            changed=0;
            for(mb_y=0; mb_y<s->mb_height; mb_y++){
                for(mb_x=0; mb_x<s->mb_width; mb_x++){
                    const int mb_xy= mb_x + mb_y*s->mb_stride;
                    int mv_predictor[8][2]={{0}};
                    int pred_count=0;
                    int j;
                    int best_score=256*256*256*64;
                    int best_pred=0;
                    const int mot_stride= s->b8_stride;
                    const int mot_index= mb_x*2 + mb_y*2*mot_stride;
                    int prev_x= s->current_picture.motion_val[0][mot_index][0];
                    int prev_y= s->current_picture.motion_val[0][mot_index][1];

                    if((mb_x^mb_y^pass)&1) continue;

                    if(fixed[mb_xy]==MV_FROZEN) continue;
                    assert(!IS_INTRA(s->current_picture.mb_type[mb_xy]));
                    assert(s->last_picture_ptr && s->last_picture_ptr->data[0]);

                    j=0;
                    if(mb_x>0           && fixed[mb_xy-1        ]==MV_FROZEN) j=1;
                    if(mb_x+1<mb_width  && fixed[mb_xy+1        ]==MV_FROZEN) j=1;
                    if(mb_y>0           && fixed[mb_xy-mb_stride]==MV_FROZEN) j=1;
                    if(mb_y+1<mb_height && fixed[mb_xy+mb_stride]==MV_FROZEN) j=1;
                    if(j==0) continue;

                    j=0;
                    if(mb_x>0           && fixed[mb_xy-1        ]==MV_CHANGED) j=1;
                    if(mb_x+1<mb_width  && fixed[mb_xy+1        ]==MV_CHANGED) j=1;
                    if(mb_y>0           && fixed[mb_xy-mb_stride]==MV_CHANGED) j=1;
                    if(mb_y+1<mb_height && fixed[mb_xy+mb_stride]==MV_CHANGED) j=1;
                    if(j==0 && pass>1) continue;

                    none_left=0;

                    if(mb_x>0 && fixed[mb_xy-1]){
                        mv_predictor[pred_count][0]= s->current_picture.motion_val[0][mot_index - 2][0];
                        mv_predictor[pred_count][1]= s->current_picture.motion_val[0][mot_index - 2][1];
                        pred_count++;
                    }
                    if(mb_x+1<mb_width && fixed[mb_xy+1]){
                        mv_predictor[pred_count][0]= s->current_picture.motion_val[0][mot_index + 2][0];
                        mv_predictor[pred_count][1]= s->current_picture.motion_val[0][mot_index + 2][1];
                        pred_count++;
                    }
                    if(mb_y>0 && fixed[mb_xy-mb_stride]){
                        mv_predictor[pred_count][0]= s->current_picture.motion_val[0][mot_index - mot_stride*2][0];
                        mv_predictor[pred_count][1]= s->current_picture.motion_val[0][mot_index - mot_stride*2][1];
                        pred_count++;
                    }
                    if(mb_y+1<mb_height && fixed[mb_xy+mb_stride]){
                        mv_predictor[pred_count][0]= s->current_picture.motion_val[0][mot_index + mot_stride*2][0];
                        mv_predictor[pred_count][1]= s->current_picture.motion_val[0][mot_index + mot_stride*2][1];
                        pred_count++;
                    }
                    if(pred_count==0) continue;

                    if(pred_count>1){
                        int sum_x=0, sum_y=0;
                        int max_x, max_y, min_x, min_y;

                        for(j=0; j<pred_count; j++){
                            sum_x+= mv_predictor[j][0];
                            sum_y+= mv_predictor[j][1];
                        }

                        /* mean */
                        mv_predictor[pred_count][0] = sum_x/j;
                        mv_predictor[pred_count][1] = sum_y/j;

                        /* median */
                        if(pred_count>=3){
                            min_y= min_x= 99999;
                            max_y= max_x=-99999;
                        }else{
                            min_x=min_y=max_x=max_y=0;
                        }
                        for(j=0; j<pred_count; j++){
                            max_x= FFMAX(max_x, mv_predictor[j][0]);
                            max_y= FFMAX(max_y, mv_predictor[j][1]);
                            min_x= FFMIN(min_x, mv_predictor[j][0]);
                            min_y= FFMIN(min_y, mv_predictor[j][1]);
                        }
                        mv_predictor[pred_count+1][0] = sum_x - max_x - min_x;
                        mv_predictor[pred_count+1][1] = sum_y - max_y - min_y;

                        if(pred_count==4){
                            mv_predictor[pred_count+1][0] /= 2;
                            mv_predictor[pred_count+1][1] /= 2;
                        }
                        pred_count+=2;
                    }

                    /* zero MV */
                    pred_count++;

                    /* last MV */
                    mv_predictor[pred_count][0]= s->current_picture.motion_val[0][mot_index][0];
                    mv_predictor[pred_count][1]= s->current_picture.motion_val[0][mot_index][1];
                    pred_count++;

                    s->mv_dir = MV_DIR_FORWARD;
                    s->mb_intra=0;
                    s->mv_type = MV_TYPE_16X16;
                    s->mb_skipped=0;

                    s->dsp.clear_blocks(s->block[0]);

                    s->mb_x= mb_x;
                    s->mb_y= mb_y;

                    for(j=0; j<pred_count; j++){
                        int score=0;
                        uint8_t *src= s->current_picture.data[0] + mb_x*16 + mb_y*16*s->linesize;

                        s->current_picture.motion_val[0][mot_index][0]= s->mv[0][0][0]= mv_predictor[j][0];
                        s->current_picture.motion_val[0][mot_index][1]= s->mv[0][0][1]= mv_predictor[j][1];

                        decode_mb(s);

                        if(mb_x>0 && fixed[mb_xy-1]){
                            int k;
                            for(k=0; k<16; k++)
                                score += FFABS(src[k*s->linesize-1 ]-src[k*s->linesize   ]);
                        }
                        if(mb_x+1<mb_width && fixed[mb_xy+1]){
                            int k;
                            for(k=0; k<16; k++)
                                score += FFABS(src[k*s->linesize+15]-src[k*s->linesize+16]);
                        }
                        if(mb_y>0 && fixed[mb_xy-mb_stride]){
                            int k;
                            for(k=0; k<16; k++)
                                score += FFABS(src[k-s->linesize   ]-src[k               ]);
                        }
                        if(mb_y+1<mb_height && fixed[mb_xy+mb_stride]){
                            int k;
                            for(k=0; k<16; k++)
                                score += FFABS(src[k+s->linesize*15]-src[k+s->linesize*16]);
                        }

                        if(score <= best_score){ // <= will favor the last MV
                            best_score= score;
                            best_pred= j;
                        }
                    }
score_sum+= best_score;
//FIXME no need to set s->current_picture.motion_val[0][mot_index][0] explicit
                    s->current_picture.motion_val[0][mot_index][0]= s->mv[0][0][0]= mv_predictor[best_pred][0];
                    s->current_picture.motion_val[0][mot_index][1]= s->mv[0][0][1]= mv_predictor[best_pred][1];

                    decode_mb(s);


                    if(s->mv[0][0][0] != prev_x || s->mv[0][0][1] != prev_y){
                        fixed[mb_xy]=MV_CHANGED;
                        changed++;
                    }else
                        fixed[mb_xy]=MV_UNCHANGED;
                }
            }

//            printf(".%d/%d", changed, score_sum); fflush(stdout);
        }

        if(none_left)
            return;

        for(i=0; i<s->mb_num; i++){
            int mb_xy= s->mb_index2xy[i];
            if(fixed[mb_xy])
                fixed[mb_xy]=MV_FROZEN;
        }
//        printf(":"); fflush(stdout);
    }
}

static int is_intra_more_likely(MpegEncContext *s){
    int is_intra_likely, i, j, undamaged_count, skip_amount, mb_x, mb_y;

    if(s->last_picture_ptr==NULL) return 1; //no previous frame available -> use spatial prediction

    undamaged_count=0;
    for(i=0; i<s->mb_num; i++){
        const int mb_xy= s->mb_index2xy[i];
        const int error= s->error_status_table[mb_xy];
        if(!((error&DC_ERROR) && (error&MV_ERROR)))
            undamaged_count++;
    }

    if(undamaged_count < 5) return 0; //allmost all MBs damaged -> use temporal prediction

#ifdef HAVE_XVMC
    //prevent dsp.sad() check, that requires access to the image
    if(s->avctx->xvmc_acceleration && s->pict_type==I_TYPE) return 1;
#endif

    skip_amount= FFMAX(undamaged_count/50, 1); //check only upto 50 MBs
    is_intra_likely=0;

    j=0;
    for(mb_y= 0; mb_y<s->mb_height-1; mb_y++){
        for(mb_x= 0; mb_x<s->mb_width; mb_x++){
            int error;
            const int mb_xy= mb_x + mb_y*s->mb_stride;

            error= s->error_status_table[mb_xy];
            if((error&DC_ERROR) && (error&MV_ERROR))
                continue; //skip damaged

            j++;
            if((j%skip_amount) != 0) continue; //skip a few to speed things up

            if(s->pict_type==I_TYPE){
                uint8_t *mb_ptr     = s->current_picture.data[0] + mb_x*16 + mb_y*16*s->linesize;
                uint8_t *last_mb_ptr= s->last_picture.data   [0] + mb_x*16 + mb_y*16*s->linesize;

                is_intra_likely += s->dsp.sad[0](NULL, last_mb_ptr, mb_ptr                    , s->linesize, 16);
                is_intra_likely -= s->dsp.sad[0](NULL, last_mb_ptr, last_mb_ptr+s->linesize*16, s->linesize, 16);
            }else{
                if(IS_INTRA(s->current_picture.mb_type[mb_xy]))
                   is_intra_likely++;
                else
                   is_intra_likely--;
            }
        }
    }
//printf("is_intra_likely: %d type:%d\n", is_intra_likely, s->pict_type);
    return is_intra_likely > 0;
}

void ff_er_frame_start(MpegEncContext *s){
    if(!s->error_resilience) return;

    memset(s->error_status_table, MV_ERROR|AC_ERROR|DC_ERROR|VP_START|AC_END|DC_END|MV_END, s->mb_stride*s->mb_height*sizeof(uint8_t));
    s->error_count= 3*s->mb_num;
}

/**
 * adds a slice.
 * @param endx x component of the last macroblock, can be -1 for the last of the previous line
 * @param status the status at the end (MV_END, AC_ERROR, ...), it is assumed that no earlier end or
 *               error of the same type occured
 */
void ff_er_add_slice(MpegEncContext *s, int startx, int starty, int endx, int endy, int status){
    const int start_i= av_clip(startx + starty * s->mb_width    , 0, s->mb_num-1);
    const int end_i  = av_clip(endx   + endy   * s->mb_width    , 0, s->mb_num);
    const int start_xy= s->mb_index2xy[start_i];
    const int end_xy  = s->mb_index2xy[end_i];
    int mask= -1;

    if(start_i > end_i || start_xy > end_xy){
        av_log(s->avctx, AV_LOG_ERROR, "internal error, slice end before start\n");
        return;
    }

    if(!s->error_resilience) return;

    mask &= ~VP_START;
    if(status & (AC_ERROR|AC_END)){
        mask &= ~(AC_ERROR|AC_END);
        s->error_count -= end_i - start_i + 1;
    }
    if(status & (DC_ERROR|DC_END)){
        mask &= ~(DC_ERROR|DC_END);
        s->error_count -= end_i - start_i + 1;
    }
    if(status & (MV_ERROR|MV_END)){
        mask &= ~(MV_ERROR|MV_END);
        s->error_count -= end_i - start_i + 1;
    }

    if(status & (AC_ERROR|DC_ERROR|MV_ERROR)) s->error_count= INT_MAX;

    if(mask == ~0x7F){
        memset(&s->error_status_table[start_xy], 0, (end_xy - start_xy) * sizeof(uint8_t));
    }else{
        int i;
        for(i=start_xy; i<end_xy; i++){
            s->error_status_table[ i ] &= mask;
        }
    }

    if(end_i == s->mb_num)
        s->error_count= INT_MAX;
    else{
        s->error_status_table[end_xy] &= mask;
        s->error_status_table[end_xy] |= status;
    }

    s->error_status_table[start_xy] |= VP_START;

    if(start_xy > 0 && s->avctx->thread_count <= 1 && s->avctx->skip_top*s->mb_width < start_i){
        int prev_status= s->error_status_table[ s->mb_index2xy[start_i - 1] ];

        prev_status &= ~ VP_START;
        if(prev_status != (MV_END|DC_END|AC_END)) s->error_count= INT_MAX;
    }
}

void ff_er_frame_end(MpegEncContext *s){
    int i, mb_x, mb_y, error, error_type, dc_error, mv_error, ac_error;
    int distance;
    int threshold_part[4]= {100,100,100};
    int threshold= 50;
    int is_intra_likely;
    int size = s->b8_stride * 2 * s->mb_height;
    Picture *pic= s->current_picture_ptr;

    if(!s->error_resilience || s->error_count==0 ||
       s->error_count==3*s->mb_width*(s->avctx->skip_top + s->avctx->skip_bottom)) return;

    if(s->current_picture.motion_val[0] == NULL){
        av_log(s->avctx, AV_LOG_ERROR, "Warning MVs not available\n");

        for(i=0; i<2; i++){
            pic->ref_index[i]= av_mallocz(size * sizeof(uint8_t));
            pic->motion_val_base[i]= av_mallocz((size+4) * 2 * sizeof(uint16_t));
            pic->motion_val[i]= pic->motion_val_base[i]+4;
        }
        pic->motion_subsample_log2= 3;