/*

 * Error resilience / concealment

 *

 * Copyright (c) 2002-2004 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

 */

/**

 * @file

 * Error resilience / concealment.

 */

#include <limits.h>

#include "libavutil/avassert.h"

#include "libavutil/attributes.h"

#include "libavutil/mem.h"

#include "avcodec.h"

#include "error_resilience.h"

#include "mathops.h"

#include "me_cmp.h"

#include "mpegutils.h"

#include "mpegvideo.h"

#include "threadframe.h"

#include "threadprogress.h"

av_cold int ff_er_init(ERContext *const s)

{

    MECmpContext mecc;

    unsigned mb_array_size = s->mb_height * s->mb_stride;

    s->error_status_table = av_mallocz(mb_array_size);

    if (!s->error_status_table)

        return AVERROR(ENOMEM);

    s->er_temp_buffer = av_malloc_array(mb_array_size, 4*sizeof(int) + 1);

    if (!s->er_temp_buffer)

        return AVERROR(ENOMEM);

    ff_me_cmp_init(&mecc, s->avctx);

    s->sad = mecc.sad[0];

    return 0;

}

/**

 * @param stride the number of MVs to get to the next row

 * @param mv_step the number of MVs per row or column in a macroblock

 */

static void set_mv_strides(ERContext *s, ptrdiff_t *mv_step, ptrdiff_t *stride)

{

    if (s->avctx->codec_id == AV_CODEC_ID_H264) {

        av_assert0(s->quarter_sample);

        *mv_step = 4;

        *stride  = s->mb_width * 4;

    } else {

        *mv_step = 2;

        *stride  = s->b8_stride;

    }

}

/**

 * Replace the current MB with a flat dc-only version.

 */

static void put_dc(ERContext *s, uint8_t *dest_y, uint8_t *dest_cb,

                   uint8_t *dest_cr, int mb_x, int mb_y)

{

    int *linesize = s->cur_pic.f->linesize;

    int dc, dcu, dcv, y, i;

    for (i = 0; i < 4; i++) {

        dc = s->dc_val[0][mb_x * 2 + (i &  1) + (mb_y * 2 + (i >> 1)) * s->b8_stride];

        if (dc < 0)

            dc = 0;

        else if (dc > 2040)

            dc = 2040;

        for (y = 0; y < 8; y++) {

            int x;

            for (x = 0; x < 8; x++)

                dest_y[x + (i &  1) * 8 + (y + (i >> 1) * 8) * linesize[0]] = dc / 8;

        }

    }

    dcu = s->dc_val[1][mb_x + mb_y * s->mb_stride];

    dcv = s->dc_val[2][mb_x + mb_y * s->mb_stride];

    if (dcu < 0)

        dcu = 0;

    else if (dcu > 2040)

        dcu = 2040;

    if (dcv < 0)

        dcv = 0;

    else if (dcv > 2040)

        dcv = 2040;

    if (dest_cr)

    for (y = 0; y < 8; y++) {

        int x;

        for (x = 0; x < 8; x++) {

            dest_cb[x + y * linesize[1]] = dcu / 8;

            dest_cr[x + y * linesize[2]] = dcv / 8;

        }

    }

}

static void filter181(int16_t *data, int width, int height, ptrdiff_t stride)

{

    int x, y;

    /* horizontal filter */

    for (y = 1; y < height - 1; y++) {

        int prev_dc = data[0 + y * stride];

        for (x = 1; x < width - 1; x++) {

            int dc;

            dc = -prev_dc +

                 data[x     + y * stride] * 8 -

                 data[x + 1 + y * stride];

            dc = (av_clip(dc, INT_MIN/10923, INT_MAX/10923 - 32768) * 10923 + 32768) >> 16;

            prev_dc = data[x + y * stride];

            data[x + y * stride] = dc;

        }

    }

    /* vertical filter */

    for (x = 1; x < width - 1; x++) {

        int prev_dc = data[x];

        for (y = 1; y < height - 1; y++) {

            int dc;

            dc = -prev_dc +

                 data[x +  y      * stride] * 8 -

                 data[x + (y + 1) * stride];

            dc = (av_clip(dc, INT_MIN/10923, INT_MAX/10923 - 32768) * 10923 + 32768) >> 16;

            prev_dc = data[x + y * stride];

            data[x + y * stride] = dc;

        }

    }

}

/**

 * guess the dc of blocks which do not have an undamaged dc

 * @param w     width in 8 pixel blocks

 * @param h     height in 8 pixel blocks

 */

static void guess_dc(ERContext *s, int16_t *dc, int w,

                     int h, ptrdiff_t stride, int is_luma)

{

    int b_x, b_y;

    int16_t  (*col )[4] = av_malloc_array(stride, h*sizeof( int16_t)*4);

    uint32_t (*dist)[4] = av_malloc_array(stride, h*sizeof(uint32_t)*4);

    if(!col || !dist) {

        av_log(s->avctx, AV_LOG_ERROR, "guess_dc() is out of memory\n");

        goto fail;

    }

    for(b_y=0; b_y<h; b_y++){

        int color= 1024;

        int distance= -1;

        for(b_x=0; b_x<w; b_x++){

            int mb_index_j= (b_x>>is_luma) + (b_y>>is_luma)*s->mb_stride;

            int error_j= s->error_status_table[mb_index_j];

            int intra_j = IS_INTRA(s->cur_pic.mb_type[mb_index_j]);

            if(intra_j==0 || !(error_j&ER_DC_ERROR)){

                color= dc[b_x + b_y*stride];

                distance= b_x;

            }

            col [b_x + b_y*stride][1]= color;

            dist[b_x + b_y*stride][1]= distance >= 0 ? b_x-distance : 9999;

        }

        color= 1024;

        distance= -1;

        for(b_x=w-1; b_x>=0; b_x--){

            int mb_index_j= (b_x>>is_luma) + (b_y>>is_luma)*s->mb_stride;

            int error_j= s->error_status_table[mb_index_j];

            int intra_j = IS_INTRA(s->cur_pic.mb_type[mb_index_j]);

            if(intra_j==0 || !(error_j&ER_DC_ERROR)){

                color= dc[b_x + b_y*stride];

                distance= b_x;

            }

            col [b_x + b_y*stride][0]= color;

            dist[b_x + b_y*stride][0]= distance >= 0 ? distance-b_x : 9999;

        }

    }

    for(b_x=0; b_x<w; b_x++){

        int color= 1024;

        int distance= -1;

        for(b_y=0; b_y<h; b_y++){

            int mb_index_j= (b_x>>is_luma) + (b_y>>is_luma)*s->mb_stride;

            int error_j= s->error_status_table[mb_index_j];

            int intra_j = IS_INTRA(s->cur_pic.mb_type[mb_index_j]);

            if(intra_j==0 || !(error_j&ER_DC_ERROR)){

                color= dc[b_x + b_y*stride];

                distance= b_y;

            }

            col [b_x + b_y*stride][3]= color;

            dist[b_x + b_y*stride][3]= distance >= 0 ? b_y-distance : 9999;

        }

        color= 1024;

        distance= -1;

        for(b_y=h-1; b_y>=0; b_y--){

            int mb_index_j= (b_x>>is_luma) + (b_y>>is_luma)*s->mb_stride;

            int error_j= s->error_status_table[mb_index_j];

            int intra_j = IS_INTRA(s->cur_pic.mb_type[mb_index_j]);

            if(intra_j==0 || !(error_j&ER_DC_ERROR)){

                color= dc[b_x + b_y*stride];

                distance= b_y;

            }

            col [b_x + b_y*stride][2]= color;

            dist[b_x + b_y*stride][2]= distance >= 0 ? distance-b_y : 9999;

        }

    }

    for (b_y = 0; b_y < h; b_y++) {

        for (b_x = 0; b_x < w; b_x++) {

            int mb_index, error, j;

            int64_t guess, weight_sum;

            mb_index = (b_x >> is_luma) + (b_y >> is_luma) * s->mb_stride;

            error    = s->error_status_table[mb_index];

            if (IS_INTER(s->cur_pic.mb_type[mb_index]))

                continue; // inter

            if (!(error & ER_DC_ERROR))

                continue; // dc-ok

            weight_sum = 0;

            guess      = 0;

            for (j = 0; j < 4; j++) {

                int64_t weight  = 256 * 256 * 256 * 16 / FFMAX(dist[b_x + b_y*stride][j], 1);

                guess          += weight*(int64_t)col[b_x + b_y*stride][j];

                weight_sum     += weight;

            }

            guess = (guess + weight_sum / 2) / weight_sum;

            dc[b_x + b_y * stride] = guess;

        }

    }

fail:

    av_freep(&col);

    av_freep(&dist);

}

/**

 * simple horizontal deblocking filter used for error resilience

 * @param w     width in 8 pixel blocks

 * @param h     height in 8 pixel blocks

 */

static void h_block_filter(ERContext *s, uint8_t *dst, int w,

                           int h, ptrdiff_t stride, int is_luma)

{

    int b_x, b_y;

    ptrdiff_t mvx_stride, mvy_stride;

    const uint8_t *cm = ff_crop_tab + MAX_NEG_CROP;

    set_mv_strides(s, &mvx_stride, &mvy_stride);

    mvx_stride >>= is_luma;

    mvy_stride *= mvx_stride;

    for (b_y = 0; b_y < h; b_y++) {

        for (b_x = 0; b_x < w - 1; b_x++) {

            int y;

            int left_status  = s->error_status_table[( b_x      >> is_luma) + (b_y >> is_luma) * s->mb_stride];

            int right_status = s->error_status_table[((b_x + 1) >> is_luma) + (b_y >> is_luma) * s->mb_stride];

            int left_intra   = IS_INTRA(s->cur_pic.mb_type[( b_x      >> is_luma) + (b_y >> is_luma) * s->mb_stride]);

            int right_intra  = IS_INTRA(s->cur_pic.mb_type[((b_x + 1) >> is_luma) + (b_y >> is_luma) * s->mb_stride]);

            int left_damage  = left_status & ER_MB_ERROR;

            int right_damage = right_status & ER_MB_ERROR;

            int offset       = b_x * 8 + b_y * stride * 8;

            int16_t *left_mv  = s->cur_pic.motion_val[0][mvy_stride * b_y + mvx_stride *  b_x];

            int16_t *right_mv = s->cur_pic.motion_val[0][mvy_stride * b_y + mvx_stride * (b_x + 1)];

            if (!(left_damage || right_damage))

                continue; // both undamaged

            if ((!left_intra) && (!right_intra) &&

                FFABS(left_mv[0] - right_mv[0]) +

                FFABS(left_mv[1] + right_mv[1]) < 2)

                continue;

            for (y = 0; y < 8; y++) {

                int a, b, c, d;

                a = dst[offset + 7 + y * stride] - dst[offset + 6 + y * stride];

                b = dst[offset + 8 + y * stride] - dst[offset + 7 + y * stride];

                c = dst[offset + 9 + y * stride] - dst[offset + 8 + y * stride];

                d = FFABS(b) - ((FFABS(a) + FFABS(c) + 1) >> 1);

                d = FFMAX(d, 0);

                if (b < 0)

                    d = -d;

                if (d == 0)

                    continue;

                if (!(left_damage && right_damage))

                    d = d * 16 / 9;

                if (left_damage) {

                    dst[offset + 7 + y * stride] = cm[dst[offset + 7 + y * stride] + ((d * 7) >> 4)];

                    dst[offset + 6 + y * stride] = cm[dst[offset + 6 + y * stride] + ((d * 5) >> 4)];

                    dst[offset + 5 + y * stride] = cm[dst[offset + 5 + y * stride] + ((d * 3) >> 4)];

                    dst[offset + 4 + y * stride] = cm[dst[offset + 4 + y * stride] + ((d * 1) >> 4)];

                }

                if (right_damage) {

                    dst[offset + 8 + y * stride] = cm[dst[offset +  8 + y * stride] - ((d * 7) >> 4)];

                    dst[offset + 9 + y * stride] = cm[dst[offset +  9 + y * stride] - ((d * 5) >> 4)];

                    dst[offset + 10+ y * stride] = cm[dst[offset + 10 + y * stride] - ((d * 3) >> 4)];

                    dst[offset + 11+ y * stride] = cm[dst[offset + 11 + y * stride] - ((d * 1) >> 4)];

                }

            }

        }

    }

}

/**

 * simple vertical deblocking filter used for error resilience

 * @param w     width in 8 pixel blocks

 * @param h     height in 8 pixel blocks

 */

static void v_block_filter(ERContext *s, uint8_t *dst, int w, int h,

                           ptrdiff_t stride, int is_luma)

{

    int b_x, b_y;

    ptrdiff_t mvx_stride, mvy_stride;

    const uint8_t *cm = ff_crop_tab + MAX_NEG_CROP;

    set_mv_strides(s, &mvx_stride, &mvy_stride);

    mvx_stride >>= is_luma;

    mvy_stride *= mvx_stride;

    for (b_y = 0; b_y < h - 1; b_y++) {

        for (b_x = 0; b_x < w; b_x++) {

            int x;

            int top_status    = s->error_status_table[(b_x >> is_luma) +  (b_y      >> is_luma) * s->mb_stride];

            int bottom_status = s->error_status_table[(b_x >> is_luma) + ((b_y + 1) >> is_luma) * s->mb_stride];

            int top_intra     = IS_INTRA(s->cur_pic.mb_type[(b_x >> is_luma) + ( b_y      >> is_luma) * s->mb_stride]);

            int bottom_intra  = IS_INTRA(s->cur_pic.mb_type[(b_x >> is_luma) + ((b_y + 1) >> is_luma) * s->mb_stride]);

            int top_damage    = top_status & ER_MB_ERROR;

            int bottom_damage = bottom_status & ER_MB_ERROR;

            int offset        = b_x * 8 + b_y * stride * 8;

            int16_t *top_mv    = s->cur_pic.motion_val[0][mvy_stride *  b_y      + mvx_stride * b_x];

            int16_t *bottom_mv = s->cur_pic.motion_val[0][mvy_stride * (b_y + 1) + mvx_stride * b_x];

            if (!(top_damage || bottom_damage))

                continue; // both undamaged

            if ((!top_intra) && (!bottom_intra) &&

                FFABS(top_mv[0] - bottom_mv[0]) +

                FFABS(top_mv[1] + bottom_mv[1]) < 2)

                continue;

            for (x = 0; x < 8; x++) {

                int a, b, c, d;

                a = dst[offset + x + 7 * stride] - dst[offset + x + 6 * stride];

                b = dst[offset + x + 8 * stride] - dst[offset + x + 7 * stride];

                c = dst[offset + x + 9 * stride] - dst[offset + x + 8 * stride];

                d = FFABS(b) - ((FFABS(a) + FFABS(c) + 1) >> 1);

                d = FFMAX(d, 0);

                if (b < 0)

                    d = -d;

                if (d == 0)

                    continue;

                if (!(top_damage && bottom_damage))

                    d = d * 16 / 9;

                if (top_damage) {

                    dst[offset + x +  7 * stride] = cm[dst[offset + x +  7 * stride] + ((d * 7) >> 4)];

                    dst[offset + x +  6 * stride] = cm[dst[offset + x +  6 * stride] + ((d * 5) >> 4)];

                    dst[offset + x +  5 * stride] = cm[dst[offset + x +  5 * stride] + ((d * 3) >> 4)];

                    dst[offset + x +  4 * stride] = cm[dst[offset + x +  4 * stride] + ((d * 1) >> 4)];

                }

                if (bottom_damage) {

                    dst[offset + x +  8 * stride] = cm[dst[offset + x +  8 * stride] - ((d * 7) >> 4)];

                    dst[offset + x +  9 * stride] = cm[dst[offset + x +  9 * stride] - ((d * 5) >> 4)];

                    dst[offset + x + 10 * stride] = cm[dst[offset + x + 10 * stride] - ((d * 3) >> 4)];

                    dst[offset + x + 11 * stride] = cm[dst[offset + x + 11 * stride] - ((d * 1) >> 4)];

                }

            }

        }

    }

}

#define MV_FROZEN    8

#define MV_CHANGED   4

#define MV_UNCHANGED 2

#define MV_LISTED    1

static av_always_inline void add_blocklist(int (*blocklist)[2], int *blocklist_length, uint8_t *fixed, int mb_x, int mb_y, int mb_xy)

{

    if (fixed[mb_xy])

        return;

    fixed[mb_xy] = MV_LISTED;

    blocklist[ *blocklist_length   ][0] = mb_x;

    blocklist[(*blocklist_length)++][1] = mb_y;

}

static void guess_mv(ERContext *s)

{

    int (*blocklist)[2], (*next_blocklist)[2];

    uint8_t *fixed;

    const ptrdiff_t mb_stride = s->mb_stride;

    const int mb_width  = s->mb_width;

    int mb_height = s->mb_height;

    int i, num_avail;

    int mb_x, mb_y;

    ptrdiff_t mot_step, mot_stride;

    int blocklist_length, next_blocklist_length;

    if (s->last_pic.f && s->last_pic.f->data[0])

        mb_height = FFMIN(mb_height, (s->last_pic.f->height+15)>>4);

    if (s->next_pic.f && s->next_pic.f->data[0])

        mb_height = FFMIN(mb_height, (s->next_pic.f->height+15)>>4);

    blocklist      = (int (*)[2])s->er_temp_buffer;

    next_blocklist = blocklist + s->mb_stride * s->mb_height;

    fixed          = (uint8_t *)(next_blocklist + s->mb_stride * s->mb_height);

    set_mv_strides(s, &mot_step, &mot_stride);

    num_avail = 0;

    if (s->last_pic.motion_val[0]) {

        if (s->last_pic.tf)

            ff_thread_await_progress(s->last_pic.tf, mb_height-1, 0);

        else

            ff_thread_progress_await(s->last_pic.progress, mb_height - 1);

    }

    for (i = 0; i < mb_width * mb_height; i++) {

        const int mb_xy = s->mb_index2xy[i];

        int f = 0;

        int error = s->error_status_table[mb_xy];

        if (IS_INTRA(s->cur_pic.mb_type[mb_xy]))

            f = MV_FROZEN; // intra // FIXME check

        if (!(error & ER_MV_ERROR))

            f = MV_FROZEN; // inter with undamaged MV

        fixed[mb_xy] = f;

        if (f == MV_FROZEN)

            num_avail++;

        else if(s->last_pic.f->data[0] && s->last_pic.motion_val[0]){

            const int mb_y= mb_xy / s->mb_stride;

            const int mb_x= mb_xy % s->mb_stride;

            const int mot_index= (mb_x + mb_y*mot_stride) * mot_step;

            s->cur_pic.motion_val[0][mot_index][0]= s->last_pic.motion_val[0][mot_index][0];

            s->cur_pic.motion_val[0][mot_index][1]= s->last_pic.motion_val[0][mot_index][1];

            s->cur_pic.ref_index[0][4*mb_xy]      = s->last_pic.ref_index[0][4*mb_xy];

        }

    }

    if ((!(s->avctx->error_concealment&FF_EC_GUESS_MVS)) ||

        num_avail <= FFMAX(mb_width, mb_height) / 2) {

        for (mb_y = 0; mb_y < 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_dir = (s->last_pic.f && s->last_pic.f->data[0]) ? MV_DIR_FORWARD : MV_DIR_BACKWARD;

                if (IS_INTRA(s->cur_pic.mb_type[mb_xy]))

                    continue;

                if (!(s->error_status_table[mb_xy] & ER_MV_ERROR))

                    continue;

                s->mv[0][0][0] = 0;

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

                s->decode_mb(s->opaque, 0, mv_dir, MV_TYPE_16X16, &s->mv,

                             mb_x, mb_y, 0, 0);

            }

        }

        return;

    }

    blocklist_length = 0;

    for (mb_y = 0; mb_y < mb_height; mb_y++) {

        for (mb_x = 0; mb_x < mb_width; mb_x++) {

            const int mb_xy = mb_x + mb_y * mb_stride;

            if (fixed[mb_xy] == MV_FROZEN) {

                if (mb_x)               add_blocklist(blocklist, &blocklist_length, fixed, mb_x - 1, mb_y, mb_xy - 1);

                if (mb_y)               add_blocklist(blocklist, &blocklist_length, fixed, mb_x, mb_y - 1, mb_xy - mb_stride);

                if (mb_x+1 < mb_width)  add_blocklist(blocklist, &blocklist_length, fixed, mb_x + 1, mb_y, mb_xy + 1);

                if (mb_y+1 < mb_height) add_blocklist(blocklist, &blocklist_length, fixed, mb_x, mb_y + 1, mb_xy + mb_stride);

            }

        }

    }

    for (;;) {

        int changed, pass, none_left;

        int blocklist_index;

        none_left = 1;

        changed   = 1;

        for (pass = 0; (changed || pass < 2) && pass < 10; pass++) {

            changed = 0;

            for (blocklist_index = 0; blocklist_index < blocklist_length; blocklist_index++) {

                const int mb_x = blocklist[blocklist_index][0];

                const int mb_y = blocklist[blocklist_index][1];

                const int mb_xy = mb_x + mb_y * mb_stride;

                int mv_predictor[8][2];

                int ref[8];

                int pred_count;

                int j;

                int best_score;

                int best_pred;

                int mot_index;

                int prev_x, prev_y, prev_ref;

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

                    continue;

                av_assert2(fixed[mb_xy] != MV_FROZEN);

                av_assert1(!IS_INTRA(s->cur_pic.mb_type[mb_xy]));

                av_assert1(s->last_pic.f && s->last_pic.f->data[0]);

                j = 0;

                if (mb_x > 0)

                    j |= fixed[mb_xy - 1];

                if (mb_x + 1 < mb_width)

                    j |= fixed[mb_xy + 1];

                if (mb_y > 0)

                    j |= fixed[mb_xy - mb_stride];

                if (mb_y + 1 < mb_height)

                    j |= fixed[mb_xy + mb_stride];

                av_assert2(j & MV_FROZEN);

                if (!(j & MV_CHANGED) && pass > 1)

                    continue;

                none_left = 0;

                pred_count = 0;

                mot_index  = (mb_x + mb_y * mot_stride) * mot_step;

                if (mb_x > 0 && fixed[mb_xy - 1] > 1) {

                    mv_predictor[pred_count][0] =

                        s->cur_pic.motion_val[0][mot_index - mot_step][0];

                    mv_predictor[pred_count][1] =

                        s->cur_pic.motion_val[0][mot_index - mot_step][1];

                    ref[pred_count] =

                        s->cur_pic.ref_index[0][4 * (mb_xy - 1)];

                    pred_count++;

                }

                if (mb_x + 1 < mb_width && fixed[mb_xy + 1] > 1) {

                    mv_predictor[pred_count][0] =

                        s->cur_pic.motion_val[0][mot_index + mot_step][0];

                    mv_predictor[pred_count][1] =

                        s->cur_pic.motion_val[0][mot_index + mot_step][1];

                    ref[pred_count] =

                        s->cur_pic.ref_index[0][4 * (mb_xy + 1)];

                    pred_count++;

                }

                if (mb_y > 0 && fixed[mb_xy - mb_stride] > 1) {

                    mv_predictor[pred_count][0] =

                        s->cur_pic.motion_val[0][mot_index - mot_stride * mot_step][0];

                    mv_predictor[pred_count][1] =

                        s->cur_pic.motion_val[0][mot_index - mot_stride * mot_step][1];

                    ref[pred_count] =

                        s->cur_pic.ref_index[0][4 * (mb_xy - s->mb_stride)];

                    pred_count++;

                }

                if (mb_y + 1<mb_height && fixed[mb_xy + mb_stride] > 1) {

                    mv_predictor[pred_count][0] =

                        s->cur_pic.motion_val[0][mot_index + mot_stride * mot_step][0];

                    mv_predictor[pred_count][1] =

                        s->cur_pic.motion_val[0][mot_index + mot_stride * mot_step][1];

                    ref[pred_count] =

                        s->cur_pic.ref_index[0][4 * (mb_xy + s->mb_stride)];

                    pred_count++;

                }

                if (pred_count == 0)

                    continue;

                if (pred_count > 1) {

                    int sum_x = 0, sum_y = 0, sum_r = 0;

                    int max_x, max_y, min_x, min_y, max_r, min_r;

                    for (j = 0; j < pred_count; j++) {

                        sum_x += mv_predictor[j][0];

                        sum_y += mv_predictor[j][1];

                        sum_r += ref[j];

                        if (j && ref[j] != ref[j - 1])

                            goto skip_mean_and_median;

                    }

                    /* mean */

                    mv_predictor[pred_count][0] = sum_x / j;

                    mv_predictor[pred_count][1] = sum_y / j;

                             ref[pred_count]    = sum_r / j;

                    /* median */

                    if (pred_count >= 3) {

                        min_y = min_x = min_r =  99999;

                        max_y = max_x = max_r = -99999;

                    } else {

                        min_x = min_y = max_x = max_y = min_r = max_r = 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]);

                        max_r = FFMAX(max_r, ref[j]);

                        min_x = FFMIN(min_x, mv_predictor[j][0]);

                        min_y = FFMIN(min_y, mv_predictor[j][1]);

                        min_r = FFMIN(min_r, ref[j]);

                    }

                    mv_predictor[pred_count + 1][0] = sum_x - max_x - min_x;

                    mv_predictor[pred_count + 1][1] = sum_y - max_y - min_y;

                             ref[pred_count + 1]    = sum_r - max_r - min_r;

                    if (pred_count == 4) {

                        mv_predictor[pred_count + 1][0] /= 2;

                        mv_predictor[pred_count + 1][1] /= 2;

                                 ref[pred_count + 1]    /= 2;

                    }

                    pred_count += 2;

                }

skip_mean_and_median:

                /* zero MV */

                mv_predictor[pred_count][0] =

                mv_predictor[pred_count][1] =

                         ref[pred_count]    = 0;

                pred_count++;

                prev_x   = s->cur_pic.motion_val[0][mot_index][0];

                prev_y   = s->cur_pic.motion_val[0][mot_index][1];

                prev_ref = s->cur_pic.ref_index[0][4 * mb_xy];

                /* last MV */

                mv_predictor[pred_count][0] = prev_x;

                mv_predictor[pred_count][1] = prev_y;

                         ref[pred_count]    = prev_ref;

                pred_count++;

                best_pred = 0;

                best_score = 256 * 256 * 256 * 64;

                for (j = 0; j < pred_count; j++) {

                    int *linesize = s->cur_pic.f->linesize;

                    int score = 0;

                    uint8_t *src = s->cur_pic.f->data[0] +

                                   mb_x * 16 + mb_y * 16 * linesize[0];

                    s->cur_pic.motion_val[0][mot_index][0] =

                        s->mv[0][0][0] = mv_predictor[j][0];

                    s->cur_pic.motion_val[0][mot_index][1] =

                        s->mv[0][0][1] = mv_predictor[j][1];

                    // predictor intra or otherwise not available

                    if (ref[j] < 0)

                        continue;

                    s->decode_mb(s->opaque, ref[j], MV_DIR_FORWARD,

                                 MV_TYPE_16X16, &s->mv, mb_x, mb_y, 0, 0);

                    if (mb_x > 0 && fixed[mb_xy - 1] > 1) {

                        int k;

                        for (k = 0; k < 16; k++)

                            score += FFABS(src[k * linesize[0] - 1] -

                                           src[k * linesize[0]]);

                    }

                    if (mb_x + 1 < mb_width && fixed[mb_xy + 1] > 1) {

                        int k;

                        for (k = 0; k < 16; k++)

                            score += FFABS(src[k * linesize[0] + 15] -

                                           src[k * linesize[0] + 16]);

                    }

                    if (mb_y > 0 && fixed[mb_xy - mb_stride] > 1) {

                        int k;

                        for (k = 0; k < 16; k++)

                            score += FFABS(src[k - linesize[0]] - src[k]);

                    }

                    if (mb_y + 1 < mb_height && fixed[mb_xy + mb_stride] > 1) {

                        int k;

                        for (k = 0; k < 16; k++)

                            score += FFABS(src[k + linesize[0] * 15] -

                                           src[k + linesize[0] * 16]);

                    }

                    if (score <= best_score) { // <= will favor the last MV

                        best_score = score;

                        best_pred  = j;

                    }

                }

                s->mv[0][0][0] = mv_predictor[best_pred][0];

                s->mv[0][0][1] = mv_predictor[best_pred][1];

                for (i = 0; i < mot_step; i++)

                    for (j = 0; j < mot_step; j++) {

                        s->cur_pic.motion_val[0][mot_index + i + j * mot_stride][0] = s->mv[0][0][0];

                        s->cur_pic.motion_val[0][mot_index + i + j * mot_stride][1] = s->mv[0][0][1];

                    }

                s->decode_mb(s->opaque, ref[best_pred], MV_DIR_FORWARD,

                             MV_TYPE_16X16, &s->mv, mb_x, mb_y, 0, 0);

                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;

            }

        }

        if (none_left)

            return;

        next_blocklist_length = 0;

        for (blocklist_index = 0; blocklist_index < blocklist_length; blocklist_index++) {

            const int mb_x = blocklist[blocklist_index][0];

            const int mb_y = blocklist[blocklist_index][1];

            const int mb_xy = mb_x + mb_y * mb_stride;

            if (fixed[mb_xy] & (MV_CHANGED|MV_UNCHANGED|MV_FROZEN)) {

                fixed[mb_xy] = MV_FROZEN;

                if (mb_x > 0)

                    add_blocklist(next_blocklist, &next_blocklist_length, fixed, mb_x - 1, mb_y, mb_xy - 1);

                if (mb_y > 0)

                    add_blocklist(next_blocklist, &next_blocklist_length, fixed, mb_x, mb_y - 1, mb_xy - mb_stride);

                if (mb_x + 1 < mb_width)

                    add_blocklist(next_blocklist, &next_blocklist_length, fixed, mb_x + 1, mb_y, mb_xy + 1);

                if (mb_y + 1 < mb_height)

                    add_blocklist(next_blocklist, &next_blocklist_length, fixed, mb_x, mb_y + 1, mb_xy + mb_stride);

            }

        }

        av_assert0(next_blocklist_length <= mb_height * mb_width);

        FFSWAP(int , blocklist_length, next_blocklist_length);

        FFSWAP(void*, blocklist, next_blocklist);

    }

}

static int is_intra_more_likely(ERContext *s)

{

    int is_intra_likely, i, j, undamaged_count, skip_amount, mb_x, mb_y;

    if (!s->last_pic.f || !s->last_pic.f->data[0])

        return 1; // no previous frame available -> use spatial prediction

    if (s->avctx->error_concealment & FF_EC_FAVOR_INTER)

        return 0;

    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 & ER_DC_ERROR) && (error & ER_MV_ERROR)))

            undamaged_count++;

    }

    if (undamaged_count < 5)

        return 0; // almost all MBs damaged -> use temporal prediction

    skip_amount     = FFMAX(undamaged_count / 50, 1); // check only up to 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 & ER_DC_ERROR) && (error & ER_MV_ERROR))

                continue; // skip damaged

            j++;

            // skip a few to speed things up

            if ((j % skip_amount) != 0)

                continue;

            if (s->cur_pic.f->pict_type == AV_PICTURE_TYPE_I) {

                int *linesize = s->cur_pic.f->linesize;

                uint8_t *mb_ptr      = s->cur_pic.f->data[0] +

                                       mb_x * 16 + mb_y * 16 * linesize[0];

                uint8_t *last_mb_ptr = s->last_pic.f->data[0] +

                                       mb_x * 16 + mb_y * 16 * linesize[0];

                if (s->avctx->codec_id == AV_CODEC_ID_H264) {

                    // FIXME

                } else {

                    ff_thread_progress_await(s->last_pic.progress, mb_y);

                }

                is_intra_likely += s->sad(NULL, last_mb_ptr, mb_ptr,

                                          linesize[0], 16);

                // FIXME need await_progress() here

                is_intra_likely -= s->sad(NULL, last_mb_ptr,

                                          last_mb_ptr + linesize[0] * 16,

                                          linesize[0], 16);

            } else {

                if (IS_INTRA(s->cur_pic.mb_type[mb_xy]))

                   is_intra_likely++;

                else

                   is_intra_likely--;

            }

        }

    }

//      av_log(NULL, AV_LOG_ERROR, "is_intra_likely: %d type:%d\n", is_intra_likely, s->pict_type);

    return is_intra_likely > 0;

}

void ff_er_frame_start(ERContext *s)

{

    if (!s->avctx->error_concealment)

        return;

    memset(s->error_status_table, ER_MB_ERROR | VP_START | ER_MB_END,

           s->mb_stride * s->mb_height * sizeof(uint8_t));

    atomic_init(&s->error_count, 3 * s->mb_num);

    s->error_occurred = 0;

}

static int er_supported(ERContext *s)

{

    if (s->avctx->hwaccel ||

       !s->cur_pic.f                                                  ||

       s->cur_pic.field_picture

    )

        return 0;

    return 1;

}

/**

 * Add 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 (ER_MV_END, ER_AC_ERROR, ...), it is

 *               assumed that no earlier end or error of the same type occurred

 */

void ff_er_add_slice(ERContext *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 (s->avctx->hwaccel)

        return;

    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->avctx->error_concealment)

        return;

    mask &= ~VP_START;

    if (status & (ER_AC_ERROR | ER_AC_END)) {

        mask           &= ~(ER_AC_ERROR | ER_AC_END);

        atomic_fetch_add(&s->error_count, start_i - end_i - 1);

    }

    if (status & (ER_DC_ERROR | ER_DC_END)) {

        mask           &= ~(ER_DC_ERROR | ER_DC_END);

        atomic_fetch_add(&s->error_count, start_i - end_i - 1);

    }

    if (status & (ER_MV_ERROR | ER_MV_END)) {

        mask           &= ~(ER_MV_ERROR | ER_MV_END);

        atomic_fetch_add(&s->error_count, start_i - end_i - 1);

    }

    if (status & ER_MB_ERROR) {

        s->error_occurred = 1;

        atomic_store(&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)

        atomic_store(&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->active_thread_type & FF_THREAD_SLICE) &&

        er_supported(s) && 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 != (ER_MV_END | ER_DC_END | ER_AC_END)) {

            s->error_occurred = 1;

            atomic_store(&s->error_count, INT_MAX);

        }

    }

}

void ff_er_frame_end(ERContext *s, int *decode_error_flags)

{

    int *linesize = NULL;

    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;

    int guessed_mb_type;

    /* We do not support ER of field pictures yet,

     * though it should not crash if enabled. */

    if (!s->avctx->error_concealment || !atomic_load(&s->error_count)  ||

        s->avctx->lowres                                               ||

        !er_supported(s)                                               ||

        atomic_load(&s->error_count) == 3 * s->mb_width *

                          (s->avctx->skip_top + s->avctx->skip_bottom)) {

        return;

    }

    linesize = s->cur_pic.f->linesize;

    if (   s->avctx->codec_id == AV_CODEC_ID_MPEG2VIDEO

        && (FFALIGN(s->avctx->height, 16)&16)

        && atomic_load(&s->error_count) == 3 * s->mb_width * (s->avctx->skip_top + s->avctx->skip_bottom + 1)) {

        for (mb_x = 0; mb_x < s->mb_width; mb_x++) {

            int status = s->error_status_table[mb_x + (s->mb_height - 1) * s->mb_stride];

            if (status != 0x7F)

                break;

        }

        if (mb_x == s->mb_width) {

            av_log(s->avctx, AV_LOG_DEBUG, "ignoring last missing slice\n");

            return;

        }

    }

    if (s->last_pic.f) {

        if (s->last_pic.f->width  != s->cur_pic.f->width  ||

            s->last_pic.f->height != s->cur_pic.f->height ||

            s->last_pic.f->format != s->cur_pic.f->format) {

            av_log(s->avctx, AV_LOG_WARNING, "Cannot use previous picture in error concealment\n");

            memset(&s->last_pic, 0, sizeof(s->last_pic));

        }

    }

    if (s->next_pic.f) {

        if (s->next_pic.f->width  != s->cur_pic.f->width  ||

            s->next_pic.f->height != s->cur_pic.f->height ||

            s->next_pic.f->format != s->cur_pic.f->format) {

            av_log(s->avctx, AV_LOG_WARNING, "Cannot use next picture in error concealment\n");

            memset(&s->next_pic, 0, sizeof(s->next_pic));

        }

    }

    if (!s->cur_pic.motion_val[0] || !s->cur_pic.ref_index[0]) {

        av_log(s->avctx, AV_LOG_ERROR, "Warning MVs not available\n");

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

            s->ref_index[i]       = av_calloc(s->mb_stride * s->mb_height, 4 * sizeof(uint8_t));

            s->motion_val_base[i] = av_calloc(size + 4, 2 * sizeof(uint16_t));

            if (!s->ref_index[i] || !s->motion_val_base[i])

                goto cleanup;

            s->cur_pic.ref_index[i]  = s->ref_index[i];

            s->cur_pic.motion_val[i] = s->motion_val_base[i] + 4;

        }

    }

    if (s->avctx->debug & FF_DEBUG_ER) {

        for (mb_y = 0; mb_y < s->mb_height; mb_y++) {

            for (mb_x = 0; mb_x < s->mb_width; mb_x++) {

                int status = s->error_status_table[mb_x + mb_y * s->mb_stride];

                av_log(s->avctx, AV_LOG_DEBUG, "%2X ", status);

            }

            av_log(s->avctx, AV_LOG_DEBUG, "\n");

        }

    }

#if 1

    /* handle overlapping slices */

    for (error_type = 1; error_type <= 3; error_type++) {

        int end_ok = 0;

        for (i = s->mb_num - 1; i >= 0; i--) {

            const int mb_xy = s->mb_index2xy[i];

            int error       = s->error_status_table[mb_xy];

            if (error & (1 << error_type))

                end_ok = 1;

            if (error & (8 << error_type))

                end_ok = 1;

            if (!end_ok)

                s->error_status_table[mb_xy] |= 1 << error_type;

            if (error & VP_START)

                end_ok = 0;

        }

    }

#endif

#if 1

    /* handle slices with partitions of different length */

    if (s->partitioned_frame) {

        int end_ok = 0;

        for (i = s->mb_num - 1; i >= 0; i--) {

            const int mb_xy = s->mb_index2xy[i];

            int error       = s->error_status_table[mb_xy];

            if (error & ER_AC_END)

                end_ok = 0;