h264_refs.c 28.7 KB
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/*
 * H.26L/H.264/AVC/JVT/14496-10/... reference picture handling
 * Copyright (c) 2003 Michael Niedermayer <michaelni@gmx.at>
 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * 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.
 *
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 * Libav is distributed in the hope that it will be useful,
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 * 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
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
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 * @file
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 * H.264 / AVC / MPEG4 part10  reference picture handling.
 * @author Michael Niedermayer <michaelni@gmx.at>
 */

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#include <inttypes.h>

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#include "internal.h"
#include "avcodec.h"
#include "h264.h"
#include "golomb.h"
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#include "mpegutils.h"
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#include <assert.h>

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static void pic_as_field(H264Ref *pic, const int parity)
{
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    int i;
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    for (i = 0; i < FF_ARRAY_ELEMS(pic->data); ++i) {
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        if (parity == PICT_BOTTOM_FIELD)
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            pic->data[i]   += pic->linesize[i];
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        pic->reference      = parity;
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        pic->linesize[i] *= 2;
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    }
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    pic->poc = pic->parent->field_poc[parity == PICT_BOTTOM_FIELD];
}

static void ref_from_h264pic(H264Ref *dst, H264Picture *src)
{
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    memcpy(dst->data,     src->f->data,     sizeof(dst->data));
    memcpy(dst->linesize, src->f->linesize, sizeof(dst->linesize));
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    dst->reference = src->reference;
    dst->poc       = src->poc;
    dst->pic_id    = src->pic_id;
    dst->parent = src;
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}

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static int split_field_copy(H264Ref *dest, H264Picture *src, int parity, int id_add)
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{
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    int match = !!(src->reference & parity);
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    if (match) {
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        ref_from_h264pic(dest, src);
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        if (parity != PICT_FRAME) {
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            pic_as_field(dest, parity);
            dest->pic_id *= 2;
            dest->pic_id += id_add;
        }
    }

    return match;
}

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static int build_def_list(H264Ref *def, int def_len,
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                          H264Picture * const *in, int len, int is_long, int sel)
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{
    int  i[2] = { 0 };
    int index = 0;
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    while ((i[0] < len || i[1] < len) && index < def_len) {
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        while (i[0] < len && !(in[i[0]] && (in[i[0]]->reference & sel)))
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            i[0]++;
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        while (i[1] < len && !(in[i[1]] && (in[i[1]]->reference & (sel ^ 3))))
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            i[1]++;
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        if (i[0] < len && index < def_len) {
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            in[i[0]]->pic_id = is_long ? i[0] : in[i[0]]->frame_num;
            split_field_copy(&def[index++], in[i[0]++], sel, 1);
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        }
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        if (i[1] < len && index < def_len) {
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            in[i[1]]->pic_id = is_long ? i[1] : in[i[1]]->frame_num;
            split_field_copy(&def[index++], in[i[1]++], sel ^ 3, 0);
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        }
    }

    return index;
}

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static int add_sorted(H264Picture **sorted, H264Picture * const *src,
                      int len, int limit, int dir)
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{
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    int i, best_poc;
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    int out_i = 0;
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    for (;;) {
        best_poc = dir ? INT_MIN : INT_MAX;
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        for (i = 0; i < len; i++) {
            const int poc = src[i]->poc;
            if (((poc > limit) ^ dir) && ((poc < best_poc) ^ dir)) {
                best_poc      = poc;
                sorted[out_i] = src[i];
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            }
        }
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        if (best_poc == (dir ? INT_MIN : INT_MAX))
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            break;
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        limit = sorted[out_i++]->poc - dir;
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    }
    return out_i;
}

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static void h264_initialise_ref_list(const H264Context *h, H264SliceContext *sl)
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{
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    int i, len;

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    if (sl->slice_type_nos == AV_PICTURE_TYPE_B) {
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        H264Picture *sorted[32];
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        int cur_poc, list;
        int lens[2];

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        if (FIELD_PICTURE(h))
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            cur_poc = h->cur_pic_ptr->field_poc[h->picture_structure == PICT_BOTTOM_FIELD];
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        else
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            cur_poc = h->cur_pic_ptr->poc;

        for (list = 0; list < 2; list++) {
            len  = add_sorted(sorted,       h->short_ref, h->short_ref_count, cur_poc, 1 ^ list);
            len += add_sorted(sorted + len, h->short_ref, h->short_ref_count, cur_poc, 0 ^ list);
            assert(len <= 32);
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            len  = build_def_list(sl->ref_list[list], FF_ARRAY_ELEMS(sl->ref_list[0]),
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                                  sorted, len, 0, h->picture_structure);
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            len += build_def_list(sl->ref_list[list] + len,
                                  FF_ARRAY_ELEMS(sl->ref_list[0]) - len,
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                                  h->long_ref, 16, 1, h->picture_structure);
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            if (len < sl->ref_count[list])
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                memset(&sl->ref_list[list][len], 0, sizeof(H264Ref) * (sl->ref_count[list] - len));
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            lens[list] = len;
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        }

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        if (lens[0] == lens[1] && lens[1] > 1) {
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            for (i = 0; i < lens[0] &&
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                        sl->ref_list[0][i].parent->f->buf[0]->buffer ==
                        sl->ref_list[1][i].parent->f->buf[0]->buffer; i++);
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            if (i == lens[0]) {
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                FFSWAP(H264Ref, sl->ref_list[1][0], sl->ref_list[1][1]);
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            }
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        }
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    } else {
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        len  = build_def_list(sl->ref_list[0], FF_ARRAY_ELEMS(sl->ref_list[0]),
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                              h->short_ref, h->short_ref_count, 0, h->picture_structure);
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        len += build_def_list(sl->ref_list[0] + len,
                              FF_ARRAY_ELEMS(sl->ref_list[0]) - len,
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                              h-> long_ref, 16, 1, h->picture_structure);

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        if (len < sl->ref_count[0])
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            memset(&sl->ref_list[0][len], 0, sizeof(H264Ref) * (sl->ref_count[0] - len));
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    }
}

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/**
 * print short term list
 */
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static void print_short_term(const H264Context *h)
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{
    uint32_t i;
    if (h->avctx->debug & FF_DEBUG_MMCO) {
        av_log(h->avctx, AV_LOG_DEBUG, "short term list:\n");
        for (i = 0; i < h->short_ref_count; i++) {
            H264Picture *pic = h->short_ref[i];
            av_log(h->avctx, AV_LOG_DEBUG, "%"PRIu32" fn:%d poc:%d %p\n",
                   i, pic->frame_num, pic->poc, pic->f->data[0]);
        }
    }
}

/**
 * print long term list
 */
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static void print_long_term(const H264Context *h)
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{
    uint32_t i;
    if (h->avctx->debug & FF_DEBUG_MMCO) {
        av_log(h->avctx, AV_LOG_DEBUG, "long term list:\n");
        for (i = 0; i < 16; i++) {
            H264Picture *pic = h->long_ref[i];
            if (pic) {
                av_log(h->avctx, AV_LOG_DEBUG, "%"PRIu32" fn:%d poc:%d %p\n",
                       i, pic->frame_num, pic->poc, pic->f->data[0]);
            }
        }
    }
}
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/**
 * Extract structure information about the picture described by pic_num in
 * the current decoding context (frame or field). Note that pic_num is
 * picture number without wrapping (so, 0<=pic_num<max_pic_num).
 * @param pic_num picture number for which to extract structure information
 * @param structure one of PICT_XXX describing structure of picture
 *                      with pic_num
 * @return frame number (short term) or long term index of picture
 *         described by pic_num
 */
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static int pic_num_extract(const H264Context *h, int pic_num, int *structure)
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{
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    *structure = h->picture_structure;
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    if (FIELD_PICTURE(h)) {
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        if (!(pic_num & 1))
            /* opposite field */
            *structure ^= PICT_FRAME;
        pic_num >>= 1;
    }

    return pic_num;
}

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int ff_h264_decode_ref_pic_list_reordering(const H264Context *h, H264SliceContext *sl)
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{
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    int list, index, pic_structure;
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    print_short_term(h);
    print_long_term(h);

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    h264_initialise_ref_list(h, sl);
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    for (list = 0; list < sl->list_count; list++) {
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        if (get_bits1(&sl->gb)) {    // ref_pic_list_modification_flag_l[01]
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            int pred = h->curr_pic_num;
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            for (index = 0; ; index++) {
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                unsigned int modification_of_pic_nums_idc = get_ue_golomb_31(&sl->gb);
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                unsigned int pic_id;
                int i;
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                H264Picture *ref = NULL;
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                if (modification_of_pic_nums_idc == 3)
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                    break;

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                if (index >= sl->ref_count[list]) {
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                    av_log(h->avctx, AV_LOG_ERROR, "reference count overflow\n");
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                    return -1;
                }

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                switch (modification_of_pic_nums_idc) {
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                case 0:
                case 1: {
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                    const unsigned int abs_diff_pic_num = get_ue_golomb(&sl->gb) + 1;
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                    int frame_num;

                    if (abs_diff_pic_num > h->max_pic_num) {
                        av_log(h->avctx, AV_LOG_ERROR,
                               "abs_diff_pic_num overflow\n");
                        return AVERROR_INVALIDDATA;
                    }

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                    if (modification_of_pic_nums_idc == 0)
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                        pred -= abs_diff_pic_num;
                    else
                        pred += abs_diff_pic_num;
                    pred &= h->max_pic_num - 1;

                    frame_num = pic_num_extract(h, pred, &pic_structure);

                    for (i = h->short_ref_count - 1; i >= 0; i--) {
                        ref = h->short_ref[i];
                        assert(ref->reference);
                        assert(!ref->long_ref);
                        if (ref->frame_num == frame_num &&
                            (ref->reference & pic_structure))
                            break;
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                    }
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                    if (i >= 0)
                        ref->pic_id = pred;
                    break;
                }
                case 2: {
                    int long_idx;
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                    pic_id = get_ue_golomb(&sl->gb); // long_term_pic_idx
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                    long_idx = pic_num_extract(h, pic_id, &pic_structure);
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                    if (long_idx > 31) {
                        av_log(h->avctx, AV_LOG_ERROR,
                               "long_term_pic_idx overflow\n");
                        return AVERROR_INVALIDDATA;
                    }
                    ref = h->long_ref[long_idx];
                    assert(!(ref && !ref->reference));
                    if (ref && (ref->reference & pic_structure)) {
                        ref->pic_id = pic_id;
                        assert(ref->long_ref);
                        i = 0;
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                    } else {
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                        i = -1;
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                    }
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                    break;
                }
                default:
                    av_log(h->avctx, AV_LOG_ERROR,
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                           "illegal modification_of_pic_nums_idc %u\n",
                           modification_of_pic_nums_idc);
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                    return AVERROR_INVALIDDATA;
                }

                if (i < 0) {
                    av_log(h->avctx, AV_LOG_ERROR,
                           "reference picture missing during reorder\n");
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                    memset(&sl->ref_list[list][index], 0, sizeof(sl->ref_list[0][0])); // FIXME
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                } else {
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                    for (i = index; i + 1 < sl->ref_count[list]; i++) {
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                        if (sl->ref_list[list][i].parent &&
                            ref->long_ref == sl->ref_list[list][i].parent->long_ref &&
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                            ref->pic_id   == sl->ref_list[list][i].pic_id)
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                            break;
                    }
                    for (; i > index; i--) {
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                        sl->ref_list[list][i] = sl->ref_list[list][i - 1];
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                    }
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                    ref_from_h264pic(&sl->ref_list[list][index], ref);
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                    if (FIELD_PICTURE(h)) {
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                        pic_as_field(&sl->ref_list[list][index], pic_structure);
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                    }
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                }
            }
        }
    }
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    for (list = 0; list < sl->list_count; list++) {
        for (index = 0; index < sl->ref_count[list]; index++) {
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            if (!sl->ref_list[list][index].parent) {
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                av_log(h->avctx, AV_LOG_ERROR, "Missing reference picture\n");
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                if (index == 0 || h->avctx->err_recognition & AV_EF_EXPLODE)
                    return AVERROR_INVALIDDATA;
                else
                    sl->ref_list[list][index] = sl->ref_list[list][index - 1];
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            }
        }
    }

    return 0;
}

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void ff_h264_fill_mbaff_ref_list(H264SliceContext *sl)
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{
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    int list, i, j;
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    for (list = 0; list < sl->list_count; list++) { //FIXME try list_count
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        for (i = 0; i < sl->ref_count[list]; i++) {
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            H264Ref *frame = &sl->ref_list[list][i];
            H264Ref *field = &sl->ref_list[list][16 + 2 * i];

            field[0] = *frame;

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            for (j = 0; j < 3; j++)
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                field[0].linesize[j] <<= 1;
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            field[0].reference = PICT_TOP_FIELD;
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            field[0].poc       = field[0].parent->field_poc[0];

            field[1] = field[0];

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            for (j = 0; j < 3; j++)
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                field[1].data[j] += frame->parent->f->linesize[j];
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            field[1].reference = PICT_BOTTOM_FIELD;
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            field[1].poc       = field[1].parent->field_poc[1];
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            sl->pwt.luma_weight[16 + 2 * i][list][0] = sl->pwt.luma_weight[16 + 2 * i + 1][list][0] = sl->pwt.luma_weight[i][list][0];
            sl->pwt.luma_weight[16 + 2 * i][list][1] = sl->pwt.luma_weight[16 + 2 * i + 1][list][1] = sl->pwt.luma_weight[i][list][1];
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            for (j = 0; j < 2; j++) {
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                sl->pwt.chroma_weight[16 + 2 * i][list][j][0] = sl->pwt.chroma_weight[16 + 2 * i + 1][list][j][0] = sl->pwt.chroma_weight[i][list][j][0];
                sl->pwt.chroma_weight[16 + 2 * i][list][j][1] = sl->pwt.chroma_weight[16 + 2 * i + 1][list][j][1] = sl->pwt.chroma_weight[i][list][j][1];
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            }
        }
    }
}

/**
 * Mark a picture as no longer needed for reference. The refmask
 * argument allows unreferencing of individual fields or the whole frame.
 * If the picture becomes entirely unreferenced, but is being held for
 * display purposes, it is marked as such.
 * @param refmask mask of fields to unreference; the mask is bitwise
 *                anded with the reference marking of pic
 * @return non-zero if pic becomes entirely unreferenced (except possibly
 *         for display purposes) zero if one of the fields remains in
 *         reference
 */
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static inline int unreference_pic(H264Context *h, H264Picture *pic, int refmask)
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{
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    int i;
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    if (pic->reference &= refmask) {
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        return 0;
    } else {
        for(i = 0; h->delayed_pic[i]; i++)
            if(pic == h->delayed_pic[i]){
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                pic->reference = DELAYED_PIC_REF;
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                break;
            }
        return 1;
    }
}

/**
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 * Find a H264Picture in the short term reference list by frame number.
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 * @param frame_num frame number to search for
 * @param idx the index into h->short_ref where returned picture is found
 *            undefined if no picture found.
 * @return pointer to the found picture, or NULL if no pic with the provided
 *                 frame number is found
 */
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static H264Picture *find_short(H264Context *h, int frame_num, int *idx)
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{
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    int i;

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    for (i = 0; i < h->short_ref_count; i++) {
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        H264Picture *pic = h->short_ref[i];
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        if (h->avctx->debug & FF_DEBUG_MMCO)
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            av_log(h->avctx, AV_LOG_DEBUG, "%d %d %p\n", i, pic->frame_num, pic);
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        if (pic->frame_num == frame_num) {
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            *idx = i;
            return pic;
        }
    }
    return NULL;
}

/**
 * Remove a picture from the short term reference list by its index in
 * that list.  This does no checking on the provided index; it is assumed
 * to be valid. Other list entries are shifted down.
 * @param i index into h->short_ref of picture to remove.
 */
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static void remove_short_at_index(H264Context *h, int i)
{
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    assert(i >= 0 && i < h->short_ref_count);
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    h->short_ref[i] = NULL;
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    if (--h->short_ref_count)
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        memmove(&h->short_ref[i], &h->short_ref[i + 1],
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                (h->short_ref_count - i) * sizeof(H264Picture*));
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}

/**
 * @return the removed picture or NULL if an error occurs
 */
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static H264Picture *remove_short(H264Context *h, int frame_num, int ref_mask)
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{
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    H264Picture *pic;
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    int i;

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    if (h->avctx->debug & FF_DEBUG_MMCO)
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        av_log(h->avctx, AV_LOG_DEBUG, "remove short %d count %d\n", frame_num, h->short_ref_count);
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    pic = find_short(h, frame_num, &i);
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    if (pic) {
        if (unreference_pic(h, pic, ref_mask))
            remove_short_at_index(h, i);
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    }

    return pic;
}

/**
 * Remove a picture from the long term reference list by its index in
 * that list.
 * @return the removed picture or NULL if an error occurs
 */
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static H264Picture *remove_long(H264Context *h, int i, int ref_mask)
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{
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    H264Picture *pic;
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    pic = h->long_ref[i];
    if (pic) {
        if (unreference_pic(h, pic, ref_mask)) {
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            assert(h->long_ref[i]->long_ref == 1);
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            h->long_ref[i]->long_ref = 0;
            h->long_ref[i]           = NULL;
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            h->long_ref_count--;
        }
    }

    return pic;
}

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void ff_h264_remove_all_refs(H264Context *h)
{
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    int i;

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    for (i = 0; i < 16; i++) {
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        remove_long(h, i, 0);
    }
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    assert(h->long_ref_count == 0);
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    for (i = 0; i < h->short_ref_count; i++) {
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        unreference_pic(h, h->short_ref[i], 0);
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        h->short_ref[i] = NULL;
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    }
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    h->short_ref_count = 0;
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}

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static int check_opcodes(MMCO *mmco1, MMCO *mmco2, int n_mmcos)
{
    int i;

    for (i = 0; i < n_mmcos; i++) {
        if (mmco1[i].opcode != mmco2[i].opcode)
            return -1;
    }

    return 0;
}

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int ff_generate_sliding_window_mmcos(H264Context *h, int first_slice)
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{
    MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = first_slice ? h->mmco : mmco_temp;
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    int mmco_index = 0, i = 0;
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    assert(h->long_ref_count + h->short_ref_count <= h->ps.sps->ref_frame_count);
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    if (h->short_ref_count &&
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        h->long_ref_count + h->short_ref_count == h->ps.sps->ref_frame_count &&
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        !(FIELD_PICTURE(h) && !h->first_field && h->cur_pic_ptr->reference)) {
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        mmco[0].opcode        = MMCO_SHORT2UNUSED;
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        mmco[0].short_pic_num = h->short_ref[h->short_ref_count - 1]->frame_num;
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        mmco_index            = 1;
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        if (FIELD_PICTURE(h)) {
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            mmco[0].short_pic_num *= 2;
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            mmco[1].opcode         = MMCO_SHORT2UNUSED;
            mmco[1].short_pic_num  = mmco[0].short_pic_num + 1;
            mmco_index             = 2;
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        }
    }
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    if (first_slice) {
        h->mmco_index = mmco_index;
    } else if (!first_slice && mmco_index >= 0 &&
               (mmco_index != h->mmco_index ||
                (i = check_opcodes(h->mmco, mmco_temp, mmco_index)))) {
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        av_log(h->avctx, AV_LOG_ERROR,
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               "Inconsistent MMCO state between slices [%d, %d, %d]\n",
               mmco_index, h->mmco_index, i);
        return AVERROR_INVALIDDATA;
    }
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    return 0;
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}

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int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count)
{
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    int i, av_uninit(j);
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    int current_ref_assigned = 0, err = 0;
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    H264Picture *av_uninit(pic);
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    if ((h->avctx->debug & FF_DEBUG_MMCO) && mmco_count == 0)
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        av_log(h->avctx, AV_LOG_DEBUG, "no mmco here\n");
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    for (i = 0; i < mmco_count; i++) {
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        int av_uninit(structure), av_uninit(frame_num);
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        if (h->avctx->debug & FF_DEBUG_MMCO)
            av_log(h->avctx, AV_LOG_DEBUG, "mmco:%d %d %d\n", h->mmco[i].opcode,
                   h->mmco[i].short_pic_num, h->mmco[i].long_arg);
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        if (mmco[i].opcode == MMCO_SHORT2UNUSED ||
            mmco[i].opcode == MMCO_SHORT2LONG) {
573
            frame_num = pic_num_extract(h, mmco[i].short_pic_num, &structure);
574 575 576 577 578
            pic       = find_short(h, frame_num, &j);
            if (!pic) {
                if (mmco[i].opcode != MMCO_SHORT2LONG ||
                    !h->long_ref[mmco[i].long_arg]    ||
                    h->long_ref[mmco[i].long_arg]->frame_num != frame_num) {
579
                    av_log(h->avctx, AV_LOG_ERROR, "mmco: unref short failure\n");
580 581
                    err = AVERROR_INVALIDDATA;
                }
582 583 584 585
                continue;
            }
        }

586
        switch (mmco[i].opcode) {
587
        case MMCO_SHORT2UNUSED:
588 589 590
            if (h->avctx->debug & FF_DEBUG_MMCO)
                av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref short %d count %d\n",
                       h->mmco[i].short_pic_num, h->short_ref_count);
591 592 593 594 595 596 597
            remove_short(h, frame_num, structure ^ PICT_FRAME);
            break;
        case MMCO_SHORT2LONG:
                if (h->long_ref[mmco[i].long_arg] != pic)
                    remove_long(h, mmco[i].long_arg, 0);

                remove_short_at_index(h, j);
598 599 600
                h->long_ref[ mmco[i].long_arg ] = pic;
                if (h->long_ref[mmco[i].long_arg]) {
                    h->long_ref[mmco[i].long_arg]->long_ref = 1;
601 602 603 604
                    h->long_ref_count++;
                }
            break;
        case MMCO_LONG2UNUSED:
605
            j   = pic_num_extract(h, mmco[i].long_arg, &structure);
606 607 608
            pic = h->long_ref[j];
            if (pic) {
                remove_long(h, j, structure ^ PICT_FRAME);
609
            } else if (h->avctx->debug & FF_DEBUG_MMCO)
610
                av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref long failure\n");
611 612 613 614 615 616 617 618 619
            break;
        case MMCO_LONG:
                    // Comment below left from previous code as it is an interresting note.
                    /* First field in pair is in short term list or
                     * at a different long term index.
                     * This is not allowed; see 7.4.3.3, notes 2 and 3.
                     * Report the problem and keep the pair where it is,
                     * and mark this field valid.
                     */
620 621
            if (h->short_ref[0] == h->cur_pic_ptr)
                remove_short_at_index(h, 0);
622

623 624 625 626 627 628 629 630 631
            /* make sure the current picture is not already assigned as a long ref */
            if (h->cur_pic_ptr->long_ref) {
                for (j = 0; j < FF_ARRAY_ELEMS(h->long_ref); j++) {
                    if (h->long_ref[j] == h->cur_pic_ptr)
                        remove_long(h, j, 0);
                }
            }


632
            if (h->long_ref[mmco[i].long_arg] != h->cur_pic_ptr) {
633 634
                remove_long(h, mmco[i].long_arg, 0);

635 636
                h->long_ref[mmco[i].long_arg]           = h->cur_pic_ptr;
                h->long_ref[mmco[i].long_arg]->long_ref = 1;
637 638 639
                h->long_ref_count++;
            }

640
            h->cur_pic_ptr->reference |= h->picture_structure;
641
            current_ref_assigned = 1;
642 643 644 645
            break;
        case MMCO_SET_MAX_LONG:
            assert(mmco[i].long_arg <= 16);
            // just remove the long term which index is greater than new max
646
            for (j = mmco[i].long_arg; j < 16; j++) {
647 648 649 650
                remove_long(h, j, 0);
            }
            break;
        case MMCO_RESET:
651
            while (h->short_ref_count) {
652 653
                remove_short(h, h->short_ref[0]->frame_num, 0);
            }
654
            for (j = 0; j < 16; j++) {
655 656
                remove_long(h, j, 0);
            }
657
            h->poc.frame_num = h->cur_pic_ptr->frame_num = 0;
658
            h->mmco_reset = 1;
659
            h->cur_pic_ptr->mmco_reset = 1;
660 661 662 663 664 665 666 667 668 669 670 671
            break;
        default: assert(0);
        }
    }

    if (!current_ref_assigned) {
        /* Second field of complementary field pair; the first field of
         * which is already referenced. If short referenced, it
         * should be first entry in short_ref. If not, it must exist
         * in long_ref; trying to put it on the short list here is an
         * error in the encoded bit stream (ref: 7.4.3.3, NOTE 2 and 3).
         */
672
        if (h->short_ref_count && h->short_ref[0] == h->cur_pic_ptr) {
673
            /* Just mark the second field valid */
674
            h->cur_pic_ptr->reference = PICT_FRAME;
675 676 677 678 679
        } else if (h->cur_pic_ptr->long_ref) {
            av_log(h->avctx, AV_LOG_ERROR, "illegal short term reference "
                                           "assignment for second field "
                                           "in complementary field pair "
                                           "(first field is long term)\n");
680
            err = AVERROR_INVALIDDATA;
681
        } else {
682 683
            pic = remove_short(h, h->cur_pic_ptr->frame_num, 0);
            if (pic) {
684
                av_log(h->avctx, AV_LOG_ERROR, "illegal short term buffer state detected\n");
685
                err = AVERROR_INVALIDDATA;
686 687
            }

688 689
            if (h->short_ref_count)
                memmove(&h->short_ref[1], &h->short_ref[0],
690
                        h->short_ref_count * sizeof(H264Picture*));
691

692
            h->short_ref[0] = h->cur_pic_ptr;
693
            h->short_ref_count++;
694
            h->cur_pic_ptr->reference |= h->picture_structure;
695 696 697
        }
    }

698
    if (h->long_ref_count + h->short_ref_count -
699
        (h->short_ref[0] == h->cur_pic_ptr) > h->ps.sps->ref_frame_count) {
700 701 702 703 704

        /* We have too many reference frames, probably due to corrupted
         * stream. Need to discard one frame. Prevents overrun of the
         * short_ref and long_ref buffers.
         */
705
        av_log(h->avctx, AV_LOG_ERROR,
706 707
               "number of reference frames (%d+%d) exceeds max (%d; probably "
               "corrupt input), discarding one\n",
708
               h->long_ref_count, h->short_ref_count, h->ps.sps->ref_frame_count);
709
        err = AVERROR_INVALIDDATA;
710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725

        if (h->long_ref_count && !h->short_ref_count) {
            for (i = 0; i < 16; ++i)
                if (h->long_ref[i])
                    break;

            assert(i < 16);
            remove_long(h, i, 0);
        } else {
            pic = h->short_ref[h->short_ref_count - 1];
            remove_short(h, pic->frame_num, 0);
        }
    }

    print_short_term(h);
    print_long_term(h);
726
    return (h->avctx->err_recognition & AV_EF_EXPLODE) ? err : 0;
727 728
}

729 730 731
int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb,
                                   int first_slice)
{
732
    int i, ret;
733 734 735
    MMCO mmco_temp[MAX_MMCO_COUNT], *mmco = first_slice ? h->mmco : mmco_temp;
    int mmco_index = 0;

736
    if (h->nal_unit_type == NAL_IDR_SLICE) { // FIXME fields
737
        skip_bits1(gb); // broken_link
738 739
        if (get_bits1(gb)) {
            mmco[0].opcode   = MMCO_LONG;
740
            mmco[0].long_arg = 0;
741
            mmco_index       = 1;
742
        }
743 744 745 746 747 748
    } else {
        if (get_bits1(gb)) { // adaptive_ref_pic_marking_mode_flag
            for (i = 0; i < MAX_MMCO_COUNT; i++) {
                MMCOOpcode opcode = get_ue_golomb_31(gb);

                mmco[i].opcode = opcode;
749
                if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG) {
750 751 752 753 754
                    mmco[i].short_pic_num =
                        (h->curr_pic_num - get_ue_golomb(gb) - 1) &
                            (h->max_pic_num - 1);
#if 0
                    if (mmco[i].short_pic_num >= h->short_ref_count ||
755
                        !h->short_ref[mmco[i].short_pic_num]) {
756 757 758
                        av_log(s->avctx, AV_LOG_ERROR,
                               "illegal short ref in memory management control "
                               "operation %d\n", mmco);
759
                        return -1;
760 761
                    }
#endif
762
                }
763 764 765 766 767 768
                if (opcode == MMCO_SHORT2LONG || opcode == MMCO_LONG2UNUSED ||
                    opcode == MMCO_LONG || opcode == MMCO_SET_MAX_LONG) {
                    unsigned int long_arg = get_ue_golomb_31(gb);
                    if (long_arg >= 32 ||
                        (long_arg >= 16 && !(opcode == MMCO_SET_MAX_LONG &&
                                             long_arg == 16) &&
769
                         !(opcode == MMCO_LONG2UNUSED && FIELD_PICTURE(h)))) {
770
                        av_log(h->avctx, AV_LOG_ERROR,
771 772
                               "illegal long ref in memory management control "
                               "operation %d\n", opcode);
773 774
                        return -1;
                    }
775
                    mmco[i].long_arg = long_arg;
776 777
                }

778
                if (opcode > (unsigned) MMCO_LONG) {
779
                    av_log(h->avctx, AV_LOG_ERROR,
780 781
                           "illegal memory management control operation %d\n",
                           opcode);
782 783
                    return -1;
                }
784
                if (opcode == MMCO_END)
785 786
                    break;
            }
787 788
            mmco_index = i;
        } else {
789 790
            if (first_slice) {
                ret = ff_generate_sliding_window_mmcos(h, first_slice);
791
                if (ret < 0 && h->avctx->err_recognition & AV_EF_EXPLODE)
792 793
                    return ret;
            }
794
            mmco_index = -1;
795 796 797
        }
    }

798 799 800 801
    if (first_slice && mmco_index != -1) {
        h->mmco_index = mmco_index;
    } else if (!first_slice && mmco_index >= 0 &&
               (mmco_index != h->mmco_index ||
802
                check_opcodes(h->mmco, mmco_temp, mmco_index))) {
803
        av_log(h->avctx, AV_LOG_ERROR,
804 805
               "Inconsistent MMCO state between slices [%d, %d]\n",
               mmco_index, h->mmco_index);
806 807 808
        return AVERROR_INVALIDDATA;
    }

809 810
    return 0;
}