/*
  * H.26L/H.264/AVC/JVT/14496-10/... reference picture handling
  * Copyright (c) 2003 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

  * H.264 / AVC / MPEG-4 part10  reference picture handling.

  * @author Michael Niedermayer <michaelni@gmx.at>
  */
 

 #include <inttypes.h>
 

 #include "libavutil/avassert.h"

 #include "internal.h"
 #include "avcodec.h"

 #include "h264.h"

 #include "h264dec.h"

 #include "golomb.h"

 #include "mpegutils.h"

 
 #include <assert.h>
 

 static void pic_as_field(H264Ref *pic, const int parity)
 {

     int i;

     for (i = 0; i < FF_ARRAY_ELEMS(pic->data); ++i) {

         if (parity == PICT_BOTTOM_FIELD)

             pic->data[i]   += pic->linesize[i];

         pic->reference      = parity;

         pic->linesize[i] *= 2;

     }

     pic->poc = pic->parent->field_poc[parity == PICT_BOTTOM_FIELD];
 }
 
 static void ref_from_h264pic(H264Ref *dst, H264Picture *src)
 {

     memcpy(dst->data,     src->f->data,     sizeof(dst->data));
     memcpy(dst->linesize, src->f->linesize, sizeof(dst->linesize));

     dst->reference = src->reference;
     dst->poc       = src->poc;
     dst->pic_id    = src->pic_id;
     dst->parent = src;

 }
 

 static int split_field_copy(H264Ref *dest, H264Picture *src, int parity, int id_add)

 {

     int match = !!(src->reference & parity);

 
     if (match) {

         ref_from_h264pic(dest, src);

         if (parity != PICT_FRAME) {

             pic_as_field(dest, parity);
             dest->pic_id *= 2;
             dest->pic_id += id_add;
         }
     }
 
     return match;
 }
 

 static int build_def_list(H264Ref *def, int def_len,

                           H264Picture * const *in, int len, int is_long, int sel)

 {
     int  i[2] = { 0 };
     int index = 0;

     while (i[0] < len || i[1] < len) {

         while (i[0] < len && !(in[i[0]] && (in[i[0]]->reference & sel)))

             i[0]++;

         while (i[1] < len && !(in[i[1]] && (in[i[1]]->reference & (sel ^ 3))))

             i[1]++;

         if (i[0] < len) {

             av_assert0(index < def_len);

             in[i[0]]->pic_id = is_long ? i[0] : in[i[0]]->frame_num;
             split_field_copy(&def[index++], in[i[0]++], sel, 1);

         }

         if (i[1] < len) {

             av_assert0(index < def_len);

             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);

         }
     }
 
     return index;
 }
 

 static int add_sorted(H264Picture **sorted, H264Picture * const *src,
                       int len, int limit, int dir)

 {

     int i, best_poc;

     int out_i = 0;

     for (;;) {
         best_poc = dir ? INT_MIN : INT_MAX;

         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];

             }
         }

         if (best_poc == (dir ? INT_MIN : INT_MAX))

             break;

         limit = sorted[out_i++]->poc - dir;

     }
     return out_i;
 }
 

 static int mismatches_ref(const H264Context *h, const H264Picture *pic)

 {

     const AVFrame *f = pic->f;

     return (h->cur_pic_ptr->f->width  != f->width ||
             h->cur_pic_ptr->f->height != f->height ||
             h->cur_pic_ptr->f->format != f->format);
 }
 

 static void h264_initialise_ref_list(H264Context *h, H264SliceContext *sl)

 {

     int i, len;

     int j;

     if (sl->slice_type_nos == AV_PICTURE_TYPE_B) {

         H264Picture *sorted[32];

         int cur_poc, list;
         int lens[2];
 

         if (FIELD_PICTURE(h))

             cur_poc = h->cur_pic_ptr->field_poc[h->picture_structure == PICT_BOTTOM_FIELD];

         else

             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);

             av_assert0(len <= 32);

             len  = build_def_list(sl->ref_list[list], FF_ARRAY_ELEMS(sl->ref_list[0]),

                                   sorted, len, 0, h->picture_structure);

             len += build_def_list(sl->ref_list[list] + len,
                                   FF_ARRAY_ELEMS(sl->ref_list[0]) - len,

                                   h->long_ref, 16, 1, h->picture_structure);

             av_assert0(len <= 32);

             if (len < sl->ref_count[list])

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

             lens[list] = len;

         }
 

         if (lens[0] == lens[1] && lens[1] > 1) {

             for (i = 0; i < lens[0] &&

                         sl->ref_list[0][i].parent->f->buf[0]->buffer ==
                         sl->ref_list[1][i].parent->f->buf[0]->buffer; i++);

             if (i == lens[0]) {

                 FFSWAP(H264Ref, sl->ref_list[1][0], sl->ref_list[1][1]);

             }

         }

     } else {

         len  = build_def_list(sl->ref_list[0], FF_ARRAY_ELEMS(sl->ref_list[0]),

                               h->short_ref, h->short_ref_count, 0, h->picture_structure);

         len += build_def_list(sl->ref_list[0] + len,
                               FF_ARRAY_ELEMS(sl->ref_list[0]) - len,

                               h-> long_ref, 16, 1, h->picture_structure);

         av_assert0(len <= 32);

         if (len < sl->ref_count[0])

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

     }

 #ifdef TRACE
     for (i = 0; i < sl->ref_count[0]; i++) {
         ff_tlog(h->avctx, "List0: %s fn:%d 0x%p\n",
                 (sl->ref_list[0][i].parent ? (sl->ref_list[0][i].parent->long_ref ? "LT" : "ST") : "??"),
                 sl->ref_list[0][i].pic_id,
                 sl->ref_list[0][i].data[0]);
     }
     if (sl->slice_type_nos == AV_PICTURE_TYPE_B) {
         for (i = 0; i < sl->ref_count[1]; i++) {
             ff_tlog(h->avctx, "List1: %s fn:%d 0x%p\n",
                     (sl->ref_list[1][i].parent ? (sl->ref_list[1][i].parent->long_ref ? "LT" : "ST") : "??"),
                     sl->ref_list[1][i].pic_id,
                     sl->ref_list[1][i].data[0]);
         }
     }
 #endif

 
     for (j = 0; j<1+(sl->slice_type_nos == AV_PICTURE_TYPE_B); j++) {
         for (i = 0; i < sl->ref_count[j]; i++) {

             if (sl->ref_list[j][i].parent) {
                 if (mismatches_ref(h, sl->ref_list[j][i].parent)) {

                     av_log(h->avctx, AV_LOG_ERROR, "Discarding mismatching reference\n");

                     memset(&sl->ref_list[j][i], 0, sizeof(sl->ref_list[j][i]));

                 }
             }
         }
     }

     for (i = 0; i < sl->list_count; i++)
         h->default_ref[i] = sl->ref_list[i][0];

 }
 

 /**
  * print short term list
  */

 static void print_short_term(const H264Context *h)

 {
     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
  */

 static void print_long_term(const H264Context *h)

 {
     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]);
             }
         }
     }
 }

 
 /**
  * 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
  */

 static int pic_num_extract(const H264Context *h, int pic_num, int *structure)

 {

     *structure = h->picture_structure;

     if (FIELD_PICTURE(h)) {

         if (!(pic_num & 1))
             /* opposite field */
             *structure ^= PICT_FRAME;
         pic_num >>= 1;
     }
 
     return pic_num;
 }
 

 static void h264_fill_mbaff_ref_list(H264SliceContext *sl)
 {
     int list, i, j;
     for (list = 0; list < sl->list_count; list++) {
         for (i = 0; i < sl->ref_count[list]; i++) {
             H264Ref *frame = &sl->ref_list[list][i];
             H264Ref *field = &sl->ref_list[list][16 + 2 * i];
 
             field[0] = *frame;
 
             for (j = 0; j < 3; j++)
                 field[0].linesize[j] <<= 1;
             field[0].reference = PICT_TOP_FIELD;
             field[0].poc       = field[0].parent->field_poc[0];
 
             field[1] = field[0];
 
             for (j = 0; j < 3; j++)
                 field[1].data[j] += frame->parent->f->linesize[j];
             field[1].reference = PICT_BOTTOM_FIELD;
             field[1].poc       = field[1].parent->field_poc[1];
         }
     }
 }
 

 int ff_h264_build_ref_list(H264Context *h, H264SliceContext *sl)

 {

     int list, index, pic_structure;

 
     print_short_term(h);
     print_long_term(h);
 

     h264_initialise_ref_list(h, sl);

     for (list = 0; list < sl->list_count; list++) {

         int pred = sl->curr_pic_num;

 
         for (index = 0; index < sl->nb_ref_modifications[list]; index++) {
             unsigned int modification_of_pic_nums_idc = sl->ref_modifications[list][index].op;
             unsigned int                          val = sl->ref_modifications[list][index].val;
             unsigned int pic_id;
             int i;
             H264Picture *ref = NULL;
 
             switch (modification_of_pic_nums_idc) {
             case 0:
             case 1: {
                 const unsigned int abs_diff_pic_num = val + 1;
                 int frame_num;
 

                 if (abs_diff_pic_num > sl->max_pic_num) {

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

                 }
 

                 if (modification_of_pic_nums_idc == 0)
                     pred -= abs_diff_pic_num;
                 else
                     pred += abs_diff_pic_num;

                 pred &= sl->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;

                 }

                 if (i >= 0)
                     ref->pic_id = pred;
                 break;
             }
             case 2: {
                 int long_idx;
                 pic_id = val; // long_term_pic_idx
 
                 long_idx = pic_num_extract(h, pic_id, &pic_structure);
 

                 if (long_idx > 31U) {

                     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;

                 } else {

                     i = -1;
                 }
                 break;
             }

             default:

                 av_assert0(0);

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

                 }
             }
         }
     }

     for (list = 0; list < sl->list_count; list++) {
         for (index = 0; index < sl->ref_count[list]; index++) {

             if (   !sl->ref_list[list][index].parent

                 || (!FIELD_PICTURE(h) && (sl->ref_list[list][index].reference&3) != 3)) {

                 int i;

                 av_log(h->avctx, AV_LOG_ERROR, "Missing reference picture, default is %d\n", h->default_ref[list].poc);

                 for (i = 0; i < FF_ARRAY_ELEMS(h->last_pocs); i++)

                     h->last_pocs[i] = INT_MIN;

                 if (h->default_ref[list].parent
                     && !(!FIELD_PICTURE(h) && (h->default_ref[list].reference&3) != 3))
                     sl->ref_list[list][index] = h->default_ref[list];
                 else
                     return -1;

             }

             av_assert0(av_buffer_get_ref_count(sl->ref_list[list][index].parent->f->buf[0]) > 0);

         }
     }
 

     if (FRAME_MBAFF(h))
         h264_fill_mbaff_ref_list(sl);

     return 0;

 }
 

 int ff_h264_decode_ref_pic_list_reordering(H264SliceContext *sl, void *logctx)

 {
     int list, index;
 
     sl->nb_ref_modifications[0] = 0;
     sl->nb_ref_modifications[1] = 0;
 
     for (list = 0; list < sl->list_count; list++) {
         if (!get_bits1(&sl->gb))    // ref_pic_list_modification_flag_l[01]
             continue;
 
         for (index = 0; ; index++) {
             unsigned int op = get_ue_golomb_31(&sl->gb);
 
             if (op == 3)
                 break;
 
             if (index >= sl->ref_count[list]) {

                 av_log(logctx, AV_LOG_ERROR, "reference count overflow\n");

                 return AVERROR_INVALIDDATA;
             } else if (op > 2) {

                 av_log(logctx, AV_LOG_ERROR,

                        "illegal modification_of_pic_nums_idc %u\n",
                        op);
                 return AVERROR_INVALIDDATA;
             }

             sl->ref_modifications[list][index].val = get_ue_golomb_long(&sl->gb);

             sl->ref_modifications[list][index].op  = op;
             sl->nb_ref_modifications[list]++;
         }
     }
 
     return 0;
 }
 

 /**
  * 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
  */

 static inline int unreference_pic(H264Context *h, H264Picture *pic, int refmask)

 {

     int i;

     if (pic->reference &= refmask) {

         return 0;
     } else {
         for(i = 0; h->delayed_pic[i]; i++)
             if(pic == h->delayed_pic[i]){

                 pic->reference = DELAYED_PIC_REF;

                 break;
             }
         return 1;
     }
 }
 
 /**

  * Find a H264Picture in the short term reference list by frame number.

  * @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
  */

 static H264Picture *find_short(H264Context *h, int frame_num, int *idx)

 {

     int i;
 

     for (i = 0; i < h->short_ref_count; i++) {

         H264Picture *pic = h->short_ref[i];

         if (h->avctx->debug & FF_DEBUG_MMCO)

             av_log(h->avctx, AV_LOG_DEBUG, "%d %d %p\n", i, pic->frame_num, pic);

         if (pic->frame_num == frame_num) {

             *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.
  */

 static void remove_short_at_index(H264Context *h, int i)
 {

     assert(i >= 0 && i < h->short_ref_count);

     h->short_ref[i] = NULL;

     if (--h->short_ref_count)

         memmove(&h->short_ref[i], &h->short_ref[i + 1],

                 (h->short_ref_count - i) * sizeof(H264Picture*));

 }
 
 /**
  * @return the removed picture or NULL if an error occurs
  */

 static H264Picture *remove_short(H264Context *h, int frame_num, int ref_mask)

 {

     H264Picture *pic;

     int i;
 

     if (h->avctx->debug & FF_DEBUG_MMCO)

         av_log(h->avctx, AV_LOG_DEBUG, "remove short %d count %d\n", frame_num, h->short_ref_count);

 
     pic = find_short(h, frame_num, &i);

     if (pic) {
         if (unreference_pic(h, pic, ref_mask))
             remove_short_at_index(h, i);

     }
 
     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
  */

 static H264Picture *remove_long(H264Context *h, int i, int ref_mask)

 {

     H264Picture *pic;

     pic = h->long_ref[i];
     if (pic) {
         if (unreference_pic(h, pic, ref_mask)) {

             assert(h->long_ref[i]->long_ref == 1);

             h->long_ref[i]->long_ref = 0;
             h->long_ref[i]           = NULL;

             h->long_ref_count--;
         }
     }
 
     return pic;
 }
 

 void ff_h264_remove_all_refs(H264Context *h)
 {

     int i;
 

     for (i = 0; i < 16; i++) {

         remove_long(h, i, 0);
     }

     assert(h->long_ref_count == 0);

     if (h->short_ref_count && !h->last_pic_for_ec.f->data[0]) {

         ff_h264_unref_picture(h, &h->last_pic_for_ec);

         ff_h264_ref_picture(h, &h->last_pic_for_ec, h->short_ref[0]);

     }

     for (i = 0; i < h->short_ref_count; i++) {

         unreference_pic(h, h->short_ref[i], 0);

         h->short_ref[i] = NULL;

     }

     h->short_ref_count = 0;

     memset(h->default_ref, 0, sizeof(h->default_ref));

 }
 

 static void generate_sliding_window_mmcos(H264Context *h)

 {

     MMCO *mmco = h->mmco;
     int nb_mmco = 0;

 
     if (h->short_ref_count &&

         h->long_ref_count + h->short_ref_count >= h->ps.sps->ref_frame_count &&

         !(FIELD_PICTURE(h) && !h->first_field && h->cur_pic_ptr->reference)) {

         mmco[0].opcode        = MMCO_SHORT2UNUSED;

         mmco[0].short_pic_num = h->short_ref[h->short_ref_count - 1]->frame_num;

         nb_mmco               = 1;

         if (FIELD_PICTURE(h)) {

             mmco[0].short_pic_num *= 2;

             mmco[1].opcode         = MMCO_SHORT2UNUSED;
             mmco[1].short_pic_num  = mmco[0].short_pic_num + 1;

             nb_mmco                = 2;

         }
     }

     h->nb_mmco = nb_mmco;

 }
 

 int ff_h264_execute_ref_pic_marking(H264Context *h)

 {

     MMCO *mmco = h->mmco;
     int mmco_count;

     int i, av_uninit(j);

     int pps_ref_count[2] = {0};

     int current_ref_assigned = 0, err = 0;

     H264Picture *av_uninit(pic);

     if (!h->ps.sps) {
         av_log(h->avctx, AV_LOG_ERROR, "SPS is unset\n");
         err = AVERROR_INVALIDDATA;
         goto out;
     }
 

     if (!h->explicit_ref_marking)
         generate_sliding_window_mmcos(h);
     mmco_count = h->nb_mmco;
 

     if ((h->avctx->debug & FF_DEBUG_MMCO) && mmco_count == 0)

         av_log(h->avctx, AV_LOG_DEBUG, "no mmco here\n");

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

         int av_uninit(structure), av_uninit(frame_num);

         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);

         if (mmco[i].opcode == MMCO_SHORT2UNUSED ||
             mmco[i].opcode == MMCO_SHORT2LONG) {

             frame_num = pic_num_extract(h, mmco[i].short_pic_num, &structure);

             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) {

                     av_log(h->avctx, h->short_ref_count ? AV_LOG_ERROR : AV_LOG_DEBUG, "mmco: unref short failure\n");

                     err = AVERROR_INVALIDDATA;
                 }

                 continue;
             }
         }
 

         switch (mmco[i].opcode) {

         case MMCO_SHORT2UNUSED:

             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);

             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);

                 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;

                     h->long_ref_count++;
                 }
             break;
         case MMCO_LONG2UNUSED:

             j   = pic_num_extract(h, mmco[i].long_arg, &structure);

             pic = h->long_ref[j];
             if (pic) {
                 remove_long(h, j, structure ^ PICT_FRAME);

             } else if (h->avctx->debug & FF_DEBUG_MMCO)

                 av_log(h->avctx, AV_LOG_DEBUG, "mmco: unref long failure\n");

             break;
         case MMCO_LONG:

                     // Comment below left from previous code as it is an interesting 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.
                      */

             if (h->short_ref[0] == h->cur_pic_ptr) {
                 av_log(h->avctx, AV_LOG_ERROR, "mmco: cannot assign current picture to short and long at the same time\n");

                 remove_short_at_index(h, 0);

             }

             /* 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) {
                         if (j != mmco[i].long_arg)

                             av_log(h->avctx, AV_LOG_ERROR, "mmco: cannot assign current picture to 2 long term references\n");

                         remove_long(h, j, 0);

                     }
                 }

             }
 

             if (h->long_ref[mmco[i].long_arg] != h->cur_pic_ptr) {

                 av_assert0(!h->cur_pic_ptr->long_ref);

                 remove_long(h, mmco[i].long_arg, 0);
 

                 h->long_ref[mmco[i].long_arg]           = h->cur_pic_ptr;
                 h->long_ref[mmco[i].long_arg]->long_ref = 1;

                 h->long_ref_count++;
             }
 

             h->cur_pic_ptr->reference |= h->picture_structure;

             current_ref_assigned = 1;

             break;
         case MMCO_SET_MAX_LONG:
             assert(mmco[i].long_arg <= 16);
             // just remove the long term which index is greater than new max

             for (j = mmco[i].long_arg; j < 16; j++) {

                 remove_long(h, j, 0);
             }
             break;
         case MMCO_RESET:

             while (h->short_ref_count) {

                 remove_short(h, h->short_ref[0]->frame_num, 0);
             }

             for (j = 0; j < 16; j++) {

                 remove_long(h, j, 0);
             }

             h->poc.frame_num = h->cur_pic_ptr->frame_num = 0;

             h->mmco_reset = 1;

             h->cur_pic_ptr->mmco_reset = 1;

             for (j = 0; j < MAX_DELAYED_PIC_COUNT; j++)
                 h->last_pocs[j] = INT_MIN;

             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).
          */

         if (h->short_ref_count && h->short_ref[0] == h->cur_pic_ptr) {

             /* Just mark the second field valid */

             h->cur_pic_ptr->reference |= h->picture_structure;

         } 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");

             err = AVERROR_INVALIDDATA;

         } else {

             pic = remove_short(h, h->cur_pic_ptr->frame_num, 0);
             if (pic) {

                 av_log(h->avctx, AV_LOG_ERROR, "illegal short term buffer state detected\n");

                 err = AVERROR_INVALIDDATA;

             }
 

             if (h->short_ref_count)
                 memmove(&h->short_ref[1], &h->short_ref[0],

                         h->short_ref_count * sizeof(H264Picture*));

             h->short_ref[0] = h->cur_pic_ptr;

             h->short_ref_count++;

             h->cur_pic_ptr->reference |= h->picture_structure;

         }
     }
 

     if (h->long_ref_count + h->short_ref_count > FFMAX(h->ps.sps->ref_frame_count, 1)) {

 
         /* 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.
          */

         av_log(h->avctx, AV_LOG_ERROR,

                "number of reference frames (%d+%d) exceeds max (%d; probably "
                "corrupt input), discarding one\n",

                h->long_ref_count, h->short_ref_count, h->ps.sps->ref_frame_count);

         err = AVERROR_INVALIDDATA;

 
         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);
         }
     }
 

     for (i = 0; i<h->short_ref_count; i++) {
         pic = h->short_ref[i];
         if (pic->invalid_gap) {

             int d = av_mod_uintp2(h->cur_pic_ptr->frame_num - pic->frame_num, h->ps.sps->log2_max_frame_num);
             if (d > h->ps.sps->ref_frame_count)

                 remove_short(h, pic->frame_num, 0);
         }
     }
 

     print_short_term(h);
     print_long_term(h);

     for (i = 0; i < FF_ARRAY_ELEMS(h->ps.pps_list); i++) {
         if (h->ps.pps_list[i]) {
             const PPS *pps = (const PPS *)h->ps.pps_list[i]->data;
             pps_ref_count[0] = FFMAX(pps_ref_count[0], pps->ref_count[0]);
             pps_ref_count[1] = FFMAX(pps_ref_count[1], pps->ref_count[1]);

         }

     }

     if (   err >= 0
         && h->long_ref_count==0

         && (   h->short_ref_count<=2
             || pps_ref_count[0] <= 1 + (h->picture_structure != PICT_FRAME) && pps_ref_count[1] <= 1)

         && pps_ref_count[0]<=2 + (h->picture_structure != PICT_FRAME) + (2*!h->has_recovery_point)

         && h->cur_pic_ptr->f->pict_type == AV_PICTURE_TYPE_I){

         h->cur_pic_ptr->recovered |= 1;

         if(!h->avctx->has_b_frames)

             h->frame_recovered |= FRAME_RECOVERED_SEI;

     }
 

 out:

     return (h->avctx->err_recognition & AV_EF_EXPLODE) ? err : 0;

 }
 

 int ff_h264_decode_ref_pic_marking(H264SliceContext *sl, GetBitContext *gb,
                                    const H2645NAL *nal, void *logctx)

 {

     int i;

     MMCO *mmco = sl->mmco;

     int nb_mmco = 0;

     if (nal->type == H264_NAL_IDR_SLICE) { // FIXME fields

         skip_bits1(gb); // broken_link

         if (get_bits1(gb)) {
             mmco[0].opcode   = MMCO_LONG;

             mmco[0].long_arg = 0;

             nb_mmco          = 1;

         }

         sl->explicit_ref_marking = 1;

     } else {

         sl->explicit_ref_marking = get_bits1(gb);
         if (sl->explicit_ref_marking) {

             for (i = 0; i < MAX_MMCO_COUNT; i++) {
                 MMCOOpcode opcode = get_ue_golomb_31(gb);
 
                 mmco[i].opcode = opcode;

                 if (opcode == MMCO_SHORT2UNUSED || opcode == MMCO_SHORT2LONG) {

                     mmco[i].short_pic_num =

                         (sl->curr_pic_num - get_ue_golomb_long(gb) - 1) &

                             (sl->max_pic_num - 1);

                 }

                 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) &&

                          !(opcode == MMCO_LONG2UNUSED && FIELD_PICTURE(sl)))) {
                         av_log(logctx, AV_LOG_ERROR,

                                "illegal long ref in memory management control "
                                "operation %d\n", opcode);

                         return -1;
                     }

                     mmco[i].long_arg = long_arg;

                 }
 

                 if (opcode > (unsigned) MMCO_LONG) {

                     av_log(logctx, AV_LOG_ERROR,

                            "illegal memory management control operation %d\n",
                            opcode);

                     return -1;
                 }

                 if (opcode == MMCO_END)

                     break;
             }

             nb_mmco = i;

         }
     }
 

     sl->nb_mmco = nb_mmco;

     return 0;
 }