PeerStreamer

/*

 * 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 / MPEG4 part10  reference picture handling.

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

 */

#include "internal.h"

#include "dsputil.h"

#include "avcodec.h"

#include "h264.h"

#include "golomb.h"

//#undef NDEBUG

#include <assert.h>

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

    int i;

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

        if (parity == PICT_BOTTOM_FIELD)

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

        pic->reference = parity;

        pic->linesize[i] *= 2;

    }

    pic->poc= pic->field_poc[parity == PICT_BOTTOM_FIELD];

}

static int split_field_copy(Picture *dest, Picture *src,

                            int parity, int id_add){

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

    if (match) {

        *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(Picture *def, Picture **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){

            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){

            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(Picture **sorted, Picture **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;

}

int ff_h264_fill_default_ref_list(H264Context *h){

    MpegEncContext * const s = &h->s;

    int i, len;

    if(h->slice_type_nos==FF_B_TYPE){

        Picture *sorted[32];

        int cur_poc, list;

        int lens[2];

        if(FIELD_PICTURE)

            cur_poc= s->current_picture_ptr->field_poc[ s->picture_structure == PICT_BOTTOM_FIELD ];

        else

            cur_poc= s->current_picture_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);

            len= build_def_list(h->default_ref_list[list]    , sorted     , len, 0, s->picture_structure);

            len+=build_def_list(h->default_ref_list[list]+len, h->long_ref, 16 , 1, s->picture_structure);

            assert(len<=32);

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

                memset(&h->default_ref_list[list][len], 0, sizeof(Picture)*(h->ref_count[list] - len));

            lens[list]= len;

        }

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

            for(i=0; h->default_ref_list[0][i].data[0] == h->default_ref_list[1][i].data[0] && i<lens[0]; i++);

            if(i == lens[0])

                FFSWAP(Picture, h->default_ref_list[1][0], h->default_ref_list[1][1]);

        }

    }else{

        len = build_def_list(h->default_ref_list[0]    , h->short_ref, h->short_ref_count, 0, s->picture_structure);

        len+= build_def_list(h->default_ref_list[0]+len, h-> long_ref, 16                , 1, s->picture_structure);

        assert(len <= 32);

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

            memset(&h->default_ref_list[0][len], 0, sizeof(Picture)*(h->ref_count[0] - len));

    }

#ifdef TRACE

    for (i=0; i<h->ref_count[0]; i++) {

        tprintf(h->s.avctx, "List0: %s fn:%d 0x%p\n", (h->default_ref_list[0][i].long_ref ? "LT" : "ST"), h->default_ref_list[0][i].pic_id, h->default_ref_list[0][i].data[0]);

    }

    if(h->slice_type_nos==FF_B_TYPE){

        for (i=0; i<h->ref_count[1]; i++) {

            tprintf(h->s.avctx, "List1: %s fn:%d 0x%p\n", (h->default_ref_list[1][i].long_ref ? "LT" : "ST"), h->default_ref_list[1][i].pic_id, h->default_ref_list[1][i].data[0]);

        }

    }

#endif

    return 0;

}

static void print_short_term(H264Context *h);

static void print_long_term(H264Context *h);

/**

 * 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(H264Context *h, int pic_num, int *structure){

    MpegEncContext * const s = &h->s;

    *structure = s->picture_structure;

    if(FIELD_PICTURE){

        if (!(pic_num & 1))

            /* opposite field */

            *structure ^= PICT_FRAME;

        pic_num >>= 1;

    }

    return pic_num;

}

int ff_h264_decode_ref_pic_list_reordering(H264Context *h){

    MpegEncContext * const s = &h->s;

    int list, index, pic_structure;

    print_short_term(h);

    print_long_term(h);

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

        memcpy(h->ref_list[list], h->default_ref_list[list], sizeof(Picture)*h->ref_count[list]);

        if(get_bits1(&s->gb)){

            int pred= h->curr_pic_num;

            for(index=0; ; index++){

                unsigned int reordering_of_pic_nums_idc= get_ue_golomb_31(&s->gb);

                unsigned int pic_id;

                int i;

                Picture *ref = NULL;

                if(reordering_of_pic_nums_idc==3)

                    break;

                if(index >= h->ref_count[list]){

                    av_log(h->s.avctx, AV_LOG_ERROR, "reference count overflow\n");

                    return -1;

                }

                if(reordering_of_pic_nums_idc<3){

                    if(reordering_of_pic_nums_idc<2){

                        const unsigned int abs_diff_pic_num= get_ue_golomb(&s->gb) + 1;

                        int frame_num;

                        if(abs_diff_pic_num > h->max_pic_num){

                            av_log(h->s.avctx, AV_LOG_ERROR, "abs_diff_pic_num overflow\n");

                            return -1;

                        }

                        if(reordering_of_pic_nums_idc == 0) 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;

                        }

                        if(i>=0)

                            ref->pic_id= pred;

                    }else{

                        int long_idx;

                        pic_id= get_ue_golomb(&s->gb); //long_term_pic_idx

                        long_idx= pic_num_extract(h, pic_id, &pic_structure);

                        if(long_idx>31){

                            av_log(h->s.avctx, AV_LOG_ERROR, "long_term_pic_idx overflow\n");

                            return -1;

                        }

                        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;

                        }

                    }

                    if (i < 0) {

                        av_log(h->s.avctx, AV_LOG_ERROR, "reference picture missing during reorder\n");

                        memset(&h->ref_list[list][index], 0, sizeof(Picture)); //FIXME

                    } else {

                        for(i=index; i+1<h->ref_count[list]; i++){

                            if(ref->long_ref == h->ref_list[list][i].long_ref && ref->pic_id == h->ref_list[list][i].pic_id)

                                break;

                        }

                        for(; i > index; i--){

                            h->ref_list[list][i]= h->ref_list[list][i-1];

                        }

                        h->ref_list[list][index]= *ref;

                        if (FIELD_PICTURE){

                            pic_as_field(&h->ref_list[list][index], pic_structure);

                        }

                    }

                }else{

                    av_log(h->s.avctx, AV_LOG_ERROR, "illegal reordering_of_pic_nums_idc\n");

                    return -1;

                }

            }

        }

    }

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

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

            if(!h->ref_list[list][index].data[0]){

                av_log(h->s.avctx, AV_LOG_ERROR, "Missing reference picture\n");

                if(h->default_ref_list[list][0].data[0])

                    h->ref_list[list][index]= h->default_ref_list[list][0];

                else

                    return -1;

            }

        }

    }

    return 0;

}

void ff_h264_fill_mbaff_ref_list(H264Context *h){

    int list, i, j;

    for(list=0; list<2; list++){ //FIXME try list_count

        for(i=0; i<h->ref_count[list]; i++){

            Picture *frame = &h->ref_list[list][i];

            Picture *field = &h->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].field_poc[0];

            field[1] = field[0];

            for(j=0; j<3; j++)

                field[1].data[j] += frame->linesize[j];

            field[1].reference = PICT_BOTTOM_FIELD;

            field[1].poc= field[1].field_poc[1];

            h->luma_weight[16+2*i][list][0] = h->luma_weight[16+2*i+1][list][0] = h->luma_weight[i][list][0];

            h->luma_weight[16+2*i][list][1] = h->luma_weight[16+2*i+1][list][1] = h->luma_weight[i][list][1];

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

                h->chroma_weight[16+2*i][list][j][0] = h->chroma_weight[16+2*i+1][list][j][0] = h->chroma_weight[i][list][j][0];

                h->chroma_weight[16+2*i][list][j][1] = h->chroma_weight[16+2*i+1][list][j][1] = h->chroma_weight[i][list][j][1];

            }

        }

    }

}

/**

 * 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, Picture *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 Picture 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 Picture * find_short(H264Context *h, int frame_num, int *idx){

    MpegEncContext * const s = &h->s;

    int i;

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

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

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

            av_log(h->s.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(Picture*));

}

/**

 *

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

 */

static Picture * remove_short(H264Context *h, int frame_num, int ref_mask){

    MpegEncContext * const s = &h->s;

    Picture *pic;

    int i;

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

        av_log(h->s.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 Picture * remove_long(H264Context *h, int i, int ref_mask){

    Picture *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);

    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;

}

/**

 * print short term list

 */

static void print_short_term(H264Context *h) {

    uint32_t i;

    if(h->s.avctx->debug&FF_DEBUG_MMCO) {

        av_log(h->s.avctx, AV_LOG_DEBUG, "short term list:\n");

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

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

            av_log(h->s.avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->data[0]);

        }

    }

}

/**

 * print long term list

 */

static void print_long_term(H264Context *h) {

    uint32_t i;

    if(h->s.avctx->debug&FF_DEBUG_MMCO) {

        av_log(h->s.avctx, AV_LOG_DEBUG, "long term list:\n");

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

            Picture *pic= h->long_ref[i];

            if (pic) {

                av_log(h->s.avctx, AV_LOG_DEBUG, "%d fn:%d poc:%d %p\n", i, pic->frame_num, pic->poc, pic->data[0]);

            }

        }

    }

}

void ff_generate_sliding_window_mmcos(H264Context *h) {

    MpegEncContext * const s = &h->s;

    assert(h->long_ref_count + h->short_ref_count <= h->sps.ref_frame_count);

    h->mmco_index= 0;

    if(h->short_ref_count && h->long_ref_count + h->short_ref_count == h->sps.ref_frame_count &&

            !(FIELD_PICTURE && !s->first_field && s->current_picture_ptr->reference)) {

        h->mmco[0].opcode= MMCO_SHORT2UNUSED;

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

        h->mmco_index= 1;

        if (FIELD_PICTURE) {

            h->mmco[0].short_pic_num *= 2;

            h->mmco[1].opcode= MMCO_SHORT2UNUSED;

            h->mmco[1].short_pic_num= h->mmco[0].short_pic_num + 1;

            h->mmco_index= 2;

        }

    }

}

int ff_h264_execute_ref_pic_marking(H264Context *h, MMCO *mmco, int mmco_count){

    MpegEncContext * const s = &h->s;

    int i, av_uninit(j);

    int current_ref_assigned=0;

    Picture *av_uninit(pic);

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

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

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

        int av_uninit(structure), av_uninit(frame_num);

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

            av_log(h->s.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->s.avctx, AV_LOG_ERROR, "mmco: unref short failure\n");

                continue;

            }

        }

        switch(mmco[i].opcode){

        case MMCO_SHORT2UNUSED:

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

                av_log(h->s.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(s->avctx->debug&FF_DEBUG_MMCO)

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

            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.

                     */

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

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

                h->long_ref[ mmco[i].long_arg ]= s->current_picture_ptr;

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

                h->long_ref_count++;

            }

            s->current_picture_ptr->reference |= s->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);

            }

            s->current_picture_ptr->poc=

            s->current_picture_ptr->field_poc[0]=

            s->current_picture_ptr->field_poc[1]=

            h->poc_lsb=

            h->poc_msb=

            h->frame_num=

            s->current_picture_ptr->frame_num= 0;

            s->current_picture_ptr->mmco_reset=1;

            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] == s->current_picture_ptr) {

            /* Just mark the second field valid */

            s->current_picture_ptr->reference = PICT_FRAME;

        } else if (s->current_picture_ptr->long_ref) {

            av_log(h->s.avctx, AV_LOG_ERROR, "illegal short term reference "

                                             "assignment for second field "

                                             "in complementary field pair "

                                             "(first field is long term)\n");

        } else {

            pic= remove_short(h, s->current_picture_ptr->frame_num, 0);

            if(pic){

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

            }

            if(h->short_ref_count)

                memmove(&h->short_ref[1], &h->short_ref[0], h->short_ref_count*sizeof(Picture*));

            h->short_ref[0]= s->current_picture_ptr;

            h->short_ref_count++;

            s->current_picture_ptr->reference |= s->picture_structure;

        }

    }

    if (h->long_ref_count + h->short_ref_count > h->sps.ref_frame_count){

        /* 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->s.avctx, AV_LOG_ERROR,

               "number of reference frames exceeds max (probably "

               "corrupt input), discarding one\n");

        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);

    return 0;

}

int ff_h264_decode_ref_pic_marking(H264Context *h, GetBitContext *gb){

    MpegEncContext * const s = &h->s;

    int i;

    h->mmco_index= 0;

    if(h->nal_unit_type == NAL_IDR_SLICE){ //FIXME fields

        s->broken_link= get_bits1(gb) -1;

        if(get_bits1(gb)){

            h->mmco[0].opcode= MMCO_LONG;

            h->mmco[0].long_arg= 0;

            h->mmco_index= 1;

        }

    }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);

                h->mmco[i].opcode= opcode;

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

                    h->mmco[i].short_pic_num= (h->curr_pic_num - get_ue_golomb(gb) - 1) & (h->max_pic_num - 1);

/*                    if(h->mmco[i].short_pic_num >= h->short_ref_count || h->short_ref[ h->mmco[i].short_pic_num ] == NULL){

                        av_log(s->avctx, AV_LOG_ERROR, "illegal short ref in memory management control operation %d\n", mmco);

                        return -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_LONG2UNUSED && FIELD_PICTURE))){

                        av_log(h->s.avctx, AV_LOG_ERROR, "illegal long ref in memory management control operation %d\n", opcode);

                        return -1;

                    }

                    h->mmco[i].long_arg= long_arg;

                }

                if(opcode > (unsigned)MMCO_LONG){

                    av_log(h->s.avctx, AV_LOG_ERROR, "illegal memory management control operation %d\n", opcode);

                    return -1;

                }

                if(opcode == MMCO_END)

                    break;

            }

            h->mmco_index= i;

        }else{

            ff_generate_sliding_window_mmcos(h);

        }

    }

    return 0;

}