if ((dpb.fs_ref[i]->is_reference & 1) && (!(dpb.fs_ref[i]->is_long_term & 1)))
      {
        if (dpb.fs_ref[i]->top_field->pic_num == picNumX)
        {
          dpb.fs_ref[i]->top_field->used_for_reference = 0;
          dpb.fs_ref[i]->is_reference &= 2;
          if (dpb.fs_ref[i]->is_used == 3)
          {
            dpb.fs_ref[i]->frame->used_for_reference = 0;
          }
          return;
        }
      }
      if ((dpb.fs_ref[i]->is_reference & 2) && (!(dpb.fs_ref[i]->is_long_term & 2)))
      {
        if (dpb.fs_ref[i]->bottom_field->pic_num == picNumX)
        {
          dpb.fs_ref[i]->bottom_field->used_for_reference = 0;
          dpb.fs_ref[i]->is_reference &= 1;
          if (dpb.fs_ref[i]->is_used == 3)
          {
            dpb.fs_ref[i]->frame->used_for_reference = 0;
          }
          return;
        }
      }
    }
  }
}


/*!
 ************************************************************************
 * \brief
 *    Adaptive Memory Management: Mark long term picture unused
 ************************************************************************
 */
static void mm_unmark_long_term_for_reference(StorablePicture *p, int long_term_pic_num)
{
  unsigned i;
  for (i=0; i<dpb.ltref_frames_in_buffer; i++)
  {
    if (p->structure == FRAME)
    {
      if ((dpb.fs_ltref[i]->is_reference==3) && (dpb.fs_ltref[i]->is_long_term==3))
      {
        if (dpb.fs_ltref[i]->frame->long_term_pic_num == long_term_pic_num)
        {
          unmark_for_long_term_reference(dpb.fs_ltref[i]);
        }
      }
    }
    else
    {
      if ((dpb.fs_ltref[i]->is_reference & 1) && ((dpb.fs_ltref[i]->is_long_term & 1)))
      {
        if (dpb.fs_ltref[i]->top_field->long_term_pic_num == long_term_pic_num)
        {
          dpb.fs_ltref[i]->top_field->used_for_reference = 0;
          dpb.fs_ltref[i]->top_field->is_long_term = 0;
          dpb.fs_ltref[i]->is_reference &= 2;
          dpb.fs_ltref[i]->is_long_term &= 2;
          if (dpb.fs_ltref[i]->is_used == 3)
          {
            dpb.fs_ltref[i]->frame->used_for_reference = 0;
            dpb.fs_ltref[i]->frame->is_long_term = 0;
          }
          return;
        }
      }
      if ((dpb.fs_ltref[i]->is_reference & 2) && ((dpb.fs_ltref[i]->is_long_term & 2)))
      {
        if (dpb.fs_ltref[i]->bottom_field->long_term_pic_num == long_term_pic_num)
        {
          dpb.fs_ltref[i]->bottom_field->used_for_reference = 0;
          dpb.fs_ltref[i]->bottom_field->is_long_term = 0;
          dpb.fs_ltref[i]->is_reference &= 1;
          dpb.fs_ltref[i]->is_long_term &= 1;
          if (dpb.fs_ltref[i]->is_used == 3)
          {
            dpb.fs_ltref[i]->frame->used_for_reference = 0;
            dpb.fs_ltref[i]->frame->is_long_term = 0;
          }
          return;
        }
      }
    }
  }
}


/*!
 ************************************************************************
 * \brief
 *    Mark a long-term reference frame or complementary field pair unused for referemce
 ************************************************************************
 */
static void unmark_long_term_frame_for_reference_by_frame_idx(int long_term_frame_idx)
{
  unsigned i;
  for(i=0; i<dpb.ref_frames_in_buffer; i++)
  {
    if (dpb.fs_ref[i]->long_term_frame_idx == long_term_frame_idx)
      unmark_for_long_term_reference(dpb.fs_ltref[i]);
  }
}

/*!
 ************************************************************************
 * \brief
 *    Mark a long-term reference field unused for referemce only if it's not
 *    the complementary field of the picture indicated by picNumX
 ************************************************************************
 */
static void unmark_long_term_field_for_reference_by_frame_idx(StorablePicture *p, int long_term_frame_idx, int picNumX)
{
  unsigned i;
  for(i=0; i<dpb.ref_frames_in_buffer; i++)
  {
    if (dpb.fs_ref[i]->long_term_frame_idx == long_term_frame_idx)
    {
      if (p->structure == TOP_FIELD)
      {
        if (!(dpb.fs_ref[i]->is_reference == 3))
        {
          unmark_for_long_term_reference(dpb.fs_ltref[i]);
        }
        else
        {
          if (!(dpb.fs_ref[i]->is_long_term == 2))
          {
            unmark_for_long_term_reference(dpb.fs_ltref[i]);
          }
          else
          {
            if (!(dpb.fs_ref[i]->top_field->pic_num==picNumX))
              unmark_for_long_term_reference(dpb.fs_ltref[i]);
          }
        }
      }
      if (p->structure == BOTTOM_FIELD)
      {
        if (!(dpb.fs_ref[i]->is_reference == 3))
        {
          unmark_for_long_term_reference(dpb.fs_ltref[i]);
        }
        else
        {
          if (!(dpb.fs_ref[i]->is_long_term == 1))
          {
            unmark_for_long_term_reference(dpb.fs_ltref[i]);
          }
          else
          {
            if (!(dpb.fs_ref[i]->bottom_field->pic_num==picNumX))
            {
              unmark_for_long_term_reference(dpb.fs_ltref[i]);
            }
          }
        }
      }
    }
  }
}


/*!
 ************************************************************************
 * \brief
 *    mark a picture as long-term reference
 ************************************************************************
 */
static void mark_pic_long_term(StorablePicture* p, int long_term_frame_idx, int picNumX)
{
  unsigned i;
  int add_top, add_bottom;

  if (p->structure == FRAME)
  {
    for (i=0; i<dpb.ref_frames_in_buffer; i++)
    {
      if (dpb.fs_ref[i]->is_reference == 3)
      {
        if ((!dpb.fs_ref[i]->frame->is_long_term)&&(dpb.fs_ref[i]->frame->pic_num == picNumX))
        {
          dpb.fs_ref[i]->long_term_frame_idx = dpb.fs_ref[i]->frame->long_term_frame_idx
                                             = dpb.fs_ref[i]->top_field->long_term_frame_idx
                                             = dpb.fs_ref[i]->bottom_field->long_term_frame_idx
                                             = long_term_frame_idx;
          dpb.fs_ref[i]->frame->long_term_pic_num = dpb.fs_ref[i]->top_field->long_term_pic_num
                                                  = dpb.fs_ref[i]->bottom_field->long_term_pic_num
                                                  = long_term_frame_idx;
          dpb.fs_ref[i]->frame->is_long_term = dpb.fs_ref[i]->top_field->is_long_term
                                             = dpb.fs_ref[i]->bottom_field->is_long_term
                                             = 1;
          dpb.fs_ref[i]->is_long_term = 3;
          return;
        }
      }
    }
    printf ("Warning: reference frame for long term marking not found\n");
  }
  else
  {
    if (p->structure == TOP_FIELD)
    {
      add_top    = 1;
      add_bottom = 0;
    }
    else
    {
      add_top    = 0;
      add_bottom = 1;
    }
    for (i=0; i<dpb.ref_frames_in_buffer; i++)
    {
      if (dpb.fs_ref[i]->is_reference & 1)
      {
        if ((!dpb.fs_ref[i]->top_field->is_long_term)&&(dpb.fs_ref[i]->top_field->pic_num == picNumX))
        {
          if ((dpb.fs_ref[i]->is_long_term) && (dpb.fs_ref[i]->long_term_frame_idx != long_term_frame_idx))
          {
              printf ("Warning: assigning long_term_frame_idx different from other field\n");
          }

          dpb.fs_ref[i]->long_term_frame_idx = dpb.fs_ref[i]->top_field->long_term_frame_idx 
                                             = long_term_frame_idx;
          dpb.fs_ref[i]->top_field->long_term_pic_num = 2 * long_term_frame_idx + add_top;
          dpb.fs_ref[i]->top_field->is_long_term = 1;
          dpb.fs_ref[i]->is_long_term |= 1;
          if (dpb.fs_ref[i]->is_long_term == 3)
          {
            dpb.fs_ref[i]->frame->is_long_term = 1;
            dpb.fs_ref[i]->frame->long_term_frame_idx = dpb.fs_ref[i]->frame->long_term_pic_num = long_term_frame_idx;
          }
          return;
        }
      }
      if (dpb.fs_ref[i]->is_reference & 2)
      {
        if ((!dpb.fs_ref[i]->bottom_field->is_long_term)&&(dpb.fs_ref[i]->bottom_field->pic_num == picNumX))
        {
          if ((dpb.fs_ref[i]->is_long_term) && (dpb.fs_ref[i]->long_term_frame_idx != long_term_frame_idx))
          {
              printf ("Warning: assigning long_term_frame_idx different from other field\n");
          }

          dpb.fs_ref[i]->long_term_frame_idx = dpb.fs_ref[i]->bottom_field->long_term_frame_idx 
                                             = long_term_frame_idx;
          dpb.fs_ref[i]->bottom_field->long_term_pic_num = 2 * long_term_frame_idx + add_top;
          dpb.fs_ref[i]->bottom_field->is_long_term = 1;
          dpb.fs_ref[i]->is_long_term |= 2;
          if (dpb.fs_ref[i]->is_long_term == 3)
          {
            dpb.fs_ref[i]->frame->is_long_term = 1;
            dpb.fs_ref[i]->frame->long_term_frame_idx = dpb.fs_ref[i]->frame->long_term_pic_num = long_term_frame_idx;
          }
          return;
        }
      }
    }
    printf ("Warning: reference field for long term marking not found\n");
  }
}


/*!
 ************************************************************************
 * \brief
 *    Assign a long term frame index to a short term picture
 ************************************************************************
 */
static void mm_assign_long_term_frame_idx(StorablePicture* p, int difference_of_pic_nums_minus1, int long_term_frame_idx)
{
  int picNumX;

  picNumX = get_pic_num_x(p, difference_of_pic_nums_minus1);

  // remove frames/fields with same long_term_frame_idx
  if (p->structure == FRAME)
  {
    unmark_long_term_frame_for_reference_by_frame_idx(long_term_frame_idx);
  }
  else
  {
    unmark_long_term_field_for_reference_by_frame_idx(p, long_term_frame_idx, picNumX);
  }

  mark_pic_long_term(p, long_term_frame_idx, picNumX);
}

/*!
 ************************************************************************
 * \brief
 *    Set new max long_term_frame_idx
 ************************************************************************
 */
void mm_update_max_long_term_frame_idx(int max_long_term_frame_idx_plus1)
{
  unsigned i;

  dpb.max_long_term_pic_idx = max_long_term_frame_idx_plus1 - 1;

  // check for invalid frames
  for (i=0; i<dpb.ltref_frames_in_buffer; i++)
  {
    if (dpb.fs_ltref[i]->long_term_frame_idx > dpb.max_long_term_pic_idx)
    {
      unmark_for_long_term_reference(dpb.fs_ltref[i]);
    }
  }
}


/*!
 ************************************************************************
 * \brief
 *    Mark all long term reference pictures unused for reference
 ************************************************************************
 */
static void mm_unmark_all_long_term_for_reference ()
{
  mm_update_max_long_term_frame_idx(0);
}


/*!
 ************************************************************************
 * \brief
 *    Mark the current picture used for long term reference
 ************************************************************************
 */
static void mm_mark_current_picture_long_term(StorablePicture *p, int long_term_frame_idx)
{
  // remove long term pictures with same long_term_frame_idx
  if (p->structure == FRAME)
  {
    unmark_long_term_frame_for_reference_by_frame_idx(long_term_frame_idx);
  }
  else
  {
    unmark_long_term_field_for_reference_by_frame_idx(p, long_term_frame_idx, 2 * p->pic_num + 1);
  }

  p->is_long_term = 1;
  p->long_term_frame_idx = long_term_frame_idx;
}


/*!
 ************************************************************************
 * \brief
 *    Perform Adaptive memory control decoded reference picture marking process
 ************************************************************************
 */
static void adaptive_memory_management(StorablePicture* p)
{
  DecRefPicMarking_t *tmp_drpm;

  assert (!img->currentPicture->idr_flag);
  assert (!img->adaptive_ref_pic_buffering_flag);

  while (img->dec_ref_pic_marking_buffer)
  {
    tmp_drpm = img->dec_ref_pic_marking_buffer;
    switch (tmp_drpm->memory_management_control_operation)
    {
      case 0:
        if (tmp_drpm->Next != NULL)
        {
          error ("memory_management_control_operation = 0 not last operation in buffer", 500);
        }
        break;
      case 1:
        mm_unmark_short_term_for_reference(p, tmp_drpm->difference_of_pic_nums_minus1);
        update_ref_list();
        break;
      case 2:
        mm_unmark_long_term_for_reference(p, tmp_drpm->long_term_pic_num);
        update_ltref_list();
        break;
      case 3:
        mm_assign_long_term_frame_idx(p, tmp_drpm->difference_of_pic_nums_minus1, tmp_drpm->long_term_frame_idx);
        update_ref_list();
        update_ltref_list();
        break;
      case 4:
        mm_update_max_long_term_frame_idx (tmp_drpm->max_long_term_frame_idx_plus1);
        update_ltref_list();
        break;
      case 5:
        mm_unmark_all_long_term_for_reference();
        break;
      case 6:
        mm_mark_current_picture_long_term(p, tmp_drpm->long_term_frame_idx);
        break;
      default:
        error ("invalid memory_management_control_operation in buffer", 500);
    }
    img->dec_ref_pic_marking_buffer = tmp_drpm->Next;
    free (tmp_drpm);
  }
}


/*!
 ************************************************************************
 * \brief
 *    Store a picture in DPB. This includes cheking for space in DPB and 
 *    flushing frames.
 *    If we received a frame, we need to check for a new store, if we
 *    got a field, check if it's the second field of an already allocated
 *    store.
 *
 * \param p
 *    Picture to be stored
 *
 ************************************************************************
 */
void store_picture_in_dpb(StorablePicture* p)
{
  unsigned i;
  int found;
  int poc, pos;
  // diagnostics
  //printf ("Storing (%s) non-ref pic with frame_num #%d\n", (p->type == FRAME)?"FRAME":(p->type == TOP_FIELD)?"TOP_FIELD":"BOTTOM_FIELD", img->frame_num);
  // if frame, check for new store, 
  assert (p!=NULL);

  p->used_for_reference = (img->nal_reference_idc != 0);
  
  if (img->currentPicture->idr_flag)
    idr_memory_management(p);
  else
  {
    // adaptive memory management
    if (p->used_for_reference && (img->adaptive_ref_pic_buffering_flag))
      adaptive_memory_management(p);
  }

  if ((p->structure==TOP_FIELD)||(p->structure==BOTTOM_FIELD))
  {
    // check for frame store with same pic_number
    found = 0;
    for (i=0;i<dpb.used_size;i++)
    {
      if((dpb.fs[i]->frame_num == img->frame_num)&&(dpb.fs[i]->is_used<3))
      {
        found=1;
        break;
      }
    }
    if (found)
    {
      if (!(((p->structure==TOP_FIELD)&&(dpb.fs[i]->is_used&1))||((p->structure==BOTTOM_FIELD)&&(dpb.fs[i]->is_used&2))))
      {
//        printf ("store second field at pos %d\n",i);
        insert_picture_in_dpb(dpb.fs[i], p);
        update_ref_list();
        update_ltref_list();
        dump_dpb();
        return;
      }
    }