gecko/media/libtheora/lib/dec/state.c

/********************************************************************
 *                                                                  *
 * THIS FILE IS PART OF THE OggTheora SOFTWARE CODEC SOURCE CODE.   *
 * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
 * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
 * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
 *                                                                  *
 * THE Theora SOURCE CODE IS COPYRIGHT (C) 2002-2007                *
 * by the Xiph.Org Foundation http://www.xiph.org/                  *
 *                                                                  *
 ********************************************************************

  function:
    last mod: $Id: state.c 14714 2008-04-12 01:04:43Z giles $

 ********************************************************************/

#include <stdlib.h>
#include <string.h>
#include "../internal.h"
#include "idct.h"
#if defined(USE_ASM)
#if defined(_MSC_VER)
# include "x86_vc/x86int.h"
#else
# include "x86/x86int.h"
#endif
#endif
#if defined(OC_DUMP_IMAGES)
# include <stdio.h>
# include "png.h"
#endif

void oc_restore_fpu(const oc_theora_state *_state){
  _state->opt_vtable.restore_fpu();
}

void oc_restore_fpu_c(void){}

/*Returns the fragment index of the top-left block in a macro block.
  This can be used to test whether or not the whole macro block is coded.
  _sb:    The super block.
  _quadi: The quadrant number.
  Return: The index of the fragment of the upper left block in the macro
   block, or -1 if the block lies outside the coded frame.*/
static int oc_sb_quad_top_left_frag(const oc_sb *_sb,int _quadi){
  /*It so happens that under the Hilbert curve ordering described below, the
     upper-left block in each macro block is at index 0, except in macro block
     3, where it is at index 2.*/
  return _sb->map[_quadi][_quadi&_quadi<<1];
}

/*Fills in the mapping from block positions to fragment numbers for a single
   color plane.
  This function also fills in the "valid" flag of each quadrant in a super
   block.
  _sbs:    The array of super blocks for the color plane.
  _frag0:  The index of the first fragment in the plane.
  _hfrags: The number of horizontal fragments in a coded frame.
  _vfrags: The number of vertical fragments in a coded frame.*/
static void oc_sb_create_plane_mapping(oc_sb _sbs[],int _frag0,int _hfrags,
 int _vfrags){
  /*Contains the (macro_block,block) indices for a 4x4 grid of
     fragments.
    The pattern is a 4x4 Hilbert space-filling curve.
    A Hilbert curve has the nice property that as the curve grows larger, its
     fractal dimension approaches 2.
    The intuition is that nearby blocks in the curve are also close spatially,
     with the previous element always an immediate neighbor, so that runs of
     blocks should be well correlated.*/
  static const int SB_MAP[4][4][2]={
    {{0,0},{0,1},{3,2},{3,3}},
    {{0,3},{0,2},{3,1},{3,0}},
    {{1,0},{1,3},{2,0},{2,3}},
    {{1,1},{1,2},{2,1},{2,2}}
  };
  oc_sb *sb;
  int    yfrag;
  int    y;
  sb=_sbs;
  yfrag=_frag0;
  for(y=0;;y+=4){
    int imax;
    int x;
    /*Figure out how many columns of blocks in this super block lie within the
       image.*/
    imax=_vfrags-y;
    if(imax>4)imax=4;
    else if(imax<=0)break;
    for(x=0;;x+=4,sb++){
      int    xfrag;
      int    jmax;
      int    quadi;
      int    i;
      /*Figure out how many rows of blocks in this super block lie within the
         image.*/
      jmax=_hfrags-x;
      if(jmax>4)jmax=4;
      else if(jmax<=0)break;
      /*By default, set all fragment indices to -1.*/
      memset(sb->map[0],0xFF,sizeof(sb->map));
      /*Fill in the fragment map for this super block.*/
      xfrag=yfrag+x;
      for(i=0;i<imax;i++){
        int j;
        for(j=0;j<jmax;j++){
          sb->map[SB_MAP[i][j][0]][SB_MAP[i][j][1]]=xfrag+j;
        }
        xfrag+=_hfrags;
      }
      /*Mark which quadrants of this super block lie within the image.*/
      for(quadi=0;quadi<4;quadi++){
        sb->quad_valid|=(oc_sb_quad_top_left_frag(sb,quadi)>=0)<<quadi;
      }
    }
    yfrag+=_hfrags<<2;
  }
}

/*Fills in the Y plane fragment map for a macro block given the fragment
   coordinates of its upper-left hand corner.
  _mb:     The macro block to fill.
  _fplane: The description of the Y plane.
  _x:      The X location of the upper-left hand fragment in the Y plane.
  _y:      The Y location of the upper-left hand fragment in the Y plane.*/
static void oc_mb_fill_ymapping(oc_mb *_mb,const oc_fragment_plane *_fplane,
 int _x,int _y){
  int i;
  for(i=0;i<2;i++){
    int j;
    if(_y+i>=_fplane->nvfrags)break;
    for(j=0;j<2;j++){
      if(_x+j>=_fplane->nhfrags)break;
      _mb->map[0][i<<1|j]=(_y+i)*_fplane->nhfrags+_x+j;
    }
  }
}

/*Fills in the chroma plane fragment maps for a macro block.
  This version is for use with chroma decimated in the X and Y directions.
  _mb:      The macro block to fill.
  _fplanes: The descriptions of the fragment planes.
  _x:       The X location of the upper-left hand fragment in the Y plane.
  _y:       The Y location of the upper-left hand fragment in the Y plane.*/
static void oc_mb_fill_cmapping00(oc_mb *_mb,
 const oc_fragment_plane _fplanes[3],int _x,int _y){
  int fragi;
  _x>>=1;
  _y>>=1;
  fragi=_y*_fplanes[1].nhfrags+_x;
  _mb->map[1][0]=fragi+_fplanes[1].froffset;
  _mb->map[2][0]=fragi+_fplanes[2].froffset;
}

/*Fills in the chroma plane fragment maps for a macro block.
  This version is for use with chroma decimated in the Y direction.
  _mb:      The macro block to fill.
  _fplanes: The descriptions of the fragment planes.
  _x:       The X location of the upper-left hand fragment in the Y plane.
  _y:       The Y location of the upper-left hand fragment in the Y plane.*/
static void oc_mb_fill_cmapping01(oc_mb *_mb,
 const oc_fragment_plane _fplanes[3],int _x,int _y){
  int fragi;
  int j;
  _y>>=1;
  fragi=_y*_fplanes[1].nhfrags+_x;
  for(j=0;j<2;j++){
    if(_x+j>=_fplanes[1].nhfrags)break;
    _mb->map[1][j]=fragi+_fplanes[1].froffset;
    _mb->map[2][j]=fragi+_fplanes[2].froffset;
    fragi++;
  }
}

/*Fills in the chroma plane fragment maps for a macro block.
  This version is for use with chroma decimated in the X direction.
  _mb:      The macro block to fill.
  _fplanes: The descriptions of the fragment planes.
  _x:       The X location of the upper-left hand fragment in the Y plane.
  _y:       The Y location of the upper-left hand fragment in the Y plane.*/
static void oc_mb_fill_cmapping10(oc_mb *_mb,
 const oc_fragment_plane _fplanes[3],int _x,int _y){
  int fragi;
  int i;
  _x>>=1;
  fragi=_y*_fplanes[1].nhfrags+_x;
  for(i=0;i<2;i++){
    if(_y+i>=_fplanes[1].nvfrags)break;
    _mb->map[1][i<<1]=fragi+_fplanes[1].froffset;
    _mb->map[2][i<<1]=fragi+_fplanes[2].froffset;
    fragi+=_fplanes[1].nhfrags;
  }
}

/*Fills in the chroma plane fragment maps for a macro block.
  This version is for use with no chroma decimation.
  This uses the already filled-in Y plane values.
  _mb:      The macro block to fill.
  _fplanes: The descriptions of the fragment planes.*/
static void oc_mb_fill_cmapping11(oc_mb *_mb,
 const oc_fragment_plane _fplanes[3]){
  int k;
  for(k=0;k<4;k++){
    if(_mb->map[0][k]>=0){
      _mb->map[1][k]=_mb->map[0][k]+_fplanes[1].froffset;
      _mb->map[2][k]=_mb->map[0][k]+_fplanes[2].froffset;
    }
  }
}

/*The function type used to fill in the chroma plane fragment maps for a
   macro block.
  _mb:      The macro block to fill.
  _fplanes: The descriptions of the fragment planes.
  _x:       The X location of the upper-left hand fragment in the Y plane.
  _y:       The Y location of the upper-left hand fragment in the Y plane.*/
typedef void (*oc_mb_fill_cmapping_func)(oc_mb *_mb,
 const oc_fragment_plane _fplanes[3],int _xfrag0,int _yfrag0);

/*A table of functions used to fill in the chroma plane fragment maps for a
   macro block for each type of chrominance decimation.*/
static const oc_mb_fill_cmapping_func OC_MB_FILL_CMAPPING_TABLE[4]={
  oc_mb_fill_cmapping00,
  oc_mb_fill_cmapping01,
  oc_mb_fill_cmapping10,
  (oc_mb_fill_cmapping_func)oc_mb_fill_cmapping11
};

/*Fills in the mapping from macro blocks to their corresponding fragment
   numbers in each plane.
  _mbs:     The array of macro blocks.
  _fplanes: The descriptions of the fragment planes.
  _ctype:   The chroma decimation type.*/
static void oc_mb_create_mapping(oc_mb _mbs[],
 const oc_fragment_plane _fplanes[3],int _ctype){
  oc_mb_fill_cmapping_func  mb_fill_cmapping;
  oc_mb                    *mb0;
  int                       y;
  mb0=_mbs;
  mb_fill_cmapping=OC_MB_FILL_CMAPPING_TABLE[_ctype];
  /*Loop through the Y plane super blocks.*/
  for(y=0;y<_fplanes[0].nvfrags;y+=4){
    int x;
    for(x=0;x<_fplanes[0].nhfrags;x+=4,mb0+=4){
      int ymb;
      /*Loop through the macro blocks in each super block in display order.*/
      for(ymb=0;ymb<2;ymb++){
        int xmb;
        for(xmb=0;xmb<2;xmb++){
          oc_mb *mb;
          int    mbx;
          int    mby;
          mb=mb0+OC_MB_MAP[ymb][xmb];
          mbx=x|xmb<<1;
          mby=y|ymb<<1;
          mb->x=mbx<<3;
          mb->y=mby<<3;
          /*Initialize fragment indexes to -1.*/
          memset(mb->map,0xFF,sizeof(mb->map));
          /*Make sure this macro block is within the encoded region.*/
          if(mbx>=_fplanes[0].nhfrags||mby>=_fplanes[0].nvfrags){
            mb->mode=OC_MODE_INVALID;
            continue;
          }
          /*Fill in the fragment indices for the Y plane.*/
          oc_mb_fill_ymapping(mb,_fplanes,mbx,mby);
          /*Fill in the fragment indices for the chroma planes.*/
          (*mb_fill_cmapping)(mb,_fplanes,mbx,mby);
        }
      }
    }
  }
}

/*Marks the fragments which fall all or partially outside the displayable
   region of the frame.
  _state: The Theora state containing the fragments to be marked.*/
static void oc_state_border_init(oc_theora_state *_state){
  typedef struct{
    int x0;
    int y0;
    int xf;
    int yf;
  }oc_crop_rect;
  oc_fragment       *frag;
  oc_fragment       *yfrag_end;
  oc_fragment       *xfrag_end;
  oc_fragment_plane *fplane;
  oc_crop_rect      *crop;
  oc_crop_rect       crop_rects[3];
  int                pli;
  int                y;
  int                x;
  /*The method we use here is slow, but the code is dead simple and handles
     all the special cases easily.
    We only ever need to do it once.*/
  /*Loop through the fragments, marking those completely outside the
     displayable region and constructing a border mask for those that straddle
     the border.*/
  _state->nborders=0;
  yfrag_end=frag=_state->frags;
  for(pli=0;pli<3;pli++){
    fplane=_state->fplanes+pli;
    crop=crop_rects+pli;
    /*Set up the cropping rectangle for this plane.*/
    crop->x0=_state->info.pic_x;
    crop->xf=_state->info.pic_x+_state->info.pic_width;
    crop->y0=_state->info.pic_y;
    crop->yf=_state->info.pic_y+_state->info.pic_height;
    if(pli>0){
      if(!(_state->info.pixel_fmt&1)){
        crop->x0=crop->x0>>1;
        crop->xf=crop->xf+1>>1;
      }
      if(!(_state->info.pixel_fmt&2)){
        crop->y0=crop->y0>>1;
        crop->yf=crop->yf+1>>1;
      }
    }
    y=0;
    for(yfrag_end+=fplane->nfrags;frag<yfrag_end;y+=8){
      x=0;
      for(xfrag_end=frag+fplane->nhfrags;frag<xfrag_end;frag++,x+=8){
        /*First check to see if this fragment is completely outside the
           displayable region.*/
        /*Note the special checks for an empty cropping rectangle.
          This guarantees that if we count a fragment as straddling the
           border below, at least one pixel in the fragment will be inside
           the displayable region.*/
        if(x+8<=crop->x0||crop->xf<=x||y+8<=crop->y0||crop->yf<=y||
         crop->x0>=crop->xf||crop->y0>=crop->yf){
          frag->invalid=1;
        }
        /*Otherwise, check to see if it straddles the border.*/
        else if(x<crop->x0&&crop->x0<x+8||x<crop->xf&&crop->xf<x+8||
         y<crop->y0&&crop->y0<y+8||y<crop->yf&&crop->yf<y+8){
          ogg_int64_t mask;
          int         npixels;
          int         i;
          mask=npixels=0;
          for(i=0;i<8;i++){
            int j;
            for(j=0;j<8;j++){
              if(x+j>=crop->x0&&x+j<crop->xf&&y+i>=crop->y0&&y+i<crop->yf){
                mask|=(ogg_int64_t)1<<(i<<3|j);
                npixels++;
              }
            }
          }
          /*Search the fragment array for border info with the same pattern.
            In general, there will be at most 8 different patterns (per
            plane).*/
          for(i=0;;i++){
            if(i>=_state->nborders){
              _state->nborders++;
              _state->borders[i].mask=mask;
              _state->borders[i].npixels=npixels;
            }
            else if(_state->borders[i].mask!=mask)continue;
            frag->border=_state->borders+i;
            break;
          }
        }
      }
    }
  }
}

static void oc_state_frarray_init(oc_theora_state *_state){
  int yhfrags;
  int yvfrags;
  int chfrags;
  int cvfrags;
  int yfrags;
  int cfrags;
  int nfrags;
  int yhsbs;
  int yvsbs;
  int chsbs;
  int cvsbs;
  int ysbs;
  int csbs;
  int nsbs;
  int nmbs;
  int hdec;
  int vdec;
  int pli;
  /*Figure out the number of fragments in each plane.*/
  /*These parameters have already been validated to be multiples of 16.*/
  yhfrags=_state->info.frame_width>>3;
  yvfrags=_state->info.frame_height>>3;
  hdec=!(_state->info.pixel_fmt&1);
  vdec=!(_state->info.pixel_fmt&2);
  chfrags=yhfrags+hdec>>hdec;
  cvfrags=yvfrags+vdec>>vdec;
  yfrags=yhfrags*yvfrags;
  cfrags=chfrags*cvfrags;
  nfrags=yfrags+2*cfrags;
  /*Figure out the number of super blocks in each plane.*/
  yhsbs=yhfrags+3>>2;
  yvsbs=yvfrags+3>>2;
  chsbs=chfrags+3>>2;
  cvsbs=cvfrags+3>>2;
  ysbs=yhsbs*yvsbs;
  csbs=chsbs*cvsbs;
  nsbs=ysbs+2*csbs;
  nmbs=ysbs<<2;
  /*Initialize the fragment array.*/
  _state->fplanes[0].nhfrags=yhfrags;
  _state->fplanes[0].nvfrags=yvfrags;
  _state->fplanes[0].froffset=0;
  _state->fplanes[0].nfrags=yfrags;
  _state->fplanes[0].nhsbs=yhsbs;
  _state->fplanes[0].nvsbs=yvsbs;
  _state->fplanes[0].sboffset=0;
  _state->fplanes[0].nsbs=ysbs;
  _state->fplanes[1].nhfrags=_state->fplanes[2].nhfrags=chfrags;
  _state->fplanes[1].nvfrags=_state->fplanes[2].nvfrags=cvfrags;
  _state->fplanes[1].froffset=yfrags;
  _state->fplanes[2].froffset=yfrags+cfrags;
  _state->fplanes[1].nfrags=_state->fplanes[2].nfrags=cfrags;
  _state->fplanes[1].nhsbs=_state->fplanes[2].nhsbs=chsbs;
  _state->fplanes[1].nvsbs=_state->fplanes[2].nvsbs=cvsbs;
  _state->fplanes[1].sboffset=ysbs;
  _state->fplanes[2].sboffset=ysbs+csbs;
  _state->fplanes[1].nsbs=_state->fplanes[2].nsbs=csbs;
  _state->nfrags=nfrags;
  _state->frags=_ogg_calloc(nfrags,sizeof(oc_fragment));
  _state->nsbs=nsbs;
  _state->sbs=_ogg_calloc(nsbs,sizeof(oc_sb));
  _state->nhmbs=yhsbs<<1;
  _state->nvmbs=yvsbs<<1;
  _state->nmbs=nmbs;
  _state->mbs=_ogg_calloc(nmbs,sizeof(oc_mb));
  _state->coded_fragis=_ogg_malloc(nfrags*sizeof(_state->coded_fragis[0]));
  _state->uncoded_fragis=_state->coded_fragis+nfrags;
  _state->coded_mbis=_ogg_malloc(nmbs*sizeof(_state->coded_mbis[0]));
  /*Create the mapping from super blocks to fragments.*/
  for(pli=0;pli<3;pli++){
    oc_fragment_plane *fplane;
    fplane=_state->fplanes+pli;
    oc_sb_create_plane_mapping(_state->sbs+fplane->sboffset,
     fplane->froffset,fplane->nhfrags,fplane->nvfrags);
  }
  /*Create the mapping from macro blocks to fragments.*/
  oc_mb_create_mapping(_state->mbs,_state->fplanes,_state->info.pixel_fmt);
  /*Initialize the invalid and border fields of each fragment.*/
  oc_state_border_init(_state);
}

static void oc_state_frarray_clear(oc_theora_state *_state){
  _ogg_free(_state->coded_mbis);
  _ogg_free(_state->coded_fragis);
  _ogg_free(_state->mbs);
  _ogg_free(_state->sbs);
  _ogg_free(_state->frags);
}


/*Initializes the buffers used for reconstructed frames.
  These buffers are padded with 16 extra pixels on each side, to allow
   unrestricted motion vectors without special casing the boundary.
  If chroma is decimated in either direction, the padding is reduced by a
   factor of 2 on the appropriate sides.
  _enc: The encoding context to store the buffers in.*/
static void oc_state_ref_bufs_init(oc_theora_state *_state){
  th_info   *info;
  unsigned char *ref_frame_data;
  size_t         yplane_sz;
  size_t         cplane_sz;
  int            yhstride;
  int            yvstride;
  int            chstride;
  int            cvstride;
  int            yoffset;
  int            coffset;
  int            rfi;
  info=&_state->info;
  /*Compute the image buffer parameters for each plane.*/
  yhstride=info->frame_width+2*OC_UMV_PADDING;
  yvstride=info->frame_height+2*OC_UMV_PADDING;
  chstride=yhstride>>!(info->pixel_fmt&1);
  cvstride=yvstride>>!(info->pixel_fmt&2);
  yplane_sz=(size_t)yhstride*yvstride;
  cplane_sz=(size_t)chstride*cvstride;
  yoffset=OC_UMV_PADDING+OC_UMV_PADDING*yhstride;
  coffset=(OC_UMV_PADDING>>!(info->pixel_fmt&1))+
   (OC_UMV_PADDING>>!(info->pixel_fmt&2))*chstride;
  _state->ref_frame_data=ref_frame_data=_ogg_malloc(3*(yplane_sz+2*cplane_sz));
  /*Set up the width, height and stride for the image buffers.*/
  _state->ref_frame_bufs[0][0].width=info->frame_width;
  _state->ref_frame_bufs[0][0].height=info->frame_height;
  _state->ref_frame_bufs[0][0].stride=yhstride;
  _state->ref_frame_bufs[0][1].width=_state->ref_frame_bufs[0][2].width=
   info->frame_width>>!(info->pixel_fmt&1);
  _state->ref_frame_bufs[0][1].height=_state->ref_frame_bufs[0][2].height=
   info->frame_height>>!(info->pixel_fmt&2);
  _state->ref_frame_bufs[0][1].stride=_state->ref_frame_bufs[0][2].stride=
   chstride;
  memcpy(_state->ref_frame_bufs[1],_state->ref_frame_bufs[0],
   sizeof(_state->ref_frame_bufs[0]));
  memcpy(_state->ref_frame_bufs[2],_state->ref_frame_bufs[0],
   sizeof(_state->ref_frame_bufs[0]));
  /*Set up the data pointers for the image buffers.*/
  for(rfi=0;rfi<3;rfi++){
    _state->ref_frame_bufs[rfi][0].data=ref_frame_data+yoffset;
    ref_frame_data+=yplane_sz;
    _state->ref_frame_bufs[rfi][1].data=ref_frame_data+coffset;
    ref_frame_data+=cplane_sz;
    _state->ref_frame_bufs[rfi][2].data=ref_frame_data+coffset;
    ref_frame_data+=cplane_sz;
    /*Flip the buffer upside down.*/
    oc_ycbcr_buffer_flip(_state->ref_frame_bufs[rfi],
     _state->ref_frame_bufs[rfi]);
    /*Initialize the fragment pointers into this buffer.*/
    oc_state_fill_buffer_ptrs(_state,rfi,_state->ref_frame_bufs[rfi]);
  }
  /*Initialize the reference frame indexes.*/
  _state->ref_frame_idx[OC_FRAME_GOLD]=
   _state->ref_frame_idx[OC_FRAME_PREV]=
   _state->ref_frame_idx[OC_FRAME_SELF]=-1;
}

static void oc_state_ref_bufs_clear(oc_theora_state *_state){
  _ogg_free(_state->ref_frame_data);
}


void oc_state_vtable_init_c(oc_theora_state *_state){
  _state->opt_vtable.frag_recon_intra=oc_frag_recon_intra_c;
  _state->opt_vtable.frag_recon_inter=oc_frag_recon_inter_c;
  _state->opt_vtable.frag_recon_inter2=oc_frag_recon_inter2_c;
  _state->opt_vtable.state_frag_copy=oc_state_frag_copy_c;
  _state->opt_vtable.state_frag_recon=oc_state_frag_recon_c;
  _state->opt_vtable.state_loop_filter_frag_rows=
   oc_state_loop_filter_frag_rows_c;
  _state->opt_vtable.restore_fpu=oc_restore_fpu_c;
}

/*Initialize the accelerated function pointers.*/
void oc_state_vtable_init(oc_theora_state *_state){
#if defined(USE_ASM)
  oc_state_vtable_init_x86(_state);
#else
  oc_state_vtable_init_c(_state);
#endif
}


int oc_state_init(oc_theora_state *_state,const th_info *_info){
  int old_granpos;
  /*First validate the parameters.*/
  if(_info==NULL)return TH_EFAULT;
  /*The width and height of the encoded frame must be multiples of 16.
    They must also, when divided by 16, fit into a 16-bit unsigned integer.
    The displayable frame offset coordinates must fit into an 8-bit unsigned
     integer.
    Note that the offset Y in the API is specified on the opposite side from
     how it is specified in the bitstream, because the Y axis is flipped in
     the bitstream.
    The displayable frame must fit inside the encoded frame.
    The color space must be one known by the encoder.*/
  if((_info->frame_width&0xF)||(_info->frame_height&0xF)||
   _info->frame_width>=0x100000||_info->frame_height>=0x100000||
   _info->pic_x+_info->pic_width>_info->frame_width||
   _info->pic_y+_info->pic_height>_info->frame_height||
   _info->pic_x>255||
   _info->frame_height-_info->pic_height-_info->pic_y>255||
   _info->colorspace<0||_info->colorspace>=TH_CS_NSPACES||
   _info->pixel_fmt<0||_info->pixel_fmt>=TH_PF_NFORMATS){
    return TH_EINVAL;
  }
  memset(_state,0,sizeof(*_state));
  memcpy(&_state->info,_info,sizeof(*_info));
  /*Invert the sense of pic_y to match Theora's right-handed coordinate
     system.*/
  _state->info.pic_y=_info->frame_height-_info->pic_height-_info->pic_y;
  _state->frame_type=OC_UNKWN_FRAME;
  oc_state_vtable_init(_state);
  oc_state_frarray_init(_state);
  oc_state_ref_bufs_init(_state);
  /*If the keyframe_granule_shift is out of range, use the maximum allowable
     value.*/
  if(_info->keyframe_granule_shift<0||_info->keyframe_granule_shift>31){
    _state->info.keyframe_granule_shift=31;
  }
  _state->keyframe_num=1;
  _state->curframe_num=0;
  /*3.2.0 streams mark the frame index instead of the frame count.
    This was changed with stream version 3.2.1 to conform to other Ogg
     codecs.
    We subtract an extra one from the frame number for old streams.*/
  old_granpos=!TH_VERSION_CHECK(_info,3,2,1);
  _state->curframe_num-=old_granpos;
  _state->keyframe_num-=old_granpos;
  return 0;
}

void oc_state_clear(oc_theora_state *_state){
  oc_state_ref_bufs_clear(_state);
  oc_state_frarray_clear(_state);
}


/*Duplicates the pixels on the border of the image plane out into the
   surrounding padding for use by unrestricted motion vectors.
  This function only adds the left and right borders, and only for the fragment
   rows specified.
  _refi: The index of the reference buffer to pad.
  _pli:  The color plane.
  _y0:   The Y coordinate of the first row to pad.
  _yend: The Y coordinate of the row to stop padding at.*/
void oc_state_borders_fill_rows(oc_theora_state *_state,int _refi,int _pli,
 int _y0,int _yend){
  th_img_plane *iplane;
  unsigned char    *apix;
  unsigned char    *bpix;
  unsigned char    *epix;
  int               hpadding;
  hpadding=OC_UMV_PADDING>>(_pli!=0&&!(_state->info.pixel_fmt&1));
  iplane=_state->ref_frame_bufs[_refi]+_pli;
  apix=iplane->data+_y0*iplane->stride;
  bpix=apix+iplane->width-1;
  epix=iplane->data+_yend*iplane->stride;
  /*Note the use of != instead of <, which allows ystride to be negative.*/
  while(apix!=epix){
    memset(apix-hpadding,apix[0],hpadding);
    memset(bpix+1,bpix[0],hpadding);
    apix+=iplane->stride;
    bpix+=iplane->stride;
  }
}

/*Duplicates the pixels on the border of the image plane out into the
   surrounding padding for use by unrestricted motion vectors.
  This function only adds the top and bottom borders, and must be called after
   the left and right borders are added.
  _refi:      The index of the reference buffer to pad.
  _pli:       The color plane.*/
void oc_state_borders_fill_caps(oc_theora_state *_state,int _refi,int _pli){
  th_img_plane *iplane;
  unsigned char    *apix;
  unsigned char    *bpix;
  unsigned char    *epix;
  int               hpadding;
  int               vpadding;
  int               fullw;
  hpadding=OC_UMV_PADDING>>(_pli!=0&&!(_state->info.pixel_fmt&1));
  vpadding=OC_UMV_PADDING>>(_pli!=0&&!(_state->info.pixel_fmt&2));
  iplane=_state->ref_frame_bufs[_refi]+_pli;
  fullw=iplane->width+(hpadding<<1);
  apix=iplane->data-hpadding;
  bpix=iplane->data+(iplane->height-1)*iplane->stride-hpadding;
  epix=apix-iplane->stride*vpadding;
  while(apix!=epix){
    memcpy(apix-iplane->stride,apix,fullw);
    memcpy(bpix+iplane->stride,bpix,fullw);
    apix-=iplane->stride;
    bpix+=iplane->stride;
  }
}

/*Duplicates the pixels on the border of the given reference image out into
   the surrounding padding for use by unrestricted motion vectors.
  _state: The context containing the reference buffers.
  _refi:  The index of the reference buffer to pad.*/
void oc_state_borders_fill(oc_theora_state *_state,int _refi){
  int pli;
  for(pli=0;pli<3;pli++){
    oc_state_borders_fill_rows(_state,_refi,pli,0,
     _state->ref_frame_bufs[_refi][pli].height);
    oc_state_borders_fill_caps(_state,_refi,pli);
  }
}

/*Sets the buffer pointer in each fragment to point to the portion of the
   image buffer which it corresponds to.
  _state:   The Theora state to fill.
  _buf_idx: The index of the buffer pointer to fill.
            The first three correspond to our reconstructed frame buffers,
             while the last corresponds to the input image.
  _img:     The image buffer to fill the fragments with.*/
void oc_state_fill_buffer_ptrs(oc_theora_state *_state,int _buf_idx,
 th_ycbcr_buffer _img){
  int pli;
  /*Special handling for the input image to give us the opportunity to skip
     some updates.
    The other buffers do not change throughout the encoding process.*/
  if(_buf_idx==OC_FRAME_IO){
     if(memcmp(_state->input,_img,sizeof(th_ycbcr_buffer))==0)return;
     memcpy(_state->input,_img,sizeof(th_ycbcr_buffer));
  }
  for(pli=0;pli<3;pli++){
    th_img_plane  *iplane;
    oc_fragment_plane *fplane;
    oc_fragment       *frag;
    oc_fragment       *vfrag_end;
    unsigned char     *vpix;
    iplane=&_img[pli];
    fplane=&_state->fplanes[pli];
    vpix=iplane->data;
    frag=_state->frags+fplane->froffset;
    vfrag_end=frag+fplane->nfrags;
    while(frag<vfrag_end){
      oc_fragment   *hfrag_end;
      unsigned char *hpix;
      hpix=vpix;
      for(hfrag_end=frag+fplane->nhfrags;frag<hfrag_end;frag++){
        frag->buffer[_buf_idx]=hpix;
        hpix+=8;
      }
      vpix+=iplane->stride<<3;
    }
  }
}

/*Returns the macro block index of the macro block in the given position.
  _state: The Theora state the macro block is contained in.
  _mbx:   The X coordinate of the macro block (in macro blocks, not pixels).
  _mby:   The Y coordinate of the macro block (in macro blocks, not pixels).
  Return: The index of the macro block in the given position.*/
int oc_state_mbi_for_pos(oc_theora_state *_state,int _mbx,int _mby){
  return ((_mbx&~1)<<1)+(_mby&~1)*_state->nhmbs+OC_MB_MAP[_mby&1][_mbx&1];
}

/*Determines the offsets in an image buffer to use for motion compensation.
  _state:   The Theora state the offsets are to be computed with.
  _offsets: Returns the offset for the buffer(s).
            _offsets[0] is always set.
            _offsets[1] is set if the motion vector has non-zero fractional
             components.
  _dx:      The X component of the motion vector.
  _dy:      The Y component of the motion vector.
  _ystride: The Y stride in the buffer the motion vector points into.
  _pli:     The color plane index.
  Return: The number of offsets returned: 1 or 2.*/
int oc_state_get_mv_offsets(oc_theora_state *_state,int _offsets[2],
 int _dx,int _dy,int _ystride,int _pli){
  int xprec;
  int yprec;
  int xfrac;
  int yfrac;
  /*Here is a brief description of how Theora handles motion vectors:
    Motion vector components are specified to half-pixel accuracy in
     undecimated directions of each plane, and quarter-pixel accuracy in
     decimated directions.
    Integer parts are extracted by dividing (not shifting) by the
     appropriate amount, with truncation towards zero.
    These integer values are used to calculate the first offset.

    If either of the fractional parts are non-zero, then a second offset is
     computed.
    No third or fourth offsets are computed, even if both components have
     non-zero fractional parts.
    The second offset is computed by dividing (not shifting) by the
     appropriate amount, always truncating _away_ from zero.*/
  /*These two variables decide whether we are in half- or quarter-pixel
     precision in each component.*/
  xprec=1+(!(_state->info.pixel_fmt&1)&&_pli);
  yprec=1+(!(_state->info.pixel_fmt&2)&&_pli);
  /*These two variables are either 0 if all the fractional bits are 0 or 1 if
     any of them are non-zero.*/
  xfrac=!!(_dx&(1<<xprec)-1);
  yfrac=!!(_dy&(1<<yprec)-1);
  _offsets[0]=(_dx>>xprec)+(_dy>>yprec)*_ystride;
  if(xfrac||yfrac){
    /*This branchless code is equivalent to:
    if(_dx<0)_offests[0]=-(-_dx>>xprec);
    else _offsets[0]=(_dx>>xprec);
    if(_dy<0)_offsets[0]-=(-_dy>>yprec)*_ystride;
    else _offsets[0]+=(_dy>>yprec)*_ystride;
    _offsets[1]=_offsets[0];
    if(xfrac){
      if(_dx<0)_offsets[1]++;
      else _offsets[1]--;
    }
    if(yfrac){
      if(_dy<0)_offsets[1]+=_ystride;
      else _offsets[1]-=_ystride;
    }*/
    _offsets[1]=_offsets[0];
    _offsets[_dx>=0]+=xfrac;
    _offsets[_dy>=0]+=_ystride&-yfrac;
    return 2;
  }
  else return 1;
}

void oc_state_frag_recon(oc_theora_state *_state,oc_fragment *_frag,
 int _pli,ogg_int16_t _dct_coeffs[128],int _last_zzi,int _ncoefs,
 ogg_uint16_t _dc_iquant,const ogg_uint16_t _ac_iquant[64]){
  _state->opt_vtable.state_frag_recon(_state,_frag,_pli,_dct_coeffs,
   _last_zzi,_ncoefs,_dc_iquant,_ac_iquant);
}

void oc_state_frag_recon_c(oc_theora_state *_state,oc_fragment *_frag,
 int _pli,ogg_int16_t _dct_coeffs[128],int _last_zzi,int _ncoefs,
 ogg_uint16_t _dc_iquant, const ogg_uint16_t _ac_iquant[64]){
  ogg_int16_t dct_buf[64];
  ogg_int16_t res_buf[64];
  int dst_framei;
  int dst_ystride;
  int zzi;
  int ci;
  /*_last_zzi is subtly different from an actual count of the number of
     coefficients we decoded for this block.
    It contains the value of zzi BEFORE the final token in the block was
     decoded.
    In most cases this is an EOB token (the continuation of an EOB run from a
     previous block counts), and so this is the same as the coefficient count.
    However, in the case that the last token was NOT an EOB token, but filled
     the block up with exactly 64 coefficients, _last_zzi will be less than 64.
    Provided the last token was not a pure zero run, the minimum value it can
     be is 46, and so that doesn't affect any of the cases in this routine.
    However, if the last token WAS a pure zero run of length 63, then _last_zzi
     will be 1 while the number of coefficients decoded is 64.
    Thus, we will trigger the following special case, where the real
     coefficient count would not.
    Note also that a zero run of length 64 will give _last_zzi a value of 0,
     but we still process the DC coefficient, which might have a non-zero value
     due to DC prediction.
    Although convoluted, this is arguably the correct behavior: it allows us to
     dequantize fewer coefficients and use a smaller transform when the block
     ends with a long zero run instead of a normal EOB token.
    It could be smarter... multiple separate zero runs at the end of a block
     will fool it, but an encoder that generates these really deserves what it
     gets.
    Needless to say we inherited this approach from VP3.*/
  /*Special case only having a DC component.*/
  if(_last_zzi<2){
    ogg_int16_t p;
    /*Why is the iquant product rounded in this case and no others?
      Who knows.*/

    p=(ogg_int16_t)((ogg_int32_t)_frag->dc*_dc_iquant+15>>5);
    /*LOOP VECTORIZES.*/
    for(ci=0;ci<64;ci++)res_buf[ci]=p;

#ifdef _TH_DEBUG_
    {
      int i;
      _frag->freq[0] = _frag->dc*_dc_iquant;
      _frag->time[0] = p;
      for(i=1;i<64;i++){
	_frag->quant[i] = 0;
	_frag->freq[i] = 0;
	_frag->time[i] = p;
      }
    }
#endif

  }
  else{

#ifdef _TH_DEBUG_
    {
      int i;
      for(i=1;i<_ncoefs;i++)
	_frag->quant[i] = _dct_coeffs[i];
      for(;i<64;i++)
	_frag->quant[i] = 0;
    }
#endif

    /*First, dequantize the coefficients.*/
    dct_buf[0]=(ogg_int16_t)((ogg_int32_t)_frag->dc*_dc_iquant);
    for(zzi=1;zzi<_ncoefs;zzi++){
      int ci;
      ci=OC_FZIG_ZAG[zzi];
      dct_buf[ci]=(ogg_int16_t)((ogg_int32_t)_dct_coeffs[zzi]*_ac_iquant[ci]);
    }

#ifdef _TH_DEBUG_
    for(;zzi<64;zzi++){
      int ci;
      ci=OC_FZIG_ZAG[zzi];
      dct_buf[ci]=0;
    }

    {
      int i;
      for(i=0;i<64;i++)
	_frag->freq[i] = dct_buf[i];
    }
#endif

    /*Then, fill in the remainder of the coefficients with 0's, and perform
       the iDCT.*/
    if(_last_zzi<10){
      for(;zzi<10;zzi++)dct_buf[OC_FZIG_ZAG[zzi]]=0;
      oc_idct8x8_10_c(res_buf,dct_buf);
    }
    else{
      for(;zzi<64;zzi++)dct_buf[OC_FZIG_ZAG[zzi]]=0;
      oc_idct8x8_c(res_buf,dct_buf);
    }

#ifdef _TH_DEBUG_
    {
      int i;
      for(i=0;i<64;i++)
	_frag->time[i] = res_buf[i];
    }
#endif

  }
  /*Fill in the target buffer.*/
  dst_framei=_state->ref_frame_idx[OC_FRAME_SELF];
  dst_ystride=_state->ref_frame_bufs[dst_framei][_pli].stride;
  /*For now ystride values in all ref frames assumed to be equal.*/
  if(_frag->mbmode==OC_MODE_INTRA){
    oc_frag_recon_intra(_state,_frag->buffer[dst_framei],dst_ystride,res_buf);
  }
  else{
    int ref_framei;
    int ref_ystride;
    int mvoffsets[2];
    ref_framei=_state->ref_frame_idx[OC_FRAME_FOR_MODE[_frag->mbmode]];
    ref_ystride=_state->ref_frame_bufs[ref_framei][_pli].stride;
    if(oc_state_get_mv_offsets(_state,mvoffsets,_frag->mv[0],_frag->mv[1],
     ref_ystride,_pli)>1){
      oc_frag_recon_inter2(_state,_frag->buffer[dst_framei],dst_ystride,
       _frag->buffer[ref_framei]+mvoffsets[0],ref_ystride,
       _frag->buffer[ref_framei]+mvoffsets[1],ref_ystride,res_buf);
    }
    else{
      oc_frag_recon_inter(_state,_frag->buffer[dst_framei],dst_ystride,
       _frag->buffer[ref_framei]+mvoffsets[0],ref_ystride,res_buf);
    }
  }
  oc_restore_fpu(_state);
}

/*Copies the fragments specified by the lists of fragment indices from one
   frame to another.
  _fragis:    A pointer to a list of fragment indices.
  _nfragis:   The number of fragment indices to copy.
  _dst_frame: The reference frame to copy to.
  _src_frame: The reference frame to copy from.
  _pli:       The color plane the fragments lie in.*/
void oc_state_frag_copy(const oc_theora_state *_state,const int *_fragis,
 int _nfragis,int _dst_frame,int _src_frame,int _pli){
  _state->opt_vtable.state_frag_copy(_state,_fragis,_nfragis,_dst_frame,
   _src_frame,_pli);
}

void oc_state_frag_copy_c(const oc_theora_state *_state,const int *_fragis,
 int _nfragis,int _dst_frame,int _src_frame,int _pli){
  const int *fragi;
  const int *fragi_end;
  int        dst_framei;
  int        dst_ystride;
  int        src_framei;
  int        src_ystride;
  dst_framei=_state->ref_frame_idx[_dst_frame];
  src_framei=_state->ref_frame_idx[_src_frame];
  dst_ystride=_state->ref_frame_bufs[dst_framei][_pli].stride;
  src_ystride=_state->ref_frame_bufs[src_framei][_pli].stride;
  fragi_end=_fragis+_nfragis;
  for(fragi=_fragis;fragi<fragi_end;fragi++){
    oc_fragment   *frag;
    unsigned char *dst;
    unsigned char *src;
    int            j;
    frag=_state->frags+*fragi;
    dst=frag->buffer[dst_framei];
    src=frag->buffer[src_framei];
    for(j=0;j<8;j++){
      memcpy(dst,src,sizeof(dst[0])*8);
      dst+=dst_ystride;
      src+=src_ystride;
    }
  }
}

static void loop_filter_h(unsigned char *_pix,int _ystride,int *_bv){
  int y;
  _pix-=2;
  for(y=0;y<8;y++){
    int f;
    f=_pix[0]-_pix[3]+3*(_pix[2]-_pix[1]);
    /*The _bv array is used to compute the function
      f=OC_CLAMPI(OC_MINI(-_2flimit-f,0),f,OC_MAXI(_2flimit-f,0));
      where _2flimit=_state->loop_filter_limits[_state->qis[0]]<<1;*/
    f=*(_bv+(f+4>>3));
    _pix[1]=OC_CLAMP255(_pix[1]+f);
    _pix[2]=OC_CLAMP255(_pix[2]-f);
    _pix+=_ystride;
  }
}

static void loop_filter_v(unsigned char *_pix,int _ystride,int *_bv){
  int y;
  _pix-=_ystride*2;
  for(y=0;y<8;y++){
    int f;
    f=_pix[0]-_pix[_ystride*3]+3*(_pix[_ystride*2]-_pix[_ystride]);
    /*The _bv array is used to compute the function
      f=OC_CLAMPI(OC_MINI(-_2flimit-f,0),f,OC_MAXI(_2flimit-f,0));
      where _2flimit=_state->loop_filter_limits[_state->qis[0]]<<1;*/
    f=*(_bv+(f+4>>3));
    _pix[_ystride]=OC_CLAMP255(_pix[_ystride]+f);
    _pix[_ystride*2]=OC_CLAMP255(_pix[_ystride*2]-f);
    _pix++;
  }
}

/*Initialize the bounding values array used by the loop filter.
  _bv: Storage for the array.
  Return: 0 on success, or a non-zero value if no filtering need be applied.*/
int oc_state_loop_filter_init(oc_theora_state *_state,int *_bv){
  int flimit;
  int i;
  flimit=_state->loop_filter_limits[_state->qis[0]];
  if(flimit==0)return 1;
  memset(_bv,0,sizeof(_bv[0])*256);
  for(i=0;i<flimit;i++){
    if(127-i-flimit>=0)_bv[127-i-flimit]=i-flimit;
    _bv[127-i]=-i;
    _bv[127+i]=i;
    if(127+i+flimit<256)_bv[127+i+flimit]=flimit-i;
  }
  return 0;
}

/*Apply the loop filter to a given set of fragment rows in the given plane.
  The filter may be run on the bottom edge, affecting pixels in the next row of
   fragments, so this row also needs to be available.
  _bv:        The bounding values array.
  _refi:      The index of the frame buffer to filter.
  _pli:       The color plane to filter.
  _fragy0:    The Y coordinate of the first fragment row to filter.
  _fragy_end: The Y coordinate of the fragment row to stop filtering at.*/
void oc_state_loop_filter_frag_rows(oc_theora_state *_state,int *_bv,
 int _refi,int _pli,int _fragy0,int _fragy_end){
  _state->opt_vtable.state_loop_filter_frag_rows(_state,_bv,_refi,_pli,
   _fragy0,_fragy_end);
}

void oc_state_loop_filter_frag_rows_c(oc_theora_state *_state,int *_bv,
 int _refi,int _pli,int _fragy0,int _fragy_end){  
  th_img_plane      *iplane;
  oc_fragment_plane *fplane;
  oc_fragment       *frag_top;
  oc_fragment       *frag0;
  oc_fragment       *frag;
  oc_fragment       *frag_end;
  oc_fragment       *frag0_end;
  oc_fragment       *frag_bot;
  _bv+=127;
  iplane=_state->ref_frame_bufs[_refi]+_pli;
  fplane=_state->fplanes+_pli;

  /*The following loops are constructed somewhat non-intuitively on purpose.
    The main idea is: if a block boundary has at least one coded fragment on
     it, the filter is applied to it.
    However, the order that the filters are applied in matters, and VP3 chose
     the somewhat strange ordering used below.*/
  frag_top=_state->frags+fplane->froffset;
  frag0=frag_top+_fragy0*fplane->nhfrags;
  frag0_end=frag0+(_fragy_end-_fragy0)*fplane->nhfrags;
  frag_bot=_state->frags+fplane->froffset+fplane->nfrags;
  while(frag0<frag0_end){
    frag=frag0;
    frag_end=frag+fplane->nhfrags;
    while(frag<frag_end){
      if(frag->coded){
        if(frag>frag0){
          loop_filter_h(frag->buffer[_refi],iplane->stride,_bv);
        }
        if(frag0>frag_top){
          loop_filter_v(frag->buffer[_refi],iplane->stride,_bv);
        }
        if(frag+1<frag_end&&!(frag+1)->coded){
          loop_filter_h(frag->buffer[_refi]+8,iplane->stride,_bv);
        }
        if(frag+fplane->nhfrags<frag_bot&&!(frag+fplane->nhfrags)->coded){
          loop_filter_v((frag+fplane->nhfrags)->buffer[_refi],
           iplane->stride,_bv);
        }
      }


#ifdef _TH_DEBUG_
      {
	int i,j,k,l;
	unsigned char *src;
	
	for(l=0;l<5;l++){
	  oc_fragment *f;
	  switch(l){
	  case 0: 
	    f = frag;
	    break;
	  case 1: /* left */
	    if(frag == frag0)continue;
	    f = frag-1;
	    break;
	  case 2: /* bottom (top once flipped) */
	    if(frag0 == frag_top)continue;
	    f = frag - fplane->nhfrags;
	    break;
	  case 3: /* right */
	    if(frag+1 >= frag_end) continue;
	    f = frag + 1;
	    break;
	  case 4: /* top (bottom once flipped) */
	    if(frag+fplane->nhfrags >= frag_bot)continue;
	    f = frag + fplane->nhfrags;
	    break;
	  }
	  
	  src = f->buffer[_refi];
	  for(i=0,j=0;j<8;j++){
	    for(k=0;k<8;k++,i++)
	      f->loop[i] = src[k];
	    src+=iplane->stride;
	  }
	}
      }
#endif
      frag++;
    }
    frag0+=fplane->nhfrags;
  }
}

#if defined(OC_DUMP_IMAGES)
int oc_state_dump_frame(const oc_theora_state *_state,int _frame,
 const char *_suf){
  /*Dump a PNG of the reconstructed image.*/
  png_structp    png;
  png_infop      info;
  png_bytep     *image;
  FILE          *fp;
  char           fname[16];
  unsigned char *y_row;
  unsigned char *u_row;
  unsigned char *v_row;
  unsigned char *y;
  unsigned char *u;
  unsigned char *v;
  ogg_int64_t    iframe;
  ogg_int64_t    pframe;
  int            y_stride;
  int            u_stride;
  int            v_stride;
  int            framei;
  int            width;
  int            height;
  int            imgi;
  int            imgj;
  width=_state->info.frame_width;
  height=_state->info.frame_height;
  iframe=_state->granpos>>_state->info.keyframe_granule_shift;
  pframe=_state->granpos-(iframe<<_state->info.keyframe_granule_shift);
  sprintf(fname,"%08i%s.png",(int)(iframe+pframe),_suf);
  fp=fopen(fname,"wb");
  if(fp==NULL)return TH_EFAULT;
  image=(png_bytep *)oc_malloc_2d(height,6*width,sizeof(image[0][0]));
  png=png_create_write_struct(PNG_LIBPNG_VER_STRING,NULL,NULL,NULL);
  if(png==NULL){
    oc_free_2d(image);
    fclose(fp);
    return TH_EFAULT;
  }
  info=png_create_info_struct(png);
  if(info==NULL){
    png_destroy_write_struct(&png,NULL);
    oc_free_2d(image);
    fclose(fp);
    return TH_EFAULT;
  }
  if(setjmp(png_jmpbuf(png))){
    png_destroy_write_struct(&png,&info);
    oc_free_2d(image);
    fclose(fp);
    return TH_EFAULT;
  }
  framei=_state->ref_frame_idx[_frame];
  y_row=_state->ref_frame_bufs[framei][0].data;
  u_row=_state->ref_frame_bufs[framei][1].data;
  v_row=_state->ref_frame_bufs[framei][2].data;
  y_stride=_state->ref_frame_bufs[framei][0].stride;
  u_stride=_state->ref_frame_bufs[framei][1].stride;
  v_stride=_state->ref_frame_bufs[framei][2].stride;
  /*Chroma up-sampling is just done with a box filter.
    This is very likely what will actually be used in practice on a real
     display, and also removes one more layer to search in for the source of
     artifacts.
    As an added bonus, it's dead simple.*/
  for(imgi=height;imgi-->0;){
    int dc;
    y=y_row;
    u=u_row;
    v=v_row;
    for(imgj=0;imgj<6*width;){
      float    yval;
      float    uval;
      float    vval;
      unsigned rval;
      unsigned gval;
      unsigned bval;
      /*This is intentionally slow and very accurate.*/
      yval=(*y-16)*(1.0F/219);
      uval=(*u-128)*(2*(1-0.114F)/224);
      vval=(*v-128)*(2*(1-0.299F)/224);
      rval=OC_CLAMPI(0,(int)(65535*(yval+vval)+0.5F),65535);
      gval=OC_CLAMPI(0,(int)(65535*(
       yval-uval*(0.114F/0.587F)-vval*(0.299F/0.587F))+0.5F),65535);
      bval=OC_CLAMPI(0,(int)(65535*(yval+uval)+0.5F),65535);
      image[imgi][imgj++]=(unsigned char)(rval>>8);
      image[imgi][imgj++]=(unsigned char)(rval&0xFF);
      image[imgi][imgj++]=(unsigned char)(gval>>8);
      image[imgi][imgj++]=(unsigned char)(gval&0xFF);
      image[imgi][imgj++]=(unsigned char)(bval>>8);
      image[imgi][imgj++]=(unsigned char)(bval&0xFF);
      dc=(y-y_row&1)|(_state->info.pixel_fmt&1);
      y++;
      u+=dc;
      v+=dc;
    }
    dc=-((height-1-imgi&1)|_state->info.pixel_fmt>>1);
    y_row+=y_stride;
    u_row+=dc&u_stride;
    v_row+=dc&v_stride;
  }
  png_init_io(png,fp);
  png_set_compression_level(png,Z_BEST_COMPRESSION);
  png_set_IHDR(png,info,width,height,16,PNG_COLOR_TYPE_RGB,
   PNG_INTERLACE_NONE,PNG_COMPRESSION_TYPE_DEFAULT,PNG_FILTER_TYPE_DEFAULT);
  switch(_state->info.colorspace){
    case TH_CS_ITU_REC_470M:{
      png_set_gAMA(png,info,2.2);
      png_set_cHRM_fixed(png,info,31006,31616,
       67000,32000,21000,71000,14000,8000);
    }break;
    case TH_CS_ITU_REC_470BG:{
      png_set_gAMA(png,info,2.67);
      png_set_cHRM_fixed(png,info,31271,32902,
       64000,33000,29000,60000,15000,6000);
    }break;
  }
  png_set_pHYs(png,info,_state->info.aspect_numerator,
   _state->info.aspect_denominator,0);
  png_set_rows(png,info,image);
  png_write_png(png,info,PNG_TRANSFORM_IDENTITY,NULL);
  png_write_end(png,info);
  png_destroy_write_struct(&png,&info);
  oc_free_2d(image);
  fclose(fp);
  return 0;
}
#endif



ogg_int64_t th_granule_frame(void *_encdec,ogg_int64_t _granpos){
  oc_theora_state *state;
  state=(oc_theora_state *)_encdec;
  if(_granpos>=0){
    ogg_int64_t iframe;
    ogg_int64_t pframe;
    iframe=_granpos>>state->info.keyframe_granule_shift;
    pframe=_granpos-(iframe<<state->info.keyframe_granule_shift);
    /*3.2.0 streams store the frame index in the granule position.
      3.2.1 and later store the frame count.
      We return the index, so adjust the value if we have a 3.2.1 or later
       stream.*/
    return iframe+pframe-TH_VERSION_CHECK(&state->info,3,2,1);
  }
  return -1;
}

double th_granule_time(void *_encdec,ogg_int64_t _granpos){
  oc_theora_state *state;
  state=(oc_theora_state *)_encdec;
  if(_granpos>=0){
    return (th_granule_frame(_encdec, _granpos)+1)*(
     (double)state->info.fps_denominator/state->info.fps_numerator);
  }
  return -1;
}