comparison src/libvorbis-1.3.3/lib/vorbisfile.c @ 1:05aa0afa9217

Bring in flac, ogg, vorbis

+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE OggVorbis 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 OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
+ * by the Xiph.Org Foundation http://www.xiph.org/                  *
+ *                                                                  *
+ ********************************************************************
+
+ function: stdio-based convenience library for opening/seeking/decoding
+ last mod: $Id: vorbisfile.c 17573 2010-10-27 14:53:59Z xiphmont $
+
+ ********************************************************************/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <math.h>
+
+#include "vorbis/codec.h"
+
+/* we don't need or want the static callback symbols here */
+#define OV_EXCLUDE_STATIC_CALLBACKS
+#include "vorbis/vorbisfile.h"
+
+#include "os.h"
+#include "misc.h"
+
+/* A 'chained bitstream' is a Vorbis bitstream that contains more than
+   one logical bitstream arranged end to end (the only form of Ogg
+   multiplexing allowed in a Vorbis bitstream; grouping [parallel
+   multiplexing] is not allowed in Vorbis) */
+
+/* A Vorbis file can be played beginning to end (streamed) without
+   worrying ahead of time about chaining (see decoder_example.c).  If
+   we have the whole file, however, and want random access
+   (seeking/scrubbing) or desire to know the total length/time of a
+   file, we need to account for the possibility of chaining. */
+
+/* We can handle things a number of ways; we can determine the entire
+   bitstream structure right off the bat, or find pieces on demand.
+   This example determines and caches structure for the entire
+   bitstream, but builds a virtual decoder on the fly when moving
+   between links in the chain. */
+
+/* There are also different ways to implement seeking.  Enough
+   information exists in an Ogg bitstream to seek to
+   sample-granularity positions in the output.  Or, one can seek by
+   picking some portion of the stream roughly in the desired area if
+   we only want coarse navigation through the stream. */
+
+/*************************************************************************
+ * Many, many internal helpers.  The intention is not to be confusing;
+ * rampant duplication and monolithic function implementation would be
+ * harder to understand anyway.  The high level functions are last.  Begin
+ * grokking near the end of the file */
+
+/* read a little more data from the file/pipe into the ogg_sync framer
+*/
+#define CHUNKSIZE 65536 /* greater-than-page-size granularity seeking */
+#define READSIZE 2048 /* a smaller read size is needed for low-rate streaming. */
+
+static long _get_data(OggVorbis_File *vf){
+  errno=0;
+  if(!(vf->callbacks.read_func))return(-1);
+  if(vf->datasource){
+    char *buffer=ogg_sync_buffer(&vf->oy,READSIZE);
+    long bytes=(vf->callbacks.read_func)(buffer,1,READSIZE,vf->datasource);
+    if(bytes>0)ogg_sync_wrote(&vf->oy,bytes);
+    if(bytes==0 && errno)return(-1);
+    return(bytes);
+  }else
+    return(0);
+}
+
+/* save a tiny smidge of verbosity to make the code more readable */
+static int _seek_helper(OggVorbis_File *vf,ogg_int64_t offset){
+  if(vf->datasource){
+    if(!(vf->callbacks.seek_func)||
+       (vf->callbacks.seek_func)(vf->datasource, offset, SEEK_SET) == -1)
+      return OV_EREAD;
+    vf->offset=offset;
+    ogg_sync_reset(&vf->oy);
+  }else{
+    /* shouldn't happen unless someone writes a broken callback */
+    return OV_EFAULT;
+  }
+  return 0;
+}
+
+/* The read/seek functions track absolute position within the stream */
+
+/* from the head of the stream, get the next page.  boundary specifies
+   if the function is allowed to fetch more data from the stream (and
+   how much) or only use internally buffered data.
+
+   boundary: -1) unbounded search
+              0) read no additional data; use cached only
+              n) search for a new page beginning for n bytes
+
+   return:   <0) did not find a page (OV_FALSE, OV_EOF, OV_EREAD)
+              n) found a page at absolute offset n */
+
+static ogg_int64_t _get_next_page(OggVorbis_File *vf,ogg_page *og,
+                                  ogg_int64_t boundary){
+  if(boundary>0)boundary+=vf->offset;
+  while(1){
+    long more;
+
+    if(boundary>0 && vf->offset>=boundary)return(OV_FALSE);
+    more=ogg_sync_pageseek(&vf->oy,og);
+
+    if(more<0){
+      /* skipped n bytes */
+      vf->offset-=more;
+    }else{
+      if(more==0){
+        /* send more paramedics */
+        if(!boundary)return(OV_FALSE);
+        {
+          long ret=_get_data(vf);
+          if(ret==0)return(OV_EOF);
+          if(ret<0)return(OV_EREAD);
+        }
+      }else{
+        /* got a page.  Return the offset at the page beginning,
+           advance the internal offset past the page end */
+        ogg_int64_t ret=vf->offset;
+        vf->offset+=more;
+        return(ret);
+
+      }
+    }
+  }
+}
+
+/* find the latest page beginning before the current stream cursor
+   position. Much dirtier than the above as Ogg doesn't have any
+   backward search linkage.  no 'readp' as it will certainly have to
+   read. */
+/* returns offset or OV_EREAD, OV_FAULT */
+static ogg_int64_t _get_prev_page(OggVorbis_File *vf,ogg_page *og){
+  ogg_int64_t begin=vf->offset;
+  ogg_int64_t end=begin;
+  ogg_int64_t ret;
+  ogg_int64_t offset=-1;
+
+  while(offset==-1){
+    begin-=CHUNKSIZE;
+    if(begin<0)
+      begin=0;
+
+    ret=_seek_helper(vf,begin);
+    if(ret)return(ret);
+
+    while(vf->offset<end){
+      memset(og,0,sizeof(*og));
+      ret=_get_next_page(vf,og,end-vf->offset);
+      if(ret==OV_EREAD)return(OV_EREAD);
+      if(ret<0){
+        break;
+      }else{
+        offset=ret;
+      }
+    }
+  }
+
+  /* In a fully compliant, non-multiplexed stream, we'll still be
+     holding the last page.  In multiplexed (or noncompliant streams),
+     we will probably have to re-read the last page we saw */
+  if(og->header_len==0){
+    ret=_seek_helper(vf,offset);
+    if(ret)return(ret);
+
+    ret=_get_next_page(vf,og,CHUNKSIZE);
+    if(ret<0)
+      /* this shouldn't be possible */
+      return(OV_EFAULT);
+  }
+
+  return(offset);
+}
+
+static void _add_serialno(ogg_page *og,long **serialno_list, int *n){
+  long s = ogg_page_serialno(og);
+  (*n)++;
+
+  if(*serialno_list){
+    *serialno_list = _ogg_realloc(*serialno_list, sizeof(**serialno_list)*(*n));
+  }else{
+    *serialno_list = _ogg_malloc(sizeof(**serialno_list));
+  }
+
+  (*serialno_list)[(*n)-1] = s;
+}
+
+/* returns nonzero if found */
+static int _lookup_serialno(long s, long *serialno_list, int n){
+  if(serialno_list){
+    while(n--){
+      if(*serialno_list == s) return 1;
+      serialno_list++;
+    }
+  }
+  return 0;
+}
+
+static int _lookup_page_serialno(ogg_page *og, long *serialno_list, int n){
+  long s = ogg_page_serialno(og);
+  return _lookup_serialno(s,serialno_list,n);
+}
+
+/* performs the same search as _get_prev_page, but prefers pages of
+   the specified serial number. If a page of the specified serialno is
+   spotted during the seek-back-and-read-forward, it will return the
+   info of last page of the matching serial number instead of the very
+   last page.  If no page of the specified serialno is seen, it will
+   return the info of last page and alter *serialno.  */
+static ogg_int64_t _get_prev_page_serial(OggVorbis_File *vf,
+                                         long *serial_list, int serial_n,
+                                         int *serialno, ogg_int64_t *granpos){
+  ogg_page og;
+  ogg_int64_t begin=vf->offset;
+  ogg_int64_t end=begin;
+  ogg_int64_t ret;
+
+  ogg_int64_t prefoffset=-1;
+  ogg_int64_t offset=-1;
+  ogg_int64_t ret_serialno=-1;
+  ogg_int64_t ret_gran=-1;
+
+  while(offset==-1){
+    begin-=CHUNKSIZE;
+    if(begin<0)
+      begin=0;
+
+    ret=_seek_helper(vf,begin);
+    if(ret)return(ret);
+
+    while(vf->offset<end){
+      ret=_get_next_page(vf,&og,end-vf->offset);
+      if(ret==OV_EREAD)return(OV_EREAD);
+      if(ret<0){
+        break;
+      }else{
+        ret_serialno=ogg_page_serialno(&og);
+        ret_gran=ogg_page_granulepos(&og);
+        offset=ret;
+
+        if(ret_serialno == *serialno){
+          prefoffset=ret;
+          *granpos=ret_gran;
+        }
+
+        if(!_lookup_serialno(ret_serialno,serial_list,serial_n)){
+          /* we fell off the end of the link, which means we seeked
+             back too far and shouldn't have been looking in that link
+             to begin with.  If we found the preferred serial number,
+             forget that we saw it. */
+          prefoffset=-1;
+        }
+      }
+    }
+  }
+
+  /* we're not interested in the page... just the serialno and granpos. */
+  if(prefoffset>=0)return(prefoffset);
+
+  *serialno = ret_serialno;
+  *granpos = ret_gran;
+  return(offset);
+
+}
+
+/* uses the local ogg_stream storage in vf; this is important for
+   non-streaming input sources */
+static int _fetch_headers(OggVorbis_File *vf,vorbis_info *vi,vorbis_comment *vc,
+                          long **serialno_list, int *serialno_n,
+                          ogg_page *og_ptr){
+  ogg_page og;
+  ogg_packet op;
+  int i,ret;
+  int allbos=0;
+
+  if(!og_ptr){
+    ogg_int64_t llret=_get_next_page(vf,&og,CHUNKSIZE);
+    if(llret==OV_EREAD)return(OV_EREAD);
+    if(llret<0)return(OV_ENOTVORBIS);
+    og_ptr=&og;
+  }
+
+  vorbis_info_init(vi);
+  vorbis_comment_init(vc);
+  vf->ready_state=OPENED;
+
+  /* extract the serialnos of all BOS pages + the first set of vorbis
+     headers we see in the link */
+
+  while(ogg_page_bos(og_ptr)){
+    if(serialno_list){
+      if(_lookup_page_serialno(og_ptr,*serialno_list,*serialno_n)){
+        /* a dupe serialnumber in an initial header packet set == invalid stream */
+        if(*serialno_list)_ogg_free(*serialno_list);
+        *serialno_list=0;
+        *serialno_n=0;
+        ret=OV_EBADHEADER;
+        goto bail_header;
+      }
+
+      _add_serialno(og_ptr,serialno_list,serialno_n);
+    }
+
+    if(vf->ready_state<STREAMSET){
+      /* we don't have a vorbis stream in this link yet, so begin
+         prospective stream setup. We need a stream to get packets */
+      ogg_stream_reset_serialno(&vf->os,ogg_page_serialno(og_ptr));
+      ogg_stream_pagein(&vf->os,og_ptr);
+
+      if(ogg_stream_packetout(&vf->os,&op) > 0 &&
+         vorbis_synthesis_idheader(&op)){
+        /* vorbis header; continue setup */
+        vf->ready_state=STREAMSET;
+        if((ret=vorbis_synthesis_headerin(vi,vc,&op))){
+          ret=OV_EBADHEADER;
+          goto bail_header;
+        }
+      }
+    }
+
+    /* get next page */
+    {
+      ogg_int64_t llret=_get_next_page(vf,og_ptr,CHUNKSIZE);
+      if(llret==OV_EREAD){
+        ret=OV_EREAD;
+        goto bail_header;
+      }
+      if(llret<0){
+        ret=OV_ENOTVORBIS;
+        goto bail_header;
+      }
+
+      /* if this page also belongs to our vorbis stream, submit it and break */
+      if(vf->ready_state==STREAMSET &&
+         vf->os.serialno == ogg_page_serialno(og_ptr)){
+        ogg_stream_pagein(&vf->os,og_ptr);
+        break;
+      }
+    }
+  }
+
+  if(vf->ready_state!=STREAMSET){
+    ret = OV_ENOTVORBIS;
+    goto bail_header;
+  }
+
+  while(1){
+
+    i=0;
+    while(i<2){ /* get a page loop */
+
+      while(i<2){ /* get a packet loop */
+
+        int result=ogg_stream_packetout(&vf->os,&op);
+        if(result==0)break;
+        if(result==-1){
+          ret=OV_EBADHEADER;
+          goto bail_header;
+        }
+
+        if((ret=vorbis_synthesis_headerin(vi,vc,&op)))
+          goto bail_header;
+
+        i++;
+      }
+
+      while(i<2){
+        if(_get_next_page(vf,og_ptr,CHUNKSIZE)<0){
+          ret=OV_EBADHEADER;
+          goto bail_header;
+        }
+
+        /* if this page belongs to the correct stream, go parse it */
+        if(vf->os.serialno == ogg_page_serialno(og_ptr)){
+          ogg_stream_pagein(&vf->os,og_ptr);
+          break;
+        }
+
+        /* if we never see the final vorbis headers before the link
+           ends, abort */
+        if(ogg_page_bos(og_ptr)){
+          if(allbos){
+            ret = OV_EBADHEADER;
+            goto bail_header;
+          }else
+            allbos=1;
+        }
+
+        /* otherwise, keep looking */
+      }
+    }
+
+    return 0;
+  }
+
+ bail_header:
+  vorbis_info_clear(vi);
+  vorbis_comment_clear(vc);
+  vf->ready_state=OPENED;
+
+  return ret;
+}
+
+/* Starting from current cursor position, get initial PCM offset of
+   next page.  Consumes the page in the process without decoding
+   audio, however this is only called during stream parsing upon
+   seekable open. */
+static ogg_int64_t _initial_pcmoffset(OggVorbis_File *vf, vorbis_info *vi){
+  ogg_page    og;
+  ogg_int64_t accumulated=0;
+  long        lastblock=-1;
+  int         result;
+  int         serialno = vf->os.serialno;
+
+  while(1){
+    ogg_packet op;
+    if(_get_next_page(vf,&og,-1)<0)
+      break; /* should not be possible unless the file is truncated/mangled */
+
+    if(ogg_page_bos(&og)) break;
+    if(ogg_page_serialno(&og)!=serialno) continue;
+
+    /* count blocksizes of all frames in the page */
+    ogg_stream_pagein(&vf->os,&og);
+    while((result=ogg_stream_packetout(&vf->os,&op))){
+      if(result>0){ /* ignore holes */
+        long thisblock=vorbis_packet_blocksize(vi,&op);
+        if(lastblock!=-1)
+          accumulated+=(lastblock+thisblock)>>2;
+        lastblock=thisblock;
+      }
+    }
+
+    if(ogg_page_granulepos(&og)!=-1){
+      /* pcm offset of last packet on the first audio page */
+      accumulated= ogg_page_granulepos(&og)-accumulated;
+      break;
+    }
+  }
+
+  /* less than zero?  Either a corrupt file or a stream with samples
+     trimmed off the beginning, a normal occurrence; in both cases set
+     the offset to zero */
+  if(accumulated<0)accumulated=0;
+
+  return accumulated;
+}
+
+/* finds each bitstream link one at a time using a bisection search
+   (has to begin by knowing the offset of the lb's initial page).
+   Recurses for each link so it can alloc the link storage after
+   finding them all, then unroll and fill the cache at the same time */
+static int _bisect_forward_serialno(OggVorbis_File *vf,
+                                    ogg_int64_t begin,
+                                    ogg_int64_t searched,
+                                    ogg_int64_t end,
+                                    ogg_int64_t endgran,
+                                    int endserial,
+                                    long *currentno_list,
+                                    int  currentnos,
+                                    long m){
+  ogg_int64_t pcmoffset;
+  ogg_int64_t dataoffset=searched;
+  ogg_int64_t endsearched=end;
+  ogg_int64_t next=end;
+  ogg_int64_t searchgran=-1;
+  ogg_page og;
+  ogg_int64_t ret,last;
+  int serialno = vf->os.serialno;
+
+  /* invariants:
+     we have the headers and serialnos for the link beginning at 'begin'
+     we have the offset and granpos of the last page in the file (potentially
+       not a page we care about)
+  */
+
+  /* Is the last page in our list of current serialnumbers? */
+  if(_lookup_serialno(endserial,currentno_list,currentnos)){
+
+    /* last page is in the starting serialno list, so we've bisected
+       down to (or just started with) a single link.  Now we need to
+       find the last vorbis page belonging to the first vorbis stream
+       for this link. */
+
+    while(endserial != serialno){
+      endserial = serialno;
+      vf->offset=_get_prev_page_serial(vf,currentno_list,currentnos,&endserial,&endgran);
+    }
+
+    vf->links=m+1;
+    if(vf->offsets)_ogg_free(vf->offsets);
+    if(vf->serialnos)_ogg_free(vf->serialnos);
+    if(vf->dataoffsets)_ogg_free(vf->dataoffsets);
+
+    vf->offsets=_ogg_malloc((vf->links+1)*sizeof(*vf->offsets));
+    vf->vi=_ogg_realloc(vf->vi,vf->links*sizeof(*vf->vi));
+    vf->vc=_ogg_realloc(vf->vc,vf->links*sizeof(*vf->vc));
+    vf->serialnos=_ogg_malloc(vf->links*sizeof(*vf->serialnos));
+    vf->dataoffsets=_ogg_malloc(vf->links*sizeof(*vf->dataoffsets));
+    vf->pcmlengths=_ogg_malloc(vf->links*2*sizeof(*vf->pcmlengths));
+
+    vf->offsets[m+1]=end;
+    vf->offsets[m]=begin;
+    vf->pcmlengths[m*2+1]=(endgran<0?0:endgran);
+
+  }else{
+
+    long *next_serialno_list=NULL;
+    int next_serialnos=0;
+    vorbis_info vi;
+    vorbis_comment vc;
+
+    /* the below guards against garbage seperating the last and
+       first pages of two links. */
+    while(searched<endsearched){
+      ogg_int64_t bisect;
+
+      if(endsearched-searched<CHUNKSIZE){
+        bisect=searched;
+      }else{
+        bisect=(searched+endsearched)/2;
+      }
+
+      if(bisect != vf->offset){
+        ret=_seek_helper(vf,bisect);
+        if(ret)return(ret);
+      }
+
+      last=_get_next_page(vf,&og,-1);
+      if(last==OV_EREAD)return(OV_EREAD);
+      if(last<0 || !_lookup_page_serialno(&og,currentno_list,currentnos)){
+        endsearched=bisect;
+        if(last>=0)next=last;
+      }else{
+        searched=vf->offset;
+      }
+    }
+
+    /* Bisection point found */
+
+    /* for the time being, fetch end PCM offset the simple way */
+    {
+      int testserial = serialno+1;
+      vf->offset = next;
+      while(testserial != serialno){
+        testserial = serialno;
+        vf->offset=_get_prev_page_serial(vf,currentno_list,currentnos,&testserial,&searchgran);
+      }
+    }
+
+    if(vf->offset!=next){
+      ret=_seek_helper(vf,next);
+      if(ret)return(ret);
+    }
+
+    ret=_fetch_headers(vf,&vi,&vc,&next_serialno_list,&next_serialnos,NULL);
+    if(ret)return(ret);
+    serialno = vf->os.serialno;
+    dataoffset = vf->offset;
+
+    /* this will consume a page, however the next bistection always
+       starts with a raw seek */
+    pcmoffset = _initial_pcmoffset(vf,&vi);
+
+    ret=_bisect_forward_serialno(vf,next,vf->offset,end,endgran,endserial,
+                                 next_serialno_list,next_serialnos,m+1);
+    if(ret)return(ret);
+
+    if(next_serialno_list)_ogg_free(next_serialno_list);
+
+    vf->offsets[m+1]=next;
+    vf->serialnos[m+1]=serialno;
+    vf->dataoffsets[m+1]=dataoffset;
+
+    vf->vi[m+1]=vi;
+    vf->vc[m+1]=vc;
+
+    vf->pcmlengths[m*2+1]=searchgran;
+    vf->pcmlengths[m*2+2]=pcmoffset;
+    vf->pcmlengths[m*2+3]-=pcmoffset;
+    if(vf->pcmlengths[m*2+3]<0)vf->pcmlengths[m*2+3]=0;
+  }
+  return(0);
+}
+
+static int _make_decode_ready(OggVorbis_File *vf){
+  if(vf->ready_state>STREAMSET)return 0;
+  if(vf->ready_state<STREAMSET)return OV_EFAULT;
+  if(vf->seekable){
+    if(vorbis_synthesis_init(&vf->vd,vf->vi+vf->current_link))
+      return OV_EBADLINK;
+  }else{
+    if(vorbis_synthesis_init(&vf->vd,vf->vi))
+      return OV_EBADLINK;
+  }
+  vorbis_block_init(&vf->vd,&vf->vb);
+  vf->ready_state=INITSET;
+  vf->bittrack=0.f;
+  vf->samptrack=0.f;
+  return 0;
+}
+
+static int _open_seekable2(OggVorbis_File *vf){
+  ogg_int64_t dataoffset=vf->dataoffsets[0],end,endgran=-1;
+  int endserial=vf->os.serialno;
+  int serialno=vf->os.serialno;
+
+  /* we're partially open and have a first link header state in
+     storage in vf */
+
+  /* fetch initial PCM offset */
+  ogg_int64_t pcmoffset = _initial_pcmoffset(vf,vf->vi);
+
+  /* we can seek, so set out learning all about this file */
+  if(vf->callbacks.seek_func && vf->callbacks.tell_func){
+    (vf->callbacks.seek_func)(vf->datasource,0,SEEK_END);
+    vf->offset=vf->end=(vf->callbacks.tell_func)(vf->datasource);
+  }else{
+    vf->offset=vf->end=-1;
+  }
+
+  /* If seek_func is implemented, tell_func must also be implemented */
+  if(vf->end==-1) return(OV_EINVAL);
+
+  /* Get the offset of the last page of the physical bitstream, or, if
+     we're lucky the last vorbis page of this link as most OggVorbis
+     files will contain a single logical bitstream */
+  end=_get_prev_page_serial(vf,vf->serialnos+2,vf->serialnos[1],&endserial,&endgran);
+  if(end<0)return(end);
+
+  /* now determine bitstream structure recursively */
+  if(_bisect_forward_serialno(vf,0,dataoffset,vf->offset,endgran,endserial,
+                              vf->serialnos+2,vf->serialnos[1],0)<0)return(OV_EREAD);
+
+  vf->offsets[0]=0;
+  vf->serialnos[0]=serialno;
+  vf->dataoffsets[0]=dataoffset;
+  vf->pcmlengths[0]=pcmoffset;
+  vf->pcmlengths[1]-=pcmoffset;
+  if(vf->pcmlengths[1]<0)vf->pcmlengths[1]=0;
+
+  return(ov_raw_seek(vf,dataoffset));
+}
+
+/* clear out the current logical bitstream decoder */
+static void _decode_clear(OggVorbis_File *vf){
+  vorbis_dsp_clear(&vf->vd);
+  vorbis_block_clear(&vf->vb);
+  vf->ready_state=OPENED;
+}
+
+/* fetch and process a packet.  Handles the case where we're at a
+   bitstream boundary and dumps the decoding machine.  If the decoding
+   machine is unloaded, it loads it.  It also keeps pcm_offset up to
+   date (seek and read both use this.  seek uses a special hack with
+   readp).
+
+   return: <0) error, OV_HOLE (lost packet) or OV_EOF
+            0) need more data (only if readp==0)
+            1) got a packet
+*/
+
+static int _fetch_and_process_packet(OggVorbis_File *vf,
+                                     ogg_packet *op_in,
+                                     int readp,
+                                     int spanp){
+  ogg_page og;
+
+  /* handle one packet.  Try to fetch it from current stream state */
+  /* extract packets from page */
+  while(1){
+
+    if(vf->ready_state==STREAMSET){
+      int ret=_make_decode_ready(vf);
+      if(ret<0)return ret;
+    }
+
+    /* process a packet if we can. */
+
+    if(vf->ready_state==INITSET){
+      int hs=vorbis_synthesis_halfrate_p(vf->vi);
+
+      while(1) {
+              ogg_packet op;
+              ogg_packet *op_ptr=(op_in?op_in:&op);
+        int result=ogg_stream_packetout(&vf->os,op_ptr);
+        ogg_int64_t granulepos;
+
+        op_in=NULL;
+        if(result==-1)return(OV_HOLE); /* hole in the data. */
+        if(result>0){
+          /* got a packet.  process it */
+          granulepos=op_ptr->granulepos;
+          if(!vorbis_synthesis(&vf->vb,op_ptr)){ /* lazy check for lazy
+                                                    header handling.  The
+                                                    header packets aren't
+                                                    audio, so if/when we
+                                                    submit them,
+                                                    vorbis_synthesis will
+                                                    reject them */
+
+            /* suck in the synthesis data and track bitrate */
+            {
+              int oldsamples=vorbis_synthesis_pcmout(&vf->vd,NULL);
+              /* for proper use of libvorbis within libvorbisfile,
+                 oldsamples will always be zero. */
+              if(oldsamples)return(OV_EFAULT);
+
+              vorbis_synthesis_blockin(&vf->vd,&vf->vb);
+              vf->samptrack+=(vorbis_synthesis_pcmout(&vf->vd,NULL)<<hs);
+              vf->bittrack+=op_ptr->bytes*8;
+            }
+
+            /* update the pcm offset. */
+            if(granulepos!=-1 && !op_ptr->e_o_s){
+              int link=(vf->seekable?vf->current_link:0);
+              int i,samples;
+
+              /* this packet has a pcm_offset on it (the last packet
+                 completed on a page carries the offset) After processing
+                 (above), we know the pcm position of the *last* sample
+                 ready to be returned. Find the offset of the *first*
+
+                 As an aside, this trick is inaccurate if we begin
+                 reading anew right at the last page; the end-of-stream
+                 granulepos declares the last frame in the stream, and the
+                 last packet of the last page may be a partial frame.
+                 So, we need a previous granulepos from an in-sequence page
+                 to have a reference point.  Thus the !op_ptr->e_o_s clause
+                 above */
+
+              if(vf->seekable && link>0)
+                granulepos-=vf->pcmlengths[link*2];
+              if(granulepos<0)granulepos=0; /* actually, this
+                                               shouldn't be possible
+                                               here unless the stream
+                                               is very broken */
+
+              samples=(vorbis_synthesis_pcmout(&vf->vd,NULL)<<hs);
+
+              granulepos-=samples;
+              for(i=0;i<link;i++)
+                granulepos+=vf->pcmlengths[i*2+1];
+              vf->pcm_offset=granulepos;
+            }
+            return(1);
+          }
+        }
+        else
+          break;
+      }
+    }
+
+    if(vf->ready_state>=OPENED){
+      ogg_int64_t ret;
+
+      while(1){
+        /* the loop is not strictly necessary, but there's no sense in
+           doing the extra checks of the larger loop for the common
+           case in a multiplexed bistream where the page is simply
+           part of a different logical bitstream; keep reading until
+           we get one with the correct serialno */
+
+        if(!readp)return(0);
+        if((ret=_get_next_page(vf,&og,-1))<0){
+          return(OV_EOF); /* eof. leave unitialized */
+        }
+
+        /* bitrate tracking; add the header's bytes here, the body bytes
+           are done by packet above */
+        vf->bittrack+=og.header_len*8;
+
+        if(vf->ready_state==INITSET){
+          if(vf->current_serialno!=ogg_page_serialno(&og)){
+
+            /* two possibilities:
+               1) our decoding just traversed a bitstream boundary
+               2) another stream is multiplexed into this logical section */
+
+            if(ogg_page_bos(&og)){
+              /* boundary case */
+              if(!spanp)
+                return(OV_EOF);
+
+              _decode_clear(vf);
+
+              if(!vf->seekable){
+                vorbis_info_clear(vf->vi);
+                vorbis_comment_clear(vf->vc);
+              }
+              break;
+
+            }else
+              continue; /* possibility #2 */
+          }
+        }
+
+        break;
+      }
+    }
+
+    /* Do we need to load a new machine before submitting the page? */
+    /* This is different in the seekable and non-seekable cases.
+
+       In the seekable case, we already have all the header
+       information loaded and cached; we just initialize the machine
+       with it and continue on our merry way.
+
+       In the non-seekable (streaming) case, we'll only be at a
+       boundary if we just left the previous logical bitstream and
+       we're now nominally at the header of the next bitstream
+    */
+
+    if(vf->ready_state!=INITSET){
+      int link;
+
+      if(vf->ready_state<STREAMSET){
+        if(vf->seekable){
+          long serialno = ogg_page_serialno(&og);
+
+          /* match the serialno to bitstream section.  We use this rather than
+             offset positions to avoid problems near logical bitstream
+             boundaries */
+
+          for(link=0;link<vf->links;link++)
+            if(vf->serialnos[link]==serialno)break;
+
+          if(link==vf->links) continue; /* not the desired Vorbis
+                                           bitstream section; keep
+                                           trying */
+
+          vf->current_serialno=serialno;
+          vf->current_link=link;
+
+          ogg_stream_reset_serialno(&vf->os,vf->current_serialno);
+          vf->ready_state=STREAMSET;
+
+        }else{
+          /* we're streaming */
+          /* fetch the three header packets, build the info struct */
+
+          int ret=_fetch_headers(vf,vf->vi,vf->vc,NULL,NULL,&og);
+          if(ret)return(ret);
+          vf->current_serialno=vf->os.serialno;
+          vf->current_link++;
+          link=0;
+        }
+      }
+    }
+
+    /* the buffered page is the data we want, and we're ready for it;
+       add it to the stream state */
+    ogg_stream_pagein(&vf->os,&og);
+
+  }
+}
+
+/* if, eg, 64 bit stdio is configured by default, this will build with
+   fseek64 */
+static int _fseek64_wrap(FILE *f,ogg_int64_t off,int whence){
+  if(f==NULL)return(-1);
+  return fseek(f,off,whence);
+}
+
+static int _ov_open1(void *f,OggVorbis_File *vf,const char *initial,
+                     long ibytes, ov_callbacks callbacks){
+  int offsettest=((f && callbacks.seek_func)?callbacks.seek_func(f,0,SEEK_CUR):-1);
+  long *serialno_list=NULL;
+  int serialno_list_size=0;
+  int ret;
+
+  memset(vf,0,sizeof(*vf));
+  vf->datasource=f;
+  vf->callbacks = callbacks;
+
+  /* init the framing state */
+  ogg_sync_init(&vf->oy);
+
+  /* perhaps some data was previously read into a buffer for testing
+     against other stream types.  Allow initialization from this
+     previously read data (especially as we may be reading from a
+     non-seekable stream) */
+  if(initial){
+    char *buffer=ogg_sync_buffer(&vf->oy,ibytes);
+    memcpy(buffer,initial,ibytes);
+    ogg_sync_wrote(&vf->oy,ibytes);
+  }
+
+  /* can we seek? Stevens suggests the seek test was portable */
+  if(offsettest!=-1)vf->seekable=1;
+
+  /* No seeking yet; Set up a 'single' (current) logical bitstream
+     entry for partial open */
+  vf->links=1;
+  vf->vi=_ogg_calloc(vf->links,sizeof(*vf->vi));
+  vf->vc=_ogg_calloc(vf->links,sizeof(*vf->vc));
+  ogg_stream_init(&vf->os,-1); /* fill in the serialno later */
+
+  /* Fetch all BOS pages, store the vorbis header and all seen serial
+     numbers, load subsequent vorbis setup headers */
+  if((ret=_fetch_headers(vf,vf->vi,vf->vc,&serialno_list,&serialno_list_size,NULL))<0){
+    vf->datasource=NULL;
+    ov_clear(vf);
+  }else{
+    /* serial number list for first link needs to be held somewhere
+       for second stage of seekable stream open; this saves having to
+       seek/reread first link's serialnumber data then. */
+    vf->serialnos=_ogg_calloc(serialno_list_size+2,sizeof(*vf->serialnos));
+    vf->serialnos[0]=vf->current_serialno=vf->os.serialno;
+    vf->serialnos[1]=serialno_list_size;
+    memcpy(vf->serialnos+2,serialno_list,serialno_list_size*sizeof(*vf->serialnos));
+
+    vf->offsets=_ogg_calloc(1,sizeof(*vf->offsets));
+    vf->dataoffsets=_ogg_calloc(1,sizeof(*vf->dataoffsets));
+    vf->offsets[0]=0;
+    vf->dataoffsets[0]=vf->offset;
+
+    vf->ready_state=PARTOPEN;
+  }
+  if(serialno_list)_ogg_free(serialno_list);
+  return(ret);
+}
+
+static int _ov_open2(OggVorbis_File *vf){
+  if(vf->ready_state != PARTOPEN) return OV_EINVAL;
+  vf->ready_state=OPENED;
+  if(vf->seekable){
+    int ret=_open_seekable2(vf);
+    if(ret){
+      vf->datasource=NULL;
+      ov_clear(vf);
+    }
+    return(ret);
+  }else
+    vf->ready_state=STREAMSET;
+
+  return 0;
+}
+
+
+/* clear out the OggVorbis_File struct */
+int ov_clear(OggVorbis_File *vf){
+  if(vf){
+    vorbis_block_clear(&vf->vb);
+    vorbis_dsp_clear(&vf->vd);
+    ogg_stream_clear(&vf->os);
+
+    if(vf->vi && vf->links){
+      int i;
+      for(i=0;i<vf->links;i++){
+        vorbis_info_clear(vf->vi+i);
+        vorbis_comment_clear(vf->vc+i);
+      }
+      _ogg_free(vf->vi);
+      _ogg_free(vf->vc);
+    }
+    if(vf->dataoffsets)_ogg_free(vf->dataoffsets);
+    if(vf->pcmlengths)_ogg_free(vf->pcmlengths);
+    if(vf->serialnos)_ogg_free(vf->serialnos);
+    if(vf->offsets)_ogg_free(vf->offsets);
+    ogg_sync_clear(&vf->oy);
+    if(vf->datasource && vf->callbacks.close_func)
+      (vf->callbacks.close_func)(vf->datasource);
+    memset(vf,0,sizeof(*vf));
+  }
+#ifdef DEBUG_LEAKS
+  _VDBG_dump();
+#endif
+  return(0);
+}
+
+/* inspects the OggVorbis file and finds/documents all the logical
+   bitstreams contained in it.  Tries to be tolerant of logical
+   bitstream sections that are truncated/woogie.
+
+   return: -1) error
+            0) OK
+*/
+
+int ov_open_callbacks(void *f,OggVorbis_File *vf,
+    const char *initial,long ibytes,ov_callbacks callbacks){
+  int ret=_ov_open1(f,vf,initial,ibytes,callbacks);
+  if(ret)return ret;
+  return _ov_open2(vf);
+}
+
+int ov_open(FILE *f,OggVorbis_File *vf,const char *initial,long ibytes){
+  ov_callbacks callbacks = {
+    (size_t (*)(void *, size_t, size_t, void *))  fread,
+    (int (*)(void *, ogg_int64_t, int))              _fseek64_wrap,
+    (int (*)(void *))                             fclose,
+    (long (*)(void *))                            ftell
+  };
+
+  return ov_open_callbacks((void *)f, vf, initial, ibytes, callbacks);
+}
+
+int ov_fopen(const char *path,OggVorbis_File *vf){
+  int ret;
+  FILE *f = fopen(path,"rb");
+  if(!f) return -1;
+
+  ret = ov_open(f,vf,NULL,0);
+  if(ret) fclose(f);
+  return ret;
+}
+
+
+/* cheap hack for game usage where downsampling is desirable; there's
+   no need for SRC as we can just do it cheaply in libvorbis. */
+
+int ov_halfrate(OggVorbis_File *vf,int flag){
+  int i;
+  if(vf->vi==NULL)return OV_EINVAL;
+  if(vf->ready_state>STREAMSET){
+    /* clear out stream state; dumping the decode machine is needed to
+       reinit the MDCT lookups. */
+    vorbis_dsp_clear(&vf->vd);
+    vorbis_block_clear(&vf->vb);
+    vf->ready_state=STREAMSET;
+    if(vf->pcm_offset>=0){
+      ogg_int64_t pos=vf->pcm_offset;
+      vf->pcm_offset=-1; /* make sure the pos is dumped if unseekable */
+      ov_pcm_seek(vf,pos);
+    }
+  }
+
+  for(i=0;i<vf->links;i++){
+    if(vorbis_synthesis_halfrate(vf->vi+i,flag)){
+      if(flag) ov_halfrate(vf,0);
+      return OV_EINVAL;
+    }
+  }
+  return 0;
+}
+
+int ov_halfrate_p(OggVorbis_File *vf){
+  if(vf->vi==NULL)return OV_EINVAL;
+  return vorbis_synthesis_halfrate_p(vf->vi);
+}
+
+/* Only partially open the vorbis file; test for Vorbisness, and load
+   the headers for the first chain.  Do not seek (although test for
+   seekability).  Use ov_test_open to finish opening the file, else
+   ov_clear to close/free it. Same return codes as open. */
+
+int ov_test_callbacks(void *f,OggVorbis_File *vf,
+    const char *initial,long ibytes,ov_callbacks callbacks)
+{
+  return _ov_open1(f,vf,initial,ibytes,callbacks);
+}
+
+int ov_test(FILE *f,OggVorbis_File *vf,const char *initial,long ibytes){
+  ov_callbacks callbacks = {
+    (size_t (*)(void *, size_t, size_t, void *))  fread,
+    (int (*)(void *, ogg_int64_t, int))              _fseek64_wrap,
+    (int (*)(void *))                             fclose,
+    (long (*)(void *))                            ftell
+  };
+
+  return ov_test_callbacks((void *)f, vf, initial, ibytes, callbacks);
+}
+
+int ov_test_open(OggVorbis_File *vf){
+  if(vf->ready_state!=PARTOPEN)return(OV_EINVAL);
+  return _ov_open2(vf);
+}
+
+/* How many logical bitstreams in this physical bitstream? */
+long ov_streams(OggVorbis_File *vf){
+  return vf->links;
+}
+
+/* Is the FILE * associated with vf seekable? */
+long ov_seekable(OggVorbis_File *vf){
+  return vf->seekable;
+}
+
+/* returns the bitrate for a given logical bitstream or the entire
+   physical bitstream.  If the file is open for random access, it will
+   find the *actual* average bitrate.  If the file is streaming, it
+   returns the nominal bitrate (if set) else the average of the
+   upper/lower bounds (if set) else -1 (unset).
+
+   If you want the actual bitrate field settings, get them from the
+   vorbis_info structs */
+
+long ov_bitrate(OggVorbis_File *vf,int i){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(i>=vf->links)return(OV_EINVAL);
+  if(!vf->seekable && i!=0)return(ov_bitrate(vf,0));
+  if(i<0){
+    ogg_int64_t bits=0;
+    int i;
+    float br;
+    for(i=0;i<vf->links;i++)
+      bits+=(vf->offsets[i+1]-vf->dataoffsets[i])*8;
+    /* This once read: return(rint(bits/ov_time_total(vf,-1)));
+     * gcc 3.x on x86 miscompiled this at optimisation level 2 and above,
+     * so this is slightly transformed to make it work.
+     */
+    br = bits/ov_time_total(vf,-1);
+    return(rint(br));
+  }else{
+    if(vf->seekable){
+      /* return the actual bitrate */
+      return(rint((vf->offsets[i+1]-vf->dataoffsets[i])*8/ov_time_total(vf,i)));
+    }else{
+      /* return nominal if set */
+      if(vf->vi[i].bitrate_nominal>0){
+        return vf->vi[i].bitrate_nominal;
+      }else{
+        if(vf->vi[i].bitrate_upper>0){
+          if(vf->vi[i].bitrate_lower>0){
+            return (vf->vi[i].bitrate_upper+vf->vi[i].bitrate_lower)/2;
+          }else{
+            return vf->vi[i].bitrate_upper;
+          }
+        }
+        return(OV_FALSE);
+      }
+    }
+  }
+}
+
+/* returns the actual bitrate since last call.  returns -1 if no
+   additional data to offer since last call (or at beginning of stream),
+   EINVAL if stream is only partially open
+*/
+long ov_bitrate_instant(OggVorbis_File *vf){
+  int link=(vf->seekable?vf->current_link:0);
+  long ret;
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(vf->samptrack==0)return(OV_FALSE);
+  ret=vf->bittrack/vf->samptrack*vf->vi[link].rate+.5;
+  vf->bittrack=0.f;
+  vf->samptrack=0.f;
+  return(ret);
+}
+
+/* Guess */
+long ov_serialnumber(OggVorbis_File *vf,int i){
+  if(i>=vf->links)return(ov_serialnumber(vf,vf->links-1));
+  if(!vf->seekable && i>=0)return(ov_serialnumber(vf,-1));
+  if(i<0){
+    return(vf->current_serialno);
+  }else{
+    return(vf->serialnos[i]);
+  }
+}
+
+/* returns: total raw (compressed) length of content if i==-1
+            raw (compressed) length of that logical bitstream for i==0 to n
+            OV_EINVAL if the stream is not seekable (we can't know the length)
+            or if stream is only partially open
+*/
+ogg_int64_t ov_raw_total(OggVorbis_File *vf,int i){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable || i>=vf->links)return(OV_EINVAL);
+  if(i<0){
+    ogg_int64_t acc=0;
+    int i;
+    for(i=0;i<vf->links;i++)
+      acc+=ov_raw_total(vf,i);
+    return(acc);
+  }else{
+    return(vf->offsets[i+1]-vf->offsets[i]);
+  }
+}
+
+/* returns: total PCM length (samples) of content if i==-1 PCM length
+            (samples) of that logical bitstream for i==0 to n
+            OV_EINVAL if the stream is not seekable (we can't know the
+            length) or only partially open
+*/
+ogg_int64_t ov_pcm_total(OggVorbis_File *vf,int i){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable || i>=vf->links)return(OV_EINVAL);
+  if(i<0){
+    ogg_int64_t acc=0;
+    int i;
+    for(i=0;i<vf->links;i++)
+      acc+=ov_pcm_total(vf,i);
+    return(acc);
+  }else{
+    return(vf->pcmlengths[i*2+1]);
+  }
+}
+
+/* returns: total seconds of content if i==-1
+            seconds in that logical bitstream for i==0 to n
+            OV_EINVAL if the stream is not seekable (we can't know the
+            length) or only partially open
+*/
+double ov_time_total(OggVorbis_File *vf,int i){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable || i>=vf->links)return(OV_EINVAL);
+  if(i<0){
+    double acc=0;
+    int i;
+    for(i=0;i<vf->links;i++)
+      acc+=ov_time_total(vf,i);
+    return(acc);
+  }else{
+    return((double)(vf->pcmlengths[i*2+1])/vf->vi[i].rate);
+  }
+}
+
+/* seek to an offset relative to the *compressed* data. This also
+   scans packets to update the PCM cursor. It will cross a logical
+   bitstream boundary, but only if it can't get any packets out of the
+   tail of the bitstream we seek to (so no surprises).
+
+   returns zero on success, nonzero on failure */
+
+int ov_raw_seek(OggVorbis_File *vf,ogg_int64_t pos){
+  ogg_stream_state work_os;
+  int ret;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)
+    return(OV_ENOSEEK); /* don't dump machine if we can't seek */
+
+  if(pos<0 || pos>vf->end)return(OV_EINVAL);
+
+  /* is the seek position outside our current link [if any]? */
+  if(vf->ready_state>=STREAMSET){
+    if(pos<vf->offsets[vf->current_link] || pos>=vf->offsets[vf->current_link+1])
+      _decode_clear(vf); /* clear out stream state */
+  }
+
+  /* don't yet clear out decoding machine (if it's initialized), in
+     the case we're in the same link.  Restart the decode lapping, and
+     let _fetch_and_process_packet deal with a potential bitstream
+     boundary */
+  vf->pcm_offset=-1;
+  ogg_stream_reset_serialno(&vf->os,
+                            vf->current_serialno); /* must set serialno */
+  vorbis_synthesis_restart(&vf->vd);
+
+  ret=_seek_helper(vf,pos);
+  if(ret)goto seek_error;
+
+  /* we need to make sure the pcm_offset is set, but we don't want to
+     advance the raw cursor past good packets just to get to the first
+     with a granulepos.  That's not equivalent behavior to beginning
+     decoding as immediately after the seek position as possible.
+
+     So, a hack.  We use two stream states; a local scratch state and
+     the shared vf->os stream state.  We use the local state to
+     scan, and the shared state as a buffer for later decode.
+
+     Unfortuantely, on the last page we still advance to last packet
+     because the granulepos on the last page is not necessarily on a
+     packet boundary, and we need to make sure the granpos is
+     correct.
+  */
+
+  {
+    ogg_page og;
+    ogg_packet op;
+    int lastblock=0;
+    int accblock=0;
+    int thisblock=0;
+    int lastflag=0;
+    int firstflag=0;
+    ogg_int64_t pagepos=-1;
+
+    ogg_stream_init(&work_os,vf->current_serialno); /* get the memory ready */
+    ogg_stream_reset(&work_os); /* eliminate the spurious OV_HOLE
+                                   return from not necessarily
+                                   starting from the beginning */
+
+    while(1){
+      if(vf->ready_state>=STREAMSET){
+        /* snarf/scan a packet if we can */
+        int result=ogg_stream_packetout(&work_os,&op);
+
+        if(result>0){
+
+          if(vf->vi[vf->current_link].codec_setup){
+            thisblock=vorbis_packet_blocksize(vf->vi+vf->current_link,&op);
+            if(thisblock<0){
+              ogg_stream_packetout(&vf->os,NULL);
+              thisblock=0;
+            }else{
+
+              /* We can't get a guaranteed correct pcm position out of the
+                 last page in a stream because it might have a 'short'
+                 granpos, which can only be detected in the presence of a
+                 preceding page.  However, if the last page is also the first
+                 page, the granpos rules of a first page take precedence.  Not
+                 only that, but for first==last, the EOS page must be treated
+                 as if its a normal first page for the stream to open/play. */
+              if(lastflag && !firstflag)
+                ogg_stream_packetout(&vf->os,NULL);
+              else
+                if(lastblock)accblock+=(lastblock+thisblock)>>2;
+            }
+
+            if(op.granulepos!=-1){
+              int i,link=vf->current_link;
+              ogg_int64_t granulepos=op.granulepos-vf->pcmlengths[link*2];
+              if(granulepos<0)granulepos=0;
+
+              for(i=0;i<link;i++)
+                granulepos+=vf->pcmlengths[i*2+1];
+              vf->pcm_offset=granulepos-accblock;
+              if(vf->pcm_offset<0)vf->pcm_offset=0;
+              break;
+            }
+            lastblock=thisblock;
+            continue;
+          }else
+            ogg_stream_packetout(&vf->os,NULL);
+        }
+      }
+
+      if(!lastblock){
+        pagepos=_get_next_page(vf,&og,-1);
+        if(pagepos<0){
+          vf->pcm_offset=ov_pcm_total(vf,-1);
+          break;
+        }
+      }else{
+        /* huh?  Bogus stream with packets but no granulepos */
+        vf->pcm_offset=-1;
+        break;
+      }
+
+      /* has our decoding just traversed a bitstream boundary? */
+      if(vf->ready_state>=STREAMSET){
+        if(vf->current_serialno!=ogg_page_serialno(&og)){
+
+          /* two possibilities:
+             1) our decoding just traversed a bitstream boundary
+             2) another stream is multiplexed into this logical section? */
+
+          if(ogg_page_bos(&og)){
+            /* we traversed */
+            _decode_clear(vf); /* clear out stream state */
+            ogg_stream_clear(&work_os);
+          } /* else, do nothing; next loop will scoop another page */
+        }
+      }
+
+      if(vf->ready_state<STREAMSET){
+        int link;
+        long serialno = ogg_page_serialno(&og);
+
+        for(link=0;link<vf->links;link++)
+          if(vf->serialnos[link]==serialno)break;
+
+        if(link==vf->links) continue; /* not the desired Vorbis
+                                         bitstream section; keep
+                                         trying */
+        vf->current_link=link;
+        vf->current_serialno=serialno;
+        ogg_stream_reset_serialno(&vf->os,serialno);
+        ogg_stream_reset_serialno(&work_os,serialno);
+        vf->ready_state=STREAMSET;
+        firstflag=(pagepos<=vf->dataoffsets[link]);
+      }
+
+      ogg_stream_pagein(&vf->os,&og);
+      ogg_stream_pagein(&work_os,&og);
+      lastflag=ogg_page_eos(&og);
+
+    }
+  }
+
+  ogg_stream_clear(&work_os);
+  vf->bittrack=0.f;
+  vf->samptrack=0.f;
+  return(0);
+
+ seek_error:
+  /* dump the machine so we're in a known state */
+  vf->pcm_offset=-1;
+  ogg_stream_clear(&work_os);
+  _decode_clear(vf);
+  return OV_EBADLINK;
+}
+
+/* Page granularity seek (faster than sample granularity because we
+   don't do the last bit of decode to find a specific sample).
+
+   Seek to the last [granule marked] page preceding the specified pos
+   location, such that decoding past the returned point will quickly
+   arrive at the requested position. */
+int ov_pcm_seek_page(OggVorbis_File *vf,ogg_int64_t pos){
+  int link=-1;
+  ogg_int64_t result=0;
+  ogg_int64_t total=ov_pcm_total(vf,-1);
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)return(OV_ENOSEEK);
+
+  if(pos<0 || pos>total)return(OV_EINVAL);
+
+  /* which bitstream section does this pcm offset occur in? */
+  for(link=vf->links-1;link>=0;link--){
+    total-=vf->pcmlengths[link*2+1];
+    if(pos>=total)break;
+  }
+
+  /* search within the logical bitstream for the page with the highest
+     pcm_pos preceding (or equal to) pos.  There is a danger here;
+     missing pages or incorrect frame number information in the
+     bitstream could make our task impossible.  Account for that (it
+     would be an error condition) */
+
+  /* new search algorithm by HB (Nicholas Vinen) */
+  {
+    ogg_int64_t end=vf->offsets[link+1];
+    ogg_int64_t begin=vf->offsets[link];
+    ogg_int64_t begintime = vf->pcmlengths[link*2];
+    ogg_int64_t endtime = vf->pcmlengths[link*2+1]+begintime;
+    ogg_int64_t target=pos-total+begintime;
+    ogg_int64_t best=begin;
+
+    ogg_page og;
+    while(begin<end){
+      ogg_int64_t bisect;
+
+      if(end-begin<CHUNKSIZE){
+        bisect=begin;
+      }else{
+        /* take a (pretty decent) guess. */
+        bisect=begin +
+          (ogg_int64_t)((double)(target-begintime)*(end-begin)/(endtime-begintime))
+          - CHUNKSIZE;
+        if(bisect<begin+CHUNKSIZE)
+          bisect=begin;
+      }
+
+      if(bisect!=vf->offset){
+        result=_seek_helper(vf,bisect);
+        if(result) goto seek_error;
+      }
+
+      while(begin<end){
+        result=_get_next_page(vf,&og,end-vf->offset);
+        if(result==OV_EREAD) goto seek_error;
+        if(result<0){
+          if(bisect<=begin+1)
+            end=begin; /* found it */
+          else{
+            if(bisect==0) goto seek_error;
+            bisect-=CHUNKSIZE;
+            if(bisect<=begin)bisect=begin+1;
+            result=_seek_helper(vf,bisect);
+            if(result) goto seek_error;
+          }
+        }else{
+          ogg_int64_t granulepos;
+
+          if(ogg_page_serialno(&og)!=vf->serialnos[link])
+            continue;
+
+          granulepos=ogg_page_granulepos(&og);
+          if(granulepos==-1)continue;
+
+          if(granulepos<target){
+            best=result;  /* raw offset of packet with granulepos */
+            begin=vf->offset; /* raw offset of next page */
+            begintime=granulepos;
+
+            if(target-begintime>44100)break;
+            bisect=begin; /* *not* begin + 1 */
+          }else{
+            if(bisect<=begin+1)
+              end=begin;  /* found it */
+            else{
+              if(end==vf->offset){ /* we're pretty close - we'd be stuck in */
+                end=result;
+                bisect-=CHUNKSIZE; /* an endless loop otherwise. */
+                if(bisect<=begin)bisect=begin+1;
+                result=_seek_helper(vf,bisect);
+                if(result) goto seek_error;
+              }else{
+                end=bisect;
+                endtime=granulepos;
+                break;
+              }
+            }
+          }
+        }
+      }
+    }
+
+    /* found our page. seek to it, update pcm offset. Easier case than
+       raw_seek, don't keep packets preceding granulepos. */
+    {
+      ogg_page og;
+      ogg_packet op;
+
+      /* seek */
+      result=_seek_helper(vf,best);
+      vf->pcm_offset=-1;
+      if(result) goto seek_error;
+      result=_get_next_page(vf,&og,-1);
+      if(result<0) goto seek_error;
+
+      if(link!=vf->current_link){
+        /* Different link; dump entire decode machine */
+        _decode_clear(vf);
+
+        vf->current_link=link;
+        vf->current_serialno=vf->serialnos[link];
+        vf->ready_state=STREAMSET;
+
+      }else{
+        vorbis_synthesis_restart(&vf->vd);
+      }
+
+      ogg_stream_reset_serialno(&vf->os,vf->current_serialno);
+      ogg_stream_pagein(&vf->os,&og);
+
+      /* pull out all but last packet; the one with granulepos */
+      while(1){
+        result=ogg_stream_packetpeek(&vf->os,&op);
+        if(result==0){
+          /* !!! the packet finishing this page originated on a
+             preceding page. Keep fetching previous pages until we
+             get one with a granulepos or without the 'continued' flag
+             set.  Then just use raw_seek for simplicity. */
+
+          result=_seek_helper(vf,best);
+          if(result<0) goto seek_error;
+
+          while(1){
+            result=_get_prev_page(vf,&og);
+            if(result<0) goto seek_error;
+            if(ogg_page_serialno(&og)==vf->current_serialno &&
+               (ogg_page_granulepos(&og)>-1 ||
+                !ogg_page_continued(&og))){
+              return ov_raw_seek(vf,result);
+            }
+            vf->offset=result;
+          }
+        }
+        if(result<0){
+          result = OV_EBADPACKET;
+          goto seek_error;
+        }
+        if(op.granulepos!=-1){
+          vf->pcm_offset=op.granulepos-vf->pcmlengths[vf->current_link*2];
+          if(vf->pcm_offset<0)vf->pcm_offset=0;
+          vf->pcm_offset+=total;
+          break;
+        }else
+          result=ogg_stream_packetout(&vf->os,NULL);
+      }
+    }
+  }
+
+  /* verify result */
+  if(vf->pcm_offset>pos || pos>ov_pcm_total(vf,-1)){
+    result=OV_EFAULT;
+    goto seek_error;
+  }
+  vf->bittrack=0.f;
+  vf->samptrack=0.f;
+  return(0);
+
+ seek_error:
+  /* dump machine so we're in a known state */
+  vf->pcm_offset=-1;
+  _decode_clear(vf);
+  return (int)result;
+}
+
+/* seek to a sample offset relative to the decompressed pcm stream
+   returns zero on success, nonzero on failure */
+
+int ov_pcm_seek(OggVorbis_File *vf,ogg_int64_t pos){
+  int thisblock,lastblock=0;
+  int ret=ov_pcm_seek_page(vf,pos);
+  if(ret<0)return(ret);
+  if((ret=_make_decode_ready(vf)))return ret;
+
+  /* discard leading packets we don't need for the lapping of the
+     position we want; don't decode them */
+
+  while(1){
+    ogg_packet op;
+    ogg_page og;
+
+    int ret=ogg_stream_packetpeek(&vf->os,&op);
+    if(ret>0){
+      thisblock=vorbis_packet_blocksize(vf->vi+vf->current_link,&op);
+      if(thisblock<0){
+        ogg_stream_packetout(&vf->os,NULL);
+        continue; /* non audio packet */
+      }
+      if(lastblock)vf->pcm_offset+=(lastblock+thisblock)>>2;
+
+      if(vf->pcm_offset+((thisblock+
+                          vorbis_info_blocksize(vf->vi,1))>>2)>=pos)break;
+
+      /* remove the packet from packet queue and track its granulepos */
+      ogg_stream_packetout(&vf->os,NULL);
+      vorbis_synthesis_trackonly(&vf->vb,&op);  /* set up a vb with
+                                                   only tracking, no
+                                                   pcm_decode */
+      vorbis_synthesis_blockin(&vf->vd,&vf->vb);
+
+      /* end of logical stream case is hard, especially with exact
+         length positioning. */
+
+      if(op.granulepos>-1){
+        int i;
+        /* always believe the stream markers */
+        vf->pcm_offset=op.granulepos-vf->pcmlengths[vf->current_link*2];
+        if(vf->pcm_offset<0)vf->pcm_offset=0;
+        for(i=0;i<vf->current_link;i++)
+          vf->pcm_offset+=vf->pcmlengths[i*2+1];
+      }
+
+      lastblock=thisblock;
+
+    }else{
+      if(ret<0 && ret!=OV_HOLE)break;
+
+      /* suck in a new page */
+      if(_get_next_page(vf,&og,-1)<0)break;
+      if(ogg_page_bos(&og))_decode_clear(vf);
+
+      if(vf->ready_state<STREAMSET){
+        long serialno=ogg_page_serialno(&og);
+        int link;
+
+        for(link=0;link<vf->links;link++)
+          if(vf->serialnos[link]==serialno)break;
+        if(link==vf->links) continue;
+        vf->current_link=link;
+
+        vf->ready_state=STREAMSET;
+        vf->current_serialno=ogg_page_serialno(&og);
+        ogg_stream_reset_serialno(&vf->os,serialno);
+        ret=_make_decode_ready(vf);
+        if(ret)return ret;
+        lastblock=0;
+      }
+
+      ogg_stream_pagein(&vf->os,&og);
+    }
+  }
+
+  vf->bittrack=0.f;
+  vf->samptrack=0.f;
+  /* discard samples until we reach the desired position. Crossing a
+     logical bitstream boundary with abandon is OK. */
+  {
+    /* note that halfrate could be set differently in each link, but
+       vorbisfile encoforces all links are set or unset */
+    int hs=vorbis_synthesis_halfrate_p(vf->vi);
+    while(vf->pcm_offset<((pos>>hs)<<hs)){
+      ogg_int64_t target=(pos-vf->pcm_offset)>>hs;
+      long samples=vorbis_synthesis_pcmout(&vf->vd,NULL);
+
+      if(samples>target)samples=target;
+      vorbis_synthesis_read(&vf->vd,samples);
+      vf->pcm_offset+=samples<<hs;
+
+      if(samples<target)
+        if(_fetch_and_process_packet(vf,NULL,1,1)<=0)
+          vf->pcm_offset=ov_pcm_total(vf,-1); /* eof */
+    }
+  }
+  return 0;
+}
+
+/* seek to a playback time relative to the decompressed pcm stream
+   returns zero on success, nonzero on failure */
+int ov_time_seek(OggVorbis_File *vf,double seconds){
+  /* translate time to PCM position and call ov_pcm_seek */
+
+  int link=-1;
+  ogg_int64_t pcm_total=0;
+  double time_total=0.;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)return(OV_ENOSEEK);
+  if(seconds<0)return(OV_EINVAL);
+
+  /* which bitstream section does this time offset occur in? */
+  for(link=0;link<vf->links;link++){
+    double addsec = ov_time_total(vf,link);
+    if(seconds<time_total+addsec)break;
+    time_total+=addsec;
+    pcm_total+=vf->pcmlengths[link*2+1];
+  }
+
+  if(link==vf->links)return(OV_EINVAL);
+
+  /* enough information to convert time offset to pcm offset */
+  {
+    ogg_int64_t target=pcm_total+(seconds-time_total)*vf->vi[link].rate;
+    return(ov_pcm_seek(vf,target));
+  }
+}
+
+/* page-granularity version of ov_time_seek
+   returns zero on success, nonzero on failure */
+int ov_time_seek_page(OggVorbis_File *vf,double seconds){
+  /* translate time to PCM position and call ov_pcm_seek */
+
+  int link=-1;
+  ogg_int64_t pcm_total=0;
+  double time_total=0.;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)return(OV_ENOSEEK);
+  if(seconds<0)return(OV_EINVAL);
+
+  /* which bitstream section does this time offset occur in? */
+  for(link=0;link<vf->links;link++){
+    double addsec = ov_time_total(vf,link);
+    if(seconds<time_total+addsec)break;
+    time_total+=addsec;
+    pcm_total+=vf->pcmlengths[link*2+1];
+  }
+
+  if(link==vf->links)return(OV_EINVAL);
+
+  /* enough information to convert time offset to pcm offset */
+  {
+    ogg_int64_t target=pcm_total+(seconds-time_total)*vf->vi[link].rate;
+    return(ov_pcm_seek_page(vf,target));
+  }
+}
+
+/* tell the current stream offset cursor.  Note that seek followed by
+   tell will likely not give the set offset due to caching */
+ogg_int64_t ov_raw_tell(OggVorbis_File *vf){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  return(vf->offset);
+}
+
+/* return PCM offset (sample) of next PCM sample to be read */
+ogg_int64_t ov_pcm_tell(OggVorbis_File *vf){
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  return(vf->pcm_offset);
+}
+
+/* return time offset (seconds) of next PCM sample to be read */
+double ov_time_tell(OggVorbis_File *vf){
+  int link=0;
+  ogg_int64_t pcm_total=0;
+  double time_total=0.f;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(vf->seekable){
+    pcm_total=ov_pcm_total(vf,-1);
+    time_total=ov_time_total(vf,-1);
+
+    /* which bitstream section does this time offset occur in? */
+    for(link=vf->links-1;link>=0;link--){
+      pcm_total-=vf->pcmlengths[link*2+1];
+      time_total-=ov_time_total(vf,link);
+      if(vf->pcm_offset>=pcm_total)break;
+    }
+  }
+
+  return((double)time_total+(double)(vf->pcm_offset-pcm_total)/vf->vi[link].rate);
+}
+
+/*  link:   -1) return the vorbis_info struct for the bitstream section
+                currently being decoded
+           0-n) to request information for a specific bitstream section
+
+    In the case of a non-seekable bitstream, any call returns the
+    current bitstream.  NULL in the case that the machine is not
+    initialized */
+
+vorbis_info *ov_info(OggVorbis_File *vf,int link){
+  if(vf->seekable){
+    if(link<0)
+      if(vf->ready_state>=STREAMSET)
+        return vf->vi+vf->current_link;
+      else
+      return vf->vi;
+    else
+      if(link>=vf->links)
+        return NULL;
+      else
+        return vf->vi+link;
+  }else{
+    return vf->vi;
+  }
+}
+
+/* grr, strong typing, grr, no templates/inheritence, grr */
+vorbis_comment *ov_comment(OggVorbis_File *vf,int link){
+  if(vf->seekable){
+    if(link<0)
+      if(vf->ready_state>=STREAMSET)
+        return vf->vc+vf->current_link;
+      else
+        return vf->vc;
+    else
+      if(link>=vf->links)
+        return NULL;
+      else
+        return vf->vc+link;
+  }else{
+    return vf->vc;
+  }
+}
+
+static int host_is_big_endian() {
+  ogg_int32_t pattern = 0xfeedface; /* deadbeef */
+  unsigned char *bytewise = (unsigned char *)&pattern;
+  if (bytewise[0] == 0xfe) return 1;
+  return 0;
+}
+
+/* up to this point, everything could more or less hide the multiple
+   logical bitstream nature of chaining from the toplevel application
+   if the toplevel application didn't particularly care.  However, at
+   the point that we actually read audio back, the multiple-section
+   nature must surface: Multiple bitstream sections do not necessarily
+   have to have the same number of channels or sampling rate.
+
+   ov_read returns the sequential logical bitstream number currently
+   being decoded along with the PCM data in order that the toplevel
+   application can take action on channel/sample rate changes.  This
+   number will be incremented even for streamed (non-seekable) streams
+   (for seekable streams, it represents the actual logical bitstream
+   index within the physical bitstream.  Note that the accessor
+   functions above are aware of this dichotomy).
+
+   ov_read_filter is exactly the same as ov_read except that it processes
+   the decoded audio data through a filter before packing it into the
+   requested format. This gives greater accuracy than applying a filter
+   after the audio has been converted into integral PCM.
+
+   input values: buffer) a buffer to hold packed PCM data for return
+                 length) the byte length requested to be placed into buffer
+                 bigendianp) should the data be packed LSB first (0) or
+                             MSB first (1)
+                 word) word size for output.  currently 1 (byte) or
+                       2 (16 bit short)
+
+   return values: <0) error/hole in data (OV_HOLE), partial open (OV_EINVAL)
+                   0) EOF
+                   n) number of bytes of PCM actually returned.  The
+                   below works on a packet-by-packet basis, so the
+                   return length is not related to the 'length' passed
+                   in, just guaranteed to fit.
+
+            *section) set to the logical bitstream number */
+
+long ov_read_filter(OggVorbis_File *vf,char *buffer,int length,
+                    int bigendianp,int word,int sgned,int *bitstream,
+                    void (*filter)(float **pcm,long channels,long samples,void *filter_param),void *filter_param){
+  int i,j;
+  int host_endian = host_is_big_endian();
+  int hs;
+
+  float **pcm;
+  long samples;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+
+  while(1){
+    if(vf->ready_state==INITSET){
+      samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
+      if(samples)break;
+    }
+
+    /* suck in another packet */
+    {
+      int ret=_fetch_and_process_packet(vf,NULL,1,1);
+      if(ret==OV_EOF)
+        return(0);
+      if(ret<=0)
+        return(ret);
+    }
+
+  }
+
+  if(samples>0){
+
+    /* yay! proceed to pack data into the byte buffer */
+
+    long channels=ov_info(vf,-1)->channels;
+    long bytespersample=word * channels;
+    vorbis_fpu_control fpu;
+    if(samples>length/bytespersample)samples=length/bytespersample;
+
+    if(samples <= 0)
+      return OV_EINVAL;
+
+    /* Here. */
+    if(filter)
+      filter(pcm,channels,samples,filter_param);
+
+    /* a tight loop to pack each size */
+    {
+      int val;
+      if(word==1){
+        int off=(sgned?0:128);
+        vorbis_fpu_setround(&fpu);
+        for(j=0;j<samples;j++)
+          for(i=0;i<channels;i++){
+            val=vorbis_ftoi(pcm[i][j]*128.f);
+            if(val>127)val=127;
+            else if(val<-128)val=-128;
+            *buffer++=val+off;
+          }
+        vorbis_fpu_restore(fpu);
+      }else{
+        int off=(sgned?0:32768);
+
+        if(host_endian==bigendianp){
+          if(sgned){
+
+            vorbis_fpu_setround(&fpu);
+            for(i=0;i<channels;i++) { /* It's faster in this order */
+              float *src=pcm[i];
+              short *dest=((short *)buffer)+i;
+              for(j=0;j<samples;j++) {
+                val=vorbis_ftoi(src[j]*32768.f);
+                if(val>32767)val=32767;
+                else if(val<-32768)val=-32768;
+                *dest=val;
+                dest+=channels;
+              }
+            }
+            vorbis_fpu_restore(fpu);
+
+          }else{
+
+            vorbis_fpu_setround(&fpu);
+            for(i=0;i<channels;i++) {
+              float *src=pcm[i];
+              short *dest=((short *)buffer)+i;
+              for(j=0;j<samples;j++) {
+                val=vorbis_ftoi(src[j]*32768.f);
+                if(val>32767)val=32767;
+                else if(val<-32768)val=-32768;
+                *dest=val+off;
+                dest+=channels;
+              }
+            }
+            vorbis_fpu_restore(fpu);
+
+          }
+        }else if(bigendianp){
+
+          vorbis_fpu_setround(&fpu);
+          for(j=0;j<samples;j++)
+            for(i=0;i<channels;i++){
+              val=vorbis_ftoi(pcm[i][j]*32768.f);
+              if(val>32767)val=32767;
+              else if(val<-32768)val=-32768;
+              val+=off;
+              *buffer++=(val>>8);
+              *buffer++=(val&0xff);
+            }
+          vorbis_fpu_restore(fpu);
+
+        }else{
+          int val;
+          vorbis_fpu_setround(&fpu);
+          for(j=0;j<samples;j++)
+            for(i=0;i<channels;i++){
+              val=vorbis_ftoi(pcm[i][j]*32768.f);
+              if(val>32767)val=32767;
+              else if(val<-32768)val=-32768;
+              val+=off;
+              *buffer++=(val&0xff);
+              *buffer++=(val>>8);
+                  }
+          vorbis_fpu_restore(fpu);
+
+        }
+      }
+    }
+
+    vorbis_synthesis_read(&vf->vd,samples);
+    hs=vorbis_synthesis_halfrate_p(vf->vi);
+    vf->pcm_offset+=(samples<<hs);
+    if(bitstream)*bitstream=vf->current_link;
+    return(samples*bytespersample);
+  }else{
+    return(samples);
+  }
+}
+
+long ov_read(OggVorbis_File *vf,char *buffer,int length,
+             int bigendianp,int word,int sgned,int *bitstream){
+  return ov_read_filter(vf, buffer, length, bigendianp, word, sgned, bitstream, NULL, NULL);
+}
+
+/* input values: pcm_channels) a float vector per channel of output
+                 length) the sample length being read by the app
+
+   return values: <0) error/hole in data (OV_HOLE), partial open (OV_EINVAL)
+                   0) EOF
+                   n) number of samples of PCM actually returned.  The
+                   below works on a packet-by-packet basis, so the
+                   return length is not related to the 'length' passed
+                   in, just guaranteed to fit.
+
+            *section) set to the logical bitstream number */
+
+
+
+long ov_read_float(OggVorbis_File *vf,float ***pcm_channels,int length,
+                   int *bitstream){
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+
+  while(1){
+    if(vf->ready_state==INITSET){
+      float **pcm;
+      long samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
+      if(samples){
+        int hs=vorbis_synthesis_halfrate_p(vf->vi);
+        if(pcm_channels)*pcm_channels=pcm;
+        if(samples>length)samples=length;
+        vorbis_synthesis_read(&vf->vd,samples);
+        vf->pcm_offset+=samples<<hs;
+        if(bitstream)*bitstream=vf->current_link;
+        return samples;
+
+      }
+    }
+
+    /* suck in another packet */
+    {
+      int ret=_fetch_and_process_packet(vf,NULL,1,1);
+      if(ret==OV_EOF)return(0);
+      if(ret<=0)return(ret);
+    }
+
+  }
+}
+
+extern float *vorbis_window(vorbis_dsp_state *v,int W);
+
+static void _ov_splice(float **pcm,float **lappcm,
+                       int n1, int n2,
+                       int ch1, int ch2,
+                       float *w1, float *w2){
+  int i,j;
+  float *w=w1;
+  int n=n1;
+
+  if(n1>n2){
+    n=n2;
+    w=w2;
+  }
+
+  /* splice */
+  for(j=0;j<ch1 && j<ch2;j++){
+    float *s=lappcm[j];
+    float *d=pcm[j];
+
+    for(i=0;i<n;i++){
+      float wd=w[i]*w[i];
+      float ws=1.-wd;
+      d[i]=d[i]*wd + s[i]*ws;
+    }
+  }
+  /* window from zero */
+  for(;j<ch2;j++){
+    float *d=pcm[j];
+    for(i=0;i<n;i++){
+      float wd=w[i]*w[i];
+      d[i]=d[i]*wd;
+    }
+  }
+
+}
+
+/* make sure vf is INITSET */
+static int _ov_initset(OggVorbis_File *vf){
+  while(1){
+    if(vf->ready_state==INITSET)break;
+    /* suck in another packet */
+    {
+      int ret=_fetch_and_process_packet(vf,NULL,1,0);
+      if(ret<0 && ret!=OV_HOLE)return(ret);
+    }
+  }
+  return 0;
+}
+
+/* make sure vf is INITSET and that we have a primed buffer; if
+   we're crosslapping at a stream section boundary, this also makes
+   sure we're sanity checking against the right stream information */
+static int _ov_initprime(OggVorbis_File *vf){
+  vorbis_dsp_state *vd=&vf->vd;
+  while(1){
+    if(vf->ready_state==INITSET)
+      if(vorbis_synthesis_pcmout(vd,NULL))break;
+
+    /* suck in another packet */
+    {
+      int ret=_fetch_and_process_packet(vf,NULL,1,0);
+      if(ret<0 && ret!=OV_HOLE)return(ret);
+    }
+  }
+  return 0;
+}
+
+/* grab enough data for lapping from vf; this may be in the form of
+   unreturned, already-decoded pcm, remaining PCM we will need to
+   decode, or synthetic postextrapolation from last packets. */
+static void _ov_getlap(OggVorbis_File *vf,vorbis_info *vi,vorbis_dsp_state *vd,
+                       float **lappcm,int lapsize){
+  int lapcount=0,i;
+  float **pcm;
+
+  /* try first to decode the lapping data */
+  while(lapcount<lapsize){
+    int samples=vorbis_synthesis_pcmout(vd,&pcm);
+    if(samples){
+      if(samples>lapsize-lapcount)samples=lapsize-lapcount;
+      for(i=0;i<vi->channels;i++)
+        memcpy(lappcm[i]+lapcount,pcm[i],sizeof(**pcm)*samples);
+      lapcount+=samples;
+      vorbis_synthesis_read(vd,samples);
+    }else{
+    /* suck in another packet */
+      int ret=_fetch_and_process_packet(vf,NULL,1,0); /* do *not* span */
+      if(ret==OV_EOF)break;
+    }
+  }
+  if(lapcount<lapsize){
+    /* failed to get lapping data from normal decode; pry it from the
+       postextrapolation buffering, or the second half of the MDCT
+       from the last packet */
+    int samples=vorbis_synthesis_lapout(&vf->vd,&pcm);
+    if(samples==0){
+      for(i=0;i<vi->channels;i++)
+        memset(lappcm[i]+lapcount,0,sizeof(**pcm)*lapsize-lapcount);
+      lapcount=lapsize;
+    }else{
+      if(samples>lapsize-lapcount)samples=lapsize-lapcount;
+      for(i=0;i<vi->channels;i++)
+        memcpy(lappcm[i]+lapcount,pcm[i],sizeof(**pcm)*samples);
+      lapcount+=samples;
+    }
+  }
+}
+
+/* this sets up crosslapping of a sample by using trailing data from
+   sample 1 and lapping it into the windowing buffer of sample 2 */
+int ov_crosslap(OggVorbis_File *vf1, OggVorbis_File *vf2){
+  vorbis_info *vi1,*vi2;
+  float **lappcm;
+  float **pcm;
+  float *w1,*w2;
+  int n1,n2,i,ret,hs1,hs2;
+
+  if(vf1==vf2)return(0); /* degenerate case */
+  if(vf1->ready_state<OPENED)return(OV_EINVAL);
+  if(vf2->ready_state<OPENED)return(OV_EINVAL);
+
+  /* the relevant overlap buffers must be pre-checked and pre-primed
+     before looking at settings in the event that priming would cross
+     a bitstream boundary.  So, do it now */
+
+  ret=_ov_initset(vf1);
+  if(ret)return(ret);
+  ret=_ov_initprime(vf2);
+  if(ret)return(ret);
+
+  vi1=ov_info(vf1,-1);
+  vi2=ov_info(vf2,-1);
+  hs1=ov_halfrate_p(vf1);
+  hs2=ov_halfrate_p(vf2);
+
+  lappcm=alloca(sizeof(*lappcm)*vi1->channels);
+  n1=vorbis_info_blocksize(vi1,0)>>(1+hs1);
+  n2=vorbis_info_blocksize(vi2,0)>>(1+hs2);
+  w1=vorbis_window(&vf1->vd,0);
+  w2=vorbis_window(&vf2->vd,0);
+
+  for(i=0;i<vi1->channels;i++)
+    lappcm[i]=alloca(sizeof(**lappcm)*n1);
+
+  _ov_getlap(vf1,vi1,&vf1->vd,lappcm,n1);
+
+  /* have a lapping buffer from vf1; now to splice it into the lapping
+     buffer of vf2 */
+  /* consolidate and expose the buffer. */
+  vorbis_synthesis_lapout(&vf2->vd,&pcm);
+
+#if 0
+  _analysis_output_always("pcmL",0,pcm[0],n1*2,0,0,0);
+  _analysis_output_always("pcmR",0,pcm[1],n1*2,0,0,0);
+#endif
+
+  /* splice */
+  _ov_splice(pcm,lappcm,n1,n2,vi1->channels,vi2->channels,w1,w2);
+
+  /* done */
+  return(0);
+}
+
+static int _ov_64_seek_lap(OggVorbis_File *vf,ogg_int64_t pos,
+                           int (*localseek)(OggVorbis_File *,ogg_int64_t)){
+  vorbis_info *vi;
+  float **lappcm;
+  float **pcm;
+  float *w1,*w2;
+  int n1,n2,ch1,ch2,hs;
+  int i,ret;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  ret=_ov_initset(vf);
+  if(ret)return(ret);
+  vi=ov_info(vf,-1);
+  hs=ov_halfrate_p(vf);
+
+  ch1=vi->channels;
+  n1=vorbis_info_blocksize(vi,0)>>(1+hs);
+  w1=vorbis_window(&vf->vd,0);  /* window arrays from libvorbis are
+                                   persistent; even if the decode state
+                                   from this link gets dumped, this
+                                   window array continues to exist */
+
+  lappcm=alloca(sizeof(*lappcm)*ch1);
+  for(i=0;i<ch1;i++)
+    lappcm[i]=alloca(sizeof(**lappcm)*n1);
+  _ov_getlap(vf,vi,&vf->vd,lappcm,n1);
+
+  /* have lapping data; seek and prime the buffer */
+  ret=localseek(vf,pos);
+  if(ret)return ret;
+  ret=_ov_initprime(vf);
+  if(ret)return(ret);
+
+ /* Guard against cross-link changes; they're perfectly legal */
+  vi=ov_info(vf,-1);
+  ch2=vi->channels;
+  n2=vorbis_info_blocksize(vi,0)>>(1+hs);
+  w2=vorbis_window(&vf->vd,0);
+
+  /* consolidate and expose the buffer. */
+  vorbis_synthesis_lapout(&vf->vd,&pcm);
+
+  /* splice */
+  _ov_splice(pcm,lappcm,n1,n2,ch1,ch2,w1,w2);
+
+  /* done */
+  return(0);
+}
+
+int ov_raw_seek_lap(OggVorbis_File *vf,ogg_int64_t pos){
+  return _ov_64_seek_lap(vf,pos,ov_raw_seek);
+}
+
+int ov_pcm_seek_lap(OggVorbis_File *vf,ogg_int64_t pos){
+  return _ov_64_seek_lap(vf,pos,ov_pcm_seek);
+}
+
+int ov_pcm_seek_page_lap(OggVorbis_File *vf,ogg_int64_t pos){
+  return _ov_64_seek_lap(vf,pos,ov_pcm_seek_page);
+}
+
+static int _ov_d_seek_lap(OggVorbis_File *vf,double pos,
+                           int (*localseek)(OggVorbis_File *,double)){
+  vorbis_info *vi;
+  float **lappcm;
+  float **pcm;
+  float *w1,*w2;
+  int n1,n2,ch1,ch2,hs;
+  int i,ret;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  ret=_ov_initset(vf);
+  if(ret)return(ret);
+  vi=ov_info(vf,-1);
+  hs=ov_halfrate_p(vf);
+
+  ch1=vi->channels;
+  n1=vorbis_info_blocksize(vi,0)>>(1+hs);
+  w1=vorbis_window(&vf->vd,0);  /* window arrays from libvorbis are
+                                   persistent; even if the decode state
+                                   from this link gets dumped, this
+                                   window array continues to exist */
+
+  lappcm=alloca(sizeof(*lappcm)*ch1);
+  for(i=0;i<ch1;i++)
+    lappcm[i]=alloca(sizeof(**lappcm)*n1);
+  _ov_getlap(vf,vi,&vf->vd,lappcm,n1);
+
+  /* have lapping data; seek and prime the buffer */
+  ret=localseek(vf,pos);
+  if(ret)return ret;
+  ret=_ov_initprime(vf);
+  if(ret)return(ret);
+
+ /* Guard against cross-link changes; they're perfectly legal */
+  vi=ov_info(vf,-1);
+  ch2=vi->channels;
+  n2=vorbis_info_blocksize(vi,0)>>(1+hs);
+  w2=vorbis_window(&vf->vd,0);
+
+  /* consolidate and expose the buffer. */
+  vorbis_synthesis_lapout(&vf->vd,&pcm);
+
+  /* splice */
+  _ov_splice(pcm,lappcm,n1,n2,ch1,ch2,w1,w2);
+
+  /* done */
+  return(0);
+}
+
+int ov_time_seek_lap(OggVorbis_File *vf,double pos){
+  return _ov_d_seek_lap(vf,pos,ov_time_seek);
+}
+
+int ov_time_seek_page_lap(OggVorbis_File *vf,double pos){
+  return _ov_d_seek_lap(vf,pos,ov_time_seek_page);
+}