Put root level of Tremor in CVS

git-svn-id: https://svn.xiph.org/trunk/Tremor@3890 0101bb08-14d6-0310-b084-bc0e0c8e3800

1 files changed, 1417 insertions, 0 deletions

diff --git a/vorbisfile.c b/vorbisfile.c
new file mode 100644
index 0000000..296f86c
--- /dev/null
+++ b/vorbisfile.c
@@ -0,0 +1,1417 @@
+/********************************************************************
+ *                                                                  *
+ * THIS FILE IS PART OF THE OggVorbis 'TREMOR' CODEC SOURCE CODE.   *
+ *                                                                  *
+ * THE OggVorbis 'TREMOR' SOURCE CODE IS (C) COPYRIGHT 1994-2002    *
+ * BY THE Xiph.Org FOUNDATION http://www.xiph.org/                  *
+ * ALL REDISTRIBUTION RIGHTS RESERVED.                              *
+ *                                                                  *
+ ********************************************************************
+
+ function: stdio-based convenience library for opening/seeking/decoding
+
+ ********************************************************************/
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <math.h>
+
+#include "ivorbiscodec.h"
+#include "ivorbisfile.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
+*/
+static long _get_data(OggVorbis_File *vf){
+  errno=0;
+  if(vf->datasource){
+    char *buffer=ogg_sync_buffer(&vf->oy,CHUNKSIZE);
+    long bytes=(vf->callbacks.read_func)(buffer,1,CHUNKSIZE,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 void _seek_helper(OggVorbis_File *vf,long offset){
+  if(vf->datasource){ 
+    (vf->callbacks.seek_func)(vf->datasource, offset, SEEK_SET);
+    vf->offset=offset;
+    ogg_sync_reset(&vf->oy);
+  }else{
+    /* shouldn't happen unless someone writes a broken callback */
+    return;
+  }
+}
+
+/* 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 long _get_next_page(OggVorbis_File *vf,ogg_page *og,int 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 */
+	long 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 long _get_prev_page(OggVorbis_File *vf,ogg_page *og){
+  long begin=vf->offset;
+  long ret;
+  int offset=-1;
+
+  while(offset==-1){
+    begin-=CHUNKSIZE;
+    if(begin<0)
+      begin=0;
+    _seek_helper(vf,begin);
+    while(vf->offset<begin+CHUNKSIZE){
+      ret=_get_next_page(vf,og,begin+CHUNKSIZE-vf->offset);
+      if(ret==OV_EREAD)return(OV_EREAD);
+      if(ret<0){
+	break;
+      }else{
+	offset=ret;
+      }
+    }
+  }
+
+  /* we have the offset.  Actually snork and hold the page now */
+  _seek_helper(vf,offset);
+  ret=_get_next_page(vf,og,CHUNKSIZE);
+  if(ret<0)
+    /* this shouldn't be possible */
+    return(OV_EFAULT);
+
+  return(offset);
+}
+
+/* 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,
+				    long begin,
+				    long searched,
+				    long end,
+				    long currentno,
+				    long m){
+  long endsearched=end;
+  long next=end;
+  ogg_page og;
+  long ret;
+  
+  /* the below guards against garbage seperating the last and
+     first pages of two links. */
+  while(searched<endsearched){
+    long bisect;
+    
+    if(endsearched-searched<CHUNKSIZE){
+      bisect=searched;
+    }else{
+      bisect=(searched+endsearched)/2;
+    }
+    
+    _seek_helper(vf,bisect);
+    ret=_get_next_page(vf,&og,-1);
+    if(ret==OV_EREAD)return(OV_EREAD);
+    if(ret<0 || ogg_page_serialno(&og)!=currentno){
+      endsearched=bisect;
+      if(ret>=0)next=ret;
+    }else{
+      searched=ret+og.header_len+og.body_len;
+    }
+  }
+
+  _seek_helper(vf,next);
+  ret=_get_next_page(vf,&og,-1);
+  if(ret==OV_EREAD)return(OV_EREAD);
+  
+  if(searched>=end || ret<0){
+    vf->links=m+1;
+    vf->offsets=(ogg_int64_t *)_ogg_malloc((m+2)*sizeof(*vf->offsets));
+    vf->offsets[m+1]=searched;
+  }else{
+    ret=_bisect_forward_serialno(vf,next,vf->offset,
+				 end,ogg_page_serialno(&og),m+1);
+    if(ret==OV_EREAD)return(OV_EREAD);
+  }
+  
+  vf->offsets[m]=begin;
+  return(0);
+}
+
+/* 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,ogg_page *og_ptr){
+  ogg_page og;
+  ogg_packet op;
+  int i,ret=0;
+  
+  if(!og_ptr){
+    ret=_get_next_page(vf,&og,CHUNKSIZE);
+    if(ret==OV_EREAD)return(OV_EREAD);
+    if(ret<0)return OV_ENOTVORBIS;
+    og_ptr=&og;
+  }
+
+  if(serialno)*serialno=ogg_page_serialno(og_ptr);
+  ogg_stream_init(&vf->os,ogg_page_serialno(og_ptr));
+  vf->ready_state=STREAMSET;
+  
+  /* extract the initial header from the first page and verify that the
+     Ogg bitstream is in fact Vorbis data */
+  
+  vorbis_info_init(vi);
+  vorbis_comment_init(vc);
+  
+  i=0;
+  while(i<3){
+    ogg_stream_pagein(&vf->os,og_ptr);
+    while(i<3){
+      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++;
+    }
+    if(i<3)
+      if(_get_next_page(vf,og_ptr,CHUNKSIZE)<0){
+	ret=OV_EBADHEADER;
+	goto bail_header;
+      }
+  }
+  return 0; 
+
+ bail_header:
+  vorbis_info_clear(vi);
+  vorbis_comment_clear(vc);
+  ogg_stream_clear(&vf->os);
+  vf->ready_state=OPENED;
+
+  return ret;
+}
+
+/* last step of the OggVorbis_File initialization; get all the
+   vorbis_info structs and PCM positions.  Only called by the seekable
+   initialization (local stream storage is hacked slightly; pay
+   attention to how that's done) */
+
+/* this is void and does not propogate errors up because we want to be
+   able to open and use damaged bitstreams as well as we can.  Just
+   watch out for missing information for links in the OggVorbis_File
+   struct */
+static void _prefetch_all_headers(OggVorbis_File *vf, long dataoffset){
+  ogg_page og;
+  int i,ret;
+  
+  vf->vi=(vorbis_info *)_ogg_realloc(vf->vi,vf->links*sizeof(*vf->vi));
+  vf->vc=(vorbis_comment *)_ogg_realloc(vf->vc,vf->links*sizeof(*vf->vc));
+  vf->dataoffsets=(ogg_int64_t *)_ogg_malloc(vf->links*sizeof(*vf->dataoffsets));
+  vf->pcmlengths=(ogg_int64_t *)_ogg_malloc(vf->links*sizeof(*vf->pcmlengths));
+  vf->serialnos=(long *)_ogg_malloc(vf->links*sizeof(*vf->serialnos));
+  
+  for(i=0;i<vf->links;i++){
+    if(i==0){
+      /* we already grabbed the initial header earlier.  Just set the offset */
+      vf->dataoffsets[i]=dataoffset;
+    }else{
+
+      /* seek to the location of the initial header */
+
+      _seek_helper(vf,vf->offsets[i]);
+      if(_fetch_headers(vf,vf->vi+i,vf->vc+i,NULL,NULL)<0){
+    	vf->dataoffsets[i]=-1;
+      }else{
+	vf->dataoffsets[i]=vf->offset;
+        ogg_stream_clear(&vf->os);
+      }
+    }
+
+    /* get the serial number and PCM length of this link. To do this,
+       get the last page of the stream */
+    {
+      long end=vf->offsets[i+1];
+      _seek_helper(vf,end);
+
+      while(1){
+	ret=_get_prev_page(vf,&og);
+	if(ret<0){
+	  /* this should not be possible */
+	  vorbis_info_clear(vf->vi+i);
+	  vorbis_comment_clear(vf->vc+i);
+	  break;
+	}
+	if(ogg_page_granulepos(&og)!=-1){
+	  vf->serialnos[i]=ogg_page_serialno(&og);
+	  vf->pcmlengths[i]=ogg_page_granulepos(&og);
+	  break;
+	}
+	vf->offset=ret;
+      }
+    }
+  }
+}
+
+static void _make_decode_ready(OggVorbis_File *vf){
+  if(vf->ready_state!=STREAMSET)return;
+  if(vf->seekable){
+    vorbis_synthesis_init(&vf->vd,vf->vi+vf->current_link);
+  }else{
+    vorbis_synthesis_init(&vf->vd,vf->vi);
+  }    
+  vorbis_block_init(&vf->vd,&vf->vb);
+  vf->ready_state=INITSET;
+  return;
+}
+
+static int _open_seekable2(OggVorbis_File *vf){
+  long serialno=vf->current_serialno,end;
+  long dataoffset=vf->offset;
+  ogg_page og;
+
+  /* we're partially open and have a first link header state in
+     storage in vf */
+  /* we can seek, so set out learning all about this file */
+  (vf->callbacks.seek_func)(vf->datasource,0,SEEK_END);
+  vf->offset=vf->end=(vf->callbacks.tell_func)(vf->datasource);
+  
+  /* We get the offset for the last page of the physical bitstream.
+     Most OggVorbis files will contain a single logical bitstream */
+  end=_get_prev_page(vf,&og);
+  if(end<0){
+    ov_clear(vf);
+    return(end);
+  }
+
+  /* more than one logical bitstream? */
+  if(ogg_page_serialno(&og)!=serialno){
+
+    /* Chained bitstream. Bisect-search each logical bitstream
+       section.  Do so based on serial number only */
+    if(_bisect_forward_serialno(vf,0,0,end+1,serialno,0)<0){
+      ov_clear(vf);
+      return(OV_EREAD);
+    }
+
+  }else{
+
+    /* Only one logical bitstream */
+    if(_bisect_forward_serialno(vf,0,end,end+1,serialno,0)){
+      ov_clear(vf);
+      return(OV_EREAD);
+    }
+
+  }
+
+  /* the initial header memory is referenced by vf after; don't free it */
+  _prefetch_all_headers(vf,dataoffset);
+  return(ov_raw_seek(vf,0));
+}
+
+/* clear out the current logical bitstream decoder */ 
+static void _decode_clear(OggVorbis_File *vf){
+  ogg_stream_clear(&vf->os);
+  vorbis_dsp_clear(&vf->vd);
+  vorbis_block_clear(&vf->vb);
+  vf->ready_state=OPENED;
+
+  vf->bittrack=0;
+  vf->samptrack=0;
+}
+
+/* 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 _process_packet(OggVorbis_File *vf,int readp){
+  ogg_page og;
+
+  /* handle one packet.  Try to fetch it from current stream state */
+  /* extract packets from page */
+  while(1){
+    
+    /* process a packet if we can.  If the machine isn't loaded,
+       neither is a page */
+    if(vf->ready_state==INITSET){
+      while(1) {
+      	ogg_packet op;
+	int result=ogg_stream_packetout(&vf->os,&op);
+	ogg_int64_t granulepos;
+
+	if(result==-1)return(OV_HOLE); /* hole in the data. */
+	if(result>0){
+	  /* got a packet.  process it */
+	  granulepos=op.granulepos;
+	  if(!vorbis_synthesis(&vf->vb,&op)){ /* 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);
+	      vorbis_synthesis_blockin(&vf->vd,&vf->vb);
+	      vf->samptrack+=vorbis_synthesis_pcmout(&vf->vd,NULL)-oldsamples;
+	      vf->bittrack+=op.bytes*8;
+	    }
+	  
+	    /* update the pcm offset. */
+	    if(granulepos!=-1 && !op.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.e_o_s clause
+	         above */
+	    
+	      samples=vorbis_synthesis_pcmout(&vf->vd,NULL);
+	    
+	      granulepos-=samples;
+	      for(i=0;i<link;i++)
+	        granulepos+=vf->pcmlengths[i];
+	      vf->pcm_offset=granulepos;
+	    }
+	    return(1);
+	  }
+	}
+	else 
+	  break;
+      }
+    }
+
+    if(vf->ready_state>=OPENED){
+      if(!readp)return(0);
+      if(_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;
+      
+      /* has our decoding just traversed a bitstream boundary? */
+      if(vf->ready_state==INITSET){
+	if(vf->current_serialno!=ogg_page_serialno(&og)){
+	  _decode_clear(vf);
+	  
+	  if(!vf->seekable){
+	    vorbis_info_clear(vf->vi);
+	    vorbis_comment_clear(vf->vc);
+	  }
+	}
+      }
+    }
+
+    /* 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){
+	  vf->current_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]==vf->current_serialno)break;
+	  if(link==vf->links)return(OV_EBADLINK); /* sign of a bogus
+						     stream.  error out,
+						     leave machine
+						     uninitialized */
+	  
+	  vf->current_link=link;
+	  
+	  ogg_stream_init(&vf->os,vf->current_serialno);
+	  ogg_stream_reset(&vf->os); 
+	  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,&vf->current_serialno,&og);
+	  if(ret)return(ret);
+	  vf->current_link++;
+	  link=0;
+	}
+      }
+      
+      _make_decode_ready(vf);
+    }
+    ogg_stream_pagein(&vf->os,&og);
+  }
+}
+
+static int _fseek64_wrap(FILE *f,ogg_int64_t off,int whence){
+  if(f==NULL)return(-1);
+  return fseek(f,(int)off,whence);
+}
+
+static int _ov_open1(void *f,OggVorbis_File *vf,char *initial,
+		     long ibytes, ov_callbacks callbacks){
+  long offset=(f?callbacks.seek_func(f,0,SEEK_CUR):-1);
+  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 (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(offset!=-1)vf->seekable=1;
+
+  /* No seeking yet; Set up a 'single' (current) logical bitstream
+     entry for partial open */
+  vf->links=1;
+  vf->vi=(vorbis_info *)_ogg_calloc(vf->links,sizeof(*vf->vi));
+  vf->vc=(vorbis_comment *)_ogg_calloc(vf->links,sizeof(*vf->vc));
+  
+  /* Try to fetch the headers, maintaining all the storage */
+  if((ret=_fetch_headers(vf,vf->vi,vf->vc,&vf->current_serialno,NULL))<0){
+    vf->datasource=NULL;
+    ov_clear(vf);
+  }else if(vf->ready_state < PARTOPEN)
+    vf->ready_state=PARTOPEN;
+  return(ret);
+}
+
+static int _ov_open2(OggVorbis_File *vf){
+  if(vf->ready_state < OPENED)
+    vf->ready_state=OPENED;
+  if(vf->seekable){
+    int ret=_open_seekable2(vf);
+    if(ret){
+      vf->datasource=NULL;
+      ov_clear(vf);
+    }
+    return(ret);
+  }
+  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->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,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,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);
+}
+  
+/* 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,char *initial,long ibytes,
+    ov_callbacks callbacks)
+{
+  return _ov_open1(f,vf,initial,ibytes,callbacks);
+}
+
+int ov_test(FILE *f,OggVorbis_File *vf,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;
+    for(i=0;i<vf->links;i++)
+      bits+=(vf->offsets[i+1]-vf->dataoffsets[i])*8;
+    return(bits*1000/ov_time_total(vf,-1));
+  }else{
+    if(vf->seekable){
+      /* return the actual bitrate */
+      return((vf->offsets[i+1]-vf->dataoffsets[i])*8000/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;
+  vf->bittrack=0;
+  vf->samptrack=0;
+  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){
+    long 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]);
+  }
+}
+
+/* returns: total milliseconds 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 
+*/
+ogg_int64_t 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){
+    ogg_int64_t acc=0;
+    int i;
+    for(i=0;i<vf->links;i++)
+      acc+=ov_time_total(vf,i);
+    return(acc);
+  }else{
+    return(((ogg_int64_t)vf->pcmlengths[i])*1000/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,long pos){
+  ogg_stream_state work_os;
+
+  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->offsets[vf->links])return(OV_EINVAL);
+  
+  /* clear out decoding machine state */
+  vf->pcm_offset=-1;
+  _decode_clear(vf);
+  
+  _seek_helper(vf,pos);
+
+  /* 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
+     a 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=-1;
+    int eosflag=0;
+
+    memset(&work_os,0,sizeof(work_os));/* so that it's safe to clear
+					  it later even if we don't
+					  init it */
+
+    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(eosflag)
+	    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;
+	    
+	    for(i=0;i<link;i++)
+	      granulepos+=vf->pcmlengths[i];
+	    vf->pcm_offset=granulepos-accblock;
+	    break;
+	  }
+	  lastblock=thisblock;
+	  continue;
+	}
+      }
+      
+      if(!lastblock){
+	if(_get_next_page(vf,&og,-1)<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)){
+	_decode_clear(vf); /* clear out stream state */
+	ogg_stream_clear(&work_os);
+      }
+
+      if(vf->ready_state<STREAMSET){
+	int link;
+	
+	vf->current_serialno=ogg_page_serialno(&og);
+	for(link=0;link<vf->links;link++)
+	  if(vf->serialnos[link]==vf->current_serialno)break;
+	if(link==vf->links)goto seek_error; /* sign of a bogus stream.
+					       error out, leave
+					       machine uninitialized */
+	vf->current_link=link;
+	
+	ogg_stream_init(&vf->os,vf->current_serialno);
+	ogg_stream_reset(&vf->os); 
+	ogg_stream_init(&work_os,vf->current_serialno);
+	ogg_stream_reset(&work_os); 
+	vf->ready_state=STREAMSET;
+	
+      }
+    
+      ogg_stream_pagein(&vf->os,&og);
+      ogg_stream_pagein(&work_os,&og);
+      eosflag=ogg_page_eos(&og);
+    }
+  }
+
+  ogg_stream_clear(&work_os);
+  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 preceeding 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;
+  long ret;
+  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];
+    if(pos>=total)break;
+  }
+
+  /* search within the logical bitstream for the page with the highest
+     pcm_pos preceeding (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 target=pos-total;
+    long end=vf->offsets[link+1];
+    long begin=vf->offsets[link];
+    ogg_int64_t endtime = vf->pcmlengths[link];
+    ogg_int64_t begintime = 0;
+    long best=begin;
+    
+    ogg_page og;
+    while(begin<end){
+      long bisect;
+      
+      if(end-begin<CHUNKSIZE){
+	bisect=begin;
+      }else{
+	/* take a (pretty decent) guess. */
+	bisect=begin + 
+	  (target-begintime)*(end-begin)/(endtime-begintime) - CHUNKSIZE;
+	if(bisect<=begin)
+	  bisect=begin+1;
+      }
+      _seek_helper(vf,bisect);
+    
+      while(begin<end){
+	ret=_get_next_page(vf,&og,end-bisect);
+	if(ret==OV_EREAD) goto seek_error;
+	if(ret<0){
+	  if(bisect<=begin+1)
+	    end=begin; /* found it */
+	  else{
+	    if(bisect==0)goto seek_error;
+	    bisect-=CHUNKSIZE;
+	    if(bisect<=begin)bisect=begin+1;
+	    _seek_helper(vf,bisect);
+	  }
+	}else{
+	  ogg_int64_t granulepos=ogg_page_granulepos(&og);
+	  if(granulepos<target){
+	    best=ret;  /* raw offset of packet with granulepos */ 
+	    begin=vf->offset; /* raw offset of next page */
+	    begintime=granulepos;
+	    
+	    if(target-begin>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=ret;
+		bisect-=CHUNKSIZE; /* an endless loop otherwise. */
+		if(bisect<=begin)bisect=begin+1;
+		_seek_helper(vf,bisect);
+	      }else{
+		end=ret;
+		endtime=granulepos;
+		break;
+	      }
+	    }
+	  }
+	}
+      }
+    }
+
+    /* found our page. seek to it, update pcm offset. Easier case than
+       raw_seek, don't keep packets preceeding granulepos. */
+    {
+      ogg_page og;
+      ogg_packet op;
+      /* clear out decoding machine state */
+      _decode_clear(vf);  
+      /* seek */
+      _seek_helper(vf,best);
+      
+      if(_get_next_page(vf,&og,-1)<0)return(OV_EOF); /* shouldn't happen */
+      vf->current_serialno=ogg_page_serialno(&og);
+      vf->current_link=link;
+      
+      ogg_stream_init(&vf->os,vf->current_serialno);
+      ogg_stream_reset(&vf->os); 
+      vf->ready_state=STREAMSET;
+      ogg_stream_pagein(&vf->os,&og);
+
+      /* pull out all but last packet; the one with granulepos */
+      while(1){
+	ret=ogg_stream_packetpeek(&vf->os,&op);
+	if(ret==0){
+	  /* !!! the packet finishing this page originated on a
+             preceeding 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. */
+	  while(1){
+	    ret=_get_prev_page(vf,&og);
+	    if(ret<0)goto seek_error;
+	    if(ogg_page_granulepos(&og)>-1 ||
+	       !ogg_page_continued(&og)){
+	      return ov_raw_seek(vf,ret);
+	    }
+	    vf->offset=ret;
+	  }
+	}
+	if(ret<0)goto seek_error;
+	if(op.granulepos!=-1){
+	  vf->pcm_offset=op.granulepos+total;
+	  break;
+	}else
+	  ret=ogg_stream_packetout(&vf->os,NULL);
+      }
+    }
+  }
+  
+  /* verify result */
+  if(vf->pcm_offset>pos || pos>ov_pcm_total(vf,-1)){
+    ret=OV_EFAULT;
+    goto seek_error;
+  }
+  return(0);
+  
+ seek_error:
+  /* dump machine so we're in a known state */
+  vf->pcm_offset=-1;
+  _decode_clear(vf);
+  return ret;
+}
+
+/* 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);
+
+  /* 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(lastblock)vf->pcm_offset+=(lastblock+thisblock)>>2;
+
+      if(vf->pcm_offset+((thisblock+
+			  vorbis_info_blocksize(vf->vi,1))>>2)>=pos)break;
+
+      ogg_stream_packetout(&vf->os,NULL);
+      
+
+      /* 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;
+	for(i=0;i<vf->current_link;i++)
+	  vf->pcm_offset+=vf->pcmlengths[i];
+      }
+
+      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(vf->current_serialno!=ogg_page_serialno(&og))_decode_clear(vf);
+      
+      if(vf->ready_state<STREAMSET){
+	int link;
+	
+	vf->current_serialno=ogg_page_serialno(&og);
+	for(link=0;link<vf->links;link++)
+	  if(vf->serialnos[link]==vf->current_serialno)break;
+	if(link==vf->links)return(OV_EBADLINK);
+	vf->current_link=link;
+	
+	ogg_stream_init(&vf->os,vf->current_serialno);
+	ogg_stream_reset(&vf->os); 
+	vf->ready_state=STREAMSET;      
+	lastblock=0;
+      }
+      ogg_stream_pagein(&vf->os,&og);
+    }
+  }
+
+  /* discard samples until we reach the desired position. Crossing a
+     logical bitstream boundary with abandon is OK. */
+  _make_decode_ready(vf);
+  while(vf->pcm_offset<pos){
+    ogg_int32_t **pcm;
+    long target=pos-vf->pcm_offset;
+    long samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
+
+    if(samples>target)samples=target;
+    vorbis_synthesis_read(&vf->vd,samples);
+    vf->pcm_offset+=samples;
+    
+    if(samples<target)
+      if(_process_packet(vf,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,ogg_int64_t milliseconds){
+  /* translate time to PCM position and call ov_pcm_seek */
+
+  int link=-1;
+  ogg_int64_t pcm_total=ov_pcm_total(vf,-1);
+  ogg_int64_t time_total=ov_time_total(vf,-1);
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)return(OV_ENOSEEK);
+  if(milliseconds<0 || milliseconds>time_total)return(OV_EINVAL);
+  
+  /* which bitstream section does this time offset occur in? */
+  for(link=vf->links-1;link>=0;link--){
+    pcm_total-=vf->pcmlengths[link];
+    time_total-=ov_time_total(vf,link);
+    if(milliseconds>=time_total)break;
+  }
+
+  /* enough information to convert time offset to pcm offset */
+  {
+    ogg_int64_t target=pcm_total+(milliseconds-time_total)*vf->vi[link].rate/1000;
+    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,ogg_int64_t milliseconds){
+  /* translate time to PCM position and call ov_pcm_seek */
+
+  int link=-1;
+  ogg_int64_t pcm_total=ov_pcm_total(vf,-1);
+  ogg_int64_t time_total=ov_time_total(vf,-1);
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+  if(!vf->seekable)return(OV_ENOSEEK);
+  if(milliseconds<0 || milliseconds>time_total)return(OV_EINVAL);
+  
+  /* which bitstream section does this time offset occur in? */
+  for(link=vf->links-1;link>=0;link--){
+    pcm_total-=vf->pcmlengths[link];
+    time_total-=ov_time_total(vf,link);
+    if(milliseconds>=time_total)break;
+  }
+
+  /* enough information to convert time offset to pcm offset */
+  {
+    ogg_int64_t target=pcm_total+(milliseconds-time_total)*vf->vi[link].rate/1000;
+    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 (milliseconds) of next PCM sample to be read */
+ogg_int64_t ov_time_tell(OggVorbis_File *vf){
+  /* translate time to PCM position and call ov_pcm_seek */
+
+  int link=-1;
+  ogg_int64_t pcm_total=0;
+  ogg_int64_t time_total=0;
+  
+  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];
+      time_total-=ov_time_total(vf,link);
+      if(vf->pcm_offset>=pcm_total)break;
+    }
+  }
+
+  return(time_total+(vf->pcm_offset-pcm_total)/vf->vi[link].rate*1000);
+}
+
+/*  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;
+  }
+}
+
+/* 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).
+
+   input values: buffer) a buffer to hold packed PCM data for return
+		 length) the byte length requested to be placed into buffer
+
+   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(OggVorbis_File *vf,char *buffer,int bytes_req,int *bitstream){
+  int i,j;
+
+  ogg_int32_t **pcm;
+  long samples;
+
+  if(vf->ready_state<OPENED)return(OV_EINVAL);
+
+  while(1){
+    if(vf->ready_state>=STREAMSET){
+      samples=vorbis_synthesis_pcmout(&vf->vd,&pcm);
+      if(samples)break;
+    }
+
+    /* suck in another packet */
+    {
+      int ret=_process_packet(vf,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;
+
+    if(channels==1){
+      if(samples>(bytes_req/2))
+	samples=bytes_req/2;      
+    }else{
+      if(samples>(bytes_req/4))
+	samples=bytes_req/4;
+    }
+    
+    for(i=0;i<channels;i++) { /* It's faster in this order */
+      ogg_int32_t *src=pcm[i];
+      short *dest=((short *)buffer)+i;
+      for(j=0;j<samples;j++) {
+	*dest=CLIP_TO_15(src[j]>>9);
+	dest+=channels;
+      }
+    }
+    
+    vorbis_synthesis_read(&vf->vd,samples);
+    vf->pcm_offset+=samples;
+    if(bitstream)*bitstream=vf->current_link;
+    return(samples*2*channels);
+  }else{
+    return(samples);
+  }
+}
+
+
+
+