release/src/router/libvorbis/lib/block.c

   1 /********************************************************************
   2  *                                                                  *
   3  * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE.   *
   4  * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS     *
   5  * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
   6  * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING.       *
   7  *                                                                  *
   8  * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009             *
   9  * by the Xiph.Org Foundation http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: PCM data vector blocking, windowing and dis/reassembly
  14  last mod: $Id: block.c 16227 2009-07-08 06:58:46Z xiphmont $
  15
  16  Handle windowing, overlap-add, etc of the PCM vectors.  This is made
  17  more amusing by Vorbis' current two allowed block sizes.
  18
  19  ********************************************************************/
  20
  21 #include <stdio.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <ogg/ogg.h>
  25 #include "vorbis/codec.h"
  26 #include "codec_internal.h"
  27
  28 #include "window.h"
  29 #include "mdct.h"
  30 #include "lpc.h"
  31 #include "registry.h"
  32 #include "misc.h"
  33
  34 static int ilog2(unsigned int v){
  35   int ret=0;
  36   if(v)--v;
  37   while(v){
  38     ret++;
  39     v>>=1;
  40   }
  41   return(ret);
  42 }
  43
  44 /* pcm accumulator examples (not exhaustive):
  45
  46  <-------------- lW ---------------->
  47                    <--------------- W ---------------->
  48 :            .....|.....       _______________         |
  49 :        .'''     |     '''_---      |       |\        |
  50 :.....'''         |_____--- '''......|       | \_______|
  51 :.................|__________________|_______|__|______|
  52                   |<------ Sl ------>|      > Sr <     |endW
  53                   |beginSl           |endSl  |  |endSr
  54                   |beginW            |endlW  |beginSr
  55
  56
  57                       |< lW >|
  58                    <--------------- W ---------------->
  59                   |   |  ..  ______________            |
  60                   |   | '  `/        |     ---_        |
  61                   |___.'___/`.       |         ---_____|
  62                   |_______|__|_______|_________________|
  63                   |      >|Sl|<      |<------ Sr ----->|endW
  64                   |       |  |endSl  |beginSr          |endSr
  65                   |beginW |  |endlW
  66                   mult[0] |beginSl                     mult[n]
  67
  68  <-------------- lW ----------------->
  69                           |<--W-->|
  70 :            ..............  ___  |   |
  71 :        .'''             |`/   \ |   |
  72 :.....'''                 |/`....\|...|
  73 :.........................|___|___|___|
  74                           |Sl |Sr |endW
  75                           |   |   |endSr
  76                           |   |beginSr
  77                           |   |endSl
  78                           |beginSl
  79                           |beginW
  80 */
  81
  82 /* block abstraction setup *********************************************/
  83
  84 #ifndef WORD_ALIGN
  85 #define WORD_ALIGN 8
  86 #endif
  87
  88 int vorbis_block_init(vorbis_dsp_state *v, vorbis_block *vb){
  89   int i;
  90   memset(vb,0,sizeof(*vb));
  91   vb->vd=v;
  92   vb->localalloc=0;
  93   vb->localstore=NULL;
  94   if(v->analysisp){
  95     vorbis_block_internal *vbi=
  96       vb->internal=_ogg_calloc(1,sizeof(vorbis_block_internal));
  97     vbi->ampmax=-9999;
  98
  99     for(i=0;i<PACKETBLOBS;i++){
 100       if(i==PACKETBLOBS/2){
 101         vbi->packetblob[i]=&vb->opb;
 102       }else{
 103         vbi->packetblob[i]=
 104           _ogg_calloc(1,sizeof(oggpack_buffer));
 105       }
 106       oggpack_writeinit(vbi->packetblob[i]);
 107     }
 108   }
 109
 110   return(0);
 111 }
 112
 113 void *_vorbis_block_alloc(vorbis_block *vb,long bytes){
 114   bytes=(bytes+(WORD_ALIGN-1)) & ~(WORD_ALIGN-1);
 115   if(bytes+vb->localtop>vb->localalloc){
 116     /* can't just _ogg_realloc... there are outstanding pointers */
 117     if(vb->localstore){
 118       struct alloc_chain *link=_ogg_malloc(sizeof(*link));
 119       vb->totaluse+=vb->localtop;
 120       link->next=vb->reap;
 121       link->ptr=vb->localstore;
 122       vb->reap=link;
 123     }
 124     /* highly conservative */
 125     vb->localalloc=bytes;
 126     vb->localstore=_ogg_malloc(vb->localalloc);
 127     vb->localtop=0;
 128   }
 129   {
 130     void *ret=(void *)(((char *)vb->localstore)+vb->localtop);
 131     vb->localtop+=bytes;
 132     return ret;
 133   }
 134 }
 135
 136 /* reap the chain, pull the ripcord */
 137 void _vorbis_block_ripcord(vorbis_block *vb){
 138   /* reap the chain */
 139   struct alloc_chain *reap=vb->reap;
 140   while(reap){
 141     struct alloc_chain *next=reap->next;
 142     _ogg_free(reap->ptr);
 143     memset(reap,0,sizeof(*reap));
 144     _ogg_free(reap);
 145     reap=next;
 146   }
 147   /* consolidate storage */
 148   if(vb->totaluse){
 149     vb->localstore=_ogg_realloc(vb->localstore,vb->totaluse+vb->localalloc);
 150     vb->localalloc+=vb->totaluse;
 151     vb->totaluse=0;
 152   }
 153
 154   /* pull the ripcord */
 155   vb->localtop=0;
 156   vb->reap=NULL;
 157 }
 158
 159 int vorbis_block_clear(vorbis_block *vb){
 160   int i;
 161   vorbis_block_internal *vbi=vb->internal;
 162
 163   _vorbis_block_ripcord(vb);
 164   if(vb->localstore)_ogg_free(vb->localstore);
 165
 166   if(vbi){
 167     for(i=0;i<PACKETBLOBS;i++){
 168       oggpack_writeclear(vbi->packetblob[i]);
 169       if(i!=PACKETBLOBS/2)_ogg_free(vbi->packetblob[i]);
 170     }
 171     _ogg_free(vbi);
 172   }
 173   memset(vb,0,sizeof(*vb));
 174   return(0);
 175 }
 176
 177 /* Analysis side code, but directly related to blocking.  Thus it's
 178    here and not in analysis.c (which is for analysis transforms only).
 179    The init is here because some of it is shared */
 180
 181 static int _vds_shared_init(vorbis_dsp_state *v,vorbis_info *vi,int encp){
 182   int i;
 183   codec_setup_info *ci=vi->codec_setup;
 184   private_state *b=NULL;
 185   int hs;
 186
 187   if(ci==NULL) return 1;
 188   hs=ci->halfrate_flag;
 189
 190   memset(v,0,sizeof(*v));
 191   b=v->backend_state=_ogg_calloc(1,sizeof(*b));
 192
 193   v->vi=vi;
 194   b->modebits=ilog2(ci->modes);
 195
 196   b->transform[0]=_ogg_calloc(VI_TRANSFORMB,sizeof(*b->transform[0]));
 197   b->transform[1]=_ogg_calloc(VI_TRANSFORMB,sizeof(*b->transform[1]));
 198
 199   /* MDCT is tranform 0 */
 200
 201   b->transform[0][0]=_ogg_calloc(1,sizeof(mdct_lookup));
 202   b->transform[1][0]=_ogg_calloc(1,sizeof(mdct_lookup));
 203   mdct_init(b->transform[0][0],ci->blocksizes[0]>>hs);
 204   mdct_init(b->transform[1][0],ci->blocksizes[1]>>hs);
 205
 206   /* Vorbis I uses only window type 0 */
 207   b->window[0]=ilog2(ci->blocksizes[0])-6;
 208   b->window[1]=ilog2(ci->blocksizes[1])-6;
 209
 210   if(encp){ /* encode/decode differ here */
 211
 212     /* analysis always needs an fft */
 213     drft_init(&b->fft_look[0],ci->blocksizes[0]);
 214     drft_init(&b->fft_look[1],ci->blocksizes[1]);
 215
 216     /* finish the codebooks */
 217     if(!ci->fullbooks){
 218       ci->fullbooks=_ogg_calloc(ci->books,sizeof(*ci->fullbooks));
 219       for(i=0;i<ci->books;i++)
 220         vorbis_book_init_encode(ci->fullbooks+i,ci->book_param[i]);
 221     }
 222
 223     b->psy=_ogg_calloc(ci->psys,sizeof(*b->psy));
 224     for(i=0;i<ci->psys;i++){
 225       _vp_psy_init(b->psy+i,
 226                    ci->psy_param[i],
 227                    &ci->psy_g_param,
 228                    ci->blocksizes[ci->psy_param[i]->blockflag]/2,
 229                    vi->rate);
 230     }
 231
 232     v->analysisp=1;
 233   }else{
 234     /* finish the codebooks */
 235     if(!ci->fullbooks){
 236       ci->fullbooks=_ogg_calloc(ci->books,sizeof(*ci->fullbooks));
 237       for(i=0;i<ci->books;i++){
 238         if(vorbis_book_init_decode(ci->fullbooks+i,ci->book_param[i]))
 239           return -1;
 240         /* decode codebooks are now standalone after init */
 241         vorbis_staticbook_destroy(ci->book_param[i]);
 242         ci->book_param[i]=NULL;
 243       }
 244     }
 245   }
 246
 247   /* initialize the storage vectors. blocksize[1] is small for encode,
 248      but the correct size for decode */
 249   v->pcm_storage=ci->blocksizes[1];
 250   v->pcm=_ogg_malloc(vi->channels*sizeof(*v->pcm));
 251   v->pcmret=_ogg_malloc(vi->channels*sizeof(*v->pcmret));
 252   {
 253     int i;
 254     for(i=0;i<vi->channels;i++)
 255       v->pcm[i]=_ogg_calloc(v->pcm_storage,sizeof(*v->pcm[i]));
 256   }
 257
 258   /* all 1 (large block) or 0 (small block) */
 259   /* explicitly set for the sake of clarity */
 260   v->lW=0; /* previous window size */
 261   v->W=0;  /* current window size */
 262
 263   /* all vector indexes */
 264   v->centerW=ci->blocksizes[1]/2;
 265
 266   v->pcm_current=v->centerW;
 267
 268   /* initialize all the backend lookups */
 269   b->flr=_ogg_calloc(ci->floors,sizeof(*b->flr));
 270   b->residue=_ogg_calloc(ci->residues,sizeof(*b->residue));
 271
 272   for(i=0;i<ci->floors;i++)
 273     b->flr[i]=_floor_P[ci->floor_type[i]]->
 274       look(v,ci->floor_param[i]);
 275
 276   for(i=0;i<ci->residues;i++)
 277     b->residue[i]=_residue_P[ci->residue_type[i]]->
 278       look(v,ci->residue_param[i]);
 279
 280   return 0;
 281 }
 282
 283 /* arbitrary settings and spec-mandated numbers get filled in here */
 284 int vorbis_analysis_init(vorbis_dsp_state *v,vorbis_info *vi){
 285   private_state *b=NULL;
 286
 287   if(_vds_shared_init(v,vi,1))return 1;
 288   b=v->backend_state;
 289   b->psy_g_look=_vp_global_look(vi);
 290
 291   /* Initialize the envelope state storage */
 292   b->ve=_ogg_calloc(1,sizeof(*b->ve));
 293   _ve_envelope_init(b->ve,vi);
 294
 295   vorbis_bitrate_init(vi,&b->bms);
 296
 297   /* compressed audio packets start after the headers
 298      with sequence number 3 */
 299   v->sequence=3;
 300
 301   return(0);
 302 }
 303
 304 void vorbis_dsp_clear(vorbis_dsp_state *v){
 305   int i;
 306   if(v){
 307     vorbis_info *vi=v->vi;
 308     codec_setup_info *ci=(vi?vi->codec_setup:NULL);
 309     private_state *b=v->backend_state;
 310
 311     if(b){
 312
 313       if(b->ve){
 314         _ve_envelope_clear(b->ve);
 315         _ogg_free(b->ve);
 316       }
 317
 318       if(b->transform[0]){
 319         mdct_clear(b->transform[0][0]);
 320         _ogg_free(b->transform[0][0]);
 321         _ogg_free(b->transform[0]);
 322       }
 323       if(b->transform[1]){
 324         mdct_clear(b->transform[1][0]);
 325         _ogg_free(b->transform[1][0]);
 326         _ogg_free(b->transform[1]);
 327       }
 328
 329       if(b->flr){
 330         if(ci)
 331           for(i=0;i<ci->floors;i++)
 332             _floor_P[ci->floor_type[i]]->
 333               free_look(b->flr[i]);
 334         _ogg_free(b->flr);
 335       }
 336       if(b->residue){
 337         if(ci)
 338           for(i=0;i<ci->residues;i++)
 339             _residue_P[ci->residue_type[i]]->
 340               free_look(b->residue[i]);
 341         _ogg_free(b->residue);
 342       }
 343       if(b->psy){
 344         if(ci)
 345           for(i=0;i<ci->psys;i++)
 346             _vp_psy_clear(b->psy+i);
 347         _ogg_free(b->psy);
 348       }
 349
 350       if(b->psy_g_look)_vp_global_free(b->psy_g_look);
 351       vorbis_bitrate_clear(&b->bms);
 352
 353       drft_clear(&b->fft_look[0]);
 354       drft_clear(&b->fft_look[1]);
 355
 356     }
 357
 358     if(v->pcm){
 359       if(vi)
 360         for(i=0;i<vi->channels;i++)
 361           if(v->pcm[i])_ogg_free(v->pcm[i]);
 362       _ogg_free(v->pcm);
 363       if(v->pcmret)_ogg_free(v->pcmret);
 364     }
 365
 366     if(b){
 367       /* free header, header1, header2 */
 368       if(b->header)_ogg_free(b->header);
 369       if(b->header1)_ogg_free(b->header1);
 370       if(b->header2)_ogg_free(b->header2);
 371       _ogg_free(b);
 372     }
 373
 374     memset(v,0,sizeof(*v));
 375   }
 376 }
 377
 378 float **vorbis_analysis_buffer(vorbis_dsp_state *v, int vals){
 379   int i;
 380   vorbis_info *vi=v->vi;
 381   private_state *b=v->backend_state;
 382
 383   /* free header, header1, header2 */
 384   if(b->header)_ogg_free(b->header);b->header=NULL;
 385   if(b->header1)_ogg_free(b->header1);b->header1=NULL;
 386   if(b->header2)_ogg_free(b->header2);b->header2=NULL;
 387
 388   /* Do we have enough storage space for the requested buffer? If not,
 389      expand the PCM (and envelope) storage */
 390
 391   if(v->pcm_current+vals>=v->pcm_storage){
 392     v->pcm_storage=v->pcm_current+vals*2;
 393
 394     for(i=0;i<vi->channels;i++){
 395       v->pcm[i]=_ogg_realloc(v->pcm[i],v->pcm_storage*sizeof(*v->pcm[i]));
 396     }
 397   }
 398
 399   for(i=0;i<vi->channels;i++)
 400     v->pcmret[i]=v->pcm[i]+v->pcm_current;
 401
 402   return(v->pcmret);
 403 }
 404
 405 static void _preextrapolate_helper(vorbis_dsp_state *v){
 406   int i;
 407   int order=16;
 408   float *lpc=alloca(order*sizeof(*lpc));
 409   float *work=alloca(v->pcm_current*sizeof(*work));
 410   long j;
 411   v->preextrapolate=1;
 412
 413   if(v->pcm_current-v->centerW>order*2){ /* safety */
 414     for(i=0;i<v->vi->channels;i++){
 415       /* need to run the extrapolation in reverse! */
 416       for(j=0;j<v->pcm_current;j++)
 417         work[j]=v->pcm[i][v->pcm_current-j-1];
 418
 419       /* prime as above */
 420       vorbis_lpc_from_data(work,lpc,v->pcm_current-v->centerW,order);
 421
 422 #if 0
 423       if(v->vi->channels==2){
 424         if(i==0)
 425           _analysis_output("predataL",0,work,v->pcm_current-v->centerW,0,0,0);
 426         else
 427           _analysis_output("predataR",0,work,v->pcm_current-v->centerW,0,0,0);
 428       }else{
 429         _analysis_output("predata",0,work,v->pcm_current-v->centerW,0,0,0);
 430       }
 431 #endif
 432
 433       /* run the predictor filter */
 434       vorbis_lpc_predict(lpc,work+v->pcm_current-v->centerW-order,
 435                          order,
 436                          work+v->pcm_current-v->centerW,
 437                          v->centerW);
 438
 439       for(j=0;j<v->pcm_current;j++)
 440         v->pcm[i][v->pcm_current-j-1]=work[j];
 441
 442     }
 443   }
 444 }
 445
 446
 447 /* call with val<=0 to set eof */
 448
 449 int vorbis_analysis_wrote(vorbis_dsp_state *v, int vals){
 450   vorbis_info *vi=v->vi;
 451   codec_setup_info *ci=vi->codec_setup;
 452
 453   if(vals<=0){
 454     int order=32;
 455     int i;
 456     float *lpc=alloca(order*sizeof(*lpc));
 457
 458     /* if it wasn't done earlier (very short sample) */
 459     if(!v->preextrapolate)
 460       _preextrapolate_helper(v);
 461
 462     /* We're encoding the end of the stream.  Just make sure we have
 463        [at least] a few full blocks of zeroes at the end. */
 464     /* actually, we don't want zeroes; that could drop a large
 465        amplitude off a cliff, creating spread spectrum noise that will
 466        suck to encode.  Extrapolate for the sake of cleanliness. */
 467
 468     vorbis_analysis_buffer(v,ci->blocksizes[1]*3);
 469     v->eofflag=v->pcm_current;
 470     v->pcm_current+=ci->blocksizes[1]*3;
 471
 472     for(i=0;i<vi->channels;i++){
 473       if(v->eofflag>order*2){
 474         /* extrapolate with LPC to fill in */
 475         long n;
 476
 477         /* make a predictor filter */
 478         n=v->eofflag;
 479         if(n>ci->blocksizes[1])n=ci->blocksizes[1];
 480         vorbis_lpc_from_data(v->pcm[i]+v->eofflag-n,lpc,n,order);
 481
 482         /* run the predictor filter */
 483         vorbis_lpc_predict(lpc,v->pcm[i]+v->eofflag-order,order,
 484                            v->pcm[i]+v->eofflag,v->pcm_current-v->eofflag);
 485       }else{
 486         /* not enough data to extrapolate (unlikely to happen due to
 487            guarding the overlap, but bulletproof in case that
 488            assumtion goes away). zeroes will do. */
 489         memset(v->pcm[i]+v->eofflag,0,
 490                (v->pcm_current-v->eofflag)*sizeof(*v->pcm[i]));
 491
 492       }
 493     }
 494   }else{
 495
 496     if(v->pcm_current+vals>v->pcm_storage)
 497       return(OV_EINVAL);
 498
 499     v->pcm_current+=vals;
 500
 501     /* we may want to reverse extrapolate the beginning of a stream
 502        too... in case we're beginning on a cliff! */
 503     /* clumsy, but simple.  It only runs once, so simple is good. */
 504     if(!v->preextrapolate && v->pcm_current-v->centerW>ci->blocksizes[1])
 505       _preextrapolate_helper(v);
 506
 507   }
 508   return(0);
 509 }
 510
 511 /* do the deltas, envelope shaping, pre-echo and determine the size of
 512    the next block on which to continue analysis */
 513 int vorbis_analysis_blockout(vorbis_dsp_state *v,vorbis_block *vb){
 514   int i;
 515   vorbis_info *vi=v->vi;
 516   codec_setup_info *ci=vi->codec_setup;
 517   private_state *b=v->backend_state;
 518   vorbis_look_psy_global *g=b->psy_g_look;
 519   long beginW=v->centerW-ci->blocksizes[v->W]/2,centerNext;
 520   vorbis_block_internal *vbi=(vorbis_block_internal *)vb->internal;
 521
 522   /* check to see if we're started... */
 523   if(!v->preextrapolate)return(0);
 524
 525   /* check to see if we're done... */
 526   if(v->eofflag==-1)return(0);
 527
 528   /* By our invariant, we have lW, W and centerW set.  Search for
 529      the next boundary so we can determine nW (the next window size)
 530      which lets us compute the shape of the current block's window */
 531
 532   /* we do an envelope search even on a single blocksize; we may still
 533      be throwing more bits at impulses, and envelope search handles
 534      marking impulses too. */
 535   {
 536     long bp=_ve_envelope_search(v);
 537     if(bp==-1){
 538
 539       if(v->eofflag==0)return(0); /* not enough data currently to search for a
 540                                      full long block */
 541       v->nW=0;
 542     }else{
 543
 544       if(ci->blocksizes[0]==ci->blocksizes[1])
 545         v->nW=0;
 546       else
 547         v->nW=bp;
 548     }
 549   }
 550
 551   centerNext=v->centerW+ci->blocksizes[v->W]/4+ci->blocksizes[v->nW]/4;
 552
 553   {
 554     /* center of next block + next block maximum right side. */
 555
 556     long blockbound=centerNext+ci->blocksizes[v->nW]/2;
 557     if(v->pcm_current<blockbound)return(0); /* not enough data yet;
 558                                                although this check is
 559                                                less strict that the
 560                                                _ve_envelope_search,
 561                                                the search is not run
 562                                                if we only use one
 563                                                block size */
 564
 565
 566   }
 567
 568   /* fill in the block.  Note that for a short window, lW and nW are *short*
 569      regardless of actual settings in the stream */
 570
 571   _vorbis_block_ripcord(vb);
 572   vb->lW=v->lW;
 573   vb->W=v->W;
 574   vb->nW=v->nW;
 575
 576   if(v->W){
 577     if(!v->lW || !v->nW){
 578       vbi->blocktype=BLOCKTYPE_TRANSITION;
 579       /*fprintf(stderr,"-");*/
 580     }else{
 581       vbi->blocktype=BLOCKTYPE_LONG;
 582       /*fprintf(stderr,"_");*/
 583     }
 584   }else{
 585     if(_ve_envelope_mark(v)){
 586       vbi->blocktype=BLOCKTYPE_IMPULSE;
 587       /*fprintf(stderr,"|");*/
 588
 589     }else{
 590       vbi->blocktype=BLOCKTYPE_PADDING;
 591       /*fprintf(stderr,".");*/
 592
 593     }
 594   }
 595
 596   vb->vd=v;
 597   vb->sequence=v->sequence++;
 598   vb->granulepos=v->granulepos;
 599   vb->pcmend=ci->blocksizes[v->W];
 600
 601   /* copy the vectors; this uses the local storage in vb */
 602
 603   /* this tracks 'strongest peak' for later psychoacoustics */
 604   /* moved to the global psy state; clean this mess up */
 605   if(vbi->ampmax>g->ampmax)g->ampmax=vbi->ampmax;
 606   g->ampmax=_vp_ampmax_decay(g->ampmax,v);
 607   vbi->ampmax=g->ampmax;
 608
 609   vb->pcm=_vorbis_block_alloc(vb,sizeof(*vb->pcm)*vi->channels);
 610   vbi->pcmdelay=_vorbis_block_alloc(vb,sizeof(*vbi->pcmdelay)*vi->channels);
 611   for(i=0;i<vi->channels;i++){
 612     vbi->pcmdelay[i]=
 613       _vorbis_block_alloc(vb,(vb->pcmend+beginW)*sizeof(*vbi->pcmdelay[i]));
 614     memcpy(vbi->pcmdelay[i],v->pcm[i],(vb->pcmend+beginW)*sizeof(*vbi->pcmdelay[i]));
 615     vb->pcm[i]=vbi->pcmdelay[i]+beginW;
 616
 617     /* before we added the delay
 618        vb->pcm[i]=_vorbis_block_alloc(vb,vb->pcmend*sizeof(*vb->pcm[i]));
 619        memcpy(vb->pcm[i],v->pcm[i]+beginW,ci->blocksizes[v->W]*sizeof(*vb->pcm[i]));
 620     */
 621
 622   }
 623
 624   /* handle eof detection: eof==0 means that we've not yet received EOF
 625                            eof>0  marks the last 'real' sample in pcm[]
 626                            eof<0  'no more to do'; doesn't get here */
 627
 628   if(v->eofflag){
 629     if(v->centerW>=v->eofflag){
 630       v->eofflag=-1;
 631       vb->eofflag=1;
 632       return(1);
 633     }
 634   }
 635
 636   /* advance storage vectors and clean up */
 637   {
 638     int new_centerNext=ci->blocksizes[1]/2;
 639     int movementW=centerNext-new_centerNext;
 640
 641     if(movementW>0){
 642
 643       _ve_envelope_shift(b->ve,movementW);
 644       v->pcm_current-=movementW;
 645
 646       for(i=0;i<vi->channels;i++)
 647         memmove(v->pcm[i],v->pcm[i]+movementW,
 648                 v->pcm_current*sizeof(*v->pcm[i]));
 649
 650
 651       v->lW=v->W;
 652       v->W=v->nW;
 653       v->centerW=new_centerNext;
 654
 655       if(v->eofflag){
 656         v->eofflag-=movementW;
 657         if(v->eofflag<=0)v->eofflag=-1;
 658         /* do not add padding to end of stream! */
 659         if(v->centerW>=v->eofflag){
 660           v->granulepos+=movementW-(v->centerW-v->eofflag);
 661         }else{
 662           v->granulepos+=movementW;
 663         }
 664       }else{
 665         v->granulepos+=movementW;
 666       }
 667     }
 668   }
 669
 670   /* done */
 671   return(1);
 672 }
 673
 674 int vorbis_synthesis_restart(vorbis_dsp_state *v){
 675   vorbis_info *vi=v->vi;
 676   codec_setup_info *ci;
 677   int hs;
 678
 679   if(!v->backend_state)return -1;
 680   if(!vi)return -1;
 681   ci=vi->codec_setup;
 682   if(!ci)return -1;
 683   hs=ci->halfrate_flag;
 684
 685   v->centerW=ci->blocksizes[1]>>(hs+1);
 686   v->pcm_current=v->centerW>>hs;
 687
 688   v->pcm_returned=-1;
 689   v->granulepos=-1;
 690   v->sequence=-1;
 691   v->eofflag=0;
 692   ((private_state *)(v->backend_state))->sample_count=-1;
 693
 694   return(0);
 695 }
 696
 697 int vorbis_synthesis_init(vorbis_dsp_state *v,vorbis_info *vi){
 698   if(_vds_shared_init(v,vi,0)){
 699     vorbis_dsp_clear(v);
 700     return 1;
 701   }
 702   vorbis_synthesis_restart(v);
 703   return 0;
 704 }
 705
 706 /* Unlike in analysis, the window is only partially applied for each
 707    block.  The time domain envelope is not yet handled at the point of
 708    calling (as it relies on the previous block). */
 709
 710 int vorbis_synthesis_blockin(vorbis_dsp_state *v,vorbis_block *vb){
 711   vorbis_info *vi=v->vi;
 712   codec_setup_info *ci=vi->codec_setup;
 713   private_state *b=v->backend_state;
 714   int hs=ci->halfrate_flag;
 715   int i,j;
 716
 717   if(!vb)return(OV_EINVAL);
 718   if(v->pcm_current>v->pcm_returned  && v->pcm_returned!=-1)return(OV_EINVAL);
 719
 720   v->lW=v->W;
 721   v->W=vb->W;
 722   v->nW=-1;
 723
 724   if((v->sequence==-1)||
 725      (v->sequence+1 != vb->sequence)){
 726     v->granulepos=-1; /* out of sequence; lose count */
 727     b->sample_count=-1;
 728   }
 729
 730   v->sequence=vb->sequence;
 731
 732   if(vb->pcm){  /* no pcm to process if vorbis_synthesis_trackonly
 733                    was called on block */
 734     int n=ci->blocksizes[v->W]>>(hs+1);
 735     int n0=ci->blocksizes[0]>>(hs+1);
 736     int n1=ci->blocksizes[1]>>(hs+1);
 737
 738     int thisCenter;
 739     int prevCenter;
 740
 741     v->glue_bits+=vb->glue_bits;
 742     v->time_bits+=vb->time_bits;
 743     v->floor_bits+=vb->floor_bits;
 744     v->res_bits+=vb->res_bits;
 745
 746     if(v->centerW){
 747       thisCenter=n1;
 748       prevCenter=0;
 749     }else{
 750       thisCenter=0;
 751       prevCenter=n1;
 752     }
 753
 754     /* v->pcm is now used like a two-stage double buffer.  We don't want
 755        to have to constantly shift *or* adjust memory usage.  Don't
 756        accept a new block until the old is shifted out */
 757
 758     for(j=0;j<vi->channels;j++){
 759       /* the overlap/add section */
 760       if(v->lW){
 761         if(v->W){
 762           /* large/large */
 763           float *w=_vorbis_window_get(b->window[1]-hs);
 764           float *pcm=v->pcm[j]+prevCenter;
 765           float *p=vb->pcm[j];
 766           for(i=0;i<n1;i++)
 767             pcm[i]=pcm[i]*w[n1-i-1] + p[i]*w[i];
 768         }else{
 769           /* large/small */
 770           float *w=_vorbis_window_get(b->window[0]-hs);
 771           float *pcm=v->pcm[j]+prevCenter+n1/2-n0/2;
 772           float *p=vb->pcm[j];
 773           for(i=0;i<n0;i++)
 774             pcm[i]=pcm[i]*w[n0-i-1] +p[i]*w[i];
 775         }
 776       }else{
 777         if(v->W){
 778           /* small/large */
 779           float *w=_vorbis_window_get(b->window[0]-hs);
 780           float *pcm=v->pcm[j]+prevCenter;
 781           float *p=vb->pcm[j]+n1/2-n0/2;
 782           for(i=0;i<n0;i++)
 783             pcm[i]=pcm[i]*w[n0-i-1] +p[i]*w[i];
 784           for(;i<n1/2+n0/2;i++)
 785             pcm[i]=p[i];
 786         }else{
 787           /* small/small */
 788           float *w=_vorbis_window_get(b->window[0]-hs);
 789           float *pcm=v->pcm[j]+prevCenter;
 790           float *p=vb->pcm[j];
 791           for(i=0;i<n0;i++)
 792             pcm[i]=pcm[i]*w[n0-i-1] +p[i]*w[i];
 793         }
 794       }
 795
 796       /* the copy section */
 797       {
 798         float *pcm=v->pcm[j]+thisCenter;
 799         float *p=vb->pcm[j]+n;
 800         for(i=0;i<n;i++)
 801           pcm[i]=p[i];
 802       }
 803     }
 804
 805     if(v->centerW)
 806       v->centerW=0;
 807     else
 808       v->centerW=n1;
 809
 810     /* deal with initial packet state; we do this using the explicit
 811        pcm_returned==-1 flag otherwise we're sensitive to first block
 812        being short or long */
 813
 814     if(v->pcm_returned==-1){
 815       v->pcm_returned=thisCenter;
 816       v->pcm_current=thisCenter;
 817     }else{
 818       v->pcm_returned=prevCenter;
 819       v->pcm_current=prevCenter+
 820         ((ci->blocksizes[v->lW]/4+
 821         ci->blocksizes[v->W]/4)>>hs);
 822     }
 823
 824   }
 825
 826   /* track the frame number... This is for convenience, but also
 827      making sure our last packet doesn't end with added padding.  If
 828      the last packet is partial, the number of samples we'll have to
 829      return will be past the vb->granulepos.
 830
 831      This is not foolproof!  It will be confused if we begin
 832      decoding at the last page after a seek or hole.  In that case,
 833      we don't have a starting point to judge where the last frame
 834      is.  For this reason, vorbisfile will always try to make sure
 835      it reads the last two marked pages in proper sequence */
 836
 837   if(b->sample_count==-1){
 838     b->sample_count=0;
 839   }else{
 840     b->sample_count+=ci->blocksizes[v->lW]/4+ci->blocksizes[v->W]/4;
 841   }
 842
 843   if(v->granulepos==-1){
 844     if(vb->granulepos!=-1){ /* only set if we have a position to set to */
 845
 846       v->granulepos=vb->granulepos;
 847
 848       /* is this a short page? */
 849       if(b->sample_count>v->granulepos){
 850         /* corner case; if this is both the first and last audio page,
 851            then spec says the end is cut, not beginning */
 852         if(vb->eofflag){
 853           /* trim the end */
 854           /* no preceeding granulepos; assume we started at zero (we'd
 855              have to in a short single-page stream) */
 856           /* granulepos could be -1 due to a seek, but that would result
 857              in a long count, not short count */
 858
 859           v->pcm_current-=(b->sample_count-v->granulepos)>>hs;
 860         }else{
 861           /* trim the beginning */
 862           v->pcm_returned+=(b->sample_count-v->granulepos)>>hs;
 863           if(v->pcm_returned>v->pcm_current)
 864             v->pcm_returned=v->pcm_current;
 865         }
 866
 867       }
 868
 869     }
 870   }else{
 871     v->granulepos+=ci->blocksizes[v->lW]/4+ci->blocksizes[v->W]/4;
 872     if(vb->granulepos!=-1 && v->granulepos!=vb->granulepos){
 873
 874       if(v->granulepos>vb->granulepos){
 875         long extra=v->granulepos-vb->granulepos;
 876
 877         if(extra)
 878           if(vb->eofflag){
 879             /* partial last frame.  Strip the extra samples off */
 880             v->pcm_current-=extra>>hs;
 881           } /* else {Shouldn't happen *unless* the bitstream is out of
 882                spec.  Either way, believe the bitstream } */
 883       } /* else {Shouldn't happen *unless* the bitstream is out of
 884            spec.  Either way, believe the bitstream } */
 885       v->granulepos=vb->granulepos;
 886     }
 887   }
 888
 889   /* Update, cleanup */
 890
 891   if(vb->eofflag)v->eofflag=1;
 892   return(0);
 893
 894 }
 895
 896 /* pcm==NULL indicates we just want the pending samples, no more */
 897 int vorbis_synthesis_pcmout(vorbis_dsp_state *v,float ***pcm){
 898   vorbis_info *vi=v->vi;
 899
 900   if(v->pcm_returned>-1 && v->pcm_returned<v->pcm_current){
 901     if(pcm){
 902       int i;
 903       for(i=0;i<vi->channels;i++)
 904         v->pcmret[i]=v->pcm[i]+v->pcm_returned;
 905       *pcm=v->pcmret;
 906     }
 907     return(v->pcm_current-v->pcm_returned);
 908   }
 909   return(0);
 910 }
 911
 912 int vorbis_synthesis_read(vorbis_dsp_state *v,int n){
 913   if(n && v->pcm_returned+n>v->pcm_current)return(OV_EINVAL);
 914   v->pcm_returned+=n;
 915   return(0);
 916 }
 917
 918 /* intended for use with a specific vorbisfile feature; we want access
 919    to the [usually synthetic/postextrapolated] buffer and lapping at
 920    the end of a decode cycle, specifically, a half-short-block worth.
 921    This funtion works like pcmout above, except it will also expose
 922    this implicit buffer data not normally decoded. */
 923 int vorbis_synthesis_lapout(vorbis_dsp_state *v,float ***pcm){
 924   vorbis_info *vi=v->vi;
 925   codec_setup_info *ci=vi->codec_setup;
 926   int hs=ci->halfrate_flag;
 927
 928   int n=ci->blocksizes[v->W]>>(hs+1);
 929   int n0=ci->blocksizes[0]>>(hs+1);
 930   int n1=ci->blocksizes[1]>>(hs+1);
 931   int i,j;
 932
 933   if(v->pcm_returned<0)return 0;
 934
 935   /* our returned data ends at pcm_returned; because the synthesis pcm
 936      buffer is a two-fragment ring, that means our data block may be
 937      fragmented by buffering, wrapping or a short block not filling
 938      out a buffer.  To simplify things, we unfragment if it's at all
 939      possibly needed. Otherwise, we'd need to call lapout more than
 940      once as well as hold additional dsp state.  Opt for
 941      simplicity. */
 942
 943   /* centerW was advanced by blockin; it would be the center of the
 944      *next* block */
 945   if(v->centerW==n1){
 946     /* the data buffer wraps; swap the halves */
 947     /* slow, sure, small */
 948     for(j=0;j<vi->channels;j++){
 949       float *p=v->pcm[j];
 950       for(i=0;i<n1;i++){
 951         float temp=p[i];
 952         p[i]=p[i+n1];
 953         p[i+n1]=temp;
 954       }
 955     }
 956
 957     v->pcm_current-=n1;
 958     v->pcm_returned-=n1;
 959     v->centerW=0;
 960   }
 961
 962   /* solidify buffer into contiguous space */
 963   if((v->lW^v->W)==1){
 964     /* long/short or short/long */
 965     for(j=0;j<vi->channels;j++){
 966       float *s=v->pcm[j];
 967       float *d=v->pcm[j]+(n1-n0)/2;
 968       for(i=(n1+n0)/2-1;i>=0;--i)
 969         d[i]=s[i];
 970     }
 971     v->pcm_returned+=(n1-n0)/2;
 972     v->pcm_current+=(n1-n0)/2;
 973   }else{
 974     if(v->lW==0){
 975       /* short/short */
 976       for(j=0;j<vi->channels;j++){
 977         float *s=v->pcm[j];
 978         float *d=v->pcm[j]+n1-n0;
 979         for(i=n0-1;i>=0;--i)
 980           d[i]=s[i];
 981       }
 982       v->pcm_returned+=n1-n0;
 983       v->pcm_current+=n1-n0;
 984     }
 985   }
 986
 987   if(pcm){
 988     int i;
 989     for(i=0;i<vi->channels;i++)
 990       v->pcmret[i]=v->pcm[i]+v->pcm_returned;
 991     *pcm=v->pcmret;
 992   }
 993
 994   return(n1+n-v->pcm_returned);
 995
 996 }
 997
 998 float *vorbis_window(vorbis_dsp_state *v,int W){
 999   vorbis_info *vi=v->vi;
1000   codec_setup_info *ci=vi->codec_setup;
1001   int hs=ci->halfrate_flag;
1002   private_state *b=v->backend_state;
1003
1004   if(b->window[W]-1<0)return NULL;
1005   return _vorbis_window_get(b->window[W]-hs);
1006 }