lib/bitrate.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 1994-2001             *
   9  * by the XIPHOPHORUS Company http://www.xiph.org/                  *
  10  *                                                                  *
  11  ********************************************************************
  12
  13  function: bitrate tracking and management
  14  last mod: $Id: bitrate.c,v 1.6 2001/12/19 08:10:03 xiphmont Exp $
  15
  16  ********************************************************************/
  17
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <string.h>
  21 #include <math.h>
  22 #include <ogg/ogg.h>
  23 #include "vorbis/codec.h"
  24 #include "codec_internal.h"
  25 #include "os.h"
  26 #include "bitrate.h"
  27
  28 #define BINBITS(pos,bin) ((bin)>0?bm->queue_binned[(pos)*bins+(bin)-1]:0)
  29 #define LIMITBITS(pos,bin) ((bin)>-bins?\
  30                  bm->minmax_binstack[(pos)*bins*2+((bin)+bins)-1]:0)
  31
  32 static long LACING_ADJUST(long bits){
  33   int addto=((bits+7)/8+1)/256+1;
  34   return( ((bits+7)/8+addto)*8 );
  35 }
  36
  37 static double floater_interpolate(bitrate_manager_state *bm,vorbis_info *vi,
  38                                   double desired_rate){
  39   int bin=bm->avgfloat*BITTRACK_DIVISOR-1.;
  40   double lobitrate;
  41   double hibitrate;
  42
  43   lobitrate=(double)(bin==0?0:bm->avg_binacc[bin-1])/bm->avg_sampleacc*vi->rate;
  44   while(lobitrate>desired_rate && bin>0){
  45     bin--;
  46     lobitrate=(double)(bin==0?0:bm->avg_binacc[bin-1])/bm->avg_sampleacc*vi->rate;
  47   }
  48
  49   hibitrate=(double)(bin>=bm->queue_bins?bm->avg_binacc[bm->queue_bins-1]:
  50                      bm->avg_binacc[bin])/bm->avg_sampleacc*vi->rate;
  51   while(hibitrate<desired_rate && bin<bm->queue_bins){
  52     bin++;
  53     if(bin<bm->queue_bins)
  54       hibitrate=(double)bm->avg_binacc[bin]/bm->avg_sampleacc*vi->rate;
  55   }
  56
  57   /* interpolate */
  58   if(bin==bm->queue_bins){
  59     return bin/(double)BITTRACK_DIVISOR;
  60   }else{
  61     double delta=(desired_rate-lobitrate)/(hibitrate-lobitrate);
  62     return (bin+delta)/(double)BITTRACK_DIVISOR;
  63   }
  64 }
  65
  66 /* try out a new limit */
  67 static long limit_sum(bitrate_manager_state *bm,int limit){
  68   int i=bm->minmax_stackptr;
  69   long acc=bm->minmax_acctotal;
  70   long bins=bm->queue_bins;
  71
  72   acc-=LIMITBITS(i,0);
  73   acc+=LIMITBITS(i,limit);
  74
  75   while(i-->0){
  76     if(bm->minmax_limitstack[i]<=limit)break;
  77     acc-=LIMITBITS(i,bm->minmax_limitstack[i]);
  78     acc+=LIMITBITS(i,limit);
  79   }
  80   return(acc);
  81 }
  82
  83 /* compute bitrate tracking setup, allocate circular packet size queue */
  84 void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){
  85   int i;
  86   codec_setup_info *ci=vi->codec_setup;
  87   bitrate_manager_info *bi=&ci->bi;
  88   long maxlatency;
  89
  90   memset(bm,0,sizeof(*bm));
  91
  92   if(bi){
  93
  94     bm->avg_sampledesired=bi->queue_avg_time*vi->rate;
  95     bm->avg_centerdesired=bi->queue_avg_time*vi->rate*bi->queue_avg_center;
  96     bm->minmax_sampledesired=bi->queue_minmax_time*vi->rate;
  97
  98     /* first find the max possible needed queue size */
  99     maxlatency=max(bm->avg_sampledesired-bm->avg_centerdesired,
 100                    bm->minmax_sampledesired)+bm->avg_centerdesired;
 101
 102     if(maxlatency>0 &&
 103        (bi->queue_avgmin>0 || bi->queue_avgmax>0 || bi->queue_hardmax>0 ||
 104         bi->queue_hardmin>0)){
 105       long maxpackets=maxlatency/(ci->blocksizes[0]>>1)+3;
 106       long bins=BITTRACK_DIVISOR*ci->passlimit[ci->coupling_passes-1];
 107
 108       bm->queue_size=maxpackets;
 109       bm->queue_bins=bins;
 110       bm->queue_binned=_ogg_malloc(maxpackets*bins*sizeof(*bm->queue_binned));
 111       bm->queue_actual=_ogg_malloc(maxpackets*sizeof(*bm->queue_actual));
 112
 113       if((bi->queue_avgmin>0 || bi->queue_avgmax>0) &&
 114          bi->queue_avg_time>0){
 115
 116         bm->avg_binacc=_ogg_malloc(bins*sizeof(*bm->avg_binacc));
 117         bm->avgfloat=bi->avgfloat_initial;
 118
 119
 120       }else{
 121         bm->avg_tail= -1;
 122       }
 123
 124       if((bi->queue_hardmin>0 || bi->queue_hardmax>0) &&
 125          bi->queue_minmax_time>0){
 126
 127         bm->minmax_binstack=_ogg_malloc((bins+1)*bins*2*
 128                                         sizeof(bm->minmax_binstack));
 129         bm->minmax_posstack=_ogg_malloc((bins+1)*
 130                                       sizeof(bm->minmax_posstack));
 131         bm->minmax_limitstack=_ogg_malloc((bins+1)*
 132                                           sizeof(bm->minmax_limitstack));
 133       }else{
 134         bm->minmax_tail= -1;
 135       }
 136
 137       /* space for the packet queueing */
 138       bm->queue_packet_buffers=calloc(maxpackets,sizeof(*bm->queue_packet_buffers));
 139       bm->queue_packets=calloc(maxpackets,sizeof(*bm->queue_packets));
 140       for(i=0;i<maxpackets;i++)
 141         oggpack_writeinit(bm->queue_packet_buffers+i);
 142
 143     }else{
 144       bm->queue_packet_buffers=calloc(1,sizeof(*bm->queue_packet_buffers));
 145       bm->queue_packets=calloc(1,sizeof(*bm->queue_packets));
 146       oggpack_writeinit(bm->queue_packet_buffers);
 147     }
 148   }
 149 }
 150
 151 void vorbis_bitrate_clear(bitrate_manager_state *bm){
 152   int i;
 153   if(bm){
 154     if(bm->queue_binned)_ogg_free(bm->queue_binned);
 155     if(bm->queue_actual)_ogg_free(bm->queue_actual);
 156     if(bm->avg_binacc)_ogg_free(bm->avg_binacc);
 157     if(bm->minmax_binstack)_ogg_free(bm->minmax_binstack);
 158     if(bm->minmax_posstack)_ogg_free(bm->minmax_posstack);
 159     if(bm->minmax_limitstack)_ogg_free(bm->minmax_limitstack);
 160     if(bm->queue_packet_buffers){
 161       if(bm->queue_size==0){
 162         oggpack_writeclear(bm->queue_packet_buffers);
 163         _ogg_free(bm->queue_packet_buffers);
 164       }else{
 165         for(i=0;i<bm->queue_size;i++)
 166           oggpack_writeclear(bm->queue_packet_buffers+i);
 167         _ogg_free(bm->queue_packet_buffers);
 168       }
 169     }
 170     if(bm->queue_packets)_ogg_free(bm->queue_packets);
 171     memset(bm,0,sizeof(*bm));
 172   }
 173 }
 174
 175 int vorbis_bitrate_managed(vorbis_block *vb){
 176   vorbis_dsp_state      *vd=vb->vd;
 177   backend_lookup_state  *b=vd->backend_state;
 178   bitrate_manager_state *bm=&b->bms;
 179
 180   if(bm->queue_binned)return(1);
 181   return(0);
 182 }
 183
 184 int vorbis_bitrate_maxmarkers(void){
 185   return 8*BITTRACK_DIVISOR;
 186 }
 187
 188 /* finish taking in the block we just processed */
 189 int vorbis_bitrate_addblock(vorbis_block *vb){
 190   int i;
 191   vorbis_block_internal *vbi=vb->internal;
 192   vorbis_dsp_state      *vd=vb->vd;
 193   backend_lookup_state  *b=vd->backend_state;
 194   bitrate_manager_state *bm=&b->bms;
 195   vorbis_info           *vi=vd->vi;
 196   codec_setup_info      *ci=vi->codec_setup;
 197   bitrate_manager_info  *bi=&ci->bi;
 198   int                    eofflag=vb->eofflag;
 199   int                    head=bm->queue_head;
 200   int                    next_head=head+1;
 201   int                    bins=bm->queue_bins;
 202   int                    minmax_head,new_minmax_head;
 203
 204   ogg_uint32_t           *head_ptr;
 205   oggpack_buffer          temp;
 206
 207   if(!bm->queue_binned){
 208     oggpack_buffer temp;
 209     /* not a bitrate managed stream, but for API simplicity, we'll
 210        buffer one packet to keep the code path clean */
 211
 212     if(bm->queue_head)return(-1); /* one has been submitted without
 213                                      being claimed */
 214     bm->queue_head++;
 215
 216     bm->queue_packets[0].packet=oggpack_get_buffer(&vb->opb);
 217     bm->queue_packets[0].bytes=oggpack_bytes(&vb->opb);
 218     bm->queue_packets[0].b_o_s=0;
 219     bm->queue_packets[0].e_o_s=vb->eofflag;
 220     bm->queue_packets[0].granulepos=vb->granulepos;
 221     bm->queue_packets[0].packetno=vb->sequence; /* for sake of completeness */
 222
 223     memcpy(&temp,bm->queue_packet_buffers,sizeof(vb->opb));
 224     memcpy(bm->queue_packet_buffers,&vb->opb,sizeof(vb->opb));
 225     memcpy(&vb->opb,&temp,sizeof(vb->opb));
 226
 227     return(0);
 228   }
 229
 230   /* add encoded packet to head */
 231   if(next_head>=bm->queue_size)next_head=0;
 232   head_ptr=bm->queue_binned+bins*head;
 233
 234   /* is there room to add a block? In proper use of the API, this will
 235      never come up... but guard it anyway */
 236   if(next_head==bm->avg_tail || next_head==bm->minmax_tail)return(-1);
 237
 238   /* add the block to the toplevel queue */
 239   bm->queue_head=next_head;
 240   bm->queue_actual[head]=(vb->W?0x80000000UL:0);
 241
 242   /* buffer packet fields */
 243   bm->queue_packets[head].packet=oggpack_get_buffer(&vb->opb);
 244   bm->queue_packets[head].bytes=oggpack_bytes(&vb->opb);
 245   bm->queue_packets[head].b_o_s=0;
 246   bm->queue_packets[head].e_o_s=vb->eofflag;
 247   bm->queue_packets[head].granulepos=vb->granulepos;
 248   bm->queue_packets[head].packetno=vb->sequence; /* for sake of completeness */
 249
 250   /* swap packet buffers */
 251   memcpy(&temp,bm->queue_packet_buffers+head,sizeof(vb->opb));
 252   memcpy(bm->queue_packet_buffers+head,&vb->opb,sizeof(vb->opb));
 253   memcpy(&vb->opb,&temp,sizeof(vb->opb));
 254
 255   /* save markers */
 256   memcpy(head_ptr,vbi->packet_markers,sizeof(*head_ptr)*bins);
 257
 258   if(bm->avg_binacc)
 259     new_minmax_head=minmax_head=bm->avg_center;
 260   else
 261     new_minmax_head=minmax_head=head;
 262
 263   /* the average tracking queue is updated first; its results (if it's
 264      in use) are taken into account by the min/max limiter (if min/max
 265      is in use) */
 266   if(bm->avg_binacc){
 267     unsigned long desired_center=bm->avg_centerdesired;
 268     if(eofflag)desired_center=0;
 269
 270     /* update the avg head */
 271     for(i=0;i<bins;i++)
 272       bm->avg_binacc[i]+=LACING_ADJUST(head_ptr[i]);
 273     bm->avg_sampleacc+=ci->blocksizes[vb->W]>>1;
 274     bm->avg_centeracc+=ci->blocksizes[vb->W]>>1;
 275
 276     /* update the avg tail if needed */
 277     while(bm->avg_sampleacc>bm->avg_sampledesired){
 278       int samples=
 279         ci->blocksizes[bm->queue_actual[bm->avg_tail]&0x80000000UL?1:0]>>1;
 280       for(i=0;i<bm->queue_bins;i++)
 281         bm->avg_binacc[i]-=LACING_ADJUST(bm->queue_binned[bins*bm->avg_tail+i]);
 282       bm->avg_sampleacc-=samples;
 283       bm->avg_tail++;
 284       if(bm->avg_tail>=bm->queue_size)bm->avg_tail=0;
 285     }
 286
 287     /* update the avg center */
 288     if(bm->avg_centeracc>desired_center){
 289       /* choose the new average floater */
 290       double upper=floater_interpolate(bm,vi,bi->queue_avgmax);
 291       double lower=floater_interpolate(bm,vi,bi->queue_avgmin);
 292       double new=bi->avgfloat_initial,slew;
 293       int bin;
 294
 295       if(upper>0. && upper<new)new=upper;
 296       if(lower<bi->avgfloat_minimum)
 297         lower=bi->avgfloat_minimum;
 298       if(lower>new)new=lower;
 299
 300       slew=new-bm->avgfloat;
 301
 302       if(slew<bi->avgfloat_downhyst || slew>bi->avgfloat_uphyst){
 303         if(slew<bi->avgfloat_downslew_max)
 304           new=bm->avgfloat+bi->avgfloat_downslew_max;
 305         if(slew>bi->avgfloat_upslew_max)
 306           new=bm->avgfloat+bi->avgfloat_upslew_max;
 307
 308         bm->avgfloat=new;
 309       }
 310
 311       /* apply the average floater to new blocks */
 312       bin=bm->avgfloat*BITTRACK_DIVISOR; /* truncate on purpose */
 313       while(bm->avg_centeracc>desired_center){
 314         int samples=
 315           samples=ci->blocksizes[bm->queue_actual[bm->avg_center]&
 316                                 0x80000000UL?1:0]>>1;
 317
 318         bm->queue_actual[bm->avg_center]|=bin;
 319
 320         bm->avg_centeracc-=samples;
 321         bm->avg_center++;
 322         if(bm->noisetrigger_postpone)bm->noisetrigger_postpone-=samples;
 323         if(bm->avg_center>=bm->queue_size)bm->avg_center=0;
 324       }
 325       new_minmax_head=bm->avg_center;
 326
 327       /* track noise bias triggers and noise bias */
 328       if(bm->avgfloat<bi->avgfloat_noise_lowtrigger)
 329         bm->noisetrigger_request+=1.f;
 330       else
 331         if(bm->noisetrigger_request>0. && bm->avgnoise>0.)
 332           bm->noisetrigger_request-=.2f;
 333
 334       if(bm->avgfloat>bi->avgfloat_noise_hightrigger)
 335         bm->noisetrigger_request-=1.f;
 336       else
 337         if(bm->noisetrigger_request<0 && bm->avgnoise<0.)
 338           bm->noisetrigger_request+=.2f;
 339
 340       if(bm->noisetrigger_postpone<=0){
 341         if(bm->noisetrigger_request<0.){
 342           bm->avgnoise-=1.f;
 343           if(-bm->noisetrigger_request>(signed long)(bm->avg_sampleacc)/2)
 344             bm->avgnoise-=1.f;
 345           bm->noisetrigger_postpone=bm->avg_sampleacc/2;
 346         }
 347         if(bm->noisetrigger_request>0.){
 348           bm->avgnoise+=1.f;
 349           if(bm->noisetrigger_request>(signed long)(bm->avg_sampleacc)/2)
 350             bm->avgnoise+=1.f;
 351           bm->noisetrigger_postpone=bm->avg_sampleacc/2;
 352         }
 353
 354         /* we generally want the noise bias to drift back to zero */
 355         bm->noisetrigger_request=0.f;
 356         if(bm->avgnoise>0)
 357           bm->noisetrigger_request= -1.;
 358         if(bm->avgnoise<0)
 359           bm->noisetrigger_request= +1.;
 360
 361         if(bm->avgnoise<bi->avgfloat_noise_minval)
 362           bm->avgnoise=bi->avgfloat_noise_minval;
 363         if(bm->avgnoise>bi->avgfloat_noise_maxval)
 364           bm->avgnoise=bi->avgfloat_noise_maxval;
 365       }
 366     }
 367   }else{
 368     /* if we're not using an average tracker, the 'float' is nailed to
 369        the avgfloat_initial value.  It needs to be set for the min/max
 370        to deal properly */
 371     long bin=bi->avgfloat_initial*BITTRACK_DIVISOR; /* truncate on purpose */
 372     bm->queue_actual[head]|=bin;
 373     new_minmax_head=next_head;
 374   }
 375
 376   /* update the min/max queues and enforce limits */
 377   if(bm->minmax_binstack){
 378     unsigned long sampledesired=eofflag?0:bm->minmax_sampledesired;
 379
 380     /* add to stack recent */
 381     while(minmax_head!=new_minmax_head){
 382       unsigned int i;
 383       int samples=ci->blocksizes[bm->queue_actual[minmax_head]&
 384                                 0x80000000UL?1:0]>>1;
 385
 386         /* the construction here is not parallel to the floater's
 387            stack.
 388
 389            floater[bin-1]  <-> floater supported at bin
 390            ...
 391            floater[0]      <-> floater supported at 1
 392            supported at zero is implicit.
 393            the BINBITS macro performs offsetting
 394
 395
 396       bin  minmax[bin*2-1] <-> floater supported at bin
 397            ...
 398         1  minmax[bin]     <-> floater supported at 1
 399         0  minmax[bin-1]   <-> no limit/support (limited to/supported at bin 0,
 400                                                  ie, no effect)
 401        -1  minmax[bin-2]   <-> floater limited to bin-1
 402            ...
 403     -bin+1  minmax[0]       <-> floater limited to 1
 404             limited to zero (val= -bin) is implicit
 405         */
 406       for(i=0;i<(unsigned int)bins;i++){
 407         bm->minmax_binstack[bm->minmax_stackptr*bins*2+bins+i]+=
 408           LACING_ADJUST(
 409           BINBITS(minmax_head,
 410                   (bm->queue_actual[minmax_head]&0x7fffffffUL)>i+1?
 411                   (bm->queue_actual[minmax_head]&0x7fffffffUL):i+1));
 412
 413         bm->minmax_binstack[bm->minmax_stackptr*bins*2+i]+=
 414           LACING_ADJUST(
 415           BINBITS(minmax_head,
 416                   (bm->queue_actual[minmax_head]&0x7fffffffUL)<i+1?
 417                   (bm->queue_actual[minmax_head]&0x7fffffffUL):i+1));
 418       }
 419
 420       bm->minmax_posstack[bm->minmax_stackptr]=minmax_head; /* not one
 421                                                                past
 422                                                                like
 423                                                                typical */
 424       bm->minmax_limitstack[bm->minmax_stackptr]=0;
 425       bm->minmax_sampleacc+=samples;
 426       bm->minmax_acctotal+=
 427         LACING_ADJUST(
 428         BINBITS(minmax_head,(bm->queue_actual[minmax_head]&0x7fffffffUL)));
 429
 430       minmax_head++;
 431       if(minmax_head>=bm->queue_size)minmax_head=0;
 432     }
 433
 434     /* check limits, enforce changes */
 435     if(bm->minmax_sampleacc>sampledesired){
 436       double bitrate=(double)bm->minmax_acctotal/bm->minmax_sampleacc*vi->rate;
 437       int limit=0;
 438
 439       if((bi->queue_hardmax>0 && bitrate>bi->queue_hardmax) ||
 440          (bi->queue_hardmin>0 && bitrate<bi->queue_hardmin)){
 441         int newstack;
 442         int stackctr;
 443         long bitsum=limit_sum(bm,0);
 444         bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 445
 446         /* we're off rate.  Iteratively try out new hard floater
 447            limits until we find one that brings us inside.  Here's
 448            where we see the whole point of the limit stacks.  */
 449         if(bi->queue_hardmax>0 && bitrate>bi->queue_hardmax){
 450           for(limit=-1;limit>-bins;limit--){
 451             long bitsum=limit_sum(bm,limit);
 452             bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 453             if(bitrate<=bi->queue_hardmax)break;
 454           }
 455         }else if(bitrate<bi->queue_hardmin){
 456           for(limit=1;limit<bins;limit++){
 457             long bitsum=limit_sum(bm,limit);
 458             bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 459             if(bitrate>=bi->queue_hardmin)break;
 460           }
 461           if(bitrate>bi->queue_hardmax)limit--;
 462         }
 463
 464         bitsum=limit_sum(bm,limit);
 465         bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 466
 467         /* trace the limit backward, stop when we see a lower limit */
 468         newstack=bm->minmax_stackptr-1;
 469         while(newstack>=0){
 470           if(bm->minmax_limitstack[newstack]<limit)break;
 471           newstack--;
 472         }
 473
 474         /* update bit counter with new limit and replace any stack
 475            limits that have been replaced by our new lower limit */
 476         stackctr=bm->minmax_stackptr;
 477         while(stackctr>newstack){
 478           bm->minmax_acctotal-=
 479             LIMITBITS(stackctr,bm->minmax_limitstack[stackctr]);
 480           bm->minmax_acctotal+=LIMITBITS(stackctr,limit);
 481
 482           if(stackctr<bm->minmax_stackptr)
 483             for(i=0;i<bins*2;i++)
 484               bm->minmax_binstack[stackctr*bins*2+i]+=
 485               bm->minmax_binstack[(stackctr+1)*bins*2+i];
 486
 487           stackctr--;
 488         }
 489         stackctr++;
 490         bm->minmax_posstack[stackctr]=bm->minmax_posstack[bm->minmax_stackptr];
 491         bm->minmax_limitstack[stackctr]=limit;
 492
 493         /* set up new blank stack entry */
 494         stackctr++;
 495         bm->minmax_stackptr=stackctr;
 496         memset(&bm->minmax_binstack[stackctr*bins*2],
 497                0,
 498                sizeof(*bm->minmax_binstack)*bins*2);
 499         bm->minmax_limitstack[stackctr]=0;
 500         bm->minmax_posstack[stackctr]=-1;
 501
 502       }
 503     }
 504
 505     /* remove from tail */
 506     while(bm->minmax_sampleacc>sampledesired){
 507       int samples=
 508         ci->blocksizes[bm->queue_actual[bm->minmax_tail]&0x80000000UL?1:0]>>1;
 509       int actual=bm->queue_actual[bm->minmax_tail]&0x7fffffffUL;
 510
 511       for(i=0;i<bins;i++){
 512         bm->minmax_binstack[bins+i]-= /* always comes off the stack bottom */
 513           LACING_ADJUST(BINBITS(bm->minmax_tail,actual>i+1?actual:i+1));
 514         bm->minmax_binstack[i]-=
 515           LACING_ADJUST(BINBITS(bm->minmax_tail,actual<i+1?actual:i+1));
 516       }
 517
 518       /* always perform in this order; max overrules min */
 519       if(bm->minmax_limitstack[0]>actual)
 520         actual=bm->minmax_limitstack[0];
 521       if(bins+bm->minmax_limitstack[0]<actual)
 522         actual=bins+bm->minmax_limitstack[0];
 523
 524       bm->minmax_acctotal-=LACING_ADJUST(BINBITS(bm->minmax_tail,actual));
 525       bm->minmax_sampleacc-=samples;
 526
 527       /* revise queue_actual to reflect the limit */
 528       bm->queue_actual[bm->minmax_tail]=actual;
 529
 530       if(bm->minmax_tail==bm->minmax_posstack[0]){
 531         /* the stack becomes a FIFO; the first data has fallen off */
 532         memmove(bm->minmax_binstack,bm->minmax_binstack+bins*2,
 533                 sizeof(*bm->minmax_binstack)*bins*2*bm->minmax_stackptr);
 534         memmove(bm->minmax_posstack,bm->minmax_posstack+1,
 535                 sizeof(*bm->minmax_posstack)*bm->minmax_stackptr);
 536         memmove(bm->minmax_limitstack,bm->minmax_limitstack+1,
 537                 sizeof(*bm->minmax_limitstack)*bm->minmax_stackptr);
 538         bm->minmax_stackptr--;
 539       }
 540
 541       bm->minmax_tail++;
 542       if(bm->minmax_tail>=bm->queue_size)bm->minmax_tail=0;
 543     }
 544
 545
 546     bm->last_to_flush=bm->minmax_tail;
 547   }else{
 548     bm->last_to_flush=bm->avg_center;
 549   }
 550   if(eofflag)
 551     bm->last_to_flush=bm->queue_head;
 552   return(0);
 553 }
 554
 555 int vorbis_bitrate_flushpacket(vorbis_dsp_state *vd,ogg_packet *op){
 556   backend_lookup_state  *b=vd->backend_state;
 557   bitrate_manager_state *bm=&b->bms;
 558
 559   if(bm->queue_size==0){
 560     if(bm->queue_head==0)return(0);
 561
 562     memcpy(op,bm->queue_packets,sizeof(*op));
 563     bm->queue_head=0;
 564
 565   }else{
 566     long bins=bm->queue_bins;
 567     long bin;
 568     long bytes;
 569
 570     if(bm->next_to_flush==bm->last_to_flush)return(0);
 571
 572     bin=bm->queue_actual[bm->next_to_flush]&0x7fffffffUL;
 573     bytes=(BINBITS(bm->next_to_flush,bin)+7)/8;
 574
 575     memcpy(op,bm->queue_packets+bm->next_to_flush,sizeof(*op));
 576     if(bytes<op->bytes)op->bytes=bytes;
 577
 578     bm->next_to_flush++;
 579     if(bm->next_to_flush>=bm->queue_size)bm->next_to_flush=0;
 580
 581   }
 582
 583   return(1);
 584 }