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 1.3 2001/12/14 07:21:16 xiphmont Exp $
  15
  16  ********************************************************************/
  17
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <unistd.h>
  21 #include <string.h>
  22 #include <math.h>
  23 #include <ogg/ogg.h>
  24 #include "vorbis/codec.h"
  25 #include "codec_internal.h"
  26 #include "os.h"
  27 #include "bitrate.h"
  28
  29 #define BINBITS(pos,bin) ((bin)>0?bm->queue_binned[(pos)*bins+(bin)-1]:0)
  30 #define LIMITBITS(pos,bin) ((bin)>-bins?\
  31                  bm->minmax_binstack[(pos)*bins*2+((bin)+bins)-1]:0)
  32
  33 static long LACING_ADJUST(long bits){
  34   int addto=((bits+7)/8+1)/256+1;
  35   return( ((bits+7)/8+addto)*8 );
  36 }
  37
  38 static double floater_interpolate(bitrate_manager_state *bm,vorbis_info *vi,
  39                                   double desired_rate){
  40   int bin=bm->avgfloat*BITTRACK_DIVISOR-1.;
  41   double lobitrate;
  42   double hibitrate;
  43
  44   lobitrate=(double)(bin==0?0:bm->avg_binacc[bin-1])/bm->avg_sampleacc*vi->rate;
  45   while(lobitrate>desired_rate && bin>0){
  46     bin--;
  47     lobitrate=(double)(bin==0?0:bm->avg_binacc[bin-1])/bm->avg_sampleacc*vi->rate;
  48   }
  49
  50   hibitrate=(double)(bin>=bm->queue_bins?bm->avg_binacc[bm->queue_bins-1]:
  51                      bm->avg_binacc[bin])/bm->avg_sampleacc*vi->rate;
  52   while(hibitrate<desired_rate && bin<bm->queue_bins){
  53     bin++;
  54     if(bin<bm->queue_bins)
  55       hibitrate=(double)bm->avg_binacc[bin]/bm->avg_sampleacc*vi->rate;
  56   }
  57
  58   /* interpolate */
  59   if(bin==bm->queue_bins){
  60     return bin/(double)BITTRACK_DIVISOR;
  61   }else{
  62     double delta=(desired_rate-lobitrate)/(hibitrate-lobitrate);
  63     return (bin+delta)/(double)BITTRACK_DIVISOR;
  64   }
  65 }
  66
  67 /* try out a new limit */
  68 static long limit_sum(bitrate_manager_state *bm,int limit){
  69   int i=bm->minmax_stackptr;
  70   long acc=bm->minmax_acctotal;
  71   long bins=bm->queue_bins;
  72
  73   acc-=LIMITBITS(i,0);
  74   acc+=LIMITBITS(i,limit);
  75
  76   while(i-->0){
  77     if(bm->minmax_limitstack[i]<=limit)break;
  78     acc-=LIMITBITS(i,bm->minmax_limitstack[i]);
  79     acc+=LIMITBITS(i,limit);
  80   }
  81   return(acc);
  82 }
  83
  84 /* compute bitrate tracking setup, allocate circular packet size queue */
  85 void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){
  86   int i;
  87   codec_setup_info *ci=vi->codec_setup;
  88   bitrate_manager_info *bi=&ci->bi;
  89   long maxlatency;
  90
  91   memset(bm,0,sizeof(*bm));
  92
  93   if(bi){
  94
  95     bm->avg_sampledesired=bi->queue_avg_time*vi->rate;
  96     bm->avg_centerdesired=bi->queue_avg_time*vi->rate*bi->queue_avg_center;
  97     bm->minmax_sampledesired=bi->queue_minmax_time*vi->rate;
  98
  99     /* first find the max possible needed queue size */
 100     maxlatency=max(bm->avg_sampledesired-bm->avg_centerdesired,
 101                    bm->minmax_sampledesired)+bm->avg_centerdesired;
 102
 103     if(maxlatency>0 &&
 104        (bi->queue_avgmin>0 || bi->queue_avgmax>0 || bi->queue_hardmax>0 ||
 105         bi->queue_hardmin>0)){
 106       long maxpackets=maxlatency/(ci->blocksizes[0]>>1)+3;
 107       long bins=BITTRACK_DIVISOR*ci->passlimit[ci->coupling_passes-1];
 108
 109       bm->queue_size=maxpackets;
 110       bm->queue_bins=bins;
 111       bm->queue_binned=_ogg_malloc(maxpackets*bins*sizeof(*bm->queue_binned));
 112       bm->queue_actual=_ogg_malloc(maxpackets*sizeof(*bm->queue_actual));
 113
 114       if((bi->queue_avgmin>0 || bi->queue_avgmax>0) &&
 115          bi->queue_avg_time>0){
 116
 117         bm->avg_binacc=_ogg_malloc(bins*sizeof(*bm->avg_binacc));
 118         bm->avgfloat=bi->avgfloat_initial;
 119
 120
 121       }else{
 122         bm->avg_tail= -1;
 123       }
 124
 125       if((bi->queue_hardmin>0 || bi->queue_hardmax>0) &&
 126          bi->queue_minmax_time>0){
 127
 128         bm->minmax_binstack=_ogg_malloc((bins+1)*bins*2*
 129                                         sizeof(bm->minmax_binstack));
 130         bm->minmax_posstack=_ogg_malloc((bins+1)*
 131                                       sizeof(bm->minmax_posstack));
 132         bm->minmax_limitstack=_ogg_malloc((bins+1)*
 133                                           sizeof(bm->minmax_limitstack));
 134       }else{
 135         bm->minmax_tail= -1;
 136       }
 137
 138       /* space for the packet queueing */
 139       bm->queue_packet_buffers=calloc(maxpackets,sizeof(*bm->queue_packet_buffers));
 140       bm->queue_packets=calloc(maxpackets,sizeof(*bm->queue_packets));
 141       for(i=0;i<maxpackets;i++)
 142         oggpack_writeinit(bm->queue_packet_buffers+i);
 143
 144     }else{
 145       bm->queue_packet_buffers=calloc(1,sizeof(*bm->queue_packet_buffers));
 146       bm->queue_packets=calloc(1,sizeof(*bm->queue_packets));
 147       oggpack_writeinit(bm->queue_packet_buffers);
 148     }
 149   }
 150 }
 151
 152 void vorbis_bitrate_clear(bitrate_manager_state *bm){
 153   int i;
 154   if(bm){
 155     if(bm->queue_binned)_ogg_free(bm->queue_binned);
 156     if(bm->queue_actual)_ogg_free(bm->queue_actual);
 157     if(bm->avg_binacc)_ogg_free(bm->avg_binacc);
 158     if(bm->minmax_binstack)_ogg_free(bm->minmax_binstack);
 159     if(bm->minmax_posstack)_ogg_free(bm->minmax_posstack);
 160     if(bm->minmax_limitstack)_ogg_free(bm->minmax_limitstack);
 161     if(bm->queue_packet_buffers){
 162       if(bm->queue_size==0){
 163         oggpack_writeclear(bm->queue_packet_buffers);
 164         _ogg_free(bm->queue_packet_buffers);
 165       }else{
 166         for(i=0;i<bm->queue_size;i++)
 167           oggpack_writeclear(bm->queue_packet_buffers+i);
 168         _ogg_free(bm->queue_packet_buffers);
 169       }
 170     }
 171     if(bm->queue_packets)_ogg_free(bm->queue_packets);
 172     memset(bm,0,sizeof(*bm));
 173   }
 174 }
 175
 176 int vorbis_bitrate_managed(vorbis_block *vb){
 177   vorbis_dsp_state      *vd=vb->vd;
 178   backend_lookup_state  *b=vd->backend_state;
 179   bitrate_manager_state *bm=&b->bms;
 180
 181   if(bm->queue_binned)return(1);
 182   return(0);
 183 }
 184
 185 int vorbis_bitrate_maxmarkers(void){
 186   return 8*BITTRACK_DIVISOR;
 187 }
 188
 189 /* finish taking in the block we just processed */
 190 int vorbis_bitrate_addblock(vorbis_block *vb){
 191   int i;
 192   vorbis_block_internal *vbi=vb->internal;
 193   vorbis_dsp_state      *vd=vb->vd;
 194   backend_lookup_state  *b=vd->backend_state;
 195   bitrate_manager_state *bm=&b->bms;
 196   vorbis_info           *vi=vd->vi;
 197   codec_setup_info      *ci=vi->codec_setup;
 198   bitrate_manager_info  *bi=&ci->bi;
 199   int                    eofflag=vb->eofflag;
 200   int                    head=bm->queue_head;
 201   int                    next_head=head+1;
 202   int                    bins=bm->queue_bins;
 203   int                    minmax_head,new_minmax_head;
 204
 205   ogg_uint32_t           *head_ptr;
 206   oggpack_buffer          temp;
 207
 208   if(!bm->queue_binned){
 209     oggpack_buffer temp;
 210     /* not a bitrate managed stream, but for API simplicity, we'll
 211        buffer one packet to keep the code path clean */
 212
 213     if(bm->queue_head)return(-1); /* one has been submitted without
 214                                      being claimed */
 215     bm->queue_head++;
 216
 217     bm->queue_packets[0].packet=oggpack_get_buffer(&vb->opb);
 218     bm->queue_packets[0].bytes=oggpack_bytes(&vb->opb);
 219     bm->queue_packets[0].b_o_s=0;
 220     bm->queue_packets[0].e_o_s=vb->eofflag;
 221     bm->queue_packets[0].granulepos=vb->granulepos;
 222     bm->queue_packets[0].packetno=vb->sequence; /* for sake of completeness */
 223
 224     memcpy(&temp,bm->queue_packet_buffers,sizeof(vb->opb));
 225     memcpy(bm->queue_packet_buffers,&vb->opb,sizeof(vb->opb));
 226     memcpy(&vb->opb,&temp,sizeof(vb->opb));
 227
 228     return(0);
 229   }
 230
 231   /* add encoded packet to head */
 232   if(next_head>=bm->queue_size)next_head=0;
 233   head_ptr=bm->queue_binned+bins*head;
 234
 235   /* is there room to add a block? In proper use of the API, this will
 236      never come up... but guard it anyway */
 237   if(next_head==bm->avg_tail || next_head==bm->minmax_tail)return(-1);
 238
 239   /* add the block to the toplevel queue */
 240   bm->queue_head=next_head;
 241   bm->queue_actual[head]=(vb->W?0x80000000UL:0);
 242
 243   /* buffer packet fields */
 244   bm->queue_packets[head].packet=oggpack_get_buffer(&vb->opb);
 245   bm->queue_packets[head].bytes=oggpack_bytes(&vb->opb);
 246   bm->queue_packets[head].b_o_s=0;
 247   bm->queue_packets[head].e_o_s=vb->eofflag;
 248   bm->queue_packets[head].granulepos=vb->granulepos;
 249   bm->queue_packets[head].packetno=vb->sequence; /* for sake of completeness */
 250
 251   /* swap packet buffers */
 252   memcpy(&temp,bm->queue_packet_buffers+head,sizeof(vb->opb));
 253   memcpy(bm->queue_packet_buffers+head,&vb->opb,sizeof(vb->opb));
 254   memcpy(&vb->opb,&temp,sizeof(vb->opb));
 255
 256   /* save markers */
 257   memcpy(head_ptr,vbi->packet_markers,sizeof(*head_ptr)*bins);
 258
 259   if(bm->avg_binacc)
 260     new_minmax_head=minmax_head=bm->avg_center;
 261   else
 262     new_minmax_head=minmax_head=head;
 263
 264   /* the average tracking queue is updated first; its results (if it's
 265      in use) are taken into account by the min/max limiter (if min/max
 266      is in use) */
 267   if(bm->avg_binacc){
 268     long desired_center=bm->avg_centerdesired;
 269     if(eofflag)desired_center=0;
 270
 271     /* update the avg head */
 272     for(i=0;i<bins;i++)
 273       bm->avg_binacc[i]+=LACING_ADJUST(head_ptr[i]);
 274     bm->avg_sampleacc+=ci->blocksizes[vb->W]>>1;
 275     bm->avg_centeracc+=ci->blocksizes[vb->W]>>1;
 276
 277     /* update the avg tail if needed */
 278     while(bm->avg_sampleacc>bm->avg_sampledesired){
 279       int samples=
 280         ci->blocksizes[bm->queue_actual[bm->avg_tail]&0x80000000UL?1:0]>>1;
 281       for(i=0;i<bm->queue_bins;i++)
 282         bm->avg_binacc[i]-=LACING_ADJUST(bm->queue_binned[bins*bm->avg_tail+i]);
 283       bm->avg_sampleacc-=samples;
 284       bm->avg_tail++;
 285       if(bm->avg_tail>=bm->queue_size)bm->avg_tail=0;
 286     }
 287
 288     /* update the avg center */
 289     if(bm->avg_centeracc>desired_center){
 290       /* choose the new average floater */
 291       double upper=floater_interpolate(bm,vi,bi->queue_avgmax);
 292       double lower=floater_interpolate(bm,vi,bi->queue_avgmin);
 293       double new=bi->avgfloat_initial,slew;
 294       int bin;
 295
 296       if(upper>0. && upper<new)new=upper;
 297       if(lower<bi->avgfloat_minimum)
 298         lower=bi->avgfloat_minimum;
 299       if(lower>new)new=lower;
 300
 301       slew=new-bm->avgfloat;
 302
 303       if(slew<bi->avgfloat_downhyst || slew>bi->avgfloat_uphyst){
 304         if(slew<bi->avgfloat_downslew_max)
 305           new=bm->avgfloat+bi->avgfloat_downslew_max;
 306         if(slew>bi->avgfloat_upslew_max)
 307           new=bm->avgfloat+bi->avgfloat_upslew_max;
 308
 309         bm->avgfloat=new;
 310       }
 311
 312       /* apply the average floater to new blocks */
 313       bin=bm->avgfloat*BITTRACK_DIVISOR; /* truncate on purpose */
 314       fprintf(stderr,"float:%d ",bin);
 315       while(bm->avg_centeracc>desired_center){
 316         int samples=
 317           samples=ci->blocksizes[bm->queue_actual[bm->avg_center]&
 318                                 0x80000000UL?1:0]>>1;
 319
 320         bm->queue_actual[bm->avg_center]|=bin;
 321
 322         bm->avg_centeracc-=samples;
 323         bm->avg_center++;
 324         if(bm->noisetrigger_postpone)bm->noisetrigger_postpone-=samples;
 325         if(bm->avg_center>=bm->queue_size)bm->avg_center=0;
 326       }
 327       new_minmax_head=bm->avg_center;
 328
 329       /* track noise bias triggers and noise bias */
 330       if(bm->avgfloat<bi->avgfloat_noise_lowtrigger)
 331         bm->noisetrigger_request+=1.f;
 332
 333       if(bm->avgfloat>bi->avgfloat_noise_hightrigger)
 334         bm->noisetrigger_request-=1.f;
 335
 336       if(bm->noisetrigger_postpone<=0){
 337         if(bm->noisetrigger_request<0.){
 338           bm->avgnoise-=1.f;
 339           if(bm->noisetrigger_request<bm->avg_sampleacc/2)
 340             bm->avgnoise-=1.f;
 341           bm->noisetrigger_postpone=bm->avg_sampleacc/2;
 342         }
 343         if(bm->noisetrigger_request>0.){
 344           bm->avgnoise+=1.f;
 345           if(bm->noisetrigger_request>bm->avg_sampleacc/2)
 346             bm->avgnoise+=1.f;
 347           bm->noisetrigger_postpone=bm->avg_sampleacc/2;
 348         }
 349
 350         /* we generally want the noise bias to drift back to zero */
 351         bm->noisetrigger_request=0.f;
 352         if(bm->avgnoise>0)
 353           bm->noisetrigger_request= -1.;
 354         if(bm->avgnoise<0)
 355           bm->noisetrigger_request= +1.;
 356
 357         if(bm->avgnoise<bi->avgfloat_noise_minval)
 358           bm->avgnoise=bi->avgfloat_noise_minval;
 359         if(bm->avgnoise>bi->avgfloat_noise_maxval)
 360           bm->avgnoise=bi->avgfloat_noise_maxval;
 361       }
 362       fprintf(stderr,"noise:%f req:%ld trigger:%ld\n",bm->avgnoise,
 363               bm->noisetrigger_request,bm->noisetrigger_postpone);
 364
 365     }
 366   }else{
 367     /* if we're not using an average tracker, the 'float' is nailed to
 368        the avgfloat_initial value.  It needs to be set for the min/max
 369        to deal properly */
 370     long bin=bi->avgfloat_initial*BITTRACK_DIVISOR; /* truncate on purpose */
 371     bm->queue_actual[head]|=bin;
 372     new_minmax_head=next_head;
 373   }
 374
 375   /* update the min/max queues and enforce limits */
 376   if(bm->minmax_binstack){
 377     long sampledesired=eofflag?0:bm->minmax_sampledesired;
 378
 379     /* add to stack recent */
 380     while(minmax_head!=new_minmax_head){
 381       int samples=ci->blocksizes[bm->queue_actual[minmax_head]&
 382                                 0x80000000UL?1:0]>>1;
 383
 384         /* the construction here is not parallel to the floater's
 385            stack.
 386
 387            floater[bin-1]  <-> floater supported at bin
 388            ...
 389            floater[0]      <-> floater supported at 1
 390            supported at zero is implicit.
 391            the BINBITS macro performs offsetting
 392
 393
 394       bin  minmax[bin*2-1] <-> floater supported at bin
 395            ...
 396         1  minmax[bin]     <-> floater supported at 1
 397         0  minmax[bin-1]   <-> no limit/support (limited to/supported at bin 0,
 398                                                  ie, no effect)
 399        -1  minmax[bin-2]   <-> floater limited to bin-1
 400            ...
 401     -bin+1  minmax[0]       <-> floater limited to 1
 402             limited to zero (val= -bin) is implicit
 403         */
 404       for(i=0;i<bins;i++){
 405         bm->minmax_binstack[bm->minmax_stackptr*bins*2+bins+i]+=
 406           LACING_ADJUST(
 407           BINBITS(minmax_head,
 408                   (bm->queue_actual[minmax_head]&0x7fffffffUL)>i+1?
 409                   (bm->queue_actual[minmax_head]&0x7fffffffUL):i+1));
 410
 411         bm->minmax_binstack[bm->minmax_stackptr*bins*2+i]+=
 412           LACING_ADJUST(
 413           BINBITS(minmax_head,
 414                   (bm->queue_actual[minmax_head]&0x7fffffffUL)<i+1?
 415                   (bm->queue_actual[minmax_head]&0x7fffffffUL):i+1));
 416       }
 417
 418       bm->minmax_posstack[bm->minmax_stackptr]=minmax_head; /* not one
 419                                                                past
 420                                                                like
 421                                                                typical */
 422       bm->minmax_limitstack[bm->minmax_stackptr]=0;
 423       bm->minmax_sampleacc+=samples;
 424       bm->minmax_acctotal+=
 425         LACING_ADJUST(
 426         BINBITS(minmax_head,(bm->queue_actual[minmax_head]&0x7fffffffUL)));
 427
 428       minmax_head++;
 429       if(minmax_head>=bm->queue_size)minmax_head=0;
 430     }
 431
 432     /* check limits, enforce changes */
 433     if(bm->minmax_sampleacc>sampledesired){
 434       double bitrate=(double)bm->minmax_acctotal/bm->minmax_sampleacc*vi->rate;
 435       int limit=0;
 436
 437       fprintf(stderr,"prelimit:%dkbps ",(int)bitrate/1000);
 438       if(bitrate>bi->queue_hardmax || bitrate<bi->queue_hardmin){
 439         int newstack;
 440         int stackctr;
 441         long bitsum=limit_sum(bm,0);
 442         bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 443
 444         /* we're off rate.  Iteratively try out new hard floater
 445            limits until we find one that brings us inside.  Here's
 446            where we see the whole point of the limit stacks.  */
 447         if(bitrate>bi->queue_hardmax){
 448           for(limit=-1;limit>-bins;limit--){
 449             long bitsum=limit_sum(bm,limit);
 450             bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 451             if(bitrate<=bi->queue_hardmax)break;
 452           }
 453         }else if(bitrate<bi->queue_hardmin){
 454           for(limit=1;limit<bins;limit++){
 455             long bitsum=limit_sum(bm,limit);
 456             bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 457             if(bitrate>=bi->queue_hardmin)break;
 458           }
 459           if(bitrate>bi->queue_hardmax)limit--;
 460         }
 461
 462         bitsum=limit_sum(bm,limit);
 463         bitrate=(double)bitsum/bm->minmax_sampleacc*vi->rate;
 464         fprintf(stderr,"postlimit:%dkbps ",(int)bitrate/1000);
 465
 466         /* trace the limit backward, stop when we see a lower limit */
 467         newstack=bm->minmax_stackptr-1;
 468         while(newstack>=0){
 469           if(bm->minmax_limitstack[newstack]<limit)break;
 470           newstack--;
 471         }
 472
 473         /* update bit counter with new limit and replace any stack
 474            limits that have been replaced by our new lower limit */
 475         stackctr=bm->minmax_stackptr;
 476         while(stackctr>newstack){
 477           bm->minmax_acctotal-=
 478             LIMITBITS(stackctr,bm->minmax_limitstack[stackctr]);
 479           bm->minmax_acctotal+=LIMITBITS(stackctr,limit);
 480
 481           if(stackctr<bm->minmax_stackptr)
 482             for(i=0;i<bins*2;i++)
 483               bm->minmax_binstack[stackctr*bins*2+i]+=
 484               bm->minmax_binstack[(stackctr+1)*bins*2+i];
 485
 486           stackctr--;
 487         }
 488         stackctr++;
 489         bm->minmax_posstack[stackctr]=bm->minmax_posstack[bm->minmax_stackptr];
 490         bm->minmax_limitstack[stackctr]=limit;
 491         fprintf(stderr,"limit:%d\n",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 }