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252 lines
8.3 KiB
C
252 lines
8.3 KiB
C
/********************************************************************
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* *
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* THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. *
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* USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS *
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* GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE *
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* IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. *
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* *
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* THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
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* by the Xiph.Org Foundation http://www.xiph.org/ *
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* *
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********************************************************************
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function: bitrate tracking and management
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********************************************************************/
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#include <stdlib.h>
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#include <string.h>
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#include <math.h>
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#include <ogg/ogg.h>
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#include "vorbis/codec.h"
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#include "codec_internal.h"
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#include "os.h"
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#include "misc.h"
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#include "bitrate.h"
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/* compute bitrate tracking setup */
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void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){
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codec_setup_info *ci=vi->codec_setup;
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bitrate_manager_info *bi=&ci->bi;
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memset(bm,0,sizeof(*bm));
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if(bi && (bi->reservoir_bits>0)){
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long ratesamples=vi->rate;
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int halfsamples=ci->blocksizes[0]>>1;
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bm->short_per_long=ci->blocksizes[1]/ci->blocksizes[0];
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bm->managed=1;
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bm->avg_bitsper= rint(1.*bi->avg_rate*halfsamples/ratesamples);
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bm->min_bitsper= rint(1.*bi->min_rate*halfsamples/ratesamples);
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bm->max_bitsper= rint(1.*bi->max_rate*halfsamples/ratesamples);
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bm->avgfloat=PACKETBLOBS/2;
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/* not a necessary fix, but one that leads to a more balanced
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typical initialization */
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{
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long desired_fill=bi->reservoir_bits*bi->reservoir_bias;
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bm->minmax_reservoir=desired_fill;
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bm->avg_reservoir=desired_fill;
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}
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}
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}
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void vorbis_bitrate_clear(bitrate_manager_state *bm){
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memset(bm,0,sizeof(*bm));
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return;
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}
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int vorbis_bitrate_managed(vorbis_block *vb){
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vorbis_dsp_state *vd=vb->vd;
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private_state *b=vd->backend_state;
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bitrate_manager_state *bm=&b->bms;
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if(bm && bm->managed)return(1);
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return(0);
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}
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/* finish taking in the block we just processed */
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int vorbis_bitrate_addblock(vorbis_block *vb){
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vorbis_block_internal *vbi=vb->internal;
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vorbis_dsp_state *vd=vb->vd;
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private_state *b=vd->backend_state;
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bitrate_manager_state *bm=&b->bms;
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vorbis_info *vi=vd->vi;
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codec_setup_info *ci=vi->codec_setup;
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bitrate_manager_info *bi=&ci->bi;
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int choice=rint(bm->avgfloat);
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long this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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long min_target_bits=(vb->W?bm->min_bitsper*bm->short_per_long:bm->min_bitsper);
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long max_target_bits=(vb->W?bm->max_bitsper*bm->short_per_long:bm->max_bitsper);
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int samples=ci->blocksizes[vb->W]>>1;
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long desired_fill=bi->reservoir_bits*bi->reservoir_bias;
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if(!bm->managed){
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/* not a bitrate managed stream, but for API simplicity, we'll
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buffer the packet to keep the code path clean */
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if(bm->vb)return(-1); /* one has been submitted without
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being claimed */
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bm->vb=vb;
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return(0);
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}
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bm->vb=vb;
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/* look ahead for avg floater */
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if(bm->avg_bitsper>0){
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double slew=0.;
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long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper);
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double slewlimit= 15./bi->slew_damp;
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/* choosing a new floater:
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if we're over target, we slew down
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if we're under target, we slew up
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choose slew as follows: look through packetblobs of this frame
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and set slew as the first in the appropriate direction that
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gives us the slew we want. This may mean no slew if delta is
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already favorable.
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Then limit slew to slew max */
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if(bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){
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while(choice>0 && this_bits>avg_target_bits &&
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bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){
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choice--;
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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}else if(bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){
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while(choice+1<PACKETBLOBS && this_bits<avg_target_bits &&
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bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){
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choice++;
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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}
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slew=rint(choice-bm->avgfloat)/samples*vi->rate;
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if(slew<-slewlimit)slew=-slewlimit;
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if(slew>slewlimit)slew=slewlimit;
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choice=rint(bm->avgfloat+= slew/vi->rate*samples);
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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/* enforce min(if used) on the current floater (if used) */
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if(bm->min_bitsper>0){
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/* do we need to force the bitrate up? */
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if(this_bits<min_target_bits){
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while(bm->minmax_reservoir-(min_target_bits-this_bits)<0){
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choice++;
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if(choice>=PACKETBLOBS)break;
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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}
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}
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/* enforce max (if used) on the current floater (if used) */
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if(bm->max_bitsper>0){
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/* do we need to force the bitrate down? */
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if(this_bits>max_target_bits){
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while(bm->minmax_reservoir+(this_bits-max_target_bits)>bi->reservoir_bits){
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choice--;
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if(choice<0)break;
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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}
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}
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/* Choice of packetblobs now made based on floater, and min/max
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requirements. Now boundary check extreme choices */
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if(choice<0){
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/* choosing a smaller packetblob is insufficient to trim bitrate.
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frame will need to be truncated */
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long maxsize=(max_target_bits+(bi->reservoir_bits-bm->minmax_reservoir))/8;
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bm->choice=choice=0;
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if(oggpack_bytes(vbi->packetblob[choice])>maxsize){
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oggpack_writetrunc(vbi->packetblob[choice],maxsize*8);
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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}else{
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long minsize=(min_target_bits-bm->minmax_reservoir+7)/8;
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if(choice>=PACKETBLOBS)
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choice=PACKETBLOBS-1;
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bm->choice=choice;
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/* prop up bitrate according to demand. pad this frame out with zeroes */
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minsize-=oggpack_bytes(vbi->packetblob[choice]);
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while(minsize-->0)oggpack_write(vbi->packetblob[choice],0,8);
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this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
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}
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/* now we have the final packet and the final packet size. Update statistics */
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/* min and max reservoir */
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if(bm->min_bitsper>0 || bm->max_bitsper>0){
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if(max_target_bits>0 && this_bits>max_target_bits){
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bm->minmax_reservoir+=(this_bits-max_target_bits);
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}else if(min_target_bits>0 && this_bits<min_target_bits){
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bm->minmax_reservoir+=(this_bits-min_target_bits);
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}else{
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/* inbetween; we want to take reservoir toward but not past desired_fill */
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if(bm->minmax_reservoir>desired_fill){
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if(max_target_bits>0){ /* logical bulletproofing against initialization state */
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bm->minmax_reservoir+=(this_bits-max_target_bits);
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if(bm->minmax_reservoir<desired_fill)bm->minmax_reservoir=desired_fill;
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}else{
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bm->minmax_reservoir=desired_fill;
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}
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}else{
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if(min_target_bits>0){ /* logical bulletproofing against initialization state */
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bm->minmax_reservoir+=(this_bits-min_target_bits);
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if(bm->minmax_reservoir>desired_fill)bm->minmax_reservoir=desired_fill;
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}else{
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bm->minmax_reservoir=desired_fill;
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}
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}
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}
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}
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/* avg reservoir */
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if(bm->avg_bitsper>0){
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long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper);
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bm->avg_reservoir+=this_bits-avg_target_bits;
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}
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return(0);
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}
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int vorbis_bitrate_flushpacket(vorbis_dsp_state *vd,ogg_packet *op){
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private_state *b=vd->backend_state;
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bitrate_manager_state *bm=&b->bms;
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vorbis_block *vb=bm->vb;
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int choice=PACKETBLOBS/2;
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if(!vb)return 0;
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if(op){
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vorbis_block_internal *vbi=vb->internal;
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if(vorbis_bitrate_managed(vb))
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choice=bm->choice;
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op->packet=oggpack_get_buffer(vbi->packetblob[choice]);
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op->bytes=oggpack_bytes(vbi->packetblob[choice]);
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op->b_o_s=0;
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op->e_o_s=vb->eofflag;
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op->granulepos=vb->granulepos;
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op->packetno=vb->sequence; /* for sake of completeness */
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}
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bm->vb=0;
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return(1);
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}
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