diff options
Diffstat (limited to 'vorbis/lib/bitrate.c')
| -rw-r--r-- | vorbis/lib/bitrate.c | 252 |
1 files changed, 252 insertions, 0 deletions
diff --git a/vorbis/lib/bitrate.c b/vorbis/lib/bitrate.c new file mode 100644 index 0000000..9605514 --- /dev/null +++ b/vorbis/lib/bitrate.c @@ -0,0 +1,252 @@ +/******************************************************************** + * * + * THIS FILE IS PART OF THE OggVorbis SOFTWARE CODEC SOURCE CODE. * + * USE, DISTRIBUTION AND REPRODUCTION OF THIS LIBRARY SOURCE IS * + * GOVERNED BY A BSD-STYLE SOURCE LICENSE INCLUDED WITH THIS SOURCE * + * IN 'COPYING'. PLEASE READ THESE TERMS BEFORE DISTRIBUTING. * + * * + * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 * + * by the Xiph.Org Foundation http://www.xiph.org/ * + * * + ******************************************************************** + + function: bitrate tracking and management + + ********************************************************************/ + +#include <stdlib.h> +#include <string.h> +#include <math.h> +#include <ogg/ogg.h> +#include "vorbis/codec.h" +#include "codec_internal.h" +#include "os.h" +#include "misc.h" +#include "bitrate.h" + +/* compute bitrate tracking setup */ +void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){ + codec_setup_info *ci=vi->codec_setup; + bitrate_manager_info *bi=&ci->bi; + + memset(bm,0,sizeof(*bm)); + + if(bi && (bi->reservoir_bits>0)){ + long ratesamples=vi->rate; + int halfsamples=ci->blocksizes[0]>>1; + + bm->short_per_long=ci->blocksizes[1]/ci->blocksizes[0]; + bm->managed=1; + + bm->avg_bitsper= rint(1.*bi->avg_rate*halfsamples/ratesamples); + bm->min_bitsper= rint(1.*bi->min_rate*halfsamples/ratesamples); + bm->max_bitsper= rint(1.*bi->max_rate*halfsamples/ratesamples); + + bm->avgfloat=PACKETBLOBS/2; + + /* not a necessary fix, but one that leads to a more balanced + typical initialization */ + { + long desired_fill=bi->reservoir_bits*bi->reservoir_bias; + bm->minmax_reservoir=desired_fill; + bm->avg_reservoir=desired_fill; + } + + } +} + +void vorbis_bitrate_clear(bitrate_manager_state *bm){ + memset(bm,0,sizeof(*bm)); + return; +} + +int vorbis_bitrate_managed(vorbis_block *vb){ + vorbis_dsp_state *vd=vb->vd; + private_state *b=vd->backend_state; + bitrate_manager_state *bm=&b->bms; + + if(bm && bm->managed)return(1); + return(0); +} + +/* finish taking in the block we just processed */ +int vorbis_bitrate_addblock(vorbis_block *vb){ + vorbis_block_internal *vbi=vb->internal; + vorbis_dsp_state *vd=vb->vd; + private_state *b=vd->backend_state; + bitrate_manager_state *bm=&b->bms; + vorbis_info *vi=vd->vi; + codec_setup_info *ci=vi->codec_setup; + bitrate_manager_info *bi=&ci->bi; + + int choice=rint(bm->avgfloat); + long this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + long min_target_bits=(vb->W?bm->min_bitsper*bm->short_per_long:bm->min_bitsper); + long max_target_bits=(vb->W?bm->max_bitsper*bm->short_per_long:bm->max_bitsper); + int samples=ci->blocksizes[vb->W]>>1; + long desired_fill=bi->reservoir_bits*bi->reservoir_bias; + if(!bm->managed){ + /* not a bitrate managed stream, but for API simplicity, we'll + buffer the packet to keep the code path clean */ + + if(bm->vb)return(-1); /* one has been submitted without + being claimed */ + bm->vb=vb; + return(0); + } + + bm->vb=vb; + + /* look ahead for avg floater */ + if(bm->avg_bitsper>0){ + double slew=0.; + long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper); + double slewlimit= 15./bi->slew_damp; + + /* choosing a new floater: + if we're over target, we slew down + if we're under target, we slew up + + choose slew as follows: look through packetblobs of this frame + and set slew as the first in the appropriate direction that + gives us the slew we want. This may mean no slew if delta is + already favorable. + + Then limit slew to slew max */ + + if(bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){ + while(choice>0 && this_bits>avg_target_bits && + bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){ + choice--; + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + }else if(bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){ + while(choice+1<PACKETBLOBS && this_bits<avg_target_bits && + bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){ + choice++; + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + } + + slew=rint(choice-bm->avgfloat)/samples*vi->rate; + if(slew<-slewlimit)slew=-slewlimit; + if(slew>slewlimit)slew=slewlimit; + choice=rint(bm->avgfloat+= slew/vi->rate*samples); + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + + + + /* enforce min(if used) on the current floater (if used) */ + if(bm->min_bitsper>0){ + /* do we need to force the bitrate up? */ + if(this_bits<min_target_bits){ + while(bm->minmax_reservoir-(min_target_bits-this_bits)<0){ + choice++; + if(choice>=PACKETBLOBS)break; + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + } + } + + /* enforce max (if used) on the current floater (if used) */ + if(bm->max_bitsper>0){ + /* do we need to force the bitrate down? */ + if(this_bits>max_target_bits){ + while(bm->minmax_reservoir+(this_bits-max_target_bits)>bi->reservoir_bits){ + choice--; + if(choice<0)break; + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + } + } + + /* Choice of packetblobs now made based on floater, and min/max + requirements. Now boundary check extreme choices */ + + if(choice<0){ + /* choosing a smaller packetblob is insufficient to trim bitrate. + frame will need to be truncated */ + long maxsize=(max_target_bits+(bi->reservoir_bits-bm->minmax_reservoir))/8; + bm->choice=choice=0; + + if(oggpack_bytes(vbi->packetblob[choice])>maxsize){ + + oggpack_writetrunc(vbi->packetblob[choice],maxsize*8); + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + } + }else{ + long minsize=(min_target_bits-bm->minmax_reservoir+7)/8; + if(choice>=PACKETBLOBS) + choice=PACKETBLOBS-1; + + bm->choice=choice; + + /* prop up bitrate according to demand. pad this frame out with zeroes */ + minsize-=oggpack_bytes(vbi->packetblob[choice]); + while(minsize-->0)oggpack_write(vbi->packetblob[choice],0,8); + this_bits=oggpack_bytes(vbi->packetblob[choice])*8; + + } + + /* now we have the final packet and the final packet size. Update statistics */ + /* min and max reservoir */ + if(bm->min_bitsper>0 || bm->max_bitsper>0){ + + if(max_target_bits>0 && this_bits>max_target_bits){ + bm->minmax_reservoir+=(this_bits-max_target_bits); + }else if(min_target_bits>0 && this_bits<min_target_bits){ + bm->minmax_reservoir+=(this_bits-min_target_bits); + }else{ + /* inbetween; we want to take reservoir toward but not past desired_fill */ + if(bm->minmax_reservoir>desired_fill){ + if(max_target_bits>0){ /* logical bulletproofing against initialization state */ + bm->minmax_reservoir+=(this_bits-max_target_bits); + if(bm->minmax_reservoir<desired_fill)bm->minmax_reservoir=desired_fill; + }else{ + bm->minmax_reservoir=desired_fill; + } + }else{ + if(min_target_bits>0){ /* logical bulletproofing against initialization state */ + bm->minmax_reservoir+=(this_bits-min_target_bits); + if(bm->minmax_reservoir>desired_fill)bm->minmax_reservoir=desired_fill; + }else{ + bm->minmax_reservoir=desired_fill; + } + } + } + } + + /* avg reservoir */ + if(bm->avg_bitsper>0){ + long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper); + bm->avg_reservoir+=this_bits-avg_target_bits; + } + + return(0); +} + +int vorbis_bitrate_flushpacket(vorbis_dsp_state *vd,ogg_packet *op){ + private_state *b=vd->backend_state; + bitrate_manager_state *bm=&b->bms; + vorbis_block *vb=bm->vb; + int choice=PACKETBLOBS/2; + if(!vb)return 0; + + if(op){ + vorbis_block_internal *vbi=vb->internal; + + if(vorbis_bitrate_managed(vb)) + choice=bm->choice; + + op->packet=oggpack_get_buffer(vbi->packetblob[choice]); + op->bytes=oggpack_bytes(vbi->packetblob[choice]); + op->b_o_s=0; + op->e_o_s=vb->eofflag; + op->granulepos=vb->granulepos; + op->packetno=vb->sequence; /* for sake of completeness */ + } + + bm->vb=0; + return(1); +} |