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: bitrate tracking and management 14 last mod: $Id: bitrate.c 16227 2009-07-08 06:58:46Z xiphmont $ 15 16 ********************************************************************/ 17 18 #include <stdlib.h> 19 #include <string.h> 20 #include <math.h> 21 #include <ogg/ogg.h> 22 #include "vorbis/codec.h" 23 #include "codec_internal.h" 24 #include "os.h" 25 #include "misc.h" 26 #include "bitrate.h" 27 28 /* compute bitrate tracking setup */ 29 void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){ 30 codec_setup_info *ci=vi->codec_setup; 31 bitrate_manager_info *bi=&ci->bi; 32 33 memset(bm,0,sizeof(*bm)); 34 35 if(bi && (bi->reservoir_bits>0)){ 36 long ratesamples=vi->rate; 37 int halfsamples=ci->blocksizes[0]>>1; 38 39 bm->short_per_long=ci->blocksizes[1]/ci->blocksizes[0]; 40 bm->managed=1; 41 42 bm->avg_bitsper= rint(1.*bi->avg_rate*halfsamples/ratesamples); 43 bm->min_bitsper= rint(1.*bi->min_rate*halfsamples/ratesamples); 44 bm->max_bitsper= rint(1.*bi->max_rate*halfsamples/ratesamples); 45 46 bm->avgfloat=PACKETBLOBS/2; 47 48 /* not a necessary fix, but one that leads to a more balanced 49 typical initialization */ 50 { 51 long desired_fill=bi->reservoir_bits*bi->reservoir_bias; 52 bm->minmax_reservoir=desired_fill; 53 bm->avg_reservoir=desired_fill; 54 } 55 56 } 57 } 58 59 void vorbis_bitrate_clear(bitrate_manager_state *bm){ 60 memset(bm,0,sizeof(*bm)); 61 return; 62 } 63 64 int vorbis_bitrate_managed(vorbis_block *vb){ 65 vorbis_dsp_state *vd=vb->vd; 66 private_state *b=vd->backend_state; 67 bitrate_manager_state *bm=&b->bms; 68 69 if(bm && bm->managed)return(1); 70 return(0); 71 } 72 73 /* finish taking in the block we just processed */ 74 int vorbis_bitrate_addblock(vorbis_block *vb){ 75 vorbis_block_internal *vbi=vb->internal; 76 vorbis_dsp_state *vd=vb->vd; 77 private_state *b=vd->backend_state; 78 bitrate_manager_state *bm=&b->bms; 79 vorbis_info *vi=vd->vi; 80 codec_setup_info *ci=vi->codec_setup; 81 bitrate_manager_info *bi=&ci->bi; 82 83 int choice=rint(bm->avgfloat); 84 long this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 85 long min_target_bits=(vb->W?bm->min_bitsper*bm->short_per_long:bm->min_bitsper); 86 long max_target_bits=(vb->W?bm->max_bitsper*bm->short_per_long:bm->max_bitsper); 87 int samples=ci->blocksizes[vb->W]>>1; 88 long desired_fill=bi->reservoir_bits*bi->reservoir_bias; 89 if(!bm->managed){ 90 /* not a bitrate managed stream, but for API simplicity, we'll 91 buffer the packet to keep the code path clean */ 92 93 if(bm->vb)return(-1); /* one has been submitted without 94 being claimed */ 95 bm->vb=vb; 96 return(0); 97 } 98 99 bm->vb=vb; 100 101 /* look ahead for avg floater */ 102 if(bm->avg_bitsper>0){ 103 double slew=0.; 104 long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper); 105 double slewlimit= 15./bi->slew_damp; 106 107 /* choosing a new floater: 108 if we're over target, we slew down 109 if we're under target, we slew up 110 111 choose slew as follows: look through packetblobs of this frame 112 and set slew as the first in the appropriate direction that 113 gives us the slew we want. This may mean no slew if delta is 114 already favorable. 115 116 Then limit slew to slew max */ 117 118 if(bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){ 119 while(choice>0 && this_bits>avg_target_bits && 120 bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){ 121 choice--; 122 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 123 } 124 }else if(bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){ 125 while(choice+1<PACKETBLOBS && this_bits<avg_target_bits && 126 bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){ 127 choice++; 128 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 129 } 130 } 131 132 slew=rint(choice-bm->avgfloat)/samples*vi->rate; 133 if(slew<-slewlimit)slew=-slewlimit; 134 if(slew>slewlimit)slew=slewlimit; 135 choice=rint(bm->avgfloat+= slew/vi->rate*samples); 136 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 137 } 138 139 140 141 /* enforce min(if used) on the current floater (if used) */ 142 if(bm->min_bitsper>0){ 143 /* do we need to force the bitrate up? */ 144 if(this_bits<min_target_bits){ 145 while(bm->minmax_reservoir-(min_target_bits-this_bits)<0){ 146 choice++; 147 if(choice>=PACKETBLOBS)break; 148 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 149 } 150 } 151 } 152 153 /* enforce max (if used) on the current floater (if used) */ 154 if(bm->max_bitsper>0){ 155 /* do we need to force the bitrate down? */ 156 if(this_bits>max_target_bits){ 157 while(bm->minmax_reservoir+(this_bits-max_target_bits)>bi->reservoir_bits){ 158 choice--; 159 if(choice<0)break; 160 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 161 } 162 } 163 } 164 165 /* Choice of packetblobs now made based on floater, and min/max 166 requirements. Now boundary check extreme choices */ 167 168 if(choice<0){ 169 /* choosing a smaller packetblob is insufficient to trim bitrate. 170 frame will need to be truncated */ 171 long maxsize=(max_target_bits+(bi->reservoir_bits-bm->minmax_reservoir))/8; 172 bm->choice=choice=0; 173 174 if(oggpack_bytes(vbi->packetblob[choice])>maxsize){ 175 176 oggpack_writetrunc(vbi->packetblob[choice],maxsize*8); 177 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 178 } 179 }else{ 180 long minsize=(min_target_bits-bm->minmax_reservoir+7)/8; 181 if(choice>=PACKETBLOBS) 182 choice=PACKETBLOBS-1; 183 184 bm->choice=choice; 185 186 /* prop up bitrate according to demand. pad this frame out with zeroes */ 187 minsize-=oggpack_bytes(vbi->packetblob[choice]); 188 while(minsize-->0)oggpack_write(vbi->packetblob[choice],0,8); 189 this_bits=oggpack_bytes(vbi->packetblob[choice])*8; 190 191 } 192 193 /* now we have the final packet and the final packet size. Update statistics */ 194 /* min and max reservoir */ 195 if(bm->min_bitsper>0 || bm->max_bitsper>0){ 196 197 if(max_target_bits>0 && this_bits>max_target_bits){ 198 bm->minmax_reservoir+=(this_bits-max_target_bits); 199 }else if(min_target_bits>0 && this_bits<min_target_bits){ 200 bm->minmax_reservoir+=(this_bits-min_target_bits); 201 }else{ 202 /* inbetween; we want to take reservoir toward but not past desired_fill */ 203 if(bm->minmax_reservoir>desired_fill){ 204 if(max_target_bits>0){ /* logical bulletproofing against initialization state */ 205 bm->minmax_reservoir+=(this_bits-max_target_bits); 206 if(bm->minmax_reservoir<desired_fill)bm->minmax_reservoir=desired_fill; 207 }else{ 208 bm->minmax_reservoir=desired_fill; 209 } 210 }else{ 211 if(min_target_bits>0){ /* logical bulletproofing against initialization state */ 212 bm->minmax_reservoir+=(this_bits-min_target_bits); 213 if(bm->minmax_reservoir>desired_fill)bm->minmax_reservoir=desired_fill; 214 }else{ 215 bm->minmax_reservoir=desired_fill; 216 } 217 } 218 } 219 } 220 221 /* avg reservoir */ 222 if(bm->avg_bitsper>0){ 223 long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper); 224 bm->avg_reservoir+=this_bits-avg_target_bits; 225 } 226 227 return(0); 228 } 229 230 int vorbis_bitrate_flushpacket(vorbis_dsp_state *vd,ogg_packet *op){ 231 private_state *b=vd->backend_state; 232 bitrate_manager_state *bm=&b->bms; 233 vorbis_block *vb=bm->vb; 234 int choice=PACKETBLOBS/2; 235 if(!vb)return 0; 236 237 if(op){ 238 vorbis_block_internal *vbi=vb->internal; 239 240 if(vorbis_bitrate_managed(vb)) 241 choice=bm->choice; 242 243 op->packet=oggpack_get_buffer(vbi->packetblob[choice]); 244 op->bytes=oggpack_bytes(vbi->packetblob[choice]); 245 op->b_o_s=0; 246 op->e_o_s=vb->eofflag; 247 op->granulepos=vb->granulepos; 248 op->packetno=vb->sequence; /* for sake of completeness */ 249 } 250 251 bm->vb=0; 252 return(1); 253 } 254
