1 /********************************************************************
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. *
8 * THE OggVorbis SOURCE CODE IS (C) COPYRIGHT 1994-2009 *
9 * by the Xiph.Org Foundation https://xiph.org/ *
11 ********************************************************************
13 function: bitrate tracking and management
15 ********************************************************************/
21 #include "vorbis/codec.h"
22 #include "codec_internal.h"
27 /* compute bitrate tracking setup */
28 void vorbis_bitrate_init(vorbis_info *vi,bitrate_manager_state *bm){
29 codec_setup_info *ci=vi->codec_setup;
30 bitrate_manager_info *bi=&ci->bi;
32 memset(bm,0,sizeof(*bm));
34 if(bi && (bi->reservoir_bits>0)){
35 long ratesamples=vi->rate;
36 int halfsamples=ci->blocksizes[0]>>1;
38 bm->short_per_long=ci->blocksizes[1]/ci->blocksizes[0];
41 bm->avg_bitsper= rint(1.*bi->avg_rate*halfsamples/ratesamples);
42 bm->min_bitsper= rint(1.*bi->min_rate*halfsamples/ratesamples);
43 bm->max_bitsper= rint(1.*bi->max_rate*halfsamples/ratesamples);
45 bm->avgfloat=PACKETBLOBS/2;
47 /* not a necessary fix, but one that leads to a more balanced
48 typical initialization */
50 long desired_fill=bi->reservoir_bits*bi->reservoir_bias;
51 bm->minmax_reservoir=desired_fill;
52 bm->avg_reservoir=desired_fill;
58 void vorbis_bitrate_clear(bitrate_manager_state *bm){
59 memset(bm,0,sizeof(*bm));
63 int vorbis_bitrate_managed(vorbis_block *vb){
64 vorbis_dsp_state *vd=vb->vd;
65 private_state *b=vd->backend_state;
66 bitrate_manager_state *bm=&b->bms;
68 if(bm && bm->managed)return(1);
72 /* finish taking in the block we just processed */
73 int vorbis_bitrate_addblock(vorbis_block *vb){
74 vorbis_block_internal *vbi=vb->internal;
75 vorbis_dsp_state *vd=vb->vd;
76 private_state *b=vd->backend_state;
77 bitrate_manager_state *bm=&b->bms;
78 vorbis_info *vi=vd->vi;
79 codec_setup_info *ci=vi->codec_setup;
80 bitrate_manager_info *bi=&ci->bi;
82 int choice=rint(bm->avgfloat);
83 long this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
84 long min_target_bits=(vb->W?bm->min_bitsper*bm->short_per_long:bm->min_bitsper);
85 long max_target_bits=(vb->W?bm->max_bitsper*bm->short_per_long:bm->max_bitsper);
86 int samples=ci->blocksizes[vb->W]>>1;
87 long desired_fill=bi->reservoir_bits*bi->reservoir_bias;
89 /* not a bitrate managed stream, but for API simplicity, we'll
90 buffer the packet to keep the code path clean */
92 if(bm->vb)return(-1); /* one has been submitted without
100 /* look ahead for avg floater */
101 if(bm->avg_bitsper>0){
103 long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper);
104 double slewlimit= 15./bi->slew_damp;
106 /* choosing a new floater:
107 if we're over target, we slew down
108 if we're under target, we slew up
110 choose slew as follows: look through packetblobs of this frame
111 and set slew as the first in the appropriate direction that
112 gives us the slew we want. This may mean no slew if delta is
115 Then limit slew to slew max */
117 if(bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){
118 while(choice>0 && this_bits>avg_target_bits &&
119 bm->avg_reservoir+(this_bits-avg_target_bits)>desired_fill){
121 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
123 }else if(bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){
124 while(choice+1<PACKETBLOBS && this_bits<avg_target_bits &&
125 bm->avg_reservoir+(this_bits-avg_target_bits)<desired_fill){
127 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
131 slew=rint(choice-bm->avgfloat)/samples*vi->rate;
132 if(slew<-slewlimit)slew=-slewlimit;
133 if(slew>slewlimit)slew=slewlimit;
134 choice=rint(bm->avgfloat+= slew/vi->rate*samples);
135 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
140 /* enforce min(if used) on the current floater (if used) */
141 if(bm->min_bitsper>0){
142 /* do we need to force the bitrate up? */
143 if(this_bits<min_target_bits){
144 while(bm->minmax_reservoir-(min_target_bits-this_bits)<0){
146 if(choice>=PACKETBLOBS)break;
147 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
152 /* enforce max (if used) on the current floater (if used) */
153 if(bm->max_bitsper>0){
154 /* do we need to force the bitrate down? */
155 if(this_bits>max_target_bits){
156 while(bm->minmax_reservoir+(this_bits-max_target_bits)>bi->reservoir_bits){
159 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
164 /* Choice of packetblobs now made based on floater, and min/max
165 requirements. Now boundary check extreme choices */
168 /* choosing a smaller packetblob is insufficient to trim bitrate.
169 frame will need to be truncated */
170 long maxsize=(max_target_bits+(bi->reservoir_bits-bm->minmax_reservoir))/8;
173 if(oggpack_bytes(vbi->packetblob[choice])>maxsize){
175 oggpack_writetrunc(vbi->packetblob[choice],maxsize*8);
176 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
179 long minsize=(min_target_bits-bm->minmax_reservoir+7)/8;
180 if(choice>=PACKETBLOBS)
181 choice=PACKETBLOBS-1;
185 /* prop up bitrate according to demand. pad this frame out with zeroes */
186 minsize-=oggpack_bytes(vbi->packetblob[choice]);
187 while(minsize-->0)oggpack_write(vbi->packetblob[choice],0,8);
188 this_bits=oggpack_bytes(vbi->packetblob[choice])*8;
192 /* now we have the final packet and the final packet size. Update statistics */
193 /* min and max reservoir */
194 if(bm->min_bitsper>0 || bm->max_bitsper>0){
196 if(max_target_bits>0 && this_bits>max_target_bits){
197 bm->minmax_reservoir+=(this_bits-max_target_bits);
198 }else if(min_target_bits>0 && this_bits<min_target_bits){
199 bm->minmax_reservoir+=(this_bits-min_target_bits);
201 /* inbetween; we want to take reservoir toward but not past desired_fill */
202 if(bm->minmax_reservoir>desired_fill){
203 if(max_target_bits>0){ /* logical bulletproofing against initialization state */
204 bm->minmax_reservoir+=(this_bits-max_target_bits);
205 if(bm->minmax_reservoir<desired_fill)bm->minmax_reservoir=desired_fill;
207 bm->minmax_reservoir=desired_fill;
210 if(min_target_bits>0){ /* logical bulletproofing against initialization state */
211 bm->minmax_reservoir+=(this_bits-min_target_bits);
212 if(bm->minmax_reservoir>desired_fill)bm->minmax_reservoir=desired_fill;
214 bm->minmax_reservoir=desired_fill;
221 if(bm->avg_bitsper>0){
222 long avg_target_bits=(vb->W?bm->avg_bitsper*bm->short_per_long:bm->avg_bitsper);
223 bm->avg_reservoir+=this_bits-avg_target_bits;
229 int vorbis_bitrate_flushpacket(vorbis_dsp_state *vd,ogg_packet *op){
230 private_state *b=vd->backend_state;
231 bitrate_manager_state *bm=&b->bms;
232 vorbis_block *vb=bm->vb;
233 int choice=PACKETBLOBS/2;
237 vorbis_block_internal *vbi=vb->internal;
239 if(vorbis_bitrate_managed(vb))
242 op->packet=oggpack_get_buffer(vbi->packetblob[choice]);
243 op->bytes=oggpack_bytes(vbi->packetblob[choice]);
245 op->e_o_s=vb->eofflag;
246 op->granulepos=vb->granulepos;
247 op->packetno=vb->sequence; /* for sake of completeness */