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synthesis.c (4916B)
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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 1994-2002 *
9 * by the XIPHOPHORUS Company http://www.xiph.org/ *
10 * *
11 ********************************************************************
12
13 function: single-block PCM synthesis
14 last mod: $Id: synthesis.c 1919 2005-07-24 14:18:04Z baford $
15
16 ********************************************************************/
17
18 #include <stdio.h>
19 #include <ogg/ogg.h>
20 #include "vorbis/codec.h"
21 #include "codec_internal.h"
22 #include "registry.h"
23 #include "misc.h"
24 #include "os.h"
25
26 int vorbis_synthesis(vorbis_block *vb,ogg_packet *op){
27 vorbis_dsp_state *vd=vb->vd;
28 private_state *b=vd->backend_state;
29 vorbis_info *vi=vd->vi;
30 codec_setup_info *ci=vi->codec_setup;
31 oggpack_buffer *opb=&vb->opb;
32 int type,mode,i;
33
34 /* first things first. Make sure decode is ready */
35 _vorbis_block_ripcord(vb);
36 oggpack_readinit(opb,op->packet,op->bytes);
37
38 /* Check the packet type */
39 if(oggpack_read(opb,1)!=0){
40 /* Oops. This is not an audio data packet */
41 return(OV_ENOTAUDIO);
42 }
43
44 /* read our mode and pre/post windowsize */
45 mode=oggpack_read(opb,b->modebits);
46 if(mode==-1)return(OV_EBADPACKET);
47
48 vb->mode=mode;
49 vb->W=ci->mode_param[mode]->blockflag;
50 if(vb->W){
51
52 /* this doesn;t get mapped through mode selection as it's used
53 only for window selection */
54 vb->lW=oggpack_read(opb,1);
55 vb->nW=oggpack_read(opb,1);
56 if(vb->nW==-1) return(OV_EBADPACKET);
57 }else{
58 vb->lW=0;
59 vb->nW=0;
60 }
61
62 /* more setup */
63 vb->granulepos=op->granulepos;
64 vb->sequence=op->packetno;
65 vb->eofflag=op->e_o_s;
66
67 /* alloc pcm passback storage */
68 vb->pcmend=ci->blocksizes[vb->W];
69 vb->pcm=_vorbis_block_alloc(vb,sizeof(*vb->pcm)*vi->channels);
70 for(i=0;i<vi->channels;i++)
71 vb->pcm[i]=_vorbis_block_alloc(vb,vb->pcmend*sizeof(*vb->pcm[i]));
72
73 /* unpack_header enforces range checking */
74 type=ci->map_type[ci->mode_param[mode]->mapping];
75
76 return(_mapping_P[type]->inverse(vb,ci->map_param[ci->mode_param[mode]->
77 mapping]));
78 }
79
80 /* used to track pcm position without actually performing decode.
81 Useful for sequential 'fast forward' */
82 int vorbis_synthesis_trackonly(vorbis_block *vb,ogg_packet *op){
83 vorbis_dsp_state *vd=vb->vd;
84 private_state *b=vd->backend_state;
85 vorbis_info *vi=vd->vi;
86 codec_setup_info *ci=vi->codec_setup;
87 oggpack_buffer *opb=&vb->opb;
88 int mode;
89
90 /* first things first. Make sure decode is ready */
91 _vorbis_block_ripcord(vb);
92 oggpack_readinit(opb,op->packet,op->bytes);
93
94 /* Check the packet type */
95 if(oggpack_read(opb,1)!=0){
96 /* Oops. This is not an audio data packet */
97 return(OV_ENOTAUDIO);
98 }
99
100 /* read our mode and pre/post windowsize */
101 mode=oggpack_read(opb,b->modebits);
102 if(mode==-1)return(OV_EBADPACKET);
103
104 vb->mode=mode;
105 vb->W=ci->mode_param[mode]->blockflag;
106 if(vb->W){
107 vb->lW=oggpack_read(opb,1);
108 vb->nW=oggpack_read(opb,1);
109 if(vb->nW==-1) return(OV_EBADPACKET);
110 }else{
111 vb->lW=0;
112 vb->nW=0;
113 }
114
115 /* more setup */
116 vb->granulepos=op->granulepos;
117 vb->sequence=op->packetno;
118 vb->eofflag=op->e_o_s;
119
120 /* no pcm */
121 vb->pcmend=0;
122 vb->pcm=NULL;
123
124 return(0);
125 }
126
127 long vorbis_packet_blocksize(vorbis_info *vi,ogg_packet *op){
128 codec_setup_info *ci=vi->codec_setup;
129 oggpack_buffer opb;
130 int mode;
131
132 oggpack_readinit(&opb,op->packet,op->bytes);
133
134 /* Check the packet type */
135 if(oggpack_read(&opb,1)!=0){
136 /* Oops. This is not an audio data packet */
137 return(OV_ENOTAUDIO);
138 }
139
140 {
141 int modebits=0;
142 int v=ci->modes;
143 while(v>1){
144 modebits++;
145 v>>=1;
146 }
147
148 /* read our mode and pre/post windowsize */
149 mode=oggpack_read(&opb,modebits);
150 }
151 if(mode==-1)return(OV_EBADPACKET);
152 return(ci->blocksizes[ci->mode_param[mode]->blockflag]);
153 }
154
155 int vorbis_synthesis_halfrate(vorbis_info *vi,int flag){
156 /* set / clear half-sample-rate mode */
157 codec_setup_info *ci=vi->codec_setup;
158
159 /* right now, our MDCT can't handle < 64 sample windows. */
160 if(ci->blocksizes[0]<=64 && flag)return -1;
161 ci->halfrate_flag=(flag?1:0);
162 return 0;
163 }
164
165 int vorbis_synthesis_halfrate_p(vorbis_info *vi){
166 codec_setup_info *ci=vi->codec_setup;
167 return ci->halfrate_flag;
168 }
169
170