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comparison decoders/mpglib/layer2.c @ 261:9b6e82f7c853

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Initial add.
author Ryan C. Gordon <icculus@icculus.org>
date Thu, 21 Feb 2002 19:46:09 +0000
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children 52b9f37998db
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260:44a4730a1e6f 261:9b6e82f7c853
1 /*
2 * Mpeg Layer-2 audio decoder
3 * --------------------------
4 * copyright (c) 1995 by Michael Hipp, All rights reserved. See also 'README'
5 *
6 */
7
8 #include "mpg123_sdlsound.h"
9 #include "l2tables.h"
10
11 static int grp_3tab[32 * 3] = { 0, }; /* used: 27 */
12 static int grp_5tab[128 * 3] = { 0, }; /* used: 125 */
13 static int grp_9tab[1024 * 3] = { 0, }; /* used: 729 */
14
15 real muls[27][64]; /* also used by layer 1 */
16
17 void init_layer2(void)
18 {
19 static double mulmul[27] = {
20 0.0 , -2.0/3.0 , 2.0/3.0 ,
21 2.0/7.0 , 2.0/15.0 , 2.0/31.0, 2.0/63.0 , 2.0/127.0 , 2.0/255.0 ,
22 2.0/511.0 , 2.0/1023.0 , 2.0/2047.0 , 2.0/4095.0 , 2.0/8191.0 ,
23 2.0/16383.0 , 2.0/32767.0 , 2.0/65535.0 ,
24 -4.0/5.0 , -2.0/5.0 , 2.0/5.0, 4.0/5.0 ,
25 -8.0/9.0 , -4.0/9.0 , -2.0/9.0 , 2.0/9.0 , 4.0/9.0 , 8.0/9.0 };
26 static int base[3][9] = {
27 { 1 , 0, 2 , } ,
28 { 17, 18, 0 , 19, 20 , } ,
29 { 21, 1, 22, 23, 0, 24, 25, 2, 26 } };
30 int i,j,k,l,len;
31 real *table;
32 static int tablen[3] = { 3 , 5 , 9 };
33 static int *itable,*tables[3] = { grp_3tab , grp_5tab , grp_9tab };
34
35 for(i=0;i<3;i++)
36 {
37 itable = tables[i];
38 len = tablen[i];
39 for(j=0;j<len;j++)
40 for(k=0;k<len;k++)
41 for(l=0;l<len;l++)
42 {
43 *itable++ = base[i][l];
44 *itable++ = base[i][k];
45 *itable++ = base[i][j];
46 }
47 }
48
49 for(k=0;k<27;k++)
50 {
51 double m=mulmul[k];
52 table = muls[k];
53 for(j=3,i=0;i<63;i++,j--)
54 *table++ = m * pow(2.0,(double) j / 3.0);
55 *table++ = 0.0;
56 }
57 }
58
59
60 void II_step_one(unsigned int *bit_alloc,int *scale,struct frame *fr)
61 {
62 int stereo = fr->stereo-1;
63 int sblimit = fr->II_sblimit;
64 int jsbound = fr->jsbound;
65 int sblimit2 = fr->II_sblimit<<stereo;
66 struct al_table *alloc1 = fr->alloc;
67 int i;
68 static unsigned int scfsi_buf[64];
69 unsigned int *scfsi,*bita;
70 int sc,step;
71
72 bita = bit_alloc;
73 if(stereo)
74 {
75 for (i=jsbound;i;i--,alloc1+=(1<<step))
76 {
77 *bita++ = (char) getbits(step=alloc1->bits);
78 *bita++ = (char) getbits(step);
79 }
80 for (i=sblimit-jsbound;i;i--,alloc1+=(1<<step))
81 {
82 bita[0] = (char) getbits(step=alloc1->bits);
83 bita[1] = bita[0];
84 bita+=2;
85 }
86 bita = bit_alloc;
87 scfsi=scfsi_buf;
88 for (i=sblimit2;i;i--)
89 if (*bita++)
90 *scfsi++ = (char) getbits_fast(2);
91 }
92 else /* mono */
93 {
94 for (i=sblimit;i;i--,alloc1+=(1<<step))
95 *bita++ = (char) getbits(step=alloc1->bits);
96 bita = bit_alloc;
97 scfsi=scfsi_buf;
98 for (i=sblimit;i;i--)
99 if (*bita++)
100 *scfsi++ = (char) getbits_fast(2);
101 }
102
103 bita = bit_alloc;
104 scfsi=scfsi_buf;
105 for (i=sblimit2;i;i--)
106 if (*bita++)
107 switch (*scfsi++)
108 {
109 case 0:
110 *scale++ = getbits_fast(6);
111 *scale++ = getbits_fast(6);
112 *scale++ = getbits_fast(6);
113 break;
114 case 1 :
115 *scale++ = sc = getbits_fast(6);
116 *scale++ = sc;
117 *scale++ = getbits_fast(6);
118 break;
119 case 2:
120 *scale++ = sc = getbits_fast(6);
121 *scale++ = sc;
122 *scale++ = sc;
123 break;
124 default: /* case 3 */
125 *scale++ = getbits_fast(6);
126 *scale++ = sc = getbits_fast(6);
127 *scale++ = sc;
128 break;
129 }
130
131 }
132
133 void II_step_two(unsigned int *bit_alloc,real fraction[2][4][SBLIMIT],int *scale,struct frame *fr,int x1)
134 {
135 int i,j,k,ba;
136 int stereo = fr->stereo;
137 int sblimit = fr->II_sblimit;
138 int jsbound = fr->jsbound;
139 struct al_table *alloc2,*alloc1 = fr->alloc;
140 unsigned int *bita=bit_alloc;
141 int d1,step;
142
143 for (i=0;i<jsbound;i++,alloc1+=(1<<step))
144 {
145 step = alloc1->bits;
146 for (j=0;j<stereo;j++)
147 {
148 if ( (ba=*bita++) )
149 {
150 k=(alloc2 = alloc1+ba)->bits;
151 if( (d1=alloc2->d) < 0)
152 {
153 real cm=muls[k][scale[x1]];
154 fraction[j][0][i] = ((real) ((int)getbits(k) + d1)) * cm;
155 fraction[j][1][i] = ((real) ((int)getbits(k) + d1)) * cm;
156 fraction[j][2][i] = ((real) ((int)getbits(k) + d1)) * cm;
157 }
158 else
159 {
160 static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
161 unsigned int idx,*tab,m=scale[x1];
162 idx = (unsigned int) getbits(k);
163 tab = (unsigned int *) (table[d1] + idx + idx + idx);
164 fraction[j][0][i] = muls[*tab++][m];
165 fraction[j][1][i] = muls[*tab++][m];
166 fraction[j][2][i] = muls[*tab][m];
167 }
168 scale+=3;
169 }
170 else
171 fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
172 }
173 }
174
175 for (i=jsbound;i<sblimit;i++,alloc1+=(1<<step))
176 {
177 step = alloc1->bits;
178 bita++; /* channel 1 and channel 2 bitalloc are the same */
179 if ( (ba=*bita++) )
180 {
181 k=(alloc2 = alloc1+ba)->bits;
182 if( (d1=alloc2->d) < 0)
183 {
184 real cm;
185 cm=muls[k][scale[x1+3]];
186 fraction[1][0][i] = (fraction[0][0][i] = (real) ((int)getbits(k) + d1) ) * cm;
187 fraction[1][1][i] = (fraction[0][1][i] = (real) ((int)getbits(k) + d1) ) * cm;
188 fraction[1][2][i] = (fraction[0][2][i] = (real) ((int)getbits(k) + d1) ) * cm;
189 cm=muls[k][scale[x1]];
190 fraction[0][0][i] *= cm; fraction[0][1][i] *= cm; fraction[0][2][i] *= cm;
191 }
192 else
193 {
194 static int *table[] = { 0,0,0,grp_3tab,0,grp_5tab,0,0,0,grp_9tab };
195 unsigned int idx,*tab,m1,m2;
196 m1 = scale[x1]; m2 = scale[x1+3];
197 idx = (unsigned int) getbits(k);
198 tab = (unsigned int *) (table[d1] + idx + idx + idx);
199 fraction[0][0][i] = muls[*tab][m1]; fraction[1][0][i] = muls[*tab++][m2];
200 fraction[0][1][i] = muls[*tab][m1]; fraction[1][1][i] = muls[*tab++][m2];
201 fraction[0][2][i] = muls[*tab][m1]; fraction[1][2][i] = muls[*tab][m2];
202 }
203 scale+=6;
204 }
205 else {
206 fraction[0][0][i] = fraction[0][1][i] = fraction[0][2][i] =
207 fraction[1][0][i] = fraction[1][1][i] = fraction[1][2][i] = 0.0;
208 }
209 /*
210 should we use individual scalefac for channel 2 or
211 is the current way the right one , where we just copy channel 1 to
212 channel 2 ??
213 The current 'strange' thing is, that we throw away the scalefac
214 values for the second channel ...!!
215 -> changed .. now we use the scalefac values of channel one !!
216 */
217 }
218
219 for(i=sblimit;i<SBLIMIT;i++)
220 for (j=0;j<stereo;j++)
221 fraction[j][0][i] = fraction[j][1][i] = fraction[j][2][i] = 0.0;
222
223 }
224
225 static void II_select_table(struct frame *fr)
226 {
227 static int translate[3][2][16] =
228 { { { 0,2,2,2,2,2,2,0,0,0,1,1,1,1,1,0 } ,
229 { 0,2,2,0,0,0,1,1,1,1,1,1,1,1,1,0 } } ,
230 { { 0,2,2,2,2,2,2,0,0,0,0,0,0,0,0,0 } ,
231 { 0,2,2,0,0,0,0,0,0,0,0,0,0,0,0,0 } } ,
232 { { 0,3,3,3,3,3,3,0,0,0,1,1,1,1,1,0 } ,
233 { 0,3,3,0,0,0,1,1,1,1,1,1,1,1,1,0 } } };
234
235 int table,sblim;
236 static struct al_table *tables[5] =
237 { alloc_0, alloc_1, alloc_2, alloc_3 , alloc_4 };
238 static int sblims[5] = { 27 , 30 , 8, 12 , 30 };
239
240 if(fr->lsf)
241 table = 4;
242 else
243 table = translate[fr->sampling_frequency][2-fr->stereo][fr->bitrate_index];
244 sblim = sblims[table];
245
246 fr->alloc = tables[table];
247 fr->II_sblimit = sblim;
248 }
249
250 int do_layer2(struct frame *fr,unsigned char *pcm_sample,int *pcm_point)
251 {
252 int clip=0;
253 int i,j;
254 int stereo = fr->stereo;
255 real fraction[2][4][SBLIMIT]; /* pick_table clears unused subbands */
256 unsigned int bit_alloc[64];
257 int scale[192];
258 int single = fr->single;
259
260 II_select_table(fr);
261 fr->jsbound = (fr->mode == MPG_MD_JOINT_STEREO) ?
262 (fr->mode_ext<<2)+4 : fr->II_sblimit;
263
264 if(stereo == 1 || single == 3)
265 single = 0;
266
267 II_step_one(bit_alloc, scale, fr);
268
269 for (i=0;i<SCALE_BLOCK;i++)
270 {
271 II_step_two(bit_alloc,fraction,scale,fr,i>>2);
272 for (j=0;j<3;j++) {
273 if(single >= 0) {
274 clip += synth_1to1_mono(fraction[0][j],pcm_sample,pcm_point);
275 }
276 else {
277 int p1 = *pcm_point;
278 clip += synth_1to1(fraction[0][j],0,pcm_sample,&p1);
279 clip += synth_1to1(fraction[1][j],1,pcm_sample,pcm_point);
280 }
281
282 }
283 }
284
285 return clip;
286 }
287
288