1 /*****************************************************************************
2 * adec_layer1.c: MPEG Layer I audio decoder
3 *****************************************************************************
4 * Copyright (C) 1999, 2000 VideoLAN
5 * $Id: adec_layer1.c,v 1.5 2001/04/12 01:52:45 sam Exp $
7 * Authors: Michel Kaempf <maxx@via.ecp.fr>
8 * Michel Lespinasse <walken@via.ecp.fr>
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License as published by
12 * the Free Software Foundation; either version 2 of the License, or
13 * (at your option) any later version.
15 * This program is distributed in the hope that it will be useful,
16 * but WITHOUT ANY WARRANTY; without even the implied warranty of
17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 * GNU General Public License for more details.
20 * You should have received a copy of the GNU General Public License
21 * along with this program; if not, write to the Free Software
22 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
23 *****************************************************************************/
28 * - optimiser les NeedBits() et les GetBits() du code là où c'est possible ;
34 #include <stdlib.h> /* NULL */
35 #include <string.h> /* memcpy(), memset() */
41 #include "stream_control.h"
42 #include "input_ext-dec.h"
44 #include "adec_generic.h"
45 #include "audio_decoder.h"
46 #include "adec_math.h" /* DCT32(), PCM() */
50 static float adec_scalefactor_table[64] =
52 2.0000000000000000, 1.5874010519681994, 1.2599210498948732,
53 1.0000000000000000, 0.7937005259840998, 0.6299605249474366,
54 0.5000000000000000, 0.3968502629920499, 0.3149802624737183,
55 0.2500000000000000, 0.1984251314960249, 0.1574901312368591,
56 0.1250000000000000, 0.0992125657480125, 0.0787450656184296,
57 0.0625000000000000, 0.0496062828740062, 0.0393725328092148,
58 0.0312500000000000, 0.0248031414370031, 0.0196862664046074,
59 0.0156250000000000, 0.0124015707185016, 0.0098431332023037,
60 0.0078125000000000, 0.0062007853592508, 0.0049215666011518,
61 0.0039062500000000, 0.0031003926796254, 0.0024607833005759,
62 0.0019531250000000, 0.0015501963398127, 0.0012303916502880,
63 0.0009765625000000, 0.0007750981699063, 0.0006151958251440,
64 0.0004882812500000, 0.0003875490849532, 0.0003075979125720,
65 0.0002441406250000, 0.0001937745424766, 0.0001537989562860,
66 0.0001220703125000, 0.0000968872712383, 0.0000768994781430,
67 0.0000610351562500, 0.0000484436356191, 0.0000384497390715,
68 0.0000305175781250, 0.0000242218178096, 0.0000192248695357,
69 0.0000152587890625, 0.0000121109089048, 0.0000096124347679,
70 0.0000076293945312, 0.0000060554544524, 0.0000048062173839,
71 0.0000038146972656, 0.0000030277272262, 0.0000024031086920,
72 0.0000019073486328, 0.0000015138636131, 0.0000012015543460,
73 0.0000009536743164 /* last element is not in the standard... invalid ??? */
76 static float adec_slope_table[15] =
78 0.6666666666666666, 0.2857142857142857, 0.1333333333333333,
79 0.0645161290322581, 0.0317460317460317, 0.0157480314960630,
80 0.0078431372549020, 0.0039138943248532, 0.0019550342130987,
81 0.0009770395701026, 0.0004884004884005, 0.0002441704309608,
82 0.0001220777635354, 0.0000610370189520, 0.0000305180437934
85 static float adec_offset_table[15] =
87 -0.6666666666666666, -0.8571428571428571, -0.9333333333333333,
88 -0.9677419354838710, -0.9841269841269841, -0.9921259842519685,
89 -0.9960784313725490, -0.9980430528375733, -0.9990224828934506,
90 -0.9995114802149487, -0.9997557997557998, -0.9998779147845196,
91 -0.9999389611182323, -0.9999694814905240, -0.9999847409781033
94 static u8 adec_layer1_allocation_table[15] =
96 0, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15
99 static int adec_bound_table[4] = { 4, 8, 12, 16 };
101 int adec_layer1_mono( adec_thread_t * p_adec, s16 * buffer )
113 * Parse the allocation tables
116 for (i_sb = 0; i_sb < 32; i_sb += 2)
120 /* i_read_bits will be updated at the end of the loop */
121 tmp = GetBits ( &p_adec->bit_stream, 8 );
123 if ( (tmp >> 4) > 14 )
128 allocation[i_sb] = adec_layer1_allocation_table [tmp >> 4];
135 allocation[i_sb+1] = adec_layer1_allocation_table [tmp & 15];
138 i_read_bits += 8 * 16; /* we did 16 iterations */
144 for ( i_sb = 0; i_sb < 32; i_sb++ )
146 if ( allocation[i_sb] )
151 index = GetBits( &p_adec->bit_stream, 6);
153 /* We also add the bits we'll take later in the sample parsing */
154 i_read_bits += 6 + 12 * allocation[i_sb];
156 scalefactor = adec_scalefactor_table[index];
158 slope[i_sb] = adec_slope_table[allocation[i_sb]-2] * scalefactor;
159 offset[i_sb] = adec_offset_table[allocation[i_sb]-2] * scalefactor;
167 for ( s = 0 ; s < 12; s++)
171 for (i_sb = 0; i_sb < 32; i_sb++)
173 if (!allocation[i_sb])
181 /* The bits were already counted in the scalefactors parsing */
182 code = GetBits( &p_adec->bit_stream, allocation[i_sb] );
184 sample[i_sb] = slope[i_sb] * code + offset[i_sb];
188 DCT32 (sample, &p_adec->bank_0);
190 PCM (&p_adec->bank_0, &XXX_buf, 1);
194 p_adec->i_read_bits += i_read_bits;
199 int adec_layer1_stereo( adec_thread_t * p_adec, s16 * buffer )
201 u8 allocation_0[32], allocation_1[32];
202 float slope_0[32], slope_1[32];
203 float offset_0[32], offset_1[32];
204 float sample_0[32], sample_1[32];
216 if ( (p_adec->header & 0xc0) == 0x40)
218 /* intensity stereo */
220 index = (p_adec->header >> 4) & 3;
221 bound = adec_bound_table[index];
228 for (i_sb = 0; i_sb < bound; i_sb++)
231 tmp = GetBits( &p_adec->bit_stream, 8 );
236 allocation_0[i_sb] = adec_layer1_allocation_table [tmp >> 4];
241 allocation_1[i_sb] = adec_layer1_allocation_table [tmp & 15];
244 for (; i_sb < 32; i_sb += 2)
247 tmp = GetBits( &p_adec->bit_stream, 8 );
253 allocation_0[i_sb] = allocation_1[i_sb]
254 = adec_layer1_allocation_table [tmp >> 4];
260 allocation_0[i_sb+1] = allocation_1[i_sb+1]
261 = adec_layer1_allocation_table [tmp & 15];
264 i_read_bits += 4 * ( 32 + bound ); /* we read 8*bound and 4*(32-bound) */
270 for ( i_sb = 0; i_sb < 32; i_sb++ )
272 if ( allocation_0[i_sb] )
277 index = GetBits( &p_adec->bit_stream, 6 );
280 scalefactor = adec_scalefactor_table[index];
282 slope_0[i_sb] = adec_slope_table[allocation_0[i_sb]-2] * scalefactor;
283 offset_0[i_sb] = adec_offset_table[allocation_0[i_sb]-2] * scalefactor;
286 if (allocation_1[i_sb])
291 index = GetBits( &p_adec->bit_stream, 6 );
294 scalefactor = adec_scalefactor_table[index];
296 slope_1[i_sb] = adec_slope_table[allocation_1[i_sb]-2] * scalefactor;
297 offset_1[i_sb] = adec_offset_table[allocation_1[i_sb]-2] * scalefactor;
303 for (s = 0; s < 12; s++)
307 for (i_sb = 0; i_sb < bound; i_sb++)
309 if (!allocation_0[i_sb])
317 code = GetBits( &p_adec->bit_stream, allocation_0[i_sb] );
318 i_read_bits += allocation_0[i_sb];
320 sample_0[i_sb] = slope_0[i_sb] * code + offset_0[i_sb];
323 if ( !allocation_1[i_sb] )
331 code = GetBits( &p_adec->bit_stream, allocation_1[i_sb] );
332 i_read_bits += allocation_1[i_sb];
334 sample_1[i_sb] = slope_1[i_sb] * code + offset_1[i_sb];
338 for (; i_sb < 32; i_sb++)
340 if (!allocation_0[i_sb])
349 code = GetBits( &p_adec->bit_stream, allocation_0[i_sb] );
350 i_read_bits += allocation_0[i_sb];
352 sample_0[i_sb] = slope_0[i_sb] * code + offset_0[i_sb];
353 sample_1[i_sb] = slope_1[i_sb] * code + offset_1[i_sb];
357 DCT32 (sample_0, &p_adec->bank_0);
359 PCM (&p_adec->bank_0, &XXX_buf, 2);
360 DCT32 (sample_1, &p_adec->bank_1);
362 PCM (&p_adec->bank_1, &XXX_buf, 2);
366 p_adec->i_read_bits += i_read_bits;