2 * Common code between AC3 encoder and decoder
3 * Copyright (c) 2000, 2001, 2002 Fabrice Bellard.
5 * This library is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU Lesser General Public
7 * License as published by the Free Software Foundation; either
8 * version 2 of the License, or (at your option) any later version.
10 * This library is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 * Lesser General Public License for more details.
15 * You should have received a copy of the GNU Lesser General Public
16 * License along with this library; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
22 * Common code between AC3 encoder and decoder.
25 #define AC3_MAX_CODED_FRAME_SIZE 3840 /* in bytes */
26 #define AC3_MAX_CHANNELS 6 /* including LFE channel */
28 #define NB_BLOCKS 6 /* number of PCM blocks inside an AC3 frame */
29 #define AC3_FRAME_SIZE (NB_BLOCKS * 256)
31 /* exponent encoding strategy */
39 typedef struct AC3BitAllocParameters {
40 int fscod; /* frequency */
42 int sgain, sdecay, fdecay, dbknee, floor;
43 int cplfleak, cplsleak;
44 } AC3BitAllocParameters;
46 extern const uint16_t ac3_freqs[3];
47 extern const uint16_t ac3_bitratetab[19];
48 extern const int16_t ac3_window[256];
49 extern const uint8_t sdecaytab[4];
50 extern const uint8_t fdecaytab[4];
51 extern const uint16_t sgaintab[4];
52 extern const uint16_t dbkneetab[4];
53 extern const uint16_t floortab[8];
54 extern const uint16_t fgaintab[8];
56 void ac3_common_init(void);
57 void ac3_parametric_bit_allocation(AC3BitAllocParameters *s, uint8_t *bap,
58 int8_t *exp, int start, int end,
59 int snroffset, int fgain, int is_lfe,
60 int deltbae,int deltnseg,
61 uint8_t *deltoffst, uint8_t *deltlen, uint8_t *deltba);