move aac and ac3 parsers in their own files
[libav.git] / libavcodec / ac3_parser.c
CommitLineData
99ff31dc
AJ
1/*
2 * AC3 parser
3 * Copyright (c) 2003 Fabrice Bellard.
4 * Copyright (c) 2003 Michael Niedermayer.
5 *
6 * This file is part of FFmpeg.
7 *
8 * FFmpeg is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU Lesser General Public
10 * License as published by the Free Software Foundation; either
11 * version 2.1 of the License, or (at your option) any later version.
12 *
13 * FFmpeg is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * Lesser General Public License for more details.
17 *
18 * You should have received a copy of the GNU Lesser General Public
19 * License along with FFmpeg; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
21 */
22
23#include "parser.h"
24#include "ac3_parser.h"
25#include "aac_ac3_parser.h"
26#include "bitstream.h"
27
28
29#define AC3_HEADER_SIZE 7
30
31
32static const uint8_t eac3_blocks[4] = {
33 1, 2, 3, 6
34};
35
36
37int ff_ac3_parse_header(const uint8_t buf[7], AC3HeaderInfo *hdr)
38{
39 GetBitContext gbc;
40
41 memset(hdr, 0, sizeof(*hdr));
42
43 init_get_bits(&gbc, buf, 54);
44
45 hdr->sync_word = get_bits(&gbc, 16);
46 if(hdr->sync_word != 0x0B77)
47 return -1;
48
49 /* read ahead to bsid to make sure this is AC-3, not E-AC-3 */
50 hdr->bsid = show_bits_long(&gbc, 29) & 0x1F;
51 if(hdr->bsid > 10)
52 return -2;
53
54 hdr->crc1 = get_bits(&gbc, 16);
55 hdr->fscod = get_bits(&gbc, 2);
56 if(hdr->fscod == 3)
57 return -3;
58
59 hdr->frmsizecod = get_bits(&gbc, 6);
60 if(hdr->frmsizecod > 37)
61 return -4;
62
63 skip_bits(&gbc, 5); // skip bsid, already got it
64
65 hdr->bsmod = get_bits(&gbc, 3);
66 hdr->acmod = get_bits(&gbc, 3);
67 if((hdr->acmod & 1) && hdr->acmod != 1) {
68 hdr->cmixlev = get_bits(&gbc, 2);
69 }
70 if(hdr->acmod & 4) {
71 hdr->surmixlev = get_bits(&gbc, 2);
72 }
73 if(hdr->acmod == 2) {
74 hdr->dsurmod = get_bits(&gbc, 2);
75 }
76 hdr->lfeon = get_bits1(&gbc);
77
78 hdr->halfratecod = FFMAX(hdr->bsid, 8) - 8;
79 hdr->sample_rate = ff_ac3_freqs[hdr->fscod] >> hdr->halfratecod;
80 hdr->bit_rate = (ff_ac3_bitratetab[hdr->frmsizecod>>1] * 1000) >> hdr->halfratecod;
81 hdr->channels = ff_ac3_channels[hdr->acmod] + hdr->lfeon;
82 hdr->frame_size = ff_ac3_frame_sizes[hdr->frmsizecod][hdr->fscod] * 2;
83
84 return 0;
85}
86
87static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
88 int *bit_rate, int *samples)
89{
90 int err;
91 unsigned int fscod, acmod, bsid, lfeon;
92 unsigned int strmtyp, substreamid, frmsiz, fscod2, numblkscod;
93 GetBitContext bits;
94 AC3HeaderInfo hdr;
95
96 err = ff_ac3_parse_header(buf, &hdr);
97
98 if(err < 0 && err != -2)
99 return 0;
100
101 bsid = hdr.bsid;
102 if(bsid <= 10) { /* Normal AC-3 */
103 *sample_rate = hdr.sample_rate;
104 *bit_rate = hdr.bit_rate;
105 *channels = hdr.channels;
106 *samples = AC3_FRAME_SIZE;
107 return hdr.frame_size;
108 } else if (bsid > 10 && bsid <= 16) { /* Enhanced AC-3 */
109 init_get_bits(&bits, &buf[2], (AC3_HEADER_SIZE-2) * 8);
110 strmtyp = get_bits(&bits, 2);
111 substreamid = get_bits(&bits, 3);
112
113 if (strmtyp != 0 || substreamid != 0)
114 return 0; /* Currently don't support additional streams */
115
116 frmsiz = get_bits(&bits, 11) + 1;
117 fscod = get_bits(&bits, 2);
118 if (fscod == 3) {
119 fscod2 = get_bits(&bits, 2);
120 numblkscod = 3;
121
122 if(fscod2 == 3)
123 return 0;
124
125 *sample_rate = ff_ac3_freqs[fscod2] / 2;
126 } else {
127 numblkscod = get_bits(&bits, 2);
128
129 *sample_rate = ff_ac3_freqs[fscod];
130 }
131
132 acmod = get_bits(&bits, 3);
133 lfeon = get_bits1(&bits);
134
135 *samples = eac3_blocks[numblkscod] * 256;
136 *bit_rate = frmsiz * (*sample_rate) * 16 / (*samples);
137 *channels = ff_ac3_channels[acmod] + lfeon;
138
139 return frmsiz * 2;
140 }
141
142 /* Unsupported bitstream version */
143 return 0;
144}
145
146static int ac3_parse_init(AVCodecParserContext *s1)
147{
148 AC3ParseContext *s = s1->priv_data;
149 s->inbuf_ptr = s->inbuf;
150 s->header_size = AC3_HEADER_SIZE;
151 s->sync = ac3_sync;
152 return 0;
153}
154
155
156AVCodecParser ac3_parser = {
157 { CODEC_ID_AC3 },
158 sizeof(AC3ParseContext),
159 ac3_parse_init,
160 ac3_parse,
161 NULL,
162};