Remove declarations after statements from doVertDefFilter_altivec
[libav.git] / libavcodec / ac3_parser.c
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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;
86ad4c7e 40 int frame_size_code;
646800f7 41 int num_blocks;
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42
43 memset(hdr, 0, sizeof(*hdr));
44
45 init_get_bits(&gbc, buf, 54);
46
47 hdr->sync_word = get_bits(&gbc, 16);
48 if(hdr->sync_word != 0x0B77)
3df88093 49 return AC3_PARSE_ERROR_SYNC;
99ff31dc 50
646800f7 51 /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
e59cc205 52 hdr->bitstream_id = show_bits_long(&gbc, 29) & 0x1F;
646800f7 53 if(hdr->bitstream_id > 16)
3df88093 54 return AC3_PARSE_ERROR_BSID;
99ff31dc 55
646800f7 56 if(hdr->bitstream_id <= 10) {
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57 /* Normal AC-3 */
58 hdr->crc1 = get_bits(&gbc, 16);
59 hdr->sr_code = get_bits(&gbc, 2);
60 if(hdr->sr_code == 3)
61 return AC3_PARSE_ERROR_SAMPLE_RATE;
62
63 frame_size_code = get_bits(&gbc, 6);
64 if(frame_size_code > 37)
65 return AC3_PARSE_ERROR_FRAME_SIZE;
66
67 skip_bits(&gbc, 5); // skip bsid, already got it
99ff31dc 68
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69 skip_bits(&gbc, 3); // skip bitstream mode
70 hdr->channel_mode = get_bits(&gbc, 3);
71 if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO) {
72 skip_bits(&gbc, 2); // skip center mix level
73 }
74 if(hdr->channel_mode & 4) {
75 skip_bits(&gbc, 2); // skip surround mix level
76 }
77 if(hdr->channel_mode == AC3_CHMODE_STEREO) {
78 skip_bits(&gbc, 2); // skip dolby surround mode
79 }
80 hdr->lfe_on = get_bits1(&gbc);
81
82 hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
83 hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
84 hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
85 hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
86 hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
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87 } else {
88 /* Enhanced AC-3 */
89 hdr->crc1 = 0;
90 skip_bits(&gbc, 2); // skip stream type
91 skip_bits(&gbc, 3); // skip substream id
92
93 hdr->frame_size = (get_bits(&gbc, 11) + 1) << 1;
94 if(hdr->frame_size < AC3_HEADER_SIZE)
95 return AC3_PARSE_ERROR_FRAME_SIZE;
96
97 hdr->sr_code = get_bits(&gbc, 2);
98 if (hdr->sr_code == 3) {
99 int sr_code2 = get_bits(&gbc, 2);
100 if(sr_code2 == 3)
101 return AC3_PARSE_ERROR_SAMPLE_RATE;
102 hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
103 hdr->sr_shift = 1;
104 num_blocks = 6;
105 } else {
106 num_blocks = eac3_blocks[get_bits(&gbc, 2)];
107 hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
108 hdr->sr_shift = 0;
109 }
110
111 hdr->channel_mode = get_bits(&gbc, 3);
112 hdr->lfe_on = get_bits1(&gbc);
113
114 hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
115 (num_blocks * 256.0));
116 hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
117 }
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118
119 return 0;
120}
121
122static int ac3_sync(const uint8_t *buf, int *channels, int *sample_rate,
123 int *bit_rate, int *samples)
124{
125 int err;
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126 AC3HeaderInfo hdr;
127
128 err = ff_ac3_parse_header(buf, &hdr);
129
646800f7 130 if(err < 0)
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131 return 0;
132
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133 *sample_rate = hdr.sample_rate;
134 *bit_rate = hdr.bit_rate;
135 *channels = hdr.channels;
136 *samples = AC3_FRAME_SIZE;
137 return hdr.frame_size;
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138}
139
98a6fff9 140static av_cold int ac3_parse_init(AVCodecParserContext *s1)
99ff31dc 141{
679c2294 142 AACAC3ParseContext *s = s1->priv_data;
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143 s->inbuf_ptr = s->inbuf;
144 s->header_size = AC3_HEADER_SIZE;
145 s->sync = ac3_sync;
146 return 0;
147}
148
149
150AVCodecParser ac3_parser = {
151 { CODEC_ID_AC3 },
679c2294 152 sizeof(AACAC3ParseContext),
99ff31dc 153 ac3_parse_init,
679c2294 154 ff_aac_ac3_parse,
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155 NULL,
156};