aboutsummaryrefslogtreecommitdiffstats
path: root/libavcodec/ac3_parser.c
blob: 69d88c1a76820001768e8a5a8c3a1bcb41afdd96 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
/*
 * AC-3 parser
 * Copyright (c) 2003 Fabrice Bellard
 * Copyright (c) 2003 Michael Niedermayer
 *
 * This file is part of Libav.
 *
 * Libav is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * Libav is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with Libav; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

#include "libavutil/channel_layout.h"
#include "parser.h"
#include "ac3_parser.h"
#include "aac_ac3_parser.h"
#include "get_bits.h"


#define AC3_HEADER_SIZE 7


static const uint8_t eac3_blocks[4] = {
    1, 2, 3, 6
};

/**
 * Table for center mix levels
 * reference: Section 5.4.2.4 cmixlev
 */
static const uint8_t center_levels[4] = { 4, 5, 6, 5 };

/**
 * Table for surround mix levels
 * reference: Section 5.4.2.5 surmixlev
 */
static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };


int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
{
    int frame_size_code;

    memset(hdr, 0, sizeof(*hdr));

    hdr->sync_word = get_bits(gbc, 16);
    if(hdr->sync_word != 0x0B77)
        return AAC_AC3_PARSE_ERROR_SYNC;

    /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
    hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;
    if(hdr->bitstream_id > 16)
        return AAC_AC3_PARSE_ERROR_BSID;

    hdr->num_blocks = 6;

    /* set default mix levels */
    hdr->center_mix_level   = 5;  // -4.5dB
    hdr->surround_mix_level = 6;  // -6.0dB

    /* set default dolby surround mode */
    hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;

    if(hdr->bitstream_id <= 10) {
        /* Normal AC-3 */
        hdr->crc1 = get_bits(gbc, 16);
        hdr->sr_code = get_bits(gbc, 2);
        if(hdr->sr_code == 3)
            return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;

        frame_size_code = get_bits(gbc, 6);
        if(frame_size_code > 37)
            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

        skip_bits(gbc, 5); // skip bsid, already got it

        hdr->bitstream_mode = get_bits(gbc, 3);
        hdr->channel_mode = get_bits(gbc, 3);

        if(hdr->channel_mode == AC3_CHMODE_STEREO) {
            hdr->dolby_surround_mode = get_bits(gbc, 2);
        } else {
            if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
                hdr->  center_mix_level =   center_levels[get_bits(gbc, 2)];
            if(hdr->channel_mode & 4)
                hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
        }
        hdr->lfe_on = get_bits1(gbc);

        hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
        hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
        hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
        hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
        hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
        hdr->substreamid = 0;
    } else {
        /* Enhanced AC-3 */
        hdr->crc1 = 0;
        hdr->frame_type = get_bits(gbc, 2);
        if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
            return AAC_AC3_PARSE_ERROR_FRAME_TYPE;

        hdr->substreamid = get_bits(gbc, 3);

        hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
        if(hdr->frame_size < AC3_HEADER_SIZE)
            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;

        hdr->sr_code = get_bits(gbc, 2);
        if (hdr->sr_code == 3) {
            int sr_code2 = get_bits(gbc, 2);
            if(sr_code2 == 3)
                return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
            hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
            hdr->sr_shift = 1;
        } else {
            hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
            hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
            hdr->sr_shift = 0;
        }

        hdr->channel_mode = get_bits(gbc, 3);
        hdr->lfe_on = get_bits1(gbc);

        hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
                        (hdr->num_blocks * 256.0));
        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
    }
    hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode];
    if (hdr->lfe_on)
        hdr->channel_layout |= AV_CH_LOW_FREQUENCY;

    return 0;
}

static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
        int *need_next_header, int *new_frame_start)
{
    int err;
    union {
        uint64_t u64;
        uint8_t  u8[8 + FF_INPUT_BUFFER_PADDING_SIZE];
    } tmp = { av_be2ne64(state) };
    AC3HeaderInfo hdr;
    GetBitContext gbc;

    init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
    err = avpriv_ac3_parse_header(&gbc, &hdr);

    if(err < 0)
        return 0;

    hdr_info->sample_rate = hdr.sample_rate;
    hdr_info->bit_rate = hdr.bit_rate;
    hdr_info->channels = hdr.channels;
    hdr_info->channel_layout = hdr.channel_layout;
    hdr_info->samples = hdr.num_blocks * 256;
    hdr_info->service_type = hdr.bitstream_mode;
    if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
        hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
    if(hdr.bitstream_id>10)
        hdr_info->codec_id = AV_CODEC_ID_EAC3;
    else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
        hdr_info->codec_id = AV_CODEC_ID_AC3;

    *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
    *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
    return hdr.frame_size;
}

static av_cold int ac3_parse_init(AVCodecParserContext *s1)
{
    AACAC3ParseContext *s = s1->priv_data;
    s->header_size = AC3_HEADER_SIZE;
    s->sync = ac3_sync;
    return 0;
}


AVCodecParser ff_ac3_parser = {
    .codec_ids      = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
    .priv_data_size = sizeof(AACAC3ParseContext),
    .parser_init    = ac3_parse_init,
    .parser_parse   = ff_aac_ac3_parse,
    .parser_close   = ff_parse_close,
};