1/*
2 * AC-3 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 "libavutil/channel_layout.h"
24#include "parser.h"
25#include "ac3_parser.h"
26#include "aac_ac3_parser.h"
27#include "get_bits.h"
28
29
30#define AC3_HEADER_SIZE 7
31
32
33static const uint8_t eac3_blocks[4] = {
34    1, 2, 3, 6
35};
36
37/**
38 * Table for center mix levels
39 * reference: Section 5.4.2.4 cmixlev
40 */
41static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
42
43/**
44 * Table for surround mix levels
45 * reference: Section 5.4.2.5 surmixlev
46 */
47static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
48
49
50int avpriv_ac3_parse_header2(GetBitContext *gbc, AC3HeaderInfo **phdr)
51{
52    int frame_size_code;
53    AC3HeaderInfo *hdr;
54
55    if (!*phdr)
56        *phdr = av_mallocz(sizeof(AC3HeaderInfo));
57    if (!*phdr)
58        return AVERROR(ENOMEM);
59    hdr = *phdr;
60
61    memset(hdr, 0, sizeof(*hdr));
62
63    hdr->sync_word = get_bits(gbc, 16);
64    if(hdr->sync_word != 0x0B77)
65        return AAC_AC3_PARSE_ERROR_SYNC;
66
67    /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
68    hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;
69    if(hdr->bitstream_id > 16)
70        return AAC_AC3_PARSE_ERROR_BSID;
71
72    hdr->num_blocks = 6;
73
74    /* set default mix levels */
75    hdr->center_mix_level   = 5;  // -4.5dB
76    hdr->surround_mix_level = 6;  // -6.0dB
77
78    /* set default dolby surround mode */
79    hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
80
81    if(hdr->bitstream_id <= 10) {
82        /* Normal AC-3 */
83        hdr->crc1 = get_bits(gbc, 16);
84        hdr->sr_code = get_bits(gbc, 2);
85        if(hdr->sr_code == 3)
86            return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
87
88        frame_size_code = get_bits(gbc, 6);
89        if(frame_size_code > 37)
90            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
91
92        skip_bits(gbc, 5); // skip bsid, already got it
93
94        hdr->bitstream_mode = get_bits(gbc, 3);
95        hdr->channel_mode = get_bits(gbc, 3);
96
97        if(hdr->channel_mode == AC3_CHMODE_STEREO) {
98            hdr->dolby_surround_mode = get_bits(gbc, 2);
99        } else {
100            if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
101                hdr->  center_mix_level =   center_levels[get_bits(gbc, 2)];
102            if(hdr->channel_mode & 4)
103                hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
104        }
105        hdr->lfe_on = get_bits1(gbc);
106
107        hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
108        hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
109        hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
110        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
111        hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
112        hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
113        hdr->substreamid = 0;
114    } else {
115        /* Enhanced AC-3 */
116        hdr->crc1 = 0;
117        hdr->frame_type = get_bits(gbc, 2);
118        if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
119            return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
120
121        hdr->substreamid = get_bits(gbc, 3);
122
123        hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
124        if(hdr->frame_size < AC3_HEADER_SIZE)
125            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
126
127        hdr->sr_code = get_bits(gbc, 2);
128        if (hdr->sr_code == 3) {
129            int sr_code2 = get_bits(gbc, 2);
130            if(sr_code2 == 3)
131                return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
132            hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
133            hdr->sr_shift = 1;
134        } else {
135            hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
136            hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
137            hdr->sr_shift = 0;
138        }
139
140        hdr->channel_mode = get_bits(gbc, 3);
141        hdr->lfe_on = get_bits1(gbc);
142
143        hdr->bit_rate = (uint32_t)(8.0 * hdr->frame_size * hdr->sample_rate /
144                        (hdr->num_blocks * 256.0));
145        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
146    }
147    hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode];
148    if (hdr->lfe_on)
149        hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
150
151    return 0;
152}
153
154int avpriv_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
155{
156    AC3HeaderInfo tmp, *ptmp = &tmp;
157    int ret = avpriv_ac3_parse_header2(gbc, &ptmp);
158
159    memcpy(hdr, ptmp, ((intptr_t)&tmp.channel_layout) - ((intptr_t)&tmp) + sizeof(uint64_t));
160    return ret;
161}
162
163static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
164        int *need_next_header, int *new_frame_start)
165{
166    int err;
167    union {
168        uint64_t u64;
169        uint8_t  u8[8 + FF_INPUT_BUFFER_PADDING_SIZE];
170    } tmp = { av_be2ne64(state) };
171    AC3HeaderInfo hdr, *phdr = &hdr;
172    GetBitContext gbc;
173
174    init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
175    err = avpriv_ac3_parse_header2(&gbc, &phdr);
176
177    if(err < 0)
178        return 0;
179
180    hdr_info->sample_rate = hdr.sample_rate;
181    hdr_info->bit_rate = hdr.bit_rate;
182    hdr_info->channels = hdr.channels;
183    hdr_info->channel_layout = hdr.channel_layout;
184    hdr_info->samples = hdr.num_blocks * 256;
185    hdr_info->service_type = hdr.bitstream_mode;
186    if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
187        hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
188    if(hdr.bitstream_id>10)
189        hdr_info->codec_id = AV_CODEC_ID_EAC3;
190    else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
191        hdr_info->codec_id = AV_CODEC_ID_AC3;
192
193    *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
194    *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
195    return hdr.frame_size;
196}
197
198static av_cold int ac3_parse_init(AVCodecParserContext *s1)
199{
200    AACAC3ParseContext *s = s1->priv_data;
201    s->header_size = AC3_HEADER_SIZE;
202    s->sync = ac3_sync;
203    return 0;
204}
205
206
207AVCodecParser ff_ac3_parser = {
208    .codec_ids      = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
209    .priv_data_size = sizeof(AACAC3ParseContext),
210    .parser_init    = ac3_parse_init,
211    .parser_parse   = ff_aac_ac3_parse,
212    .parser_close   = ff_parse_close,
213};
214