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 "config.h"
24#include "config_components.h"
25
26#include "libavutil/channel_layout.h"
27#include "parser.h"
28#include "ac3defs.h"
29#include "ac3tab.h"
30#include "ac3_parser.h"
31#include "ac3_parser_internal.h"
32#include "aac_ac3_parser.h"
33#include "get_bits.h"
34
35
36#define AC3_HEADER_SIZE 7
37
38#if CONFIG_AC3_PARSER
39
40static const uint8_t eac3_blocks[4] = {
41    1, 2, 3, 6
42};
43
44/**
45 * Table for center mix levels
46 * reference: Section 5.4.2.4 cmixlev
47 */
48static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
49
50/**
51 * Table for surround mix levels
52 * reference: Section 5.4.2.5 surmixlev
53 */
54static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
55
56
57int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
58{
59    int frame_size_code;
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    hdr->ac3_bit_rate_code = -1;
74
75    /* set default mix levels */
76    hdr->center_mix_level   = 5;  // -4.5dB
77    hdr->surround_mix_level = 6;  // -6.0dB
78
79    /* set default dolby surround mode */
80    hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
81
82    if(hdr->bitstream_id <= 10) {
83        /* Normal AC-3 */
84        hdr->crc1 = get_bits(gbc, 16);
85        hdr->sr_code = get_bits(gbc, 2);
86        if(hdr->sr_code == 3)
87            return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
88
89        frame_size_code = get_bits(gbc, 6);
90        if(frame_size_code > 37)
91            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
92
93        hdr->ac3_bit_rate_code = (frame_size_code >> 1);
94
95        skip_bits(gbc, 5); // skip bsid, already got it
96
97        hdr->bitstream_mode = get_bits(gbc, 3);
98        hdr->channel_mode = get_bits(gbc, 3);
99
100        if(hdr->channel_mode == AC3_CHMODE_STEREO) {
101            hdr->dolby_surround_mode = get_bits(gbc, 2);
102        } else {
103            if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
104                hdr->  center_mix_level =   center_levels[get_bits(gbc, 2)];
105            if(hdr->channel_mode & 4)
106                hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
107        }
108        hdr->lfe_on = get_bits1(gbc);
109
110        hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
111        hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
112        hdr->bit_rate = (ff_ac3_bitrate_tab[hdr->ac3_bit_rate_code] * 1000) >> hdr->sr_shift;
113        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
114        hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
115        hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
116        hdr->substreamid = 0;
117    } else {
118        /* Enhanced AC-3 */
119        hdr->crc1 = 0;
120        hdr->frame_type = get_bits(gbc, 2);
121        if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
122            return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
123
124        hdr->substreamid = get_bits(gbc, 3);
125
126        hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
127        if(hdr->frame_size < AC3_HEADER_SIZE)
128            return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
129
130        hdr->sr_code = get_bits(gbc, 2);
131        if (hdr->sr_code == 3) {
132            int sr_code2 = get_bits(gbc, 2);
133            if(sr_code2 == 3)
134                return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
135            hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
136            hdr->sr_shift = 1;
137        } else {
138            hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
139            hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
140            hdr->sr_shift = 0;
141        }
142
143        hdr->channel_mode = get_bits(gbc, 3);
144        hdr->lfe_on = get_bits1(gbc);
145
146        hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate /
147                        (hdr->num_blocks * 256);
148        hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
149    }
150    hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode];
151    if (hdr->lfe_on)
152        hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
153
154    return 0;
155}
156
157// TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
158int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
159                            size_t size)
160{
161    GetBitContext gb;
162    AC3HeaderInfo *hdr;
163    int err;
164
165    if (!*phdr)
166        *phdr = av_mallocz(sizeof(AC3HeaderInfo));
167    if (!*phdr)
168        return AVERROR(ENOMEM);
169    hdr = *phdr;
170
171    err = init_get_bits8(&gb, buf, size);
172    if (err < 0)
173        return AVERROR_INVALIDDATA;
174    err = ff_ac3_parse_header(&gb, hdr);
175    if (err < 0)
176        return AVERROR_INVALIDDATA;
177
178    return get_bits_count(&gb);
179}
180
181int av_ac3_parse_header(const uint8_t *buf, size_t size,
182                        uint8_t *bitstream_id, uint16_t *frame_size)
183{
184    GetBitContext gb;
185    AC3HeaderInfo hdr;
186    int err;
187
188    init_get_bits8(&gb, buf, size);
189    err = ff_ac3_parse_header(&gb, &hdr);
190    if (err < 0)
191        return AVERROR_INVALIDDATA;
192
193    *bitstream_id = hdr.bitstream_id;
194    *frame_size   = hdr.frame_size;
195
196    return 0;
197}
198
199static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
200        int *need_next_header, int *new_frame_start)
201{
202    int err;
203    union {
204        uint64_t u64;
205        uint8_t  u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
206    } tmp = { av_be2ne64(state) };
207    AC3HeaderInfo hdr;
208    GetBitContext gbc;
209
210    if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) {
211        FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]);
212        FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]);
213        FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]);
214    }
215
216    init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
217    err = ff_ac3_parse_header(&gbc, &hdr);
218
219    if(err < 0)
220        return 0;
221
222    hdr_info->sample_rate = hdr.sample_rate;
223    hdr_info->bit_rate = hdr.bit_rate;
224    hdr_info->channels = hdr.channels;
225    hdr_info->channel_layout = hdr.channel_layout;
226    hdr_info->samples = hdr.num_blocks * 256;
227    hdr_info->service_type = hdr.bitstream_mode;
228    if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
229        hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
230    if(hdr.bitstream_id>10)
231        hdr_info->codec_id = AV_CODEC_ID_EAC3;
232    else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
233        hdr_info->codec_id = AV_CODEC_ID_AC3;
234
235    *new_frame_start  = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
236    *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
237    return hdr.frame_size;
238}
239
240static av_cold int ac3_parse_init(AVCodecParserContext *s1)
241{
242    AACAC3ParseContext *s = s1->priv_data;
243    s->header_size = AC3_HEADER_SIZE;
244    s->sync = ac3_sync;
245    return 0;
246}
247
248
249const AVCodecParser ff_ac3_parser = {
250    .codec_ids      = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
251    .priv_data_size = sizeof(AACAC3ParseContext),
252    .parser_init    = ac3_parse_init,
253    .parser_parse   = ff_aac_ac3_parse,
254    .parser_close   = ff_parse_close,
255};
256
257#else
258
259int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
260                            size_t size)
261{
262    return AVERROR(ENOSYS);
263}
264
265int av_ac3_parse_header(const uint8_t *buf, size_t size,
266                        uint8_t *bitstream_id, uint16_t *frame_size)
267{
268    return AVERROR(ENOSYS);
269}
270#endif
271