FFmpeg
ac3_parser.c
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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 
25 #include "libavutil/channel_layout.h"
26 #include "parser.h"
27 #include "ac3_parser.h"
28 #include "ac3_parser_internal.h"
29 #include "aac_ac3_parser.h"
30 #include "get_bits.h"
31 
32 
33 #define AC3_HEADER_SIZE 7
34 
35 #if CONFIG_AC3_PARSER
36 
37 static const uint8_t eac3_blocks[4] = {
38  1, 2, 3, 6
39 };
40 
41 /**
42  * Table for center mix levels
43  * reference: Section 5.4.2.4 cmixlev
44  */
45 static const uint8_t center_levels[4] = { 4, 5, 6, 5 };
46 
47 /**
48  * Table for surround mix levels
49  * reference: Section 5.4.2.5 surmixlev
50  */
51 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
52 
53 
54 int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
55 {
56  int frame_size_code;
57 
58  memset(hdr, 0, sizeof(*hdr));
59 
60  hdr->sync_word = get_bits(gbc, 16);
61  if(hdr->sync_word != 0x0B77)
62  return AAC_AC3_PARSE_ERROR_SYNC;
63 
64  /* read ahead to bsid to distinguish between AC-3 and E-AC-3 */
65  hdr->bitstream_id = show_bits_long(gbc, 29) & 0x1F;
66  if(hdr->bitstream_id > 16)
67  return AAC_AC3_PARSE_ERROR_BSID;
68 
69  hdr->num_blocks = 6;
70 
71  /* set default mix levels */
72  hdr->center_mix_level = 5; // -4.5dB
73  hdr->surround_mix_level = 6; // -6.0dB
74 
75  /* set default dolby surround mode */
76  hdr->dolby_surround_mode = AC3_DSURMOD_NOTINDICATED;
77 
78  if(hdr->bitstream_id <= 10) {
79  /* Normal AC-3 */
80  hdr->crc1 = get_bits(gbc, 16);
81  hdr->sr_code = get_bits(gbc, 2);
82  if(hdr->sr_code == 3)
83  return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
84 
85  frame_size_code = get_bits(gbc, 6);
86  if(frame_size_code > 37)
87  return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
88 
89  skip_bits(gbc, 5); // skip bsid, already got it
90 
91  hdr->bitstream_mode = get_bits(gbc, 3);
92  hdr->channel_mode = get_bits(gbc, 3);
93 
94  if(hdr->channel_mode == AC3_CHMODE_STEREO) {
95  hdr->dolby_surround_mode = get_bits(gbc, 2);
96  } else {
97  if((hdr->channel_mode & 1) && hdr->channel_mode != AC3_CHMODE_MONO)
98  hdr-> center_mix_level = center_levels[get_bits(gbc, 2)];
99  if(hdr->channel_mode & 4)
100  hdr->surround_mix_level = surround_levels[get_bits(gbc, 2)];
101  }
102  hdr->lfe_on = get_bits1(gbc);
103 
104  hdr->sr_shift = FFMAX(hdr->bitstream_id, 8) - 8;
105  hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code] >> hdr->sr_shift;
106  hdr->bit_rate = (ff_ac3_bitrate_tab[frame_size_code>>1] * 1000) >> hdr->sr_shift;
107  hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
108  hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
109  hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
110  hdr->substreamid = 0;
111  } else {
112  /* Enhanced AC-3 */
113  hdr->crc1 = 0;
114  hdr->frame_type = get_bits(gbc, 2);
115  if(hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
116  return AAC_AC3_PARSE_ERROR_FRAME_TYPE;
117 
118  hdr->substreamid = get_bits(gbc, 3);
119 
120  hdr->frame_size = (get_bits(gbc, 11) + 1) << 1;
121  if(hdr->frame_size < AC3_HEADER_SIZE)
122  return AAC_AC3_PARSE_ERROR_FRAME_SIZE;
123 
124  hdr->sr_code = get_bits(gbc, 2);
125  if (hdr->sr_code == 3) {
126  int sr_code2 = get_bits(gbc, 2);
127  if(sr_code2 == 3)
128  return AAC_AC3_PARSE_ERROR_SAMPLE_RATE;
129  hdr->sample_rate = ff_ac3_sample_rate_tab[sr_code2] / 2;
130  hdr->sr_shift = 1;
131  } else {
132  hdr->num_blocks = eac3_blocks[get_bits(gbc, 2)];
133  hdr->sample_rate = ff_ac3_sample_rate_tab[hdr->sr_code];
134  hdr->sr_shift = 0;
135  }
136 
137  hdr->channel_mode = get_bits(gbc, 3);
138  hdr->lfe_on = get_bits1(gbc);
139 
140  hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate /
141  (hdr->num_blocks * 256);
142  hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
143  }
144  hdr->channel_layout = avpriv_ac3_channel_layout_tab[hdr->channel_mode];
145  if (hdr->lfe_on)
146  hdr->channel_layout |= AV_CH_LOW_FREQUENCY;
147 
148  return 0;
149 }
150 
151 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
152 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
153  size_t size)
154 {
155  GetBitContext gb;
156  AC3HeaderInfo *hdr;
157  int err;
158 
159  if (!*phdr)
160  *phdr = av_mallocz(sizeof(AC3HeaderInfo));
161  if (!*phdr)
162  return AVERROR(ENOMEM);
163  hdr = *phdr;
164 
165  err = init_get_bits8(&gb, buf, size);
166  if (err < 0)
167  return AVERROR_INVALIDDATA;
168  err = ff_ac3_parse_header(&gb, hdr);
169  if (err < 0)
170  return AVERROR_INVALIDDATA;
171 
172  return get_bits_count(&gb);
173 }
174 
175 int av_ac3_parse_header(const uint8_t *buf, size_t size,
176  uint8_t *bitstream_id, uint16_t *frame_size)
177 {
178  GetBitContext gb;
179  AC3HeaderInfo hdr;
180  int err;
181 
182  init_get_bits8(&gb, buf, size);
183  err = ff_ac3_parse_header(&gb, &hdr);
184  if (err < 0)
185  return AVERROR_INVALIDDATA;
186 
187  *bitstream_id = hdr.bitstream_id;
188  *frame_size = hdr.frame_size;
189 
190  return 0;
191 }
192 
193 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
194  int *need_next_header, int *new_frame_start)
195 {
196  int err;
197  union {
198  uint64_t u64;
199  uint8_t u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
200  } tmp = { av_be2ne64(state) };
201  AC3HeaderInfo hdr;
202  GetBitContext gbc;
203 
204  if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) {
205  FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]);
206  FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]);
207  FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]);
208  }
209 
210  init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
211  err = ff_ac3_parse_header(&gbc, &hdr);
212 
213  if(err < 0)
214  return 0;
215 
216  hdr_info->sample_rate = hdr.sample_rate;
217  hdr_info->bit_rate = hdr.bit_rate;
218  hdr_info->channels = hdr.channels;
219  hdr_info->channel_layout = hdr.channel_layout;
220  hdr_info->samples = hdr.num_blocks * 256;
221  hdr_info->service_type = hdr.bitstream_mode;
222  if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
223  hdr_info->service_type = AV_AUDIO_SERVICE_TYPE_KARAOKE;
224  if(hdr.bitstream_id>10)
225  hdr_info->codec_id = AV_CODEC_ID_EAC3;
226  else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
227  hdr_info->codec_id = AV_CODEC_ID_AC3;
228 
229  *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
230  *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
231  return hdr.frame_size;
232 }
233 
234 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
235 {
236  AACAC3ParseContext *s = s1->priv_data;
237  s->header_size = AC3_HEADER_SIZE;
238  s->sync = ac3_sync;
239  return 0;
240 }
241 
242 
243 AVCodecParser ff_ac3_parser = {
244  .codec_ids = { AV_CODEC_ID_AC3, AV_CODEC_ID_EAC3 },
245  .priv_data_size = sizeof(AACAC3ParseContext),
246  .parser_init = ac3_parse_init,
247  .parser_parse = ff_aac_ac3_parse,
248  .parser_close = ff_parse_close,
249 };
250 
251 #else
252 
253 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
254  size_t size)
255 {
256  return AVERROR(ENOSYS);
257 }
258 
259 int av_ac3_parse_header(const uint8_t *buf, size_t size,
260  uint8_t *bitstream_id, uint16_t *frame_size)
261 {
262  return AVERROR(ENOSYS);
263 }
264 #endif
AC3HeaderInfo::center_mix_level
int center_mix_level
Center mix level index.
Definition: ac3.h:189
AV_CODEC_ID_AC3
@ AV_CODEC_ID_AC3
Definition: codec_id.h:427
AC3HeaderInfo::frame_type
uint8_t frame_type
Definition: ac3.h:187
AC3HeaderInfo::dolby_surround_mode
int dolby_surround_mode
Definition: ac3.h:193
show_bits_long
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:602
AC3_HEADER_SIZE
#define AC3_HEADER_SIZE
Definition: ac3_parser.c:33
AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
FFSWAP
#define FFSWAP(type, a, b)
Definition: common.h:108
AC3_CHMODE_MONO
@ AC3_CHMODE_MONO
Definition: ac3.h:124
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
state
static struct @321 state
aac_ac3_parser.h
av_be2ne64
#define av_be2ne64(x)
Definition: bswap.h:94
tmp
static uint8_t tmp[11]
Definition: aes_ctr.c:27
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:323
ff_ac3_channels_tab
const uint8_t ff_ac3_channels_tab[8]
Map audio coding mode (acmod) to number of full-bandwidth channels.
Definition: ac3tab.c:82
ac3_parser.h
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
av_ac3_parse_header
int av_ac3_parse_header(const uint8_t *buf, size_t size, uint8_t *bitstream_id, uint16_t *frame_size)
Extract the bitstream ID and the frame size from AC-3 data.
Definition: ac3_parser.c:259
EAC3_FRAME_TYPE_DEPENDENT
@ EAC3_FRAME_TYPE_DEPENDENT
Definition: ac3.h:210
skip_bits
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
AC3HeaderInfo::channel_layout
uint64_t channel_layout
Definition: ac3.h:204
GetBitContext
Definition: get_bits.h:61
AC3HeaderInfo
Definition: ac3.h:176
AC3HeaderInfo::frame_size
uint16_t frame_size
Definition: ac3.h:203
AC3HeaderInfo::channel_mode
uint8_t channel_mode
Definition: ac3.h:185
AACAC3ParseContext::codec_id
enum AVCodecID codec_id
Definition: aac_ac3_parser.h:59
av_cold
#define av_cold
Definition: attributes.h:90
init_get_bits8
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
AC3HeaderInfo::sync_word
uint16_t sync_word
Definition: ac3.h:180
AV_CH_LOW_FREQUENCY
#define AV_CH_LOW_FREQUENCY
Definition: channel_layout.h:52
s
#define s(width, name)
Definition: cbs_vp9.c:257
frame_size
int frame_size
Definition: mxfenc.c:2206
s1
#define s1
Definition: regdef.h:38
AAC_AC3_PARSE_ERROR_SYNC
@ AAC_AC3_PARSE_ERROR_SYNC
Definition: aac_ac3_parser.h:31
AC3HeaderInfo::crc1
uint16_t crc1
Definition: ac3.h:181
AAC_AC3_PARSE_ERROR_BSID
@ AAC_AC3_PARSE_ERROR_BSID
Definition: aac_ac3_parser.h:32
get_bits.h
AC3HeaderInfo::sample_rate
uint16_t sample_rate
Definition: ac3.h:200
ff_aac_ac3_parse
int ff_aac_ac3_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
Definition: aac_ac3_parser.c:28
AACAC3ParseContext::sample_rate
int sample_rate
Definition: aac_ac3_parser.h:48
AVCodecParser::codec_ids
int codec_ids[5]
Definition: avcodec.h:3545
EAC3_FRAME_TYPE_AC3_CONVERT
@ EAC3_FRAME_TYPE_AC3_CONVERT
Definition: ac3.h:211
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
AC3_CHMODE_STEREO
@ AC3_CHMODE_STEREO
Definition: ac3.h:125
AC3HeaderInfo::substreamid
int substreamid
substream identification
Definition: ac3.h:188
AACAC3ParseContext
Definition: aac_ac3_parser.h:40
AC3HeaderInfo::num_blocks
int num_blocks
number of audio blocks
Definition: ac3.h:192
AV_CODEC_ID_EAC3
@ AV_CODEC_ID_EAC3
Definition: codec_id.h:464
AV_AUDIO_SERVICE_TYPE_KARAOKE
@ AV_AUDIO_SERVICE_TYPE_KARAOKE
Definition: avcodec.h:248
AC3HeaderInfo::channels
uint8_t channels
Definition: ac3.h:202
ac3_parser_internal.h
FFMAX
#define FFMAX(a, b)
Definition: common.h:103
AC3HeaderInfo::lfe_on
uint8_t lfe_on
Definition: ac3.h:186
AAC_AC3_PARSE_ERROR_SAMPLE_RATE
@ AAC_AC3_PARSE_ERROR_SAMPLE_RATE
Definition: aac_ac3_parser.h:33
size
int size
Definition: twinvq_data.h:10344
AACAC3ParseContext::service_type
int service_type
Definition: aac_ac3_parser.h:52
AC3HeaderInfo::bitstream_mode
uint8_t bitstream_mode
Definition: ac3.h:184
EAC3_FRAME_TYPE_RESERVED
@ EAC3_FRAME_TYPE_RESERVED
Definition: ac3.h:212
AACAC3ParseContext::channel_layout
uint64_t channel_layout
Definition: aac_ac3_parser.h:51
ff_ac3_sample_rate_tab
const int ff_ac3_sample_rate_tab[]
Definition: ac3tab.c:111
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:47
AAC_AC3_PARSE_ERROR_FRAME_SIZE
@ AAC_AC3_PARSE_ERROR_FRAME_SIZE
Definition: aac_ac3_parser.h:34
avpriv_ac3_channel_layout_tab
const uint16_t avpriv_ac3_channel_layout_tab[8]
Map audio coding mode (acmod) to channel layout mask.
Definition: ac3tab.c:89
avpriv_ac3_parse_header
int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size)
Definition: ac3_parser.c:253
AACAC3ParseContext::channels
int channels
Definition: aac_ac3_parser.h:47
uint8_t
uint8_t
Definition: audio_convert.c:194
av_mallocz
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:237
parser.h
ff_ac3_frame_size_tab
const uint16_t ff_ac3_frame_size_tab[38][3]
Possible frame sizes.
Definition: ac3tab.c:37
AAC_AC3_PARSE_ERROR_FRAME_TYPE
@ AAC_AC3_PARSE_ERROR_FRAME_TYPE
Definition: aac_ac3_parser.h:35
AVCodecParserContext
Definition: avcodec.h:3377
ff_ac3_parser
AVCodecParser ff_ac3_parser
ff_ac3_parse_header
int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
Parse AC-3 frame header.
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: avcodec.h:215
channel_layout.h
ff_ac3_bitrate_tab
const uint16_t ff_ac3_bitrate_tab[19]
Definition: ac3tab.c:114
AC3HeaderInfo::bitstream_id
uint8_t bitstream_id
Definition: ac3.h:183
AVCodecParser
Definition: avcodec.h:3544
AACAC3ParseContext::samples
int samples
Definition: aac_ac3_parser.h:50
AC3_DSURMOD_NOTINDICATED
@ AC3_DSURMOD_NOTINDICATED
Definition: ac3.h:135
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
AC3HeaderInfo::sr_shift
uint8_t sr_shift
Definition: ac3.h:199
AC3HeaderInfo::sr_code
uint8_t sr_code
Definition: ac3.h:182
AACAC3ParseContext::bit_rate
int bit_rate
Definition: aac_ac3_parser.h:49
AC3HeaderInfo::bit_rate
uint32_t bit_rate
Definition: ac3.h:201
AC3HeaderInfo::surround_mix_level
int surround_mix_level
Surround mix level index.
Definition: ac3.h:190
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