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 #include "config_components.h"
25 
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 
40 static 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  */
48 static 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  */
54 static const uint8_t surround_levels[4] = { 4, 6, 7, 6 };
55 
56 
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)
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)
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 */
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)
87 
88  frame_size_code = get_bits(gbc, 6);
89  if(frame_size_code > 37)
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);
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)
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)
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)];
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 = 8LL * hdr->frame_size * hdr->sample_rate /
144  (hdr->num_blocks * 256);
145  hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
146  }
148  if (hdr->lfe_on)
150 
151  return 0;
152 }
153 
154 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
155 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
156  size_t size)
157 {
158  GetBitContext gb;
159  AC3HeaderInfo *hdr;
160  int err;
161 
162  if (!*phdr)
163  *phdr = av_mallocz(sizeof(AC3HeaderInfo));
164  if (!*phdr)
165  return AVERROR(ENOMEM);
166  hdr = *phdr;
167 
168  err = init_get_bits8(&gb, buf, size);
169  if (err < 0)
170  return AVERROR_INVALIDDATA;
171  err = ff_ac3_parse_header(&gb, hdr);
172  if (err < 0)
173  return AVERROR_INVALIDDATA;
174 
175  return get_bits_count(&gb);
176 }
177 
178 int av_ac3_parse_header(const uint8_t *buf, size_t size,
179  uint8_t *bitstream_id, uint16_t *frame_size)
180 {
181  GetBitContext gb;
182  AC3HeaderInfo hdr;
183  int err;
184 
185  init_get_bits8(&gb, buf, size);
186  err = ff_ac3_parse_header(&gb, &hdr);
187  if (err < 0)
188  return AVERROR_INVALIDDATA;
189 
190  *bitstream_id = hdr.bitstream_id;
191  *frame_size = hdr.frame_size;
192 
193  return 0;
194 }
195 
196 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
197  int *need_next_header, int *new_frame_start)
198 {
199  int err;
200  union {
201  uint64_t u64;
202  uint8_t u8[8 + AV_INPUT_BUFFER_PADDING_SIZE];
203  } tmp = { av_be2ne64(state) };
204  AC3HeaderInfo hdr;
205  GetBitContext gbc;
206 
207  if (tmp.u8[1] == 0x77 && tmp.u8[2] == 0x0b) {
208  FFSWAP(uint8_t, tmp.u8[1], tmp.u8[2]);
209  FFSWAP(uint8_t, tmp.u8[3], tmp.u8[4]);
210  FFSWAP(uint8_t, tmp.u8[5], tmp.u8[6]);
211  }
212 
213  init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
214  err = ff_ac3_parse_header(&gbc, &hdr);
215 
216  if(err < 0)
217  return 0;
218 
219  hdr_info->sample_rate = hdr.sample_rate;
220  hdr_info->bit_rate = hdr.bit_rate;
221  hdr_info->channels = hdr.channels;
222  hdr_info->channel_layout = hdr.channel_layout;
223  hdr_info->samples = hdr.num_blocks * 256;
224  hdr_info->service_type = hdr.bitstream_mode;
225  if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
227  if(hdr.bitstream_id>10)
228  hdr_info->codec_id = AV_CODEC_ID_EAC3;
229  else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
230  hdr_info->codec_id = AV_CODEC_ID_AC3;
231 
232  *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
233  *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
234  return hdr.frame_size;
235 }
236 
237 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
238 {
239  AACAC3ParseContext *s = s1->priv_data;
240  s->header_size = AC3_HEADER_SIZE;
241  s->sync = ac3_sync;
242  return 0;
243 }
244 
245 
248  .priv_data_size = sizeof(AACAC3ParseContext),
249  .parser_init = ac3_parse_init,
250  .parser_parse = ff_aac_ac3_parse,
251  .parser_close = ff_parse_close,
252 };
253 
254 #else
255 
256 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
257  size_t size)
258 {
259  return AVERROR(ENOSYS);
260 }
261 
262 int av_ac3_parse_header(const uint8_t *buf, size_t size,
263  uint8_t *bitstream_id, uint16_t *frame_size)
264 {
265  return AVERROR(ENOSYS);
266 }
267 #endif
AC3HeaderInfo::center_mix_level
int center_mix_level
Center mix level index.
Definition: ac3_parser_internal.h:47
AV_CODEC_ID_AC3
@ AV_CODEC_ID_AC3
Definition: codec_id.h:428
AC3HeaderInfo::frame_type
uint8_t frame_type
Definition: ac3_parser_internal.h:45
AC3HeaderInfo::dolby_surround_mode
int dolby_surround_mode
Definition: ac3_parser_internal.h:51
show_bits_long
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:603
AC3_HEADER_SIZE
#define AC3_HEADER_SIZE
Definition: ac3_parser.c:36
ff_ac3_channel_layout_tab
const uint16_t ff_ac3_channel_layout_tab[8]
Map audio coding mode (acmod) to channel layout mask.
Definition: ac3_channel_layout_tab.h:31
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
get_bits_count
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:220
aac_ac3_parser.h
av_be2ne64
#define av_be2ne64(x)
Definition: bswap.h:94
tmp
static uint8_t tmp[11]
Definition: aes_ctr.c:28
ff_parse_close
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:284
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:80
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
ac3_parser.h
EAC3_FRAME_TYPE_RESERVED
@ EAC3_FRAME_TYPE_RESERVED
Definition: ac3defs.h:101
init_get_bits
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:660
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:262
skip_bits
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:468
get_bits
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:380
AC3HeaderInfo::channel_layout
uint64_t channel_layout
Definition: ac3_parser_internal.h:62
GetBitContext
Definition: get_bits.h:62
AC3HeaderInfo
Definition: ac3_parser_internal.h:34
AC3HeaderInfo::frame_size
uint16_t frame_size
Definition: ac3_parser_internal.h:61
EAC3_FRAME_TYPE_DEPENDENT
@ EAC3_FRAME_TYPE_DEPENDENT
Definition: ac3defs.h:99
AC3HeaderInfo::channel_mode
uint8_t channel_mode
Definition: ac3_parser_internal.h:43
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:678
AC3HeaderInfo::sync_word
uint16_t sync_word
Definition: ac3_parser_internal.h:38
AV_CH_LOW_FREQUENCY
#define AV_CH_LOW_FREQUENCY
Definition: channel_layout.h:161
s
#define s(width, name)
Definition: cbs_vp9.c:256
frame_size
int frame_size
Definition: mxfenc.c:2201
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_parser_internal.h:39
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_parser_internal.h:58
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:30
ac3defs.h
AACAC3ParseContext::sample_rate
int sample_rate
Definition: aac_ac3_parser.h:48
ff_ac3_parser
const AVCodecParser ff_ac3_parser
get_bits1
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:499
AC3HeaderInfo::substreamid
int substreamid
substream identification
Definition: ac3_parser_internal.h:46
AACAC3ParseContext
Definition: aac_ac3_parser.h:40
AC3HeaderInfo::num_blocks
int num_blocks
number of audio blocks
Definition: ac3_parser_internal.h:50
AC3_DSURMOD_NOTINDICATED
@ AC3_DSURMOD_NOTINDICATED
Definition: ac3defs.h:67
AV_CODEC_ID_EAC3
@ AV_CODEC_ID_EAC3
Definition: codec_id.h:465
EAC3_FRAME_TYPE_AC3_CONVERT
@ EAC3_FRAME_TYPE_AC3_CONVERT
Definition: ac3defs.h:100
AC3HeaderInfo::channels
uint8_t channels
Definition: ac3_parser_internal.h:60
ac3_parser_internal.h
AC3_CHMODE_STEREO
@ AC3_CHMODE_STEREO
Definition: ac3defs.h:57
AVCodecParser::codec_ids
int codec_ids[7]
Definition: avcodec.h:2950
AC3HeaderInfo::lfe_on
uint8_t lfe_on
Definition: ac3_parser_internal.h:44
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_parser_internal.h:42
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:95
AV_CODEC_ID_NONE
@ AV_CODEC_ID_NONE
Definition: codec_id.h:48
AAC_AC3_PARSE_ERROR_FRAME_SIZE
@ AAC_AC3_PARSE_ERROR_FRAME_SIZE
Definition: aac_ac3_parser.h:34
avpriv_ac3_parse_header
int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size)
Definition: ac3_parser.c:256
AACAC3ParseContext::channels
int channels
Definition: aac_ac3_parser.h:47
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:264
parser.h
ff_ac3_frame_size_tab
const uint16_t ff_ac3_frame_size_tab[38][3]
Possible frame sizes.
Definition: ac3tab.c:35
AC3_CHMODE_MONO
@ AC3_CHMODE_MONO
Definition: ac3defs.h:56
AAC_AC3_PARSE_ERROR_FRAME_TYPE
@ AAC_AC3_PARSE_ERROR_FRAME_TYPE
Definition: aac_ac3_parser.h:35
AVCodecParserContext
Definition: avcodec.h:2790
FFSWAP
#define FFSWAP(type, a, b)
Definition: macros.h:52
ff_ac3_parse_header
int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
Parse AC-3 frame header.
AV_AUDIO_SERVICE_TYPE_KARAOKE
@ AV_AUDIO_SERVICE_TYPE_KARAOKE
Definition: defs.h:66
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: defs.h:40
channel_layout.h
ff_ac3_bitrate_tab
const uint16_t ff_ac3_bitrate_tab[19]
Definition: ac3tab.c:98
state
static struct @326 state
AC3HeaderInfo::bitstream_id
uint8_t bitstream_id
Definition: ac3_parser_internal.h:41
AVCodecParser
Definition: avcodec.h:2949
AACAC3ParseContext::samples
int samples
Definition: aac_ac3_parser.h:50
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:61
AC3HeaderInfo::sr_shift
uint8_t sr_shift
Definition: ac3_parser_internal.h:57
ac3tab.h
AC3HeaderInfo::sr_code
uint8_t sr_code
Definition: ac3_parser_internal.h:40
AACAC3ParseContext::bit_rate
int bit_rate
Definition: aac_ac3_parser.h:49
AC3HeaderInfo::bit_rate
uint32_t bit_rate
Definition: ac3_parser_internal.h:59
AC3HeaderInfo::surround_mix_level
int surround_mix_level
Surround mix level index.
Definition: ac3_parser_internal.h:48