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  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 */
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)
88 
89  frame_size_code = get_bits(gbc, 6);
90  if(frame_size_code > 37)
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);
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)
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)
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)];
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  }
151  if (hdr->lfe_on)
153 
154  return 0;
155 }
156 
157 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
158 int 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 
181 int 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 
199 static 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)
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 
240 static 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 
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 
259 int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf,
260  size_t size)
261 {
262  return AVERROR(ENOSYS);
263 }
264 
265 int 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
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:429
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:265
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:466
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:2949
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
state
static struct @327 state
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
AC3HeaderInfo::ac3_bit_rate_code
int8_t ac3_bit_rate_code
Definition: ac3_parser_internal.h:63
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:259
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:2789
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
AC3HeaderInfo::bitstream_id
uint8_t bitstream_id
Definition: ac3_parser_internal.h:41
AVCodecParser
Definition: avcodec.h:2948
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