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 
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 
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)
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)
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 */
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)
84 
85  frame_size_code = get_bits(gbc, 6);
86  if(frame_size_code > 37)
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);
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)
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)
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)];
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  }
145  if (hdr->lfe_on)
147 
148  return 0;
149 }
150 
151 // TODO: Better way to pass AC3HeaderInfo fields to mov muxer.
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;
200  } tmp = { av_be2ne64(state) };
201  AC3HeaderInfo hdr;
202  GetBitContext gbc;
203 
204  init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
205  err = ff_ac3_parse_header(&gbc, &hdr);
206 
207  if(err < 0)
208  return 0;
209 
210  hdr_info->sample_rate = hdr.sample_rate;
211  hdr_info->bit_rate = hdr.bit_rate;
212  hdr_info->channels = hdr.channels;
213  hdr_info->channel_layout = hdr.channel_layout;
214  hdr_info->samples = hdr.num_blocks * 256;
215  hdr_info->service_type = hdr.bitstream_mode;
216  if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
218  if(hdr.bitstream_id>10)
219  hdr_info->codec_id = AV_CODEC_ID_EAC3;
220  else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
221  hdr_info->codec_id = AV_CODEC_ID_AC3;
222 
223  *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
224  *need_next_header = *new_frame_start || (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
225  return hdr.frame_size;
226 }
227 
228 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
229 {
232  s->sync = ac3_sync;
233  return 0;
234 }
235 
236 
239  .priv_data_size = sizeof(AACAC3ParseContext),
240  .parser_init = ac3_parse_init,
241  .parser_parse = ff_aac_ac3_parse,
242  .parser_close = ff_parse_close,
243 };
244 
245 #else
246 
248  size_t size)
249 {
250  return AVERROR(ENOSYS);
251 }
252 
253 int av_ac3_parse_header(const uint8_t *buf, size_t size,
254  uint8_t *bitstream_id, uint16_t *frame_size)
255 {
256  return AVERROR(ENOSYS);
257 }
258 #endif
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:602
uint8_t bitstream_mode
Definition: ac3.h:185
uint64_t channel_layout
Definition: ac3.h:205
int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
Parse AC-3 frame header.
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:379
const uint16_t ff_ac3_frame_size_tab[38][3]
Possible frame sizes.
Definition: ac3tab.c:37
uint16_t crc1
Definition: ac3.h:182
int codec_ids[5]
Definition: avcodec.h:5287
const uint16_t ff_ac3_sample_rate_tab[3]
Definition: ac3tab.c:129
void * av_mallocz(size_t size)
Allocate a memory block with alignment suitable for all memory accesses (including vectors if availab...
Definition: mem.c:236
int avpriv_ac3_parse_header(AC3HeaderInfo **phdr, const uint8_t *buf, size_t size)
Definition: ac3_parser.c:247
uint8_t
#define av_cold
Definition: attributes.h:82
uint8_t lfe_on
Definition: ac3.h:187
#define AV_CH_LOW_FREQUENCY
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
uint8_t sr_shift
Definition: ac3.h:200
bitstream reader API header.
uint8_t bitstream_id
Definition: ac3.h:184
ptrdiff_t size
Definition: opengl_enc.c:100
const uint16_t avpriv_ac3_channel_layout_tab[8]
Map audio coding mode (acmod) to channel layout mask.
Definition: ac3tab.c:89
uint16_t sync_word
Definition: ac3.h:181
uint8_t frame_type
Definition: ac3.h:188
uint8_t sr_code
Definition: ac3.h:183
Coded AC-3 header values up to the lfeon element, plus derived values.
Definition: ac3.h:177
uint16_t sample_rate
Definition: ac3.h:201
#define av_be2ne64(x)
Definition: bswap.h:94
#define FFMAX(a, b)
Definition: common.h:94
const uint16_t ff_ac3_bitrate_tab[19]
Definition: ac3tab.c:132
void ff_parse_close(AVCodecParserContext *s)
Definition: parser.c:319
audio channel layout utility functions
uint32_t bit_rate
Definition: ac3.h:202
#define s(width, name)
Definition: cbs_vp9.c:257
int(* sync)(uint64_t state, struct AACAC3ParseContext *hdr_info, int *need_next_header, int *new_frame_start)
int dolby_surround_mode
Definition: ac3.h:194
AVCodecParser ff_ac3_parser
int frame_size
Definition: mxfenc.c:2214
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:677
void * buf
Definition: avisynth_c.h:766
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:498
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:467
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
uint16_t frame_size
Definition: ac3.h:204
enum AVCodecID codec_id
#define s1
Definition: regdef.h:38
int ff_aac_ac3_parse(AVCodecParserContext *s1, AVCodecContext *avctx, const uint8_t **poutbuf, int *poutbuf_size, const uint8_t *buf, int buf_size)
const uint8_t ff_ac3_channels_tab[8]
Map audio coding mode (acmod) to number of full-bandwidth channels.
Definition: ac3tab.c:82
int surround_mix_level
Surround mix level index.
Definition: ac3.h:191
int center_mix_level
Center mix level index.
Definition: ac3.h:190
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:793
int substreamid
substream identification
Definition: ac3.h:189
uint8_t channels
Definition: ac3.h:203
static struct @316 state
#define AC3_HEADER_SIZE
Definition: ac3_parser.c:33
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:253
int num_blocks
number of audio blocks
Definition: ac3.h:193
uint8_t channel_mode
Definition: ac3.h:186
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
static uint8_t tmp[11]
Definition: aes_ctr.c:26