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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  init_get_bits8(&gb, buf, size);
166  err = ff_ac3_parse_header(&gb, hdr);
167  if (err < 0)
168  return AVERROR_INVALIDDATA;
169 
170  return get_bits_count(&gb);
171 }
172 
173 int av_ac3_parse_header(const uint8_t *buf, size_t size,
174  uint8_t *bitstream_id, uint16_t *frame_size)
175 {
176  GetBitContext gb;
177  AC3HeaderInfo hdr;
178  int err;
179 
180  init_get_bits8(&gb, buf, size);
181  err = ff_ac3_parse_header(&gb, &hdr);
182  if (err < 0)
183  return AVERROR_INVALIDDATA;
184 
185  *bitstream_id = hdr.bitstream_id;
186  *frame_size = hdr.frame_size;
187 
188  return 0;
189 }
190 
191 static int ac3_sync(uint64_t state, AACAC3ParseContext *hdr_info,
192  int *need_next_header, int *new_frame_start)
193 {
194  int err;
195  union {
196  uint64_t u64;
198  } tmp = { av_be2ne64(state) };
199  AC3HeaderInfo hdr;
200  GetBitContext gbc;
201 
202  init_get_bits(&gbc, tmp.u8+8-AC3_HEADER_SIZE, 54);
203  err = ff_ac3_parse_header(&gbc, &hdr);
204 
205  if(err < 0)
206  return 0;
207 
208  hdr_info->sample_rate = hdr.sample_rate;
209  hdr_info->bit_rate = hdr.bit_rate;
210  hdr_info->channels = hdr.channels;
211  hdr_info->channel_layout = hdr.channel_layout;
212  hdr_info->samples = hdr.num_blocks * 256;
213  hdr_info->service_type = hdr.bitstream_mode;
214  if (hdr.bitstream_mode == 0x7 && hdr.channels > 1)
216  if(hdr.bitstream_id>10)
217  hdr_info->codec_id = AV_CODEC_ID_EAC3;
218  else if (hdr_info->codec_id == AV_CODEC_ID_NONE)
219  hdr_info->codec_id = AV_CODEC_ID_AC3;
220 
221  *need_next_header = (hdr.frame_type != EAC3_FRAME_TYPE_AC3_CONVERT);
222  *new_frame_start = (hdr.frame_type != EAC3_FRAME_TYPE_DEPENDENT);
223  return hdr.frame_size;
224 }
225 
226 static av_cold int ac3_parse_init(AVCodecParserContext *s1)
227 {
230  s->sync = ac3_sync;
231  return 0;
232 }
233 
234 
235 AVCodecParser ff_ac3_parser = {
237  .priv_data_size = sizeof(AACAC3ParseContext),
238  .parser_init = ac3_parse_init,
239  .parser_parse = ff_aac_ac3_parse,
240  .parser_close = ff_parse_close,
241 };
242 
243 #else
244 
246  size_t size)
247 {
248  return AVERROR(ENOSYS);
249 }
250 
251 int av_ac3_parse_header(const uint8_t *buf, size_t size,
252  uint8_t *bitstream_id, uint16_t *frame_size)
253 {
254  return AVERROR(ENOSYS);
255 }
256 #endif
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:397
uint8_t bitstream_mode
Definition: ac3.h:184
uint64_t channel_layout
Definition: ac3.h:204
const char * s
Definition: avisynth_c.h:768
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:261
const uint16_t ff_ac3_frame_size_tab[38][3]
Possible frame sizes.
Definition: ac3tab.c:37
uint16_t crc1
Definition: ac3.h:181
int codec_ids[5]
Definition: avcodec.h:5007
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:245
uint8_t
#define av_cold
Definition: attributes.h:82
int(* sync)(uint64_t state, struct AACAC3ParseContext *hdr_info, int *need_next_header, int *new_frame_start)
uint8_t lfe_on
Definition: ac3.h:186
#define AV_CH_LOW_FREQUENCY
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:199
uint8_t sr_shift
Definition: ac3.h:199
bitstream reader API header.
uint8_t bitstream_id
Definition: ac3.h:183
ptrdiff_t size
Definition: opengl_enc.c:101
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:180
uint8_t frame_type
Definition: ac3.h:187
#define AVERROR(e)
Definition: error.h:43
uint8_t sr_code
Definition: ac3.h:182
Coded AC-3 header values up to the lfeon element, plus derived values.
Definition: ac3.h:176
uint16_t sample_rate
Definition: ac3.h:200
#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:329
audio channel layout utility functions
uint32_t bit_rate
Definition: ac3.h:201
static struct @271 state
int dolby_surround_mode
Definition: ac3.h:193
int frame_size
Definition: mxfenc.c:1896
static int init_get_bits8(GetBitContext *s, const uint8_t *buffer, int byte_size)
Initialize GetBitContext.
Definition: get_bits.h:456
void * buf
Definition: avisynth_c.h:690
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:313
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:306
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:425
uint16_t frame_size
Definition: ac3.h:203
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:190
int center_mix_level
Center mix level index.
Definition: ac3.h:189
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:769
int substreamid
substream identification
Definition: ac3.h:188
uint8_t channels
Definition: ac3.h:202
#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:251
int num_blocks
number of audio blocks
Definition: ac3.h:192
uint8_t channel_mode
Definition: ac3.h:185
static uint8_t tmp[11]
Definition: aes_ctr.c:26