FFmpeg
mpeg4audio.c
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1 /*
2  * MPEG-4 Audio common code
3  * Copyright (c) 2008 Baptiste Coudurier <baptiste.coudurier@free.fr>
4  * Copyright (c) 2009 Alex Converse <alex.converse@gmail.com>
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 "get_bits.h"
24 #include "put_bits.h"
25 #include "mpeg4audio.h"
26 
27 /**
28  * Parse MPEG-4 audio configuration for ALS object type.
29  * @param[in] gb bit reader context
30  * @param[in] c MPEG4AudioConfig structure to fill
31  * @return on success 0 is returned, otherwise a value < 0
32  */
34 {
35  if (get_bits_left(gb) < 112)
36  return AVERROR_INVALIDDATA;
37 
38  if (get_bits_long(gb, 32) != MKBETAG('A','L','S','\0'))
39  return AVERROR_INVALIDDATA;
40 
41  // override AudioSpecificConfig channel configuration and sample rate
42  // which are buggy in old ALS conformance files
43  c->sample_rate = get_bits_long(gb, 32);
44 
45  if (c->sample_rate <= 0) {
46  av_log(NULL, AV_LOG_ERROR, "Invalid sample rate %d\n", c->sample_rate);
47  return AVERROR_INVALIDDATA;
48  }
49 
50  // skip number of samples
51  skip_bits_long(gb, 32);
52 
53  // read number of channels
54  c->chan_config = 0;
55  c->channels = get_bits(gb, 16) + 1;
56 
57  return 0;
58 }
59 
60 /* XXX: make sure to update the copies in the different encoders if you change
61  * this table */
63  96000, 88200, 64000, 48000, 44100, 32000,
64  24000, 22050, 16000, 12000, 11025, 8000, 7350
65 };
66 
68  0, 1, 2, 3, 4, 5, 6, 8
69 };
70 
71 static inline int get_object_type(GetBitContext *gb)
72 {
73  int object_type = get_bits(gb, 5);
74  if (object_type == AOT_ESCAPE)
75  object_type = 32 + get_bits(gb, 6);
76  return object_type;
77 }
78 
79 static inline int get_sample_rate(GetBitContext *gb, int *index)
80 {
81  *index = get_bits(gb, 4);
82  return *index == 0x0f ? get_bits(gb, 24) :
84 }
85 
87  int sync_extension)
88 {
89  int specific_config_bitindex, ret;
90  int start_bit_index = get_bits_count(gb);
93  c->chan_config = get_bits(gb, 4);
96  c->sbr = -1;
97  c->ps = -1;
98  if (c->object_type == AOT_SBR || (c->object_type == AOT_PS &&
99  // check for W6132 Annex YYYY draft MP3onMP4
100  !(show_bits(gb, 3) & 0x03 && !(show_bits(gb, 9) & 0x3F)))) {
101  if (c->object_type == AOT_PS)
102  c->ps = 1;
104  c->sbr = 1;
106  c->object_type = get_object_type(gb);
107  if (c->object_type == AOT_ER_BSAC)
108  c->ext_chan_config = get_bits(gb, 4);
109  } else {
111  c->ext_sample_rate = 0;
112  }
113  specific_config_bitindex = get_bits_count(gb);
114 
115  if (c->object_type == AOT_ALS) {
116  skip_bits(gb, 5);
117  if (show_bits_long(gb, 24) != MKBETAG('\0','A','L','S'))
118  skip_bits_long(gb, 24);
119 
120  specific_config_bitindex = get_bits_count(gb);
121 
122  ret = parse_config_ALS(gb, c);
123  if (ret < 0)
124  return ret;
125  }
126 
127  if (c->ext_object_type != AOT_SBR && sync_extension) {
128  while (get_bits_left(gb) > 15) {
129  if (show_bits(gb, 11) == 0x2b7) { // sync extension
130  get_bits(gb, 11);
132  if (c->ext_object_type == AOT_SBR && (c->sbr = get_bits1(gb)) == 1) {
134  if (c->ext_sample_rate == c->sample_rate)
135  c->sbr = -1;
136  }
137  if (get_bits_left(gb) > 11 && get_bits(gb, 11) == 0x548)
138  c->ps = get_bits1(gb);
139  break;
140  } else
141  get_bits1(gb); // skip 1 bit
142  }
143  }
144 
145  //PS requires SBR
146  if (!c->sbr)
147  c->ps = 0;
148  //Limit implicit PS to the HE-AACv2 Profile
149  if ((c->ps == -1 && c->object_type != AOT_AAC_LC) || c->channels & ~0x01)
150  c->ps = 0;
151 
152  return specific_config_bitindex - start_bit_index;
153 }
154 
156  int bit_size, int sync_extension)
157 {
158  GetBitContext gb;
159  int ret;
160 
161  if (bit_size <= 0)
162  return AVERROR_INVALIDDATA;
163 
164  ret = init_get_bits(&gb, buf, bit_size);
165  if (ret < 0)
166  return ret;
167 
168  return ff_mpeg4audio_get_config_gb(c, &gb, sync_extension);
169 }
static unsigned int show_bits_long(GetBitContext *s, int n)
Show 0-32 bits.
Definition: get_bits.h:602
N Parametric Stereo.
Definition: mpeg4audio.h:100
#define NULL
Definition: coverity.c:32
#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
static void skip_bits_long(GetBitContext *s, int n)
Skips the specified number of bits.
Definition: get_bits.h:291
static int get_sample_rate(GetBitContext *gb, int *index)
Definition: mpeg4audio.c:79
uint8_t
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:219
bitstream reader API header.
Y Escape Value.
Definition: mpeg4audio.h:102
static int parse_config_ALS(GetBitContext *gb, MPEG4AudioConfig *c)
Parse MPEG-4 audio configuration for ALS object type.
Definition: mpeg4audio.c:33
#define av_log(a,...)
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:849
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
int ff_mpeg4audio_get_config_gb(MPEG4AudioConfig *c, GetBitContext *gb, int sync_extension)
Parse MPEG-4 systems extradata from a potentially unaligned GetBitContext to retrieve audio configura...
Definition: mpeg4audio.c:86
static unsigned int show_bits(GetBitContext *s, int n)
Show 1-25 bits.
Definition: get_bits.h:446
#define FF_ARRAY_ELEMS(a)
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
int index
Definition: gxfenc.c:89
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:659
N Error Resilient Bit-Sliced Arithmetic Coding.
Definition: mpeg4audio.h:93
static unsigned int get_bits_long(GetBitContext *s, int n)
Read 0-32 bits.
Definition: get_bits.h:546
static int get_object_type(GetBitContext *gb)
Definition: mpeg4audio.c:71
const int avpriv_mpeg4audio_sample_rates[16]
Definition: mpeg4audio.c:62
Y Spectral Band Replication.
Definition: mpeg4audio.h:79
int avpriv_mpeg4audio_get_config(MPEG4AudioConfig *c, const uint8_t *buf, int bit_size, int sync_extension)
Parse MPEG-4 systems extradata from a raw buffer to retrieve audio configuration. ...
Definition: mpeg4audio.c:155
#define MKBETAG(a, b, c, d)
Definition: common.h:367
Y Audio LosslesS.
Definition: mpeg4audio.h:107
const uint8_t ff_mpeg4audio_channels[8]
Definition: mpeg4audio.c:67
int sbr
-1 implicit, 1 presence
Definition: mpeg4audio.h:38
int ext_sampling_index
Definition: mpeg4audio.h:40
int ps
-1 implicit, 1 presence
Definition: mpeg4audio.h:44
Y Low Complexity.
Definition: mpeg4audio.h:76
bitstream writer API