FFmpeg: libavformat/aadec.c Source File

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aadec.c
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1 /*
2  * Audible AA demuxer
3  * Copyright (c) 2015 Vesselin Bontchev
4  *
5  * Header parsing is borrowed from https://github.com/jteeuwen/audible project.
6  * Copyright (c) 2001-2014, Jim Teeuwen
7  *
8  * Redistribution and use in source and binary forms, with or without modification,
9  * are permitted provided that the following conditions are met:
10  *
11  * 1. Redistributions of source code must retain the above copyright notice, this
12  * list of conditions and the following disclaimer.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
16  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
17  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
18  * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
19  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
20  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
21  * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
23  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
24  */
25 
26 #include "avformat.h"
27 #include "internal.h"
28 #include "libavutil/dict.h"
29 #include "libavutil/intreadwrite.h"
30 #include "libavutil/tea.h"
31 #include "libavutil/opt.h"
32 
33  #define AA_MAGIC 1469084982 /* this identifies an audible .aa file */
34  #define MAX_CODEC_SECOND_SIZE 3982
35  #define MAX_TOC_ENTRIES 16
36  #define MAX_DICTIONARY_ENTRIES 128
37  #define TEA_BLOCK_SIZE 8
38 
39  typedef struct AADemuxContext {
40   AVClass *class;
41   uint8_t *aa_fixed_key;
42   int aa_fixed_key_len;
43   int codec_second_size;
44   int current_codec_second_size;
45   int chapter_idx;
46   struct AVTEA *tea_ctx;
47   uint8_t file_key[16];
48   int64_t current_chapter_size;
49 } AADemuxContext;
50 
51  static int get_second_size(char *codec_name)
52 {
53  int result = -1;
54 
55  if (!strcmp(codec_name, "mp332")) {
56  result = 3982;
57  } else if (!strcmp(codec_name, "acelp16")) {
58  result = 2000;
59  } else if (!strcmp(codec_name, "acelp85")) {
60  result = 1045;
61  }
62 
63  return result;
64 }
65 
66  static int aa_read_header(AVFormatContext *s)
67 {
68  int i, j, idx, largest_idx = -1;
69  uint32_t nkey, nval, toc_size, npairs, header_seed = 0, start;
70  char key[128], val[128], codec_name[64] = {0};
71  uint8_t output[24], dst[8], src[8];
72  int64_t largest_size = -1, current_size = -1;
73  struct toc_entry {
74  uint32_t offset;
75  uint32_t size;
76  } TOC[MAX_TOC_ENTRIES];
77  uint32_t header_key_part[4];
78  uint8_t header_key[16] = {0};
79  AADemuxContext *c = s->priv_data;
80  AVIOContext *pb = s->pb;
81  AVStream *st;
82 
83  /* parse .aa header */
84  avio_skip(pb, 4); // file size
85  avio_skip(pb, 4); // magic string
86  toc_size = avio_rb32(pb); // TOC size
87  avio_skip(pb, 4); // unidentified integer
88  if (toc_size > MAX_TOC_ENTRIES)
89  return AVERROR_INVALIDDATA;
90  for (i = 0; i < toc_size; i++) { // read TOC
91  avio_skip(pb, 4); // TOC entry index
92  TOC[i].offset = avio_rb32(pb); // block offset
93  TOC[i].size = avio_rb32(pb); // block size
94  }
95  avio_skip(pb, 24); // header termination block (ignored)
96  npairs = avio_rb32(pb); // read dictionary entries
97  if (npairs > MAX_DICTIONARY_ENTRIES)
98  return AVERROR_INVALIDDATA;
99  for (i = 0; i < npairs; i++) {
100  memset(val, 0, sizeof(val));
101  memset(key, 0, sizeof(key));
102  avio_skip(pb, 1); // unidentified integer
103  nkey = avio_rb32(pb); // key string length
104  nval = avio_rb32(pb); // value string length
105  avio_get_str(pb, nkey, key, sizeof(key));
106  avio_get_str(pb, nval, val, sizeof(val));
107  if (!strcmp(key, "codec")) {
108  av_log(s, AV_LOG_DEBUG, "Codec is <%s>\n", val);
109  strncpy(codec_name, val, sizeof(codec_name) - 1);
110  } else if (!strcmp(key, "HeaderSeed")) {
111  av_log(s, AV_LOG_DEBUG, "HeaderSeed is <%s>\n", val);
112  header_seed = atoi(val);
113  } else if (!strcmp(key, "HeaderKey")) { // this looks like "1234567890 1234567890 1234567890 1234567890"
114  av_log(s, AV_LOG_DEBUG, "HeaderKey is <%s>\n", val);
115  sscanf(val, "%"SCNu32"%"SCNu32"%"SCNu32"%"SCNu32,
116  &header_key_part[0], &header_key_part[1], &header_key_part[2], &header_key_part[3]);
117  for (idx = 0; idx < 4; idx++) {
118  AV_WB32(&header_key[idx * 4], header_key_part[idx]); // convert each part to BE!
119  }
120  av_log(s, AV_LOG_DEBUG, "Processed HeaderKey is ");
121  for (i = 0; i < 16; i++)
122  av_log(s, AV_LOG_DEBUG, "%02x", header_key[i]);
123  av_log(s, AV_LOG_DEBUG, "\n");
124  } else {
125  av_dict_set(&s->metadata, key, val, 0);
126  }
127  }
128 
129  /* verify fixed key */
130  if (c->aa_fixed_key_len != 16) {
131  av_log(s, AV_LOG_ERROR, "aa_fixed_key value needs to be 16 bytes!\n");
132  return AVERROR(EINVAL);
133  }
134 
135  /* verify codec */
136  if ((c->codec_second_size = get_second_size(codec_name)) == -1) {
137  av_log(s, AV_LOG_ERROR, "unknown codec <%s>!\n", codec_name);
138  return AVERROR(EINVAL);
139  }
140 
141  /* decryption key derivation */
142  c->tea_ctx = av_tea_alloc();
143  if (!c->tea_ctx)
144  return AVERROR(ENOMEM);
145  av_tea_init(c->tea_ctx, c->aa_fixed_key, 16);
146  output[0] = output[1] = 0; // purely for padding purposes
147  memcpy(output + 2, header_key, 16);
148  idx = 0;
149  for (i = 0; i < 3; i++) { // TEA CBC with weird mixed endianness
150  AV_WB32(src, header_seed);
151  AV_WB32(src + 4, header_seed + 1);
152  header_seed += 2;
153  av_tea_crypt(c->tea_ctx, dst, src, 1, NULL, 0); // TEA ECB encrypt
154  for (j = 0; j < TEA_BLOCK_SIZE && idx < 18; j+=1, idx+=1) {
155  output[idx] = output[idx] ^ dst[j];
156  }
157  }
158  memcpy(c->file_key, output + 2, 16); // skip first 2 bytes of output
159  av_log(s, AV_LOG_DEBUG, "File key is ");
160  for (i = 0; i < 16; i++)
161  av_log(s, AV_LOG_DEBUG, "%02x", c->file_key[i]);
162  av_log(s, AV_LOG_DEBUG, "\n");
163 
164  /* decoder setup */
165  st = avformat_new_stream(s, NULL);
166  if (!st) {
167  av_freep(&c->tea_ctx);
168  return AVERROR(ENOMEM);
169  }
170  st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
171  if (!strcmp(codec_name, "mp332")) {
172  st->codecpar->codec_id = AV_CODEC_ID_MP3;
173  st->codecpar->sample_rate = 22050;
174  st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
175  st->start_time = 0;
176  } else if (!strcmp(codec_name, "acelp85")) {
177  st->codecpar->codec_id = AV_CODEC_ID_SIPR;
178  st->codecpar->block_align = 19;
179  st->codecpar->channels = 1;
180  st->codecpar->sample_rate = 8500;
181  st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
182  } else if (!strcmp(codec_name, "acelp16")) {
183  st->codecpar->codec_id = AV_CODEC_ID_SIPR;
184  st->codecpar->block_align = 20;
185  st->codecpar->channels = 1;
186  st->codecpar->sample_rate = 16000;
187  st->need_parsing = AVSTREAM_PARSE_FULL_RAW;
188  }
189 
190  /* determine, and jump to audio start offset */
191  for (i = 1; i < toc_size; i++) { // skip the first entry!
192  current_size = TOC[i].size;
193  if (current_size > largest_size) {
194  largest_idx = i;
195  largest_size = current_size;
196  }
197  }
198  start = TOC[largest_idx].offset;
199  avio_seek(pb, start, SEEK_SET);
200  c->current_chapter_size = 0;
201 
202  return 0;
203 }
204 
205  static int aa_read_packet(AVFormatContext *s, AVPacket *pkt)
206 {
207  uint8_t dst[TEA_BLOCK_SIZE];
208  uint8_t src[TEA_BLOCK_SIZE];
209  int i;
210  int trailing_bytes;
211  int blocks;
212  uint8_t buf[MAX_CODEC_SECOND_SIZE * 2];
213  int written = 0;
214  int ret;
215  AADemuxContext *c = s->priv_data;
216 
217  // are we at the start of a chapter?
218  if (c->current_chapter_size == 0) {
219  c->current_chapter_size = avio_rb32(s->pb);
220  if (c->current_chapter_size == 0) {
221  return AVERROR_EOF;
222  }
223  av_log(s, AV_LOG_DEBUG, "Chapter %d (%" PRId64 " bytes)\n", c->chapter_idx, c->current_chapter_size);
224  c->chapter_idx = c->chapter_idx + 1;
225  avio_skip(s->pb, 4); // data start offset
226  c->current_codec_second_size = c->codec_second_size;
227  }
228 
229  // is this the last block in this chapter?
230  if (c->current_chapter_size / c->current_codec_second_size == 0) {
231  c->current_codec_second_size = c->current_chapter_size % c->current_codec_second_size;
232  }
233 
234  // decrypt c->current_codec_second_size bytes
235  blocks = c->current_codec_second_size / TEA_BLOCK_SIZE;
236  for (i = 0; i < blocks; i++) {
237  avio_read(s->pb, src, TEA_BLOCK_SIZE);
238  av_tea_init(c->tea_ctx, c->file_key, 16);
239  av_tea_crypt(c->tea_ctx, dst, src, 1, NULL, 1);
240  memcpy(buf + written, dst, TEA_BLOCK_SIZE);
241  written = written + TEA_BLOCK_SIZE;
242  }
243  trailing_bytes = c->current_codec_second_size % TEA_BLOCK_SIZE;
244  if (trailing_bytes != 0) { // trailing bytes are left unencrypted!
245  avio_read(s->pb, src, trailing_bytes);
246  memcpy(buf + written, src, trailing_bytes);
247  written = written + trailing_bytes;
248  }
249 
250  // update state
251  c->current_chapter_size = c->current_chapter_size - c->current_codec_second_size;
252  if (c->current_chapter_size <= 0)
253  c->current_chapter_size = 0;
254 
255  ret = av_new_packet(pkt, written);
256  if (ret < 0)
257  return ret;
258  memcpy(pkt->data, buf, written);
259 
260  return 0;
261 }
262 
263  static int aa_probe(AVProbeData *p)
264 {
265  uint8_t *buf = p->buf;
266 
267  // first 4 bytes are file size, next 4 bytes are the magic
268  if (AV_RB32(buf+4) != AA_MAGIC)
269  return 0;
270 
271  return AVPROBE_SCORE_MAX / 2;
272 }
273 
274  static int aa_read_close(AVFormatContext *s)
275 {
276  AADemuxContext *c = s->priv_data;
277 
278  av_freep(&c->tea_ctx);
279 
280  return 0;
281 }
282 
283  #define OFFSET(x) offsetof(AADemuxContext, x)
284  static const AVOption aa_options[] = {
285  { "aa_fixed_key", // extracted from libAAX_SDK.so and AAXSDKWin.dll files!
286  "Fixed key used for handling Audible AA files", OFFSET(aa_fixed_key),
287  AV_OPT_TYPE_BINARY, {.str="77214d4b196a87cd520045fd2a51d673"},
288  .flags = AV_OPT_FLAG_DECODING_PARAM },
289  { NULL },
290 };
291 
292  static const AVClass aa_class = {
293  .class_name = "aa",
294  .item_name = av_default_item_name,
295  .option = aa_options,
296  .version = LIBAVUTIL_VERSION_INT,
297 };
298 
299  AVInputFormat ff_aa_demuxer = {
300  .name = "aa",
301  .long_name = NULL_IF_CONFIG_SMALL("Audible AA format files"),
302  .priv_class = &aa_class,
303  .priv_data_size = sizeof(AADemuxContext),
304  .extensions = "aa",
305  .read_probe = aa_probe,
306  .read_header = aa_read_header,
307  .read_packet = aa_read_packet,
308  .read_close = aa_read_close,
309  .flags = AVFMT_GENERIC_INDEX,
310 };
NULL
#define NULL
Definition: coverity.c:32
val
const char const char void * val
Definition: avisynth_c.h:771
s
const char * s
Definition: avisynth_c.h:768
AVIOContext
Bytestream IO Context.
Definition: avio.h:155
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
AVOption
AVOption.
Definition: opt.h:246
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AADemuxContext::file_key
uint8_t file_key[16]
Definition: aadec.c:47
AA_MAGIC
#define AA_MAGIC
Definition: aadec.c:33
aa_read_packet
static int aa_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: aadec.c:205
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:4066
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:231
AADemuxContext::current_codec_second_size
int current_codec_second_size
Definition: aadec.c:44
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:316
pkt
static AVPacket pkt
Definition: demuxing_decoding.c:54
src
#define src
Definition: vp8dsp.c:254
av_tea_alloc
struct AVTEA * av_tea_alloc(void)
Allocate an AVTEA context To free the struct: av_free(ptr)
Definition: tea.c:35
AVFormatContext
Format I/O context.
Definition: avformat.h:1349
AVClass::class_name
const char * class_name
The name of the class; usually it is the same name as the context structure type to which the AVClass...
Definition: log.h:72
dict.h
Public dictionary API.
uint8_t
uint8_t
Definition: audio_convert.c:194
aa_probe
static int aa_probe(AVProbeData *p)
Definition: aadec.c:263
opt.h
AVOptions.
MAX_CODEC_SECOND_SIZE
#define MAX_CODEC_SECOND_SIZE
Definition: aadec.c:34
avio_rb32
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:769
aa_options
static const AVOption aa_options[]
Definition: aadec.c:284
AVStream::need_parsing
enum AVStreamParseType need_parsing
Definition: avformat.h:1081
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4231
AV_RB32
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:87
AVTEA
Definition: tea.c:30
AVPacket::data
uint8_t * data
Definition: avcodec.h:1657
flags
static int flags
Definition: log.c:57
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
read_close
static av_cold int read_close(AVFormatContext *ctx)
Definition: libcdio.c:145
size
ptrdiff_t size
Definition: opengl_enc.c:101
ff_aa_demuxer
AVInputFormat ff_aa_demuxer
Definition: aadec.c:299
AVSTREAM_PARSE_FULL_RAW
full parsing and repack with timestamp and position generation by parser for raw this assumes that ea...
Definition: avformat.h:814
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:616
av_new_packet
int av_new_packet(AVPacket *pkt, int size)
Allocate the payload of a packet and initialize its fields with default values.
Definition: avpacket.c:86
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVFormatContext::metadata
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1567
av_default_item_name
av_default_item_name
Definition: libopenh264enc.c:78
AVERROR
#define AVERROR(e)
Definition: error.h:43
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:179
AV_LOG_DEBUG
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
AV_CODEC_ID_MP3
preferred ID for decoding MPEG audio layer 1, 2 or 3
Definition: avcodec.h:550
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:4062
aa_read_header
static int aa_read_header(AVFormatContext *s)
Definition: aadec.c:66
AADemuxContext::aa_fixed_key
uint8_t * aa_fixed_key
Definition: aadec.c:41
AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
offset
static const uint8_t offset[127][2]
Definition: vf_spp.c:92
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:463
AADemuxContext::current_chapter_size
int64_t current_chapter_size
Definition: aadec.c:48
AVCodecParameters::block_align
int block_align
Audio only.
Definition: avcodec.h:4183
read_probe
static int read_probe(AVProbeData *pd)
Definition: jvdec.c:55
tea.h
Public header for libavutil TEA algorithm.
av_tea_crypt
void av_tea_crypt(AVTEA *ctx, uint8_t *dst, const uint8_t *src, int count, uint8_t *iv, int decrypt)
Encrypt or decrypt a buffer using a previously initialized context.
Definition: tea.c:95
AADemuxContext::tea_ctx
struct AVTEA * tea_ctx
Definition: aadec.c:46
MAX_DICTIONARY_ENTRIES
#define MAX_DICTIONARY_ENTRIES
Definition: aadec.c:36
OFFSET
#define OFFSET(x)
Definition: aadec.c:283
AV_OPT_TYPE_BINARY
offset must point to a pointer immediately followed by an int for the length
Definition: opt.h:229
read_header
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:510
aa_read_close
static int aa_read_close(AVFormatContext *s)
Definition: aadec.c:274
AVStream
Stream structure.
Definition: avformat.h:889
read_packet
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
AVFormatContext::pb
AVIOContext * pb
I/O context.
Definition: avformat.h:1391
MAX_TOC_ENTRIES
#define MAX_TOC_ENTRIES
Definition: aadec.c:35
buf
void * buf
Definition: avisynth_c.h:690
av_dict_set
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:67
AV_WB32
#define AV_WB32(p, v)
Definition: intreadwrite.h:424
AVFMT_GENERIC_INDEX
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:487
AV_OPT_FLAG_DECODING_PARAM
#define AV_OPT_FLAG_DECODING_PARAM
a generic parameter which can be set by the user for demuxing or decoding
Definition: opt.h:277
get_second_size
static int get_second_size(char *codec_name)
Definition: aadec.c:51
aa_class
static const AVClass aa_class
Definition: aadec.c:292
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:461
AADemuxContext::chapter_idx
int chapter_idx
Definition: aadec.c:45
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: avcodec.h:4176
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:473
avformat.h
Main libavformat public API header.
av_tea_init
void av_tea_init(AVTEA *ctx, const uint8_t key[16], int rounds)
Initialize an AVTEA context.
Definition: tea.c:42
AVStream::start_time
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:936
c
static double c[64]
Definition: vsrc_mptestsrc.c:87
TEA_BLOCK_SIZE
#define TEA_BLOCK_SIZE
Definition: aadec.c:37
AADemuxContext::codec_second_size
int codec_second_size
Definition: aadec.c:43
AVTEA::key
uint32_t key[16]
Definition: tea.c:31
AADemuxContext::aa_fixed_key_len
int aa_fixed_key_len
Definition: aadec.c:42
AVFormatContext::priv_data
void * priv_data
Format private data.
Definition: avformat.h:1377
AVCodecParameters::channels
int channels
Audio only.
Definition: avcodec.h:4172
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
start
void INT64 start
Definition: avisynth_c.h:690
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:664
AVStream::codecpar
AVCodecParameters * codecpar
Definition: avformat.h:1252
avio_get_str
int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen)
Read a string from pb into buf.
Definition: aviobuf.c:794
AV_CODEC_ID_SIPR
Definition: avcodec.h:593
AVPacket
This structure stores compressed data.
Definition: avcodec.h:1634
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