FFmpeg coverage

Directory: ../../../ffmpeg/
File: src/libavformat/aadec.c
Date: 2025-10-26 07:25:09
Exec Total Coverage
Lines: 133 188 70.7%
Functions: 5 6 83.3%
Branches: 50 88 56.8%
Line Branch Exec Source
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 "demux.h"
28 #include "internal.h"
29 #include "libavutil/avstring.h"
30 #include "libavutil/dict.h"
31 #include "libavutil/intreadwrite.h"
32 #include "libavutil/mem.h"
33 #include "libavutil/tea.h"
34 #include "libavutil/opt.h"
35
36 #define AA_MAGIC 1469084982 /* this identifies an audible .aa file */
37 #define MAX_TOC_ENTRIES 16
38 #define MAX_DICTIONARY_ENTRIES 128
39 #define TEA_BLOCK_SIZE 8
40 #define CHAPTER_HEADER_SIZE 8
41 #define TIMEPREC 1000
42 #define MP3_FRAME_SIZE 104
43
44 typedef struct AADemuxContext {
45 AVClass *class;
46 uint8_t *aa_fixed_key;
47 int aa_fixed_key_len;
48 int codec_second_size;
49 int current_codec_second_size;
50 int chapter_idx;
51 struct AVTEA *tea_ctx;
52 uint8_t file_key[16];
53 int64_t current_chapter_size;
54 int64_t content_start;
55 int64_t content_end;
56 int seek_offset;
57 } AADemuxContext;
58
59 1 static int get_second_size(char *codec_name)
60 {
61 1 int result = -1;
62
63
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 1 if (!strcmp(codec_name, "mp332")) {
64 ✗ result = 3982;
65
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 1 } else if (!strcmp(codec_name, "acelp16")) {
66 ✗ result = 2000;
67
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 1 } else if (!strcmp(codec_name, "acelp85")) {
68 1 result = 1045;
69 }
70
71 1 return result;
72 }
73
74 1 static int aa_read_header(AVFormatContext *s)
75 {
76 1 int largest_idx = -1;
77 1 uint32_t toc_size, npairs, header_seed = 0, start;
78 1 char codec_name[64] = {0};
79 uint8_t buf[24];
80 1 int64_t largest_size = -1, current_size = -1, chapter_pos;
81 struct toc_entry {
82 uint32_t offset;
83 uint32_t size;
84 } TOC[MAX_TOC_ENTRIES];
85 1 uint8_t header_key[16] = {0};
86 1 AADemuxContext *c = s->priv_data;
87 char file_key[2 * sizeof(c->file_key) + 1];
88 1 AVIOContext *pb = s->pb;
89 AVStream *st;
90 FFStream *sti;
91 int ret;
92
93 /* parse .aa header */
94 1 avio_skip(pb, 4); // file size
95 1 avio_skip(pb, 4); // magic string
96 1 toc_size = avio_rb32(pb); // TOC size
97 1 avio_skip(pb, 4); // unidentified integer
98
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 1 if (toc_size > MAX_TOC_ENTRIES || toc_size < 2)
99 ✗ return AVERROR_INVALIDDATA;
100
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 13 for (uint32_t i = 0; i < toc_size; i++) { // read TOC
101 12 avio_skip(pb, 4); // TOC entry index
102 12 TOC[i].offset = avio_rb32(pb); // block offset
103 12 TOC[i].size = avio_rb32(pb); // block size
104 }
105 1 avio_skip(pb, 24); // header termination block (ignored)
106 1 npairs = avio_rb32(pb); // read dictionary entries
107
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 1 if (npairs > MAX_DICTIONARY_ENTRIES)
108 ✗ return AVERROR_INVALIDDATA;
109
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 20 for (uint32_t i = 0; i < npairs; i++) {
110 char key[128], val[128];
111 uint32_t nkey, nval;
112
113 19 avio_skip(pb, 1); // unidentified integer
114 19 nkey = avio_rb32(pb); // key string length
115 19 nval = avio_rb32(pb); // value string length
116 19 avio_get_str(pb, nkey, key, sizeof(key));
117 19 avio_get_str(pb, nval, val, sizeof(val));
118
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 19 if (!strcmp(key, "codec")) {
119 1 av_log(s, AV_LOG_DEBUG, "Codec is <%s>\n", val);
120 1 av_strlcpy(codec_name, val, sizeof(codec_name));
121
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 18 } else if (!strcmp(key, "HeaderSeed")) {
122 1 av_log(s, AV_LOG_DEBUG, "HeaderSeed is <%s>\n", val);
123 1 header_seed = atoi(val);
124
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 17 } else if (!strcmp(key, "HeaderKey")) { // this looks like "1234567890 1234567890 1234567890 1234567890"
125 uint32_t header_key_part[4];
126 1 av_log(s, AV_LOG_DEBUG, "HeaderKey is <%s>\n", val);
127
128 1 ret = sscanf(val, "%"SCNu32"%"SCNu32"%"SCNu32"%"SCNu32,
129 &header_key_part[0], &header_key_part[1], &header_key_part[2], &header_key_part[3]);
130
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 1 if (ret != 4)
131 ✗ return AVERROR_INVALIDDATA;
132
133
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 5 for (int idx = 0; idx < 4; idx++)
134 4 AV_WB32(&header_key[idx * 4], header_key_part[idx]); // convert each part to BE!
135 1 ff_data_to_hex(key, header_key, sizeof(header_key), 1);
136 1 av_log(s, AV_LOG_DEBUG, "Processed HeaderKey is %s\n", key);
137 } else {
138 16 av_dict_set(&s->metadata, key, val, 0);
139 }
140 }
141
142 /* verify fixed key */
143
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 1 if (c->aa_fixed_key_len != 16) {
144 ✗ av_log(s, AV_LOG_ERROR, "aa_fixed_key value needs to be 16 bytes!\n");
145 ✗ return AVERROR(EINVAL);
146 }
147
148 /* verify codec */
149
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 1 if ((c->codec_second_size = get_second_size(codec_name)) == -1) {
150 ✗ av_log(s, AV_LOG_ERROR, "unknown codec <%s>!\n", codec_name);
151 ✗ return AVERROR(EINVAL);
152 }
153
154 /* decryption key derivation */
155 1 c->tea_ctx = av_tea_alloc();
156
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 1 if (!c->tea_ctx)
157 ✗ return AVERROR(ENOMEM);
158 1 av_tea_init(c->tea_ctx, c->aa_fixed_key, 16);
159
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 7 for (int i = 0; i < 6; i++)
160 6 AV_WB32(buf + 4 * i, header_seed + i);
161 1 av_tea_crypt(c->tea_ctx, buf, buf, 3, NULL, 0);
162 1 AV_WN64(c->file_key, AV_RN64(buf + 2) ^ AV_RN64(header_key));
163 1 AV_WN64(c->file_key + 8, AV_RN64(buf + 10) ^ AV_RN64(header_key + 8));
164 1 ff_data_to_hex(file_key, c->file_key, sizeof(c->file_key), 1);
165 1 av_log(s, AV_LOG_DEBUG, "File key is %s\n", file_key);
166 1 av_tea_init(c->tea_ctx, c->file_key, 16);
167
168 /* decoder setup */
169 1 st = avformat_new_stream(s, NULL);
170
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 1 if (!st)
171 ✗ return AVERROR(ENOMEM);
172 1 sti = ffstream(st);
173 1 st->codecpar->codec_type = AVMEDIA_TYPE_AUDIO;
174
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 1 if (!strcmp(codec_name, "mp332")) {
175 ✗ st->codecpar->codec_id = AV_CODEC_ID_MP3;
176 ✗ st->codecpar->sample_rate = 22050;
177 ✗ sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
178 ✗ avpriv_set_pts_info(st, 64, 8, 32000 * TIMEPREC);
179 // encoded audio frame is MP3_FRAME_SIZE bytes (+1 with padding, unlikely)
180
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 1 } else if (!strcmp(codec_name, "acelp85")) {
181 1 st->codecpar->codec_id = AV_CODEC_ID_SIPR;
182 1 st->codecpar->block_align = 19;
183 1 st->codecpar->ch_layout.nb_channels = 1;
184 1 st->codecpar->sample_rate = 8500;
185 1 st->codecpar->bit_rate = 8500;
186 1 sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
187 1 avpriv_set_pts_info(st, 64, 8, 8500 * TIMEPREC);
188 ✗ } else if (!strcmp(codec_name, "acelp16")) {
189 ✗ st->codecpar->codec_id = AV_CODEC_ID_SIPR;
190 ✗ st->codecpar->block_align = 20;
191 ✗ st->codecpar->ch_layout.nb_channels = 1;
192 ✗ st->codecpar->sample_rate = 16000;
193 ✗ st->codecpar->bit_rate = 16000;
194 ✗ sti->need_parsing = AVSTREAM_PARSE_FULL_RAW;
195 ✗ avpriv_set_pts_info(st, 64, 8, 16000 * TIMEPREC);
196 }
197
198 /* determine, and jump to audio start offset */
199
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 12 for (uint32_t i = 1; i < toc_size; i++) { // skip the first entry!
200 11 current_size = TOC[i].size;
201
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 11 if (current_size > largest_size) {
202 4 largest_idx = i;
203 4 largest_size = current_size;
204 }
205 }
206 1 start = TOC[largest_idx].offset;
207 1 avio_seek(pb, start, SEEK_SET);
208
209 // extract chapter positions. since all formats have constant bit rate, use it
210 // as time base in bytes/s, for easy stream position <-> timestamp conversion
211 1 st->start_time = 0;
212 1 c->content_start = start;
213 1 c->content_end = start + largest_size;
214
215
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 3 while ((chapter_pos = avio_tell(pb)) >= 0 && chapter_pos < c->content_end) {
216 3 unsigned chapter_idx = s->nb_chapters;
217 3 uint32_t chapter_size = avio_rb32(pb);
218
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 3 if (chapter_size == 0 || avio_feof(pb))
219 break;
220 2 chapter_pos -= start + CHAPTER_HEADER_SIZE * chapter_idx;
221 2 avio_skip(pb, 4 + chapter_size);
222
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 2 if (!avpriv_new_chapter(s, chapter_idx, st->time_base,
223 chapter_pos * TIMEPREC,
224 2 (chapter_pos + chapter_size) * TIMEPREC, NULL))
225 ✗ return AVERROR(ENOMEM);
226 }
227
228 1 st->duration = (largest_size - CHAPTER_HEADER_SIZE * s->nb_chapters) * TIMEPREC;
229
230 1 avpriv_update_cur_dts(s, st, 0);
231 1 avio_seek(pb, start, SEEK_SET);
232 1 c->current_chapter_size = 0;
233 1 c->seek_offset = 0;
234
235 1 return 0;
236 }
237
238 7 static int aa_read_packet(AVFormatContext *s, AVPacket *pkt)
239 {
240 int ret;
241 7 AADemuxContext *c = s->priv_data;
242 7 uint64_t pos = avio_tell(s->pb);
243
244 // are we at the end of the audio content?
245
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 7 if (pos >= c->content_end) {
246 ✗ return AVERROR_EOF;
247 }
248
249 // are we at the start of a chapter?
250
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 7 if (c->current_chapter_size == 0) {
251 2 c->current_chapter_size = avio_rb32(s->pb);
252
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 2 if (c->current_chapter_size == 0) {
253 ✗ return AVERROR_EOF;
254 }
255 2 av_log(s, AV_LOG_DEBUG, "Chapter %d (%" PRId64 " bytes)\n", c->chapter_idx, c->current_chapter_size);
256 2 c->chapter_idx = c->chapter_idx + 1;
257 2 avio_skip(s->pb, 4); // data start offset
258 2 c->current_codec_second_size = c->codec_second_size;
259 }
260
261 // is this the last block in this chapter?
262
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 7 if (c->current_chapter_size / c->current_codec_second_size == 0) {
263 1 c->current_codec_second_size = c->current_chapter_size % c->current_codec_second_size;
264 }
265
266 7 ret = av_get_packet(s->pb, pkt, c->current_codec_second_size);
267
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 7 if (ret != c->current_codec_second_size)
268 1 return AVERROR_EOF;
269
270 // decrypt c->current_codec_second_size bytes in blocks of TEA_BLOCK_SIZE
271 // trailing bytes are left unencrypted!
272 6 av_tea_crypt(c->tea_ctx, pkt->data, pkt->data,
273 6 c->current_codec_second_size / TEA_BLOCK_SIZE, NULL, 1);
274
275 // update state
276 6 c->current_chapter_size = c->current_chapter_size - c->current_codec_second_size;
277
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 6 if (c->current_chapter_size <= 0)
278 1 c->current_chapter_size = 0;
279
280
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 6 if (c->seek_offset > c->current_codec_second_size)
281 ✗ c->seek_offset = 0; // ignore wrong estimate
282 6 pkt->data += c->seek_offset;
283 6 pkt->size -= c->seek_offset;
284 6 c->seek_offset = 0;
285
286 6 return 0;
287 }
288
289 ✗ static int aa_read_seek(AVFormatContext *s,
290 int stream_index, int64_t timestamp, int flags)
291 {
292 ✗ AADemuxContext *c = s->priv_data;
293 AVChapter *ch;
294 int64_t chapter_pos, chapter_start, chapter_size;
295 ✗ int chapter_idx = 0;
296
297 // find chapter containing seek timestamp
298 ✗ if (timestamp < 0)
299 ✗ timestamp = 0;
300
301 ✗ while (chapter_idx < s->nb_chapters && timestamp >= s->chapters[chapter_idx]->end) {
302 ✗ ++chapter_idx;
303 }
304
305 ✗ if (chapter_idx >= s->nb_chapters) {
306 ✗ chapter_idx = s->nb_chapters - 1;
307 ✗ if (chapter_idx < 0) return -1; // there is no chapter.
308 ✗ timestamp = s->chapters[chapter_idx]->end;
309 }
310
311 ✗ ch = s->chapters[chapter_idx];
312
313 // sync by clamping timestamp to nearest valid block position in its chapter
314 ✗ chapter_size = ch->end / TIMEPREC - ch->start / TIMEPREC;
315 ✗ chapter_pos = av_rescale_rnd((timestamp - ch->start) / TIMEPREC,
316 ✗ 1, c->codec_second_size,
317 ✗ (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP)
318 ✗ * c->codec_second_size;
319 ✗ if (chapter_pos >= chapter_size)
320 ✗ chapter_pos = chapter_size;
321 ✗ chapter_start = c->content_start + (ch->start / TIMEPREC) + CHAPTER_HEADER_SIZE * (1 + chapter_idx);
322
323 // reinit read state
324 ✗ avio_seek(s->pb, chapter_start + chapter_pos, SEEK_SET);
325 ✗ c->current_codec_second_size = c->codec_second_size;
326 ✗ c->current_chapter_size = chapter_size - chapter_pos;
327 ✗ c->chapter_idx = 1 + chapter_idx;
328
329 // for unaligned frames, estimate offset of first frame in block (assume no padding)
330 ✗ if (s->streams[0]->codecpar->codec_id == AV_CODEC_ID_MP3) {
331 ✗ c->seek_offset = (MP3_FRAME_SIZE - chapter_pos % MP3_FRAME_SIZE) % MP3_FRAME_SIZE;
332 }
333
334 ✗ avpriv_update_cur_dts(s, s->streams[0], ch->start + (chapter_pos + c->seek_offset) * TIMEPREC);
335
336 ✗ return 1;
337 }
338
339 7279 static int aa_probe(const AVProbeData *p)
340 {
341 7279 uint8_t *buf = p->buf;
342
343 // first 4 bytes are file size, next 4 bytes are the magic
344
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 7279 if (AV_RB32(buf+4) != AA_MAGIC)
345 7278 return 0;
346
347 1 return AVPROBE_SCORE_MAX / 2;
348 }
349
350 1 static int aa_read_close(AVFormatContext *s)
351 {
352 1 AADemuxContext *c = s->priv_data;
353
354 1 av_freep(&c->tea_ctx);
355
356 1 return 0;
357 }
358
359 #define OFFSET(x) offsetof(AADemuxContext, x)
360 static const AVOption aa_options[] = {
361 { "aa_fixed_key", // extracted from libAAX_SDK.so and AAXSDKWin.dll files!
362 "Fixed key used for handling Audible AA files", OFFSET(aa_fixed_key),
363 AV_OPT_TYPE_BINARY, {.str="77214d4b196a87cd520045fd2a51d673"},
364 .flags = AV_OPT_FLAG_DECODING_PARAM },
365 { NULL },
366 };
367
368 static const AVClass aa_class = {
369 .class_name = "aa",
370 .item_name = av_default_item_name,
371 .option = aa_options,
372 .version = LIBAVUTIL_VERSION_INT,
373 };
374
375 const FFInputFormat ff_aa_demuxer = {
376 .p.name = "aa",
377 .p.long_name = NULL_IF_CONFIG_SMALL("Audible AA format files"),
378 .p.priv_class = &aa_class,
379 .p.extensions = "aa",
380 .p.flags = AVFMT_NO_BYTE_SEEK | AVFMT_NOGENSEARCH,
381 .priv_data_size = sizeof(AADemuxContext),
382 .read_probe = aa_probe,
383 .read_header = aa_read_header,
384 .read_packet = aa_read_packet,
385 .read_seek = aa_read_seek,
386 .read_close = aa_read_close,
387 .flags_internal = FF_INFMT_FLAG_INIT_CLEANUP,
388 };
389