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vorbis_parser.c
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1 /*
2  * Copyright (c) 2012 Justin Ruggles
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public
8  * License as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14  * Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public
17  * License along with FFmpeg; if not, write to the Free Software
18  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 /**
22  * @file
23  * Vorbis audio parser
24  *
25  * Determines the duration for each packet.
26  */
27 
28 #include "libavutil/log.h"
29 
30 #include "get_bits.h"
31 #include "parser.h"
32 #include "xiph.h"
33 #include "vorbis_parser_internal.h"
34 
35 static const AVClass vorbis_parser_class = {
36  .class_name = "Vorbis parser",
37  .item_name = av_default_item_name,
38  .version = LIBAVUTIL_VERSION_INT,
39 };
40 
42  const uint8_t *buf, int buf_size)
43 {
44  /* Id header should be 30 bytes */
45  if (buf_size < 30) {
46  av_log(s, AV_LOG_ERROR, "Id header is too short\n");
47  return AVERROR_INVALIDDATA;
48  }
49 
50  /* make sure this is the Id header */
51  if (buf[0] != 1) {
52  av_log(s, AV_LOG_ERROR, "Wrong packet type in Id header\n");
53  return AVERROR_INVALIDDATA;
54  }
55 
56  /* check for header signature */
57  if (memcmp(&buf[1], "vorbis", 6)) {
58  av_log(s, AV_LOG_ERROR, "Invalid packet signature in Id header\n");
59  return AVERROR_INVALIDDATA;
60  }
61 
62  if (!(buf[29] & 0x1)) {
63  av_log(s, AV_LOG_ERROR, "Invalid framing bit in Id header\n");
64  return AVERROR_INVALIDDATA;
65  }
66 
67  s->blocksize[0] = 1 << (buf[28] & 0xF);
68  s->blocksize[1] = 1 << (buf[28] >> 4);
69 
70  return 0;
71 }
72 
74  const uint8_t *buf, int buf_size)
75 {
76  GetBitContext gb, gb0;
77  uint8_t *rev_buf;
78  int i, ret = 0;
79  int got_framing_bit, mode_count, got_mode_header, last_mode_count = 0;
80 
81  /* avoid overread */
82  if (buf_size < 7) {
83  av_log(s, AV_LOG_ERROR, "Setup header is too short\n");
84  return AVERROR_INVALIDDATA;
85  }
86 
87  /* make sure this is the Setup header */
88  if (buf[0] != 5) {
89  av_log(s, AV_LOG_ERROR, "Wrong packet type in Setup header\n");
90  return AVERROR_INVALIDDATA;
91  }
92 
93  /* check for header signature */
94  if (memcmp(&buf[1], "vorbis", 6)) {
95  av_log(s, AV_LOG_ERROR, "Invalid packet signature in Setup header\n");
96  return AVERROR_INVALIDDATA;
97  }
98 
99  /* reverse bytes so we can easily read backwards with get_bits() */
100  if (!(rev_buf = av_malloc(buf_size))) {
101  av_log(s, AV_LOG_ERROR, "Out of memory\n");
102  return AVERROR(ENOMEM);
103  }
104  for (i = 0; i < buf_size; i++)
105  rev_buf[i] = buf[buf_size - 1 - i];
106  init_get_bits(&gb, rev_buf, buf_size * 8);
107 
108  got_framing_bit = 0;
109  while (get_bits_left(&gb) > 97) {
110  if (get_bits1(&gb)) {
111  got_framing_bit = get_bits_count(&gb);
112  break;
113  }
114  }
115  if (!got_framing_bit) {
116  av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
117  ret = AVERROR_INVALIDDATA;
118  goto bad_header;
119  }
120 
121  /* Now we search backwards to find possible valid mode counts. This is not
122  * fool-proof because we could have false positive matches and read too
123  * far, but there isn't really any way to be sure without parsing through
124  * all the many variable-sized fields before the modes. This approach seems
125  * to work well in testing, and it is similar to how it is handled in
126  * liboggz. */
127  mode_count = 0;
128  got_mode_header = 0;
129  while (get_bits_left(&gb) >= 97) {
130  if (get_bits(&gb, 8) > 63 || get_bits(&gb, 16) || get_bits(&gb, 16))
131  break;
132  skip_bits(&gb, 1);
133  mode_count++;
134  if (mode_count > 64)
135  break;
136  gb0 = gb;
137  if (get_bits(&gb0, 6) + 1 == mode_count) {
138  got_mode_header = 1;
139  last_mode_count = mode_count;
140  }
141  }
142  if (!got_mode_header) {
143  av_log(s, AV_LOG_ERROR, "Invalid Setup header\n");
144  ret = AVERROR_INVALIDDATA;
145  goto bad_header;
146  }
147  /* All samples I've seen use <= 2 modes, so ask for a sample if we find
148  * more than that, as it is most likely a false positive. If we get any
149  * we may need to approach this the long way and parse the whole Setup
150  * header, but I hope very much that it never comes to that. */
151  if (last_mode_count > 2) {
153  "%d modes (either a false positive or a "
154  "sample from an unknown encoder)",
155  last_mode_count);
156  }
157  /* We're limiting the mode count to 63 so that we know that the previous
158  * block flag will be in the first packet byte. */
159  if (last_mode_count > 63) {
160  av_log(s, AV_LOG_ERROR, "Unsupported mode count: %d\n",
161  last_mode_count);
162  ret = AVERROR_INVALIDDATA;
163  goto bad_header;
164  }
165  s->mode_count = mode_count = last_mode_count;
166  /* Determine the number of bits required to code the mode and turn that
167  * into a bitmask to directly access the mode from the first frame byte. */
168  s->mode_mask = ((1 << (av_log2(mode_count - 1) + 1)) - 1) << 1;
169  /* The previous window flag is the next bit after the mode */
170  s->prev_mask = (s->mode_mask | 0x1) + 1;
171 
172  init_get_bits(&gb, rev_buf, buf_size * 8);
173  skip_bits_long(&gb, got_framing_bit);
174  for (i = mode_count - 1; i >= 0; i--) {
175  skip_bits_long(&gb, 40);
176  s->mode_blocksize[i] = get_bits1(&gb);
177  }
178 
179 bad_header:
180  av_free(rev_buf);
181  return ret;
182 }
183 
185  const uint8_t *extradata, int extradata_size)
186 {
187  const uint8_t *header_start[3];
188  int header_len[3];
189  int ret;
190 
192  s->extradata_parsed = 1;
193 
194  if ((ret = avpriv_split_xiph_headers(extradata,
195  extradata_size, 30,
196  header_start, header_len)) < 0) {
197  av_log(s, AV_LOG_ERROR, "Extradata corrupt.\n");
198  return ret;
199  }
200 
201  if ((ret = parse_id_header(s, header_start[0], header_len[0])) < 0)
202  return ret;
203 
204  if ((ret = parse_setup_header(s, header_start[2], header_len[2])) < 0)
205  return ret;
206 
207  s->valid_extradata = 1;
209 
210  return 0;
211 }
212 
214  int buf_size, int *flags)
215 {
216  int duration = 0;
217 
218  if (s->valid_extradata && buf_size > 0) {
219  int mode, current_blocksize;
220  int previous_blocksize = s->previous_blocksize;
221 
222  if (buf[0] & 1) {
223  /* If the user doesn't care about special packets, it's a bad one. */
224  if (!flags)
225  goto bad_packet;
226 
227  /* Set the flag for which kind of special packet it is. */
228  if (buf[0] == 1)
229  *flags |= VORBIS_FLAG_HEADER;
230  else if (buf[0] == 3)
231  *flags |= VORBIS_FLAG_COMMENT;
232  else
233  goto bad_packet;
234 
235  /* Special packets have no duration. */
236  return 0;
237 
238 bad_packet:
239  av_log(s, AV_LOG_ERROR, "Invalid packet\n");
240  return AVERROR_INVALIDDATA;
241  }
242  if (s->mode_count == 1)
243  mode = 0;
244  else
245  mode = (buf[0] & s->mode_mask) >> 1;
246  if (mode >= s->mode_count) {
247  av_log(s, AV_LOG_ERROR, "Invalid mode in packet\n");
248  return AVERROR_INVALIDDATA;
249  }
250  if(s->mode_blocksize[mode]){
251  int flag = !!(buf[0] & s->prev_mask);
252  previous_blocksize = s->blocksize[flag];
253  }
254  current_blocksize = s->blocksize[s->mode_blocksize[mode]];
255  duration = (previous_blocksize + current_blocksize) >> 2;
256  s->previous_blocksize = current_blocksize;
257  }
258 
259  return duration;
260 }
261 
263  int buf_size)
264 {
265  return av_vorbis_parse_frame_flags(s, buf, buf_size, NULL);
266 }
267 
269 {
270  if (s->valid_extradata)
271  s->previous_blocksize = s->blocksize[0];
272 }
273 
275 {
276  av_freep(s);
277 }
278 
280  int extradata_size)
281 {
282  AVVorbisParseContext *s = av_mallocz(sizeof(*s));
283  int ret;
284 
285  if (!s)
286  return NULL;
287 
288  ret = vorbis_parse_init(s, extradata, extradata_size);
289  if (ret < 0) {
291  return NULL;
292  }
293 
294  return s;
295 }
296 
297 #if LIBAVCODEC_VERSION_MAJOR < 57
299 {
300  return vorbis_parse_init(s, avctx->extradata, avctx->extradata_size);
301 }
303 {
305 }
307  int buf_size)
308 {
309  return av_vorbis_parse_frame(s, buf, buf_size);
310 }
312  int buf_size, int *flags)
313 {
314  return av_vorbis_parse_frame_flags(s, buf, buf_size, flags);
315 }
316 #endif
317 
318 #if CONFIG_VORBIS_PARSER
319 
320 typedef struct VorbisParseContext {
322 } VorbisParseContext;
323 
324 static int vorbis_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
325  const uint8_t **poutbuf, int *poutbuf_size,
326  const uint8_t *buf, int buf_size)
327 {
328  VorbisParseContext *s = s1->priv_data;
329  int duration;
330 
331  if (!s->vp && avctx->extradata && avctx->extradata_size) {
332  s->vp = av_vorbis_parse_init(avctx->extradata, avctx->extradata_size);
333  }
334  if (!s->vp)
335  goto end;
336 
337  if ((duration = av_vorbis_parse_frame(s->vp, buf, buf_size)) >= 0)
338  s1->duration = duration;
339 
340 end:
341  /* always return the full packet. this parser isn't doing any splitting or
342  combining, only packet analysis */
343  *poutbuf = buf;
344  *poutbuf_size = buf_size;
345  return buf_size;
346 }
347 
348 static void vorbis_parser_close(AVCodecParserContext *ctx)
349 {
350  VorbisParseContext *s = ctx->priv_data;
351  av_vorbis_parse_free(&s->vp);
352 }
353 
354 AVCodecParser ff_vorbis_parser = {
356  .priv_data_size = sizeof(VorbisParseContext),
357  .parser_parse = vorbis_parse,
358  .parser_close = vorbis_parser_close,
359 };
360 #endif /* CONFIG_VORBIS_PARSER */