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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 if (buf[0] == 5)
233  *flags |= VORBIS_FLAG_SETUP;
234  else
235  goto bad_packet;
236 
237  /* Special packets have no duration. */
238  return 0;
239 
240 bad_packet:
241  av_log(s, AV_LOG_ERROR, "Invalid packet\n");
242  return AVERROR_INVALIDDATA;
243  }
244  if (s->mode_count == 1)
245  mode = 0;
246  else
247  mode = (buf[0] & s->mode_mask) >> 1;
248  if (mode >= s->mode_count) {
249  av_log(s, AV_LOG_ERROR, "Invalid mode in packet\n");
250  return AVERROR_INVALIDDATA;
251  }
252  if(s->mode_blocksize[mode]){
253  int flag = !!(buf[0] & s->prev_mask);
254  previous_blocksize = s->blocksize[flag];
255  }
256  current_blocksize = s->blocksize[s->mode_blocksize[mode]];
257  duration = (previous_blocksize + current_blocksize) >> 2;
258  s->previous_blocksize = current_blocksize;
259  }
260 
261  return duration;
262 }
263 
265  int buf_size)
266 {
267  return av_vorbis_parse_frame_flags(s, buf, buf_size, NULL);
268 }
269 
271 {
272  if (s->valid_extradata)
273  s->previous_blocksize = s->blocksize[0];
274 }
275 
277 {
278  av_freep(s);
279 }
280 
282  int extradata_size)
283 {
284  AVVorbisParseContext *s = av_mallocz(sizeof(*s));
285  int ret;
286 
287  if (!s)
288  return NULL;
289 
290  ret = vorbis_parse_init(s, extradata, extradata_size);
291  if (ret < 0) {
293  return NULL;
294  }
295 
296  return s;
297 }
298 
299 #if CONFIG_VORBIS_PARSER
300 
301 typedef struct VorbisParseContext {
303 } VorbisParseContext;
304 
305 static int vorbis_parse(AVCodecParserContext *s1, AVCodecContext *avctx,
306  const uint8_t **poutbuf, int *poutbuf_size,
307  const uint8_t *buf, int buf_size)
308 {
309  VorbisParseContext *s = s1->priv_data;
310  int duration;
311 
312  if (!s->vp && avctx->extradata && avctx->extradata_size) {
313  s->vp = av_vorbis_parse_init(avctx->extradata, avctx->extradata_size);
314  }
315  if (!s->vp)
316  goto end;
317 
318  if ((duration = av_vorbis_parse_frame(s->vp, buf, buf_size)) >= 0)
319  s1->duration = duration;
320 
321 end:
322  /* always return the full packet. this parser isn't doing any splitting or
323  combining, only packet analysis */
324  *poutbuf = buf;
325  *poutbuf_size = buf_size;
326  return buf_size;
327 }
328 
329 static void vorbis_parser_close(AVCodecParserContext *ctx)
330 {
331  VorbisParseContext *s = ctx->priv_data;
332  av_vorbis_parse_free(&s->vp);
333 }
334 
335 AVCodecParser ff_vorbis_parser = {
337  .priv_data_size = sizeof(VorbisParseContext),
338  .parser_parse = vorbis_parse,
339  .parser_close = vorbis_parser_close,
340 };
341 #endif /* CONFIG_VORBIS_PARSER */
#define NULL
Definition: coverity.c:32
const char * s
Definition: avisynth_c.h:631
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
int extradata_parsed
we have attempted to parse extradata
static unsigned int get_bits(GetBitContext *s, int n)
Read 1-25 bits.
Definition: get_bits.h:247
#define LIBAVUTIL_VERSION_INT
Definition: version.h:70
static void skip_bits_long(GetBitContext *s, int n)
Definition: get_bits.h:204
int mode_count
number of modes
AVVorbisParseContext * av_vorbis_parse_init(const uint8_t *extradata, int extradata_size)
Allocate and initialize the Vorbis parser using headers in the extradata.
int flag
Definition: cpu.c:34
int codec_ids[5]
Definition: avcodec.h:5108
int av_log2(unsigned v)
Definition: intmath.c:26
int duration
Duration of the current frame.
Definition: avcodec.h:5062
int prev_mask
bitmask used to get the previous mode flag in each packet
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
void void avpriv_request_sample(void *avc, const char *msg,...) av_printf_format(2
Log a generic warning message about a missing feature.
uint8_t
#define av_malloc(s)
mode
Definition: f_perms.c:27
static av_cold int end(AVCodecContext *avctx)
Definition: avrndec.c:90
uint8_t * extradata
some codecs need / can use extradata like Huffman tables.
Definition: avcodec.h:1772
int64_t duration
Definition: movenc.c:63
static int get_bits_count(const GetBitContext *s)
Definition: get_bits.h:199
bitstream reader API header.
#define av_log(a,...)
static int get_bits_left(GetBitContext *gb)
Definition: get_bits.h:568
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
void av_vorbis_parse_free(AVVorbisParseContext **s)
Free the parser and everything associated with it.
int valid_extradata
extradata is valid, so we can calculate duration
av_default_item_name
#define AVERROR(e)
Definition: error.h:43
static int vorbis_parse_init(AVVorbisParseContext *s, const uint8_t *extradata, int extradata_size)
AVFormatContext * ctx
Definition: movenc.c:48
#define VORBIS_FLAG_SETUP
Definition: vorbis_parser.h:49
int avpriv_split_xiph_headers(const uint8_t *extradata, int extradata_size, int first_header_size, const uint8_t *header_start[3], int header_len[3])
Split a single extradata buffer into the three headers that most Xiph codecs use. ...
Definition: xiph.c:24
int previous_blocksize
previous window size
#define VORBIS_FLAG_COMMENT
Definition: vorbis_parser.h:48
int mode_mask
bitmask used to get the mode in each packet
#define VORBIS_FLAG_HEADER
Definition: vorbis_parser.h:47
main external API structure.
Definition: avcodec.h:1657
void * buf
Definition: avisynth_c.h:553
int extradata_size
Definition: avcodec.h:1773
static unsigned int get_bits1(GetBitContext *s)
Definition: get_bits.h:299
Describe the class of an AVClass context structure.
Definition: log.h:67
static void skip_bits(GetBitContext *s, int n)
Definition: get_bits.h:292
static const AVClass vorbis_parser_class
Definition: vorbis_parser.c:35
static int init_get_bits(GetBitContext *s, const uint8_t *buffer, int bit_size)
Initialize GetBitContext.
Definition: get_bits.h:406
#define s1
Definition: regdef.h:38
int av_vorbis_parse_frame_flags(AVVorbisParseContext *s, const uint8_t *buf, int buf_size, int *flags)
Get the duration for a Vorbis packet.
static int flags
Definition: cpu.c:47
int blocksize[2]
short and long window sizes
static int parse_id_header(AVVorbisParseContext *s, const uint8_t *buf, int buf_size)
Definition: vorbis_parser.c:41
Vorbis audio parser.
int av_vorbis_parse_frame(AVVorbisParseContext *s, const uint8_t *buf, int buf_size)
Get the duration for a Vorbis packet.
static int parse_setup_header(AVVorbisParseContext *s, const uint8_t *buf, int buf_size)
Definition: vorbis_parser.c:73
#define av_free(p)
int mode_blocksize[64]
window size mapping for each mode
#define av_freep(p)
void * av_mallocz(size_t size)
Allocate a block of size bytes with alignment suitable for all memory accesses (including vectors if ...
Definition: mem.c:252
void av_vorbis_parse_reset(AVVorbisParseContext *s)