FFmpeg
 All Data Structures Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Groups Pages
cafdec.c
Go to the documentation of this file.
1 /*
2  * Core Audio Format demuxer
3  * Copyright (c) 2007 Justin Ruggles
4  * Copyright (c) 2009 Peter Ross
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 /**
24  * @file
25  * Core Audio Format demuxer
26  */
27 
28 #include <inttypes.h>
29 
30 #include "avformat.h"
31 #include "internal.h"
32 #include "isom.h"
33 #include "mov_chan.h"
34 #include "libavutil/intreadwrite.h"
35 #include "libavutil/intfloat.h"
36 #include "libavutil/dict.h"
37 #include "caf.h"
38 
39 typedef struct {
40  int bytes_per_packet; ///< bytes in a packet, or 0 if variable
41  int frames_per_packet; ///< frames in a packet, or 0 if variable
42  int64_t num_bytes; ///< total number of bytes in stream
43 
44  int64_t packet_cnt; ///< packet counter
45  int64_t frame_cnt; ///< frame counter
46 
47  int64_t data_start; ///< data start position, in bytes
48  int64_t data_size; ///< raw data size, in bytes
49 } CaffContext;
50 
51 static int probe(AVProbeData *p)
52 {
53  if (AV_RB32(p->buf) == MKBETAG('c','a','f','f') && AV_RB16(&p->buf[4]) == 1)
54  return AVPROBE_SCORE_MAX;
55  return 0;
56 }
57 
58 /** Read audio description chunk */
60 {
61  AVIOContext *pb = s->pb;
62  CaffContext *caf = s->priv_data;
63  AVStream *st;
64  int flags;
65 
66  /* new audio stream */
67  st = avformat_new_stream(s, NULL);
68  if (!st)
69  return AVERROR(ENOMEM);
70 
71  /* parse format description */
74  st->codec->codec_tag = avio_rl32(pb);
75  flags = avio_rb32(pb);
76  caf->bytes_per_packet = avio_rb32(pb);
78  caf->frames_per_packet = avio_rb32(pb);
79  st->codec->channels = avio_rb32(pb);
81 
82  /* calculate bit rate for constant size packets */
83  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
84  st->codec->bit_rate = (uint64_t)st->codec->sample_rate * (uint64_t)caf->bytes_per_packet * 8
85  / (uint64_t)caf->frames_per_packet;
86  } else {
87  st->codec->bit_rate = 0;
88  }
89 
90  /* determine codec */
91  if (st->codec->codec_tag == MKTAG('l','p','c','m'))
92  st->codec->codec_id = ff_mov_get_lpcm_codec_id(st->codec->bits_per_coded_sample, (flags ^ 0x2) | 0x4);
93  else
95  return 0;
96 }
97 
98 /** Read magic cookie chunk */
99 static int read_kuki_chunk(AVFormatContext *s, int64_t size)
100 {
101  AVIOContext *pb = s->pb;
102  AVStream *st = s->streams[0];
103 
105  return -1;
106 
107  if (st->codec->codec_id == AV_CODEC_ID_AAC) {
108  /* The magic cookie format for AAC is an mp4 esds atom.
109  The lavc AAC decoder requires the data from the codec specific
110  description as extradata input. */
111  int strt, skip;
112 
113  strt = avio_tell(pb);
114  ff_mov_read_esds(s, pb);
115  skip = size - (avio_tell(pb) - strt);
116  if (skip < 0 || !st->codec->extradata ||
117  st->codec->codec_id != AV_CODEC_ID_AAC) {
118  av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");
119  return AVERROR_INVALIDDATA;
120  }
121  avio_skip(pb, skip);
122  } else if (st->codec->codec_id == AV_CODEC_ID_ALAC) {
123 #define ALAC_PREAMBLE 12
124 #define ALAC_HEADER 36
125 #define ALAC_NEW_KUKI 24
126  uint8_t preamble[12];
127  if (size < ALAC_NEW_KUKI) {
128  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
129  avio_skip(pb, size);
130  return AVERROR_INVALIDDATA;
131  }
132  avio_read(pb, preamble, ALAC_PREAMBLE);
133 
135  return AVERROR(ENOMEM);
136 
137  /* For the old style cookie, we skip 12 bytes, then read 36 bytes.
138  * The new style cookie only contains the last 24 bytes of what was
139  * 36 bytes in the old style cookie, so we fabricate the first 12 bytes
140  * in that case to maintain compatibility. */
141  if (!memcmp(&preamble[4], "frmaalac", 8)) {
142  if (size < ALAC_PREAMBLE + ALAC_HEADER) {
143  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
144  av_freep(&st->codec->extradata);
145  return AVERROR_INVALIDDATA;
146  }
148  avio_skip(pb, size - ALAC_PREAMBLE - ALAC_HEADER);
149  } else {
150  AV_WB32(st->codec->extradata, 36);
151  memcpy(&st->codec->extradata[4], "alac", 4);
152  AV_WB32(&st->codec->extradata[8], 0);
153  memcpy(&st->codec->extradata[12], preamble, 12);
154  avio_read(pb, &st->codec->extradata[24], ALAC_NEW_KUKI - 12);
155  avio_skip(pb, size - ALAC_NEW_KUKI);
156  }
157  } else {
158  if (ff_get_extradata(st->codec, pb, size) < 0)
159  return AVERROR(ENOMEM);
160  }
161 
162  return 0;
163 }
164 
165 /** Read packet table chunk */
166 static int read_pakt_chunk(AVFormatContext *s, int64_t size)
167 {
168  AVIOContext *pb = s->pb;
169  AVStream *st = s->streams[0];
170  CaffContext *caf = s->priv_data;
171  int64_t pos = 0, ccount, num_packets;
172  int i;
173 
174  ccount = avio_tell(pb);
175 
176  num_packets = avio_rb64(pb);
177  if (num_packets < 0 || INT32_MAX / sizeof(AVIndexEntry) < num_packets)
178  return AVERROR_INVALIDDATA;
179 
180  st->nb_frames = avio_rb64(pb); /* valid frames */
181  st->nb_frames += avio_rb32(pb); /* priming frames */
182  st->nb_frames += avio_rb32(pb); /* remainder frames */
183 
184  st->duration = 0;
185  for (i = 0; i < num_packets; i++) {
186  av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);
189  }
190 
191  if (avio_tell(pb) - ccount > size) {
192  av_log(s, AV_LOG_ERROR, "error reading packet table\n");
193  return AVERROR_INVALIDDATA;
194  }
195  avio_skip(pb, ccount + size - avio_tell(pb));
196 
197  caf->num_bytes = pos;
198  return 0;
199 }
200 
201 /** Read information chunk */
202 static void read_info_chunk(AVFormatContext *s, int64_t size)
203 {
204  AVIOContext *pb = s->pb;
205  unsigned int i;
206  unsigned int nb_entries = avio_rb32(pb);
207  for (i = 0; i < nb_entries && !avio_feof(pb); i++) {
208  char key[32];
209  char value[1024];
210  avio_get_str(pb, INT_MAX, key, sizeof(key));
211  avio_get_str(pb, INT_MAX, value, sizeof(value));
212  av_dict_set(&s->metadata, key, value, 0);
213  }
214 }
215 
217 {
218  AVIOContext *pb = s->pb;
219  CaffContext *caf = s->priv_data;
220  AVStream *st;
221  uint32_t tag = 0;
222  int found_data, ret;
223  int64_t size, pos;
224 
225  avio_skip(pb, 8); /* magic, version, file flags */
226 
227  /* audio description chunk */
228  if (avio_rb32(pb) != MKBETAG('d','e','s','c')) {
229  av_log(s, AV_LOG_ERROR, "desc chunk not present\n");
230  return AVERROR_INVALIDDATA;
231  }
232  size = avio_rb64(pb);
233  if (size != 32)
234  return AVERROR_INVALIDDATA;
235 
236  ret = read_desc_chunk(s);
237  if (ret)
238  return ret;
239  st = s->streams[0];
240 
241  /* parse each chunk */
242  found_data = 0;
243  while (!avio_feof(pb)) {
244 
245  /* stop at data chunk if seeking is not supported or
246  data chunk size is unknown */
247  if (found_data && (caf->data_size < 0 || !pb->seekable))
248  break;
249 
250  tag = avio_rb32(pb);
251  size = avio_rb64(pb);
252  pos = avio_tell(pb);
253  if (avio_feof(pb))
254  break;
255 
256  switch (tag) {
257  case MKBETAG('d','a','t','a'):
258  avio_skip(pb, 4); /* edit count */
259  caf->data_start = avio_tell(pb);
260  caf->data_size = size < 0 ? -1 : size - 4;
261  if (caf->data_size > 0 && pb->seekable)
262  avio_skip(pb, caf->data_size);
263  found_data = 1;
264  break;
265 
266  case MKBETAG('c','h','a','n'):
267  if ((ret = ff_mov_read_chan(s, s->pb, st, size)) < 0)
268  return ret;
269  break;
270 
271  /* magic cookie chunk */
272  case MKBETAG('k','u','k','i'):
273  if (read_kuki_chunk(s, size))
274  return AVERROR_INVALIDDATA;
275  break;
276 
277  /* packet table chunk */
278  case MKBETAG('p','a','k','t'):
279  if (read_pakt_chunk(s, size))
280  return AVERROR_INVALIDDATA;
281  break;
282 
283  case MKBETAG('i','n','f','o'):
284  read_info_chunk(s, size);
285  break;
286 
287  default:
288 #define _(x) ((x) >= ' ' ? (x) : ' ')
290  "skipping CAF chunk: %08"PRIX32" (%c%c%c%c), size %"PRId64"\n",
291  tag, _(tag>>24), _((tag>>16)&0xFF), _((tag>>8)&0xFF), _(tag&0xFF), size);
292 #undef _
293  case MKBETAG('f','r','e','e'):
294  if (size < 0)
295  return AVERROR_INVALIDDATA;
296  break;
297  }
298 
299  if (size > 0) {
300  if (pos > INT64_MAX - size)
301  return AVERROR_INVALIDDATA;
302  avio_skip(pb, FFMAX(0, pos + size - avio_tell(pb)));
303  }
304  }
305 
306  if (!found_data)
307  return AVERROR_INVALIDDATA;
308 
309  if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
310  if (caf->data_size > 0)
311  st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
312  } else if (st->nb_index_entries && st->duration > 0) {
313  st->codec->bit_rate = st->codec->sample_rate * caf->data_size * 8 /
314  st->duration;
315  } else {
316  av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "
317  "block size or frame size are variable.\n");
318  return AVERROR_INVALIDDATA;
319  }
320 
321  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
322  st->start_time = 0;
323 
324  /* position the stream at the start of data */
325  if (caf->data_size >= 0)
326  avio_seek(pb, caf->data_start, SEEK_SET);
327 
328  return 0;
329 }
330 
331 #define CAF_MAX_PKT_SIZE 4096
332 
334 {
335  AVIOContext *pb = s->pb;
336  AVStream *st = s->streams[0];
337  CaffContext *caf = s->priv_data;
338  int res, pkt_size = 0, pkt_frames = 0;
339  int64_t left = CAF_MAX_PKT_SIZE;
340 
341  if (avio_feof(pb))
342  return AVERROR_EOF;
343 
344  /* don't read past end of data chunk */
345  if (caf->data_size > 0) {
346  left = (caf->data_start + caf->data_size) - avio_tell(pb);
347  if (!left)
348  return AVERROR_EOF;
349  if (left < 0)
350  return AVERROR(EIO);
351  }
352 
353  pkt_frames = caf->frames_per_packet;
354  pkt_size = caf->bytes_per_packet;
355 
356  if (pkt_size > 0 && pkt_frames == 1) {
357  pkt_size = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;
358  pkt_size = FFMIN(pkt_size, left);
359  pkt_frames = pkt_size / caf->bytes_per_packet;
360  } else if (st->nb_index_entries) {
361  if (caf->packet_cnt < st->nb_index_entries - 1) {
362  pkt_size = st->index_entries[caf->packet_cnt + 1].pos - st->index_entries[caf->packet_cnt].pos;
363  pkt_frames = st->index_entries[caf->packet_cnt + 1].timestamp - st->index_entries[caf->packet_cnt].timestamp;
364  } else if (caf->packet_cnt == st->nb_index_entries - 1) {
365  pkt_size = caf->num_bytes - st->index_entries[caf->packet_cnt].pos;
366  pkt_frames = st->duration - st->index_entries[caf->packet_cnt].timestamp;
367  } else {
368  return AVERROR(EIO);
369  }
370  }
371 
372  if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)
373  return AVERROR(EIO);
374 
375  res = av_get_packet(pb, pkt, pkt_size);
376  if (res < 0)
377  return res;
378 
379  pkt->size = res;
380  pkt->stream_index = 0;
381  pkt->dts = pkt->pts = caf->frame_cnt;
382 
383  caf->packet_cnt++;
384  caf->frame_cnt += pkt_frames;
385 
386  return 0;
387 }
388 
389 static int read_seek(AVFormatContext *s, int stream_index,
390  int64_t timestamp, int flags)
391 {
392  AVStream *st = s->streams[0];
393  CaffContext *caf = s->priv_data;
394  int64_t pos, packet_cnt, frame_cnt;
395 
396  timestamp = FFMAX(timestamp, 0);
397 
398  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
399  /* calculate new byte position based on target frame position */
400  pos = caf->bytes_per_packet * (timestamp / caf->frames_per_packet);
401  if (caf->data_size > 0)
402  pos = FFMIN(pos, caf->data_size);
403  packet_cnt = pos / caf->bytes_per_packet;
404  frame_cnt = caf->frames_per_packet * packet_cnt;
405  } else if (st->nb_index_entries) {
406  packet_cnt = av_index_search_timestamp(st, timestamp, flags);
407  frame_cnt = st->index_entries[packet_cnt].timestamp;
408  pos = st->index_entries[packet_cnt].pos;
409  } else {
410  return -1;
411  }
412 
413  if (avio_seek(s->pb, pos + caf->data_start, SEEK_SET) < 0)
414  return -1;
415 
416  caf->packet_cnt = packet_cnt;
417  caf->frame_cnt = frame_cnt;
418 
419  return 0;
420 }
421 
423  .name = "caf",
424  .long_name = NULL_IF_CONFIG_SMALL("Apple CAF (Core Audio Format)"),
425  .priv_data_size = sizeof(CaffContext),
426  .read_probe = probe,
429  .read_seek = read_seek,
430  .codec_tag = (const AVCodecTag* const []){ ff_codec_caf_tags, 0 },
431 };