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cafdec.c
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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  MOVAtom atom;
113 
114  strt = avio_tell(pb);
115  ff_mov_read_esds(s, pb, atom);
116  skip = size - (avio_tell(pb) - strt);
117  if (skip < 0 || !st->codec->extradata ||
118  st->codec->codec_id != AV_CODEC_ID_AAC) {
119  av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");
120  return AVERROR_INVALIDDATA;
121  }
122  avio_skip(pb, skip);
123  } else if (st->codec->codec_id == AV_CODEC_ID_ALAC) {
124 #define ALAC_PREAMBLE 12
125 #define ALAC_HEADER 36
126 #define ALAC_NEW_KUKI 24
127  uint8_t preamble[12];
128  if (size < ALAC_NEW_KUKI) {
129  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
130  avio_skip(pb, size);
131  return AVERROR_INVALIDDATA;
132  }
133  avio_read(pb, preamble, ALAC_PREAMBLE);
134 
136  return AVERROR(ENOMEM);
137 
138  /* For the old style cookie, we skip 12 bytes, then read 36 bytes.
139  * The new style cookie only contains the last 24 bytes of what was
140  * 36 bytes in the old style cookie, so we fabricate the first 12 bytes
141  * in that case to maintain compatibility. */
142  if (!memcmp(&preamble[4], "frmaalac", 8)) {
143  if (size < ALAC_PREAMBLE + ALAC_HEADER) {
144  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
145  av_freep(&st->codec->extradata);
146  return AVERROR_INVALIDDATA;
147  }
149  avio_skip(pb, size - ALAC_PREAMBLE - ALAC_HEADER);
150  } else {
151  AV_WB32(st->codec->extradata, 36);
152  memcpy(&st->codec->extradata[4], "alac", 4);
153  AV_WB32(&st->codec->extradata[8], 0);
154  memcpy(&st->codec->extradata[12], preamble, 12);
155  avio_read(pb, &st->codec->extradata[24], ALAC_NEW_KUKI - 12);
156  avio_skip(pb, size - ALAC_NEW_KUKI);
157  }
158  } else {
159  if (ff_get_extradata(st->codec, pb, size) < 0)
160  return AVERROR(ENOMEM);
161  }
162 
163  return 0;
164 }
165 
166 /** Read packet table chunk */
167 static int read_pakt_chunk(AVFormatContext *s, int64_t size)
168 {
169  AVIOContext *pb = s->pb;
170  AVStream *st = s->streams[0];
171  CaffContext *caf = s->priv_data;
172  int64_t pos = 0, ccount, num_packets;
173  int i;
174 
175  ccount = avio_tell(pb);
176 
177  num_packets = avio_rb64(pb);
178  if (num_packets < 0 || INT32_MAX / sizeof(AVIndexEntry) < num_packets)
179  return AVERROR_INVALIDDATA;
180 
181  st->nb_frames = avio_rb64(pb); /* valid frames */
182  st->nb_frames += avio_rb32(pb); /* priming frames */
183  st->nb_frames += avio_rb32(pb); /* remainder frames */
184 
185  st->duration = 0;
186  for (i = 0; i < num_packets; i++) {
187  av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);
190  }
191 
192  if (avio_tell(pb) - ccount > size) {
193  av_log(s, AV_LOG_ERROR, "error reading packet table\n");
194  return AVERROR_INVALIDDATA;
195  }
196  avio_skip(pb, ccount + size - avio_tell(pb));
197 
198  caf->num_bytes = pos;
199  return 0;
200 }
201 
202 /** Read information chunk */
203 static void read_info_chunk(AVFormatContext *s, int64_t size)
204 {
205  AVIOContext *pb = s->pb;
206  unsigned int i;
207  unsigned int nb_entries = avio_rb32(pb);
208  for (i = 0; i < nb_entries; i++) {
209  char key[32];
210  char value[1024];
211  avio_get_str(pb, INT_MAX, key, sizeof(key));
212  avio_get_str(pb, INT_MAX, value, sizeof(value));
213  av_dict_set(&s->metadata, key, value, 0);
214  }
215 }
216 
218 {
219  AVIOContext *pb = s->pb;
220  CaffContext *caf = s->priv_data;
221  AVStream *st;
222  uint32_t tag = 0;
223  int found_data, ret;
224  int64_t size, pos;
225 
226  avio_skip(pb, 8); /* magic, version, file flags */
227 
228  /* audio description chunk */
229  if (avio_rb32(pb) != MKBETAG('d','e','s','c')) {
230  av_log(s, AV_LOG_ERROR, "desc chunk not present\n");
231  return AVERROR_INVALIDDATA;
232  }
233  size = avio_rb64(pb);
234  if (size != 32)
235  return AVERROR_INVALIDDATA;
236 
237  ret = read_desc_chunk(s);
238  if (ret)
239  return ret;
240  st = s->streams[0];
241 
242  /* parse each chunk */
243  found_data = 0;
244  while (!url_feof(pb)) {
245 
246  /* stop at data chunk if seeking is not supported or
247  data chunk size is unknown */
248  if (found_data && (caf->data_size < 0 || !pb->seekable))
249  break;
250 
251  tag = avio_rb32(pb);
252  size = avio_rb64(pb);
253  pos = avio_tell(pb);
254  if (url_feof(pb))
255  break;
256 
257  switch (tag) {
258  case MKBETAG('d','a','t','a'):
259  avio_skip(pb, 4); /* edit count */
260  caf->data_start = avio_tell(pb);
261  caf->data_size = size < 0 ? -1 : size - 4;
262  if (caf->data_size > 0 && pb->seekable)
263  avio_skip(pb, caf->data_size);
264  found_data = 1;
265  break;
266 
267  case MKBETAG('c','h','a','n'):
268  if ((ret = ff_mov_read_chan(s, s->pb, st, size)) < 0)
269  return ret;
270  break;
271 
272  /* magic cookie chunk */
273  case MKBETAG('k','u','k','i'):
274  if (read_kuki_chunk(s, size))
275  return AVERROR_INVALIDDATA;
276  break;
277 
278  /* packet table chunk */
279  case MKBETAG('p','a','k','t'):
280  if (read_pakt_chunk(s, size))
281  return AVERROR_INVALIDDATA;
282  break;
283 
284  case MKBETAG('i','n','f','o'):
285  read_info_chunk(s, size);
286  break;
287 
288  default:
289 #define _(x) ((x) >= ' ' ? (x) : ' ')
291  "skipping CAF chunk: %08"PRIX32" (%c%c%c%c), size %"PRId64"\n",
292  tag, _(tag>>24), _((tag>>16)&0xFF), _((tag>>8)&0xFF), _(tag&0xFF), size);
293 #undef _
294  case MKBETAG('f','r','e','e'):
295  if (size < 0)
296  return AVERROR_INVALIDDATA;
297  break;
298  }
299 
300  if (size > 0) {
301  if (pos > INT64_MAX - size)
302  return AVERROR_INVALIDDATA;
303  avio_skip(pb, FFMAX(0, pos + size - avio_tell(pb)));
304  }
305  }
306 
307  if (!found_data)
308  return AVERROR_INVALIDDATA;
309 
310  if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
311  if (caf->data_size > 0)
312  st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
313  } else if (st->nb_index_entries && st->duration > 0) {
314  st->codec->bit_rate = st->codec->sample_rate * caf->data_size * 8 /
315  st->duration;
316  } else {
317  av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "
318  "block size or frame size are variable.\n");
319  return AVERROR_INVALIDDATA;
320  }
321 
322  avpriv_set_pts_info(st, 64, 1, st->codec->sample_rate);
323  st->start_time = 0;
324 
325  /* position the stream at the start of data */
326  if (caf->data_size >= 0)
327  avio_seek(pb, caf->data_start, SEEK_SET);
328 
329  return 0;
330 }
331 
332 #define CAF_MAX_PKT_SIZE 4096
333 
335 {
336  AVIOContext *pb = s->pb;
337  AVStream *st = s->streams[0];
338  CaffContext *caf = s->priv_data;
339  int res, pkt_size = 0, pkt_frames = 0;
340  int64_t left = CAF_MAX_PKT_SIZE;
341 
342  if (url_feof(pb))
343  return AVERROR_EOF;
344 
345  /* don't read past end of data chunk */
346  if (caf->data_size > 0) {
347  left = (caf->data_start + caf->data_size) - avio_tell(pb);
348  if (!left)
349  return AVERROR_EOF;
350  if (left < 0)
351  return AVERROR(EIO);
352  }
353 
354  pkt_frames = caf->frames_per_packet;
355  pkt_size = caf->bytes_per_packet;
356 
357  if (pkt_size > 0 && pkt_frames == 1) {
358  pkt_size = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;
359  pkt_size = FFMIN(pkt_size, left);
360  pkt_frames = pkt_size / caf->bytes_per_packet;
361  } else if (st->nb_index_entries) {
362  if (caf->packet_cnt < st->nb_index_entries - 1) {
363  pkt_size = st->index_entries[caf->packet_cnt + 1].pos - st->index_entries[caf->packet_cnt].pos;
364  pkt_frames = st->index_entries[caf->packet_cnt + 1].timestamp - st->index_entries[caf->packet_cnt].timestamp;
365  } else if (caf->packet_cnt == st->nb_index_entries - 1) {
366  pkt_size = caf->num_bytes - st->index_entries[caf->packet_cnt].pos;
367  pkt_frames = st->duration - st->index_entries[caf->packet_cnt].timestamp;
368  } else {
369  return AVERROR(EIO);
370  }
371  }
372 
373  if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)
374  return AVERROR(EIO);
375 
376  res = av_get_packet(pb, pkt, pkt_size);
377  if (res < 0)
378  return res;
379 
380  pkt->size = res;
381  pkt->stream_index = 0;
382  pkt->dts = pkt->pts = caf->frame_cnt;
383 
384  caf->packet_cnt++;
385  caf->frame_cnt += pkt_frames;
386 
387  return 0;
388 }
389 
390 static int read_seek(AVFormatContext *s, int stream_index,
391  int64_t timestamp, int flags)
392 {
393  AVStream *st = s->streams[0];
394  CaffContext *caf = s->priv_data;
395  int64_t pos, packet_cnt, frame_cnt;
396 
397  timestamp = FFMAX(timestamp, 0);
398 
399  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
400  /* calculate new byte position based on target frame position */
401  pos = caf->bytes_per_packet * (timestamp / caf->frames_per_packet);
402  if (caf->data_size > 0)
403  pos = FFMIN(pos, caf->data_size);
404  packet_cnt = pos / caf->bytes_per_packet;
405  frame_cnt = caf->frames_per_packet * packet_cnt;
406  } else if (st->nb_index_entries) {
407  packet_cnt = av_index_search_timestamp(st, timestamp, flags);
408  frame_cnt = st->index_entries[packet_cnt].timestamp;
409  pos = st->index_entries[packet_cnt].pos;
410  } else {
411  return -1;
412  }
413 
414  if (avio_seek(s->pb, pos + caf->data_start, SEEK_SET) < 0)
415  return -1;
416 
417  caf->packet_cnt = packet_cnt;
418  caf->frame_cnt = frame_cnt;
419 
420  return 0;
421 }
422 
424  .name = "caf",
425  .long_name = NULL_IF_CONFIG_SMALL("Apple CAF (Core Audio Format)"),
426  .priv_data_size = sizeof(CaffContext),
427  .read_probe = probe,
430  .read_seek = read_seek,
431  .codec_tag = (const AVCodecTag* const []){ ff_codec_caf_tags, 0 },
432 };