FFmpeg
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 CafContext {
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 } CafContext;
50 
51 static int probe(const 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  CafContext *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->codecpar->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->codecpar->channels = avio_rb32(pb);
81 
82  if (caf->bytes_per_packet < 0 || caf->frames_per_packet < 0)
83  return AVERROR_INVALIDDATA;
84 
85  /* calculate bit rate for constant size packets */
86  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
87  st->codecpar->bit_rate = (uint64_t)st->codecpar->sample_rate * (uint64_t)caf->bytes_per_packet * 8
88  / (uint64_t)caf->frames_per_packet;
89  } else {
90  st->codecpar->bit_rate = 0;
91  }
92 
93  /* determine codec */
94  if (st->codecpar->codec_tag == MKTAG('l','p','c','m'))
96  else
98  return 0;
99 }
100 
101 /** Read magic cookie chunk */
102 static int read_kuki_chunk(AVFormatContext *s, int64_t size)
103 {
104  AVIOContext *pb = s->pb;
105  AVStream *st = s->streams[0];
106  int ret;
107 
109  return -1;
110 
111  if (st->codecpar->codec_id == AV_CODEC_ID_AAC) {
112  /* The magic cookie format for AAC is an mp4 esds atom.
113  The lavc AAC decoder requires the data from the codec specific
114  description as extradata input. */
115  int strt, skip;
116 
117  strt = avio_tell(pb);
118  ff_mov_read_esds(s, pb);
119  skip = size - (avio_tell(pb) - strt);
120  if (skip < 0 || !st->codecpar->extradata ||
122  av_log(s, AV_LOG_ERROR, "invalid AAC magic cookie\n");
123  return AVERROR_INVALIDDATA;
124  }
125  avio_skip(pb, skip);
126  } else if (st->codecpar->codec_id == AV_CODEC_ID_ALAC) {
127 #define ALAC_PREAMBLE 12
128 #define ALAC_HEADER 36
129 #define ALAC_NEW_KUKI 24
130  uint8_t preamble[12];
131  if (size < ALAC_NEW_KUKI) {
132  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
133  avio_skip(pb, size);
134  return AVERROR_INVALIDDATA;
135  }
136  if (avio_read(pb, preamble, ALAC_PREAMBLE) != ALAC_PREAMBLE) {
137  av_log(s, AV_LOG_ERROR, "failed to read preamble\n");
138  return AVERROR_INVALIDDATA;
139  }
140 
141  if ((ret = ff_alloc_extradata(st->codecpar, ALAC_HEADER)) < 0)
142  return ret;
143 
144  /* For the old style cookie, we skip 12 bytes, then read 36 bytes.
145  * The new style cookie only contains the last 24 bytes of what was
146  * 36 bytes in the old style cookie, so we fabricate the first 12 bytes
147  * in that case to maintain compatibility. */
148  if (!memcmp(&preamble[4], "frmaalac", 8)) {
149  if (size < ALAC_PREAMBLE + ALAC_HEADER) {
150  av_log(s, AV_LOG_ERROR, "invalid ALAC magic cookie\n");
151  av_freep(&st->codecpar->extradata);
152  return AVERROR_INVALIDDATA;
153  }
154  if (avio_read(pb, st->codecpar->extradata, ALAC_HEADER) != ALAC_HEADER) {
155  av_log(s, AV_LOG_ERROR, "failed to read kuki header\n");
156  av_freep(&st->codecpar->extradata);
157  return AVERROR_INVALIDDATA;
158  }
159  avio_skip(pb, size - ALAC_PREAMBLE - ALAC_HEADER);
160  } else {
161  AV_WB32(st->codecpar->extradata, 36);
162  memcpy(&st->codecpar->extradata[4], "alac", 4);
163  AV_WB32(&st->codecpar->extradata[8], 0);
164  memcpy(&st->codecpar->extradata[12], preamble, 12);
165  if (avio_read(pb, &st->codecpar->extradata[24], ALAC_NEW_KUKI - 12) != ALAC_NEW_KUKI - 12) {
166  av_log(s, AV_LOG_ERROR, "failed to read new kuki header\n");
167  av_freep(&st->codecpar->extradata);
168  return AVERROR_INVALIDDATA;
169  }
170  avio_skip(pb, size - ALAC_NEW_KUKI);
171  }
172  } else if (st->codecpar->codec_id == AV_CODEC_ID_OPUS) {
173  // The data layout for Opus is currently unknown, so we do not export
174  // extradata at all. Multichannel streams are not supported.
175  if (st->codecpar->channels > 2) {
176  avpriv_request_sample(s, "multichannel Opus in CAF");
177  return AVERROR_PATCHWELCOME;
178  }
179  avio_skip(pb, size);
180  } else if ((ret = ff_get_extradata(s, st->codecpar, pb, size)) < 0) {
181  return ret;
182  }
183 
184  return 0;
185 }
186 
187 /** Read packet table chunk */
188 static int read_pakt_chunk(AVFormatContext *s, int64_t size)
189 {
190  AVIOContext *pb = s->pb;
191  AVStream *st = s->streams[0];
192  CafContext *caf = s->priv_data;
193  int64_t pos = 0, ccount, num_packets;
194  int i;
195  int ret;
196 
197  ccount = avio_tell(pb);
198 
199  num_packets = avio_rb64(pb);
200  if (num_packets < 0 || INT32_MAX / sizeof(AVIndexEntry) < num_packets)
201  return AVERROR_INVALIDDATA;
202 
203  st->nb_frames = avio_rb64(pb); /* valid frames */
204  st->nb_frames += avio_rb32(pb); /* priming frames */
205  st->nb_frames += avio_rb32(pb); /* remainder frames */
206 
207  st->duration = 0;
208  for (i = 0; i < num_packets; i++) {
209  if (avio_feof(pb))
210  return AVERROR_INVALIDDATA;
211  ret = av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);
212  if (ret < 0)
213  return ret;
216  }
217 
218  if (avio_tell(pb) - ccount > size) {
219  av_log(s, AV_LOG_ERROR, "error reading packet table\n");
220  return AVERROR_INVALIDDATA;
221  }
222  avio_skip(pb, ccount + size - avio_tell(pb));
223 
224  caf->num_bytes = pos;
225  return 0;
226 }
227 
228 /** Read information chunk */
229 static void read_info_chunk(AVFormatContext *s, int64_t size)
230 {
231  AVIOContext *pb = s->pb;
232  unsigned int i;
233  unsigned int nb_entries = avio_rb32(pb);
234  for (i = 0; i < nb_entries && !avio_feof(pb); i++) {
235  char key[32];
236  char value[1024];
237  avio_get_str(pb, INT_MAX, key, sizeof(key));
238  avio_get_str(pb, INT_MAX, value, sizeof(value));
239  av_dict_set(&s->metadata, key, value, 0);
240  }
241 }
242 
244 {
245  AVIOContext *pb = s->pb;
246  CafContext *caf = s->priv_data;
247  AVStream *st;
248  uint32_t tag = 0;
249  int found_data, ret;
250  int64_t size, pos;
251 
252  avio_skip(pb, 8); /* magic, version, file flags */
253 
254  /* audio description chunk */
255  if (avio_rb32(pb) != MKBETAG('d','e','s','c')) {
256  av_log(s, AV_LOG_ERROR, "desc chunk not present\n");
257  return AVERROR_INVALIDDATA;
258  }
259  size = avio_rb64(pb);
260  if (size != 32)
261  return AVERROR_INVALIDDATA;
262 
263  ret = read_desc_chunk(s);
264  if (ret)
265  return ret;
266  st = s->streams[0];
267 
268  /* parse each chunk */
269  found_data = 0;
270  while (!avio_feof(pb)) {
271 
272  /* stop at data chunk if seeking is not supported or
273  data chunk size is unknown */
274  if (found_data && (caf->data_size < 0 || !(pb->seekable & AVIO_SEEKABLE_NORMAL)))
275  break;
276 
277  tag = avio_rb32(pb);
278  size = avio_rb64(pb);
279  pos = avio_tell(pb);
280  if (avio_feof(pb))
281  break;
282 
283  switch (tag) {
284  case MKBETAG('d','a','t','a'):
285  avio_skip(pb, 4); /* edit count */
286  caf->data_start = avio_tell(pb);
287  caf->data_size = size < 0 ? -1 : size - 4;
288  if (caf->data_size > 0 && (pb->seekable & AVIO_SEEKABLE_NORMAL))
289  avio_skip(pb, caf->data_size);
290  found_data = 1;
291  break;
292 
293  case MKBETAG('c','h','a','n'):
294  if ((ret = ff_mov_read_chan(s, s->pb, st, size)) < 0)
295  return ret;
296  break;
297 
298  /* magic cookie chunk */
299  case MKBETAG('k','u','k','i'):
300  if (read_kuki_chunk(s, size))
301  return AVERROR_INVALIDDATA;
302  break;
303 
304  /* packet table chunk */
305  case MKBETAG('p','a','k','t'):
306  if (read_pakt_chunk(s, size))
307  return AVERROR_INVALIDDATA;
308  break;
309 
310  case MKBETAG('i','n','f','o'):
311  read_info_chunk(s, size);
312  break;
313 
314  default:
316  "skipping CAF chunk: %08"PRIX32" (%s), size %"PRId64"\n",
317  tag, av_fourcc2str(av_bswap32(tag)), size);
318  case MKBETAG('f','r','e','e'):
319  if (size < 0 && found_data)
320  goto found_data;
321  if (size < 0)
322  return AVERROR_INVALIDDATA;
323  break;
324  }
325 
326  if (size > 0) {
327  if (pos > INT64_MAX - size)
328  return AVERROR_INVALIDDATA;
329  avio_skip(pb, FFMAX(0, pos + size - avio_tell(pb)));
330  }
331  }
332 
333  if (!found_data)
334  return AVERROR_INVALIDDATA;
335 
336 found_data:
337  if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
338  if (caf->data_size > 0)
339  st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
340  } else if (st->internal->nb_index_entries && st->duration > 0) {
341  if (st->codecpar->sample_rate && caf->data_size / st->duration > INT64_MAX / st->codecpar->sample_rate / 8) {
342  av_log(s, AV_LOG_ERROR, "Overflow during bit rate calculation %d * 8 * %"PRId64"\n",
343  st->codecpar->sample_rate, caf->data_size / st->duration);
344  return AVERROR_INVALIDDATA;
345  }
346  st->codecpar->bit_rate = st->codecpar->sample_rate * 8LL *
347  (caf->data_size / st->duration);
348  } else {
349  av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "
350  "block size or frame size are variable.\n");
351  return AVERROR_INVALIDDATA;
352  }
353 
354  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
355  st->start_time = 0;
356 
357  /* position the stream at the start of data */
358  if (caf->data_size >= 0)
359  avio_seek(pb, caf->data_start, SEEK_SET);
360 
361  return 0;
362 }
363 
364 #define CAF_MAX_PKT_SIZE 4096
365 
367 {
368  AVIOContext *pb = s->pb;
369  AVStream *st = s->streams[0];
370  CafContext *caf = s->priv_data;
371  int res, pkt_size = 0, pkt_frames = 0;
372  int64_t left = CAF_MAX_PKT_SIZE;
373 
374  if (avio_feof(pb))
375  return AVERROR_EOF;
376 
377  /* don't read past end of data chunk */
378  if (caf->data_size > 0) {
379  left = (caf->data_start + caf->data_size) - avio_tell(pb);
380  if (!left)
381  return AVERROR_EOF;
382  if (left < 0)
383  return AVERROR(EIO);
384  }
385 
386  pkt_frames = caf->frames_per_packet;
387  pkt_size = caf->bytes_per_packet;
388 
389  if (pkt_size > 0 && pkt_frames == 1) {
390  pkt_size = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;
391  pkt_size = FFMIN(pkt_size, left);
392  pkt_frames = pkt_size / caf->bytes_per_packet;
393  } else if (st->internal->nb_index_entries) {
394  if (caf->packet_cnt < st->internal->nb_index_entries - 1) {
395  pkt_size = st->internal->index_entries[caf->packet_cnt + 1].pos - st->internal->index_entries[caf->packet_cnt].pos;
396  pkt_frames = st->internal->index_entries[caf->packet_cnt + 1].timestamp - st->internal->index_entries[caf->packet_cnt].timestamp;
397  } else if (caf->packet_cnt == st->internal->nb_index_entries - 1) {
398  pkt_size = caf->num_bytes - st->internal->index_entries[caf->packet_cnt].pos;
399  pkt_frames = st->duration - st->internal->index_entries[caf->packet_cnt].timestamp;
400  } else {
401  return AVERROR(EIO);
402  }
403  }
404 
405  if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)
406  return AVERROR(EIO);
407 
408  res = av_get_packet(pb, pkt, pkt_size);
409  if (res < 0)
410  return res;
411 
412  pkt->size = res;
413  pkt->stream_index = 0;
414  pkt->dts = pkt->pts = caf->frame_cnt;
415 
416  caf->packet_cnt++;
417  caf->frame_cnt += pkt_frames;
418 
419  return 0;
420 }
421 
422 static int read_seek(AVFormatContext *s, int stream_index,
423  int64_t timestamp, int flags)
424 {
425  AVStream *st = s->streams[0];
426  CafContext *caf = s->priv_data;
427  int64_t pos, packet_cnt, frame_cnt;
428 
429  timestamp = FFMAX(timestamp, 0);
430 
431  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
432  /* calculate new byte position based on target frame position */
433  pos = caf->bytes_per_packet * (timestamp / caf->frames_per_packet);
434  if (caf->data_size > 0)
435  pos = FFMIN(pos, caf->data_size);
436  packet_cnt = pos / caf->bytes_per_packet;
437  frame_cnt = caf->frames_per_packet * packet_cnt;
438  } else if (st->internal->nb_index_entries) {
439  packet_cnt = av_index_search_timestamp(st, timestamp, flags);
440  frame_cnt = st->internal->index_entries[packet_cnt].timestamp;
441  pos = st->internal->index_entries[packet_cnt].pos;
442  } else {
443  return -1;
444  }
445 
446  if (avio_seek(s->pb, pos + caf->data_start, SEEK_SET) < 0)
447  return -1;
448 
449  caf->packet_cnt = packet_cnt;
450  caf->frame_cnt = frame_cnt;
451 
452  return 0;
453 }
454 
456  .name = "caf",
457  .long_name = NULL_IF_CONFIG_SMALL("Apple CAF (Core Audio Format)"),
458  .priv_data_size = sizeof(CafContext),
459  .read_probe = probe,
462  .read_seek = read_seek,
463  .codec_tag = (const AVCodecTag* const []){ ff_codec_caf_tags, 0 },
464 };
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cafdec.c:366
int av_add_index_entry(AVStream *st, int64_t pos, int64_t timestamp, int size, int distance, int flags)
Add an index entry into a sorted list.
Definition: utils.c:1984
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:3097
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:200
int bytes_per_packet
bytes in a packet, or 0 if variable
Definition: cafdec.c:40
void avpriv_set_pts_info(AVStream *s, int pts_wrap_bits, unsigned int pts_num, unsigned int pts_den)
Set the time base and wrapping info for a given stream.
Definition: utils.c:4871
int64_t pos
Definition: avformat.h:809
#define avpriv_request_sample(...)
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
int size
Definition: packet.h:364
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:253
CAF common code.
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:341
const char * key
static AVPacket pkt
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_WB32 unsigned int_TMPL AV_WB24 unsigned int_TMPL AV_RB16
Definition: bytestream.h:91
#define CAF_MAX_PKT_SIZE
Definition: cafdec.c:364
static int read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
Definition: cafdec.c:422
static int read_header(AVFormatContext *s)
Definition: cafdec.c:243
Format I/O context.
Definition: avformat.h:1239
#define ALAC_PREAMBLE
Public dictionary API.
static av_always_inline double av_int2double(uint64_t i)
Reinterpret a 64-bit integer as a double.
Definition: intfloat.h:60
uint8_t
static int read_kuki_chunk(AVFormatContext *s, int64_t size)
Read magic cookie chunk.
Definition: cafdec.c:102
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:785
GLsizei GLboolean const GLfloat * value
Definition: opengl_enc.c:108
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4453
uint64_t_TMPL AV_WL64 unsigned int_TMPL AV_WL32 unsigned int_TMPL AV_WL24 unsigned int_TMPL AV_WL16 uint64_t_TMPL AV_WB64 unsigned int_TMPL AV_RB32
Definition: bytestream.h:91
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1307
uint32_t tag
Definition: movenc.c:1597
#define AVERROR_EOF
End of file.
Definition: error.h:55
int av_get_packet(AVIOContext *s, AVPacket *pkt, int size)
Allocate and read the payload of a packet and initialize its fields with default values.
Definition: utils.c:305
ptrdiff_t size
Definition: opengl_enc.c:100
uint64_t avio_rb64(AVIOContext *s)
Definition: aviobuf.c:906
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
#define av_log(a,...)
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:637
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
#define AVINDEX_KEYFRAME
Definition: avformat.h:816
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1479
int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags)
Get the index for a specific timestamp.
Definition: utils.c:2101
int ff_mp4_read_descr_len(AVIOContext *pb)
Definition: isom.c:591
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:754
int64_t timestamp
Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are...
Definition: avformat.h:810
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:153
unsigned int pos
Definition: spdifenc.c:410
#define av_fourcc2str(fourcc)
Definition: avutil.h:348
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
int64_t num_bytes
total number of bytes in stream
Definition: cafdec.c:42
#define FFMAX(a, b)
Definition: common.h:94
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
AVIndexEntry * index_entries
Only used if the format does not support seeking natively.
Definition: internal.h:228
int block_align
Audio only.
Definition: codec_par.h:177
int seekable
A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
Definition: avio.h:260
int ff_alloc_extradata(AVCodecParameters *par, int size)
Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end which is always set to 0...
Definition: utils.c:3260
#define FFMIN(a, b)
Definition: common.h:96
int64_t data_start
data start position, in bytes
Definition: cafdec.c:47
int64_t data_size
raw data size, in bytes
Definition: cafdec.c:48
AVInputFormat ff_caf_demuxer
Definition: cafdec.c:455
#define s(width, name)
Definition: cbs_vp9.c:257
#define ALAC_NEW_KUKI
int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st, int64_t size)
Read &#39;chan&#39; tag from the input stream.
Definition: mov_chan.c:547
int ff_mov_read_esds(AVFormatContext *fc, AVIOContext *pb)
Definition: mov_esds.c:23
Stream structure.
Definition: avformat.h:880
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
#define av_bswap32
Definition: bswap.h:33
AVStreamInternal * internal
An opaque field for libavformat internal usage.
Definition: avformat.h:1119
AVIOContext * pb
I/O context.
Definition: avformat.h:1281
Tag MUST be and< 10hcoeff half pel interpolation filter coefficients, hcoeff[0] are the 2 middle coefficients[1] are the next outer ones and so on, resulting in a filter like:...eff[2], hcoeff[1], hcoeff[0], hcoeff[0], hcoeff[1], hcoeff[2]...the sign of the coefficients is not explicitly stored but alternates after each coeff and coeff[0] is positive, so...,+,-,+,-,+,+,-,+,-,+,...hcoeff[0] is not explicitly stored but found by subtracting the sum of all stored coefficients with signs from 32 hcoeff[0]=32-hcoeff[1]-hcoeff[2]-...a good choice for hcoeff and htaps is htaps=6 hcoeff={40,-10, 2}an alternative which requires more computations at both encoder and decoder side and may or may not be better is htaps=8 hcoeff={42,-14, 6,-2}ref_frames minimum of the number of available reference frames and max_ref_frames for example the first frame after a key frame always has ref_frames=1spatial_decomposition_type wavelet type 0 is a 9/7 symmetric compact integer wavelet 1 is a 5/3 symmetric compact integer wavelet others are reserved stored as delta from last, last is reset to 0 if always_reset||keyframeqlog quality(logarithmic quantizer scale) stored as delta from last, last is reset to 0 if always_reset||keyframemv_scale stored as delta from last, last is reset to 0 if always_reset||keyframe FIXME check that everything works fine if this changes between framesqbias dequantization bias stored as delta from last, last is reset to 0 if always_reset||keyframeblock_max_depth maximum depth of the block tree stored as delta from last, last is reset to 0 if always_reset||keyframequant_table quantization tableHighlevel bitstream structure:==============================--------------------------------------------|Header|--------------------------------------------|------------------------------------|||Block0||||split?||||yes no||||.........intra?||||:Block01:yes no||||:Block02:.................||||:Block03::y DC::ref index:||||:Block04::cb DC::motion x:||||.........:cr DC::motion y:||||.................|||------------------------------------||------------------------------------|||Block1|||...|--------------------------------------------|------------------------------------|||Y subbands||Cb subbands||Cr subbands||||------||------||------|||||LL0||HL0||||LL0||HL0||||LL0||HL0|||||------||------||------||||------||------||------|||||LH0||HH0||||LH0||HH0||||LH0||HH0|||||------||------||------||||------||------||------|||||HL1||LH1||||HL1||LH1||||HL1||LH1|||||------||------||------||||------||------||------|||||HH1||HL2||||HH1||HL2||||HH1||HL2|||||...||...||...|||------------------------------------|--------------------------------------------Decoding process:=================------------|||Subbands|------------||||------------|Intra DC||||LL0 subband prediction------------|\Dequantization-------------------\||Reference frames|\IDWT|--------------|Motion\|||Frame 0||Frame 1||Compensation.OBMC v-------|--------------|--------------.\------> Frame n output Frame Frame<----------------------------------/|...|-------------------Range Coder:============Binary Range Coder:-------------------The implemented range coder is an adapted version based upon"Range encoding: an algorithm for removing redundancy from a digitised message."by G.N.N.Martin.The symbols encoded by the Snow range coder are bits(0|1).The associated probabilities are not fix but change depending on the symbol mix seen so far.bit seen|new state---------+-----------------------------------------------0|256-state_transition_table[256-old_state];1|state_transition_table[old_state];state_transition_table={0, 0, 0, 0, 0, 0, 0, 0, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 190, 191, 192, 194, 194, 195, 196, 197, 198, 199, 200, 201, 202, 202, 204, 205, 206, 207, 208, 209, 209, 210, 211, 212, 213, 215, 215, 216, 217, 218, 219, 220, 220, 222, 223, 224, 225, 226, 227, 227, 229, 229, 230, 231, 232, 234, 234, 235, 236, 237, 238, 239, 240, 241, 242, 243, 244, 245, 246, 247, 248, 248, 0, 0, 0, 0, 0, 0, 0};FIXME Range Coding of integers:-------------------------FIXME Neighboring Blocks:===================left and top are set to the respective blocks unless they are outside of the image in which case they are set to the Null block top-left is set to the top left block unless it is outside of the image in which case it is set to the left block if this block has no larger parent block or it is at the left side of its parent block and the top right block is not outside of the image then the top right block is used for top-right else the top-left block is used Null block y, cb, cr are 128 level, ref, mx and my are 0 Motion Vector Prediction:=========================1.the motion vectors of all the neighboring blocks are scaled to compensate for the difference of reference frames scaled_mv=(mv *(256 *(current_reference+1)/(mv.reference+1))+128)> the median of the scaled left
Definition: snow.txt:206
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
Definition: dict.c:70
#define AV_WB32(p, v)
Definition: intreadwrite.h:419
int frames_per_packet
frames in a packet, or 0 if variable
Definition: cafdec.c:41
static void read_info_chunk(AVFormatContext *s, int64_t size)
Read information chunk.
Definition: cafdec.c:229
static enum AVCodecID ff_mov_get_lpcm_codec_id(int bps, int flags)
Compute codec id for &#39;lpcm&#39; tag.
Definition: isom.h:379
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
static int read_pakt_chunk(AVFormatContext *s, int64_t size)
Read packet table chunk.
Definition: cafdec.c:188
int nb_index_entries
Definition: internal.h:230
#define flags(name, subs,...)
Definition: cbs_av1.c:560
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:929
int sample_rate
Audio only.
Definition: codec_par.h:170
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
Main libavformat public API header.
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base...
Definition: avformat.h:919
int ff_get_extradata(AVFormatContext *s, AVCodecParameters *par, AVIOContext *pb, int size)
Allocate extradata with additional AV_INPUT_BUFFER_PADDING_SIZE at end which is always set to 0 and f...
Definition: utils.c:3278
int64_t nb_frames
number of frames in this stream if known or 0
Definition: avformat.h:931
#define ALAC_HEADER
#define MKBETAG(a, b, c, d)
Definition: common.h:406
#define AV_INPUT_BUFFER_PADDING_SIZE
Required number of additionally allocated bytes at the end of the input bitstream for decoding...
Definition: avcodec.h:215
void * priv_data
Format private data.
Definition: avformat.h:1267
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:102
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: codec_par.h:74
int channels
Audio only.
Definition: codec_par.h:166
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed...
Definition: packet.h:362
static int probe(const AVProbeData *p)
Definition: cafdec.c:51
#define av_freep(p)
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:652
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1045
int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen)
Read a string from pb into buf.
Definition: aviobuf.c:864
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:368
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:64
static int read_desc_chunk(AVFormatContext *s)
Read audio description chunk.
Definition: cafdec.c:59
int stream_index
Definition: packet.h:365
const AVCodecTag ff_codec_caf_tags[]
Known codec tags for CAF.
Definition: caf.c:34
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later.That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another.Frame references ownership and permissions
#define MKTAG(a, b, c, d)
Definition: common.h:405
This structure stores compressed data.
Definition: packet.h:340
int64_t packet_cnt
packet counter
Definition: cafdec.c:44
int64_t frame_cnt
frame counter
Definition: cafdec.c:45
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:356
int i
Definition: input.c:407