FFmpeg
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 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 */
73  st->codecpar->sample_rate = av_clipd(av_int2double(avio_rb64(pb)), 0, INT_MAX);
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 || st->codecpar->channels < 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 
108  if (size < 0 || size > INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE)
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  }
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  }
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  if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
208  st->duration = caf->frames_per_packet * num_packets;
209  pos = caf-> bytes_per_packet * num_packets;
210  } else {
211  st->duration = 0;
212  for (i = 0; i < num_packets; i++) {
213  if (avio_feof(pb))
214  return AVERROR_INVALIDDATA;
215  ret = av_add_index_entry(s->streams[0], pos, st->duration, 0, 0, AVINDEX_KEYFRAME);
216  if (ret < 0)
217  return ret;
220  }
221  }
222 
223  if (avio_tell(pb) - ccount > size) {
224  av_log(s, AV_LOG_ERROR, "error reading packet table\n");
225  return AVERROR_INVALIDDATA;
226  }
227  avio_skip(pb, ccount + size - avio_tell(pb));
228 
229  caf->num_bytes = pos;
230  return 0;
231 }
232 
233 /** Read information chunk */
234 static void read_info_chunk(AVFormatContext *s, int64_t size)
235 {
236  AVIOContext *pb = s->pb;
237  unsigned int i;
238  unsigned int nb_entries = avio_rb32(pb);
239  for (i = 0; i < nb_entries && !avio_feof(pb); i++) {
240  char key[32];
241  char value[1024];
242  avio_get_str(pb, INT_MAX, key, sizeof(key));
243  avio_get_str(pb, INT_MAX, value, sizeof(value));
244  av_dict_set(&s->metadata, key, value, 0);
245  }
246 }
247 
249 {
250  AVIOContext *pb = s->pb;
251  CafContext *caf = s->priv_data;
252  AVStream *st;
253  uint32_t tag = 0;
254  int found_data, ret;
255  int64_t size, pos;
256 
257  avio_skip(pb, 8); /* magic, version, file flags */
258 
259  /* audio description chunk */
260  if (avio_rb32(pb) != MKBETAG('d','e','s','c')) {
261  av_log(s, AV_LOG_ERROR, "desc chunk not present\n");
262  return AVERROR_INVALIDDATA;
263  }
264  size = avio_rb64(pb);
265  if (size != 32)
266  return AVERROR_INVALIDDATA;
267 
268  ret = read_desc_chunk(s);
269  if (ret)
270  return ret;
271  st = s->streams[0];
272 
273  /* parse each chunk */
274  found_data = 0;
275  while (!avio_feof(pb)) {
276 
277  /* stop at data chunk if seeking is not supported or
278  data chunk size is unknown */
279  if (found_data && (caf->data_size < 0 || !(pb->seekable & AVIO_SEEKABLE_NORMAL)))
280  break;
281 
282  tag = avio_rb32(pb);
283  size = avio_rb64(pb);
284  pos = avio_tell(pb);
285  if (avio_feof(pb))
286  break;
287 
288  switch (tag) {
289  case MKBETAG('d','a','t','a'):
290  avio_skip(pb, 4); /* edit count */
291  caf->data_start = avio_tell(pb);
292  caf->data_size = size < 0 ? -1 : size - 4;
293  if (caf->data_size > 0 && (pb->seekable & AVIO_SEEKABLE_NORMAL))
294  avio_skip(pb, caf->data_size);
295  found_data = 1;
296  break;
297 
298  case MKBETAG('c','h','a','n'):
299  if ((ret = ff_mov_read_chan(s, s->pb, st, size)) < 0)
300  return ret;
301  break;
302 
303  /* magic cookie chunk */
304  case MKBETAG('k','u','k','i'):
305  if (read_kuki_chunk(s, size))
306  return AVERROR_INVALIDDATA;
307  break;
308 
309  /* packet table chunk */
310  case MKBETAG('p','a','k','t'):
311  if (read_pakt_chunk(s, size))
312  return AVERROR_INVALIDDATA;
313  break;
314 
315  case MKBETAG('i','n','f','o'):
317  break;
318 
319  default:
321  "skipping CAF chunk: %08"PRIX32" (%s), size %"PRId64"\n",
323  case MKBETAG('f','r','e','e'):
324  if (size < 0 && found_data)
325  goto found_data;
326  if (size < 0)
327  return AVERROR_INVALIDDATA;
328  break;
329  }
330 
331  if (size > 0) {
332  if (pos > INT64_MAX - size)
333  return AVERROR_INVALIDDATA;
334  avio_skip(pb, FFMAX(0, pos + size - avio_tell(pb)));
335  }
336  }
337 
338  if (!found_data)
339  return AVERROR_INVALIDDATA;
340 
341 found_data:
342  if (caf->bytes_per_packet > 0 && caf->frames_per_packet > 0) {
343  if (caf->data_size > 0)
344  st->nb_frames = (caf->data_size / caf->bytes_per_packet) * caf->frames_per_packet;
345  } else if (st->internal->nb_index_entries && st->duration > 0) {
346  if (st->codecpar->sample_rate && caf->data_size / st->duration > INT64_MAX / st->codecpar->sample_rate / 8) {
347  av_log(s, AV_LOG_ERROR, "Overflow during bit rate calculation %d * 8 * %"PRId64"\n",
348  st->codecpar->sample_rate, caf->data_size / st->duration);
349  return AVERROR_INVALIDDATA;
350  }
351  st->codecpar->bit_rate = st->codecpar->sample_rate * 8LL *
352  (caf->data_size / st->duration);
353  } else {
354  av_log(s, AV_LOG_ERROR, "Missing packet table. It is required when "
355  "block size or frame size are variable.\n");
356  return AVERROR_INVALIDDATA;
357  }
358 
359  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
360  st->start_time = 0;
361 
362  /* position the stream at the start of data */
363  if (caf->data_size >= 0)
364  avio_seek(pb, caf->data_start, SEEK_SET);
365 
366  return 0;
367 }
368 
369 #define CAF_MAX_PKT_SIZE 4096
370 
372 {
373  AVIOContext *pb = s->pb;
374  AVStream *st = s->streams[0];
375  CafContext *caf = s->priv_data;
376  int res, pkt_size = 0, pkt_frames = 0;
377  int64_t left = CAF_MAX_PKT_SIZE;
378 
379  if (avio_feof(pb))
380  return AVERROR_EOF;
381 
382  /* don't read past end of data chunk */
383  if (caf->data_size > 0) {
384  left = (caf->data_start + caf->data_size) - avio_tell(pb);
385  if (!left)
386  return AVERROR_EOF;
387  if (left < 0)
388  return AVERROR(EIO);
389  }
390 
391  pkt_frames = caf->frames_per_packet;
392  pkt_size = caf->bytes_per_packet;
393 
394  if (pkt_size > 0 && pkt_frames == 1) {
395  pkt_size = (CAF_MAX_PKT_SIZE / pkt_size) * pkt_size;
396  pkt_size = FFMIN(pkt_size, left);
397  pkt_frames = pkt_size / caf->bytes_per_packet;
398  } else if (st->internal->nb_index_entries) {
399  if (caf->packet_cnt < st->internal->nb_index_entries - 1) {
400  pkt_size = st->internal->index_entries[caf->packet_cnt + 1].pos - st->internal->index_entries[caf->packet_cnt].pos;
401  pkt_frames = st->internal->index_entries[caf->packet_cnt + 1].timestamp - st->internal->index_entries[caf->packet_cnt].timestamp;
402  } else if (caf->packet_cnt == st->internal->nb_index_entries - 1) {
403  pkt_size = caf->num_bytes - st->internal->index_entries[caf->packet_cnt].pos;
404  pkt_frames = st->duration - st->internal->index_entries[caf->packet_cnt].timestamp;
405  } else {
406  return AVERROR(EIO);
407  }
408  }
409 
410  if (pkt_size == 0 || pkt_frames == 0 || pkt_size > left)
411  return AVERROR(EIO);
412 
413  res = av_get_packet(pb, pkt, pkt_size);
414  if (res < 0)
415  return res;
416 
417  pkt->size = res;
418  pkt->stream_index = 0;
419  pkt->dts = pkt->pts = caf->frame_cnt;
420 
421  caf->packet_cnt++;
422  caf->frame_cnt += pkt_frames;
423 
424  return 0;
425 }
426 
427 static int read_seek(AVFormatContext *s, int stream_index,
428  int64_t timestamp, int flags)
429 {
430  AVStream *st = s->streams[0];
431  CafContext *caf = s->priv_data;
432  int64_t pos, packet_cnt, frame_cnt;
433 
434  timestamp = FFMAX(timestamp, 0);
435 
436  if (caf->frames_per_packet > 0 && caf->bytes_per_packet > 0) {
437  /* calculate new byte position based on target frame position */
438  pos = caf->bytes_per_packet * (timestamp / caf->frames_per_packet);
439  if (caf->data_size > 0)
440  pos = FFMIN(pos, caf->data_size);
441  packet_cnt = pos / caf->bytes_per_packet;
442  frame_cnt = caf->frames_per_packet * packet_cnt;
443  } else if (st->internal->nb_index_entries) {
444  packet_cnt = av_index_search_timestamp(st, timestamp, flags);
445  frame_cnt = st->internal->index_entries[packet_cnt].timestamp;
446  pos = st->internal->index_entries[packet_cnt].pos;
447  } else {
448  return -1;
449  }
450 
451  if (avio_seek(s->pb, pos + caf->data_start, SEEK_SET) < 0)
452  return -1;
453 
454  caf->packet_cnt = packet_cnt;
455  caf->frame_cnt = frame_cnt;
456 
457  return 0;
458 }
459 
461  .name = "caf",
462  .long_name = NULL_IF_CONFIG_SMALL("Apple CAF (Core Audio Format)"),
463  .priv_data_size = sizeof(CafContext),
464  .read_probe = probe,
467  .read_seek = read_seek,
468  .codec_tag = ff_caf_codec_tags_list,
469 };
AV_LOG_WARNING
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:187
AVCodecParameters::extradata
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: codec_par.h:74
AVERROR
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
avformat_new_stream
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4374
AVCodecParameters::codec_type
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
ff_get_extradata
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:3279
CafContext::packet_cnt
int64_t packet_cnt
packet counter
Definition: cafdec.c:44
read_info_chunk
static void read_info_chunk(AVFormatContext *s, int64_t size)
Read information chunk.
Definition: cafdec.c:234
caf.h
CAF_MAX_PKT_SIZE
#define CAF_MAX_PKT_SIZE
Definition: cafdec.c:369
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:55
MKTAG
#define MKTAG(a, b, c, d)
Definition: common.h:478
av_int2double
static av_always_inline double av_int2double(uint64_t i)
Reinterpret a 64-bit integer as a double.
Definition: intfloat.h:60
AVStream::internal
AVStreamInternal * internal
An opaque field for libavformat internal usage.
Definition: avformat.h:1008
AV_CODEC_ID_ALAC
@ AV_CODEC_ID_ALAC
Definition: codec_id.h:437
AVCodecParameters::codec_tag
uint32_t codec_tag
Additional information about the codec (corresponds to the AVI FOURCC).
Definition: codec_par.h:64
intfloat.h
AVIndexEntry
Definition: avformat.h:762
AVINDEX_KEYFRAME
#define AVINDEX_KEYFRAME
Definition: avformat.h:770
AVPROBE_SCORE_MAX
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
AVCodecParameters::channels
int channels
Audio only.
Definition: codec_par.h:166
av_add_index_entry
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:1937
avio_tell
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
ff_caf_demuxer
const AVInputFormat ff_caf_demuxer
Definition: cafdec.c:460
AVStream::duration
int64_t duration
Decoding: duration of the stream, in stream time base.
Definition: avformat.h:875
read_desc_chunk
static int read_desc_chunk(AVFormatContext *s)
Read audio description chunk.
Definition: cafdec.c:59
av_bswap32
#define av_bswap32
Definition: bswap.h:33
avio_rb32
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:764
pkt
AVPacket * pkt
Definition: movenc.c:59
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:181
AVInputFormat
Definition: avformat.h:616
ff_mov_read_esds
int ff_mov_read_esds(AVFormatContext *fc, AVIOContext *pb)
Definition: mov_esds.c:23
intreadwrite.h
s
#define s(width, name)
Definition: cbs_vp9.c:257
AVInputFormat::name
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:621
AVProbeData::buf
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
AVIndexEntry::timestamp
int64_t timestamp
Timestamp in AVStream.time_base units, preferably the time from which on correctly decoded frames are...
Definition: avformat.h:764
key
const char * key
Definition: hwcontext_opencl.c:168
CafContext::data_size
int64_t data_size
raw data size, in bytes
Definition: cafdec.c:48
ff_mov_get_lpcm_codec_id
static enum AVCodecID ff_mov_get_lpcm_codec_id(int bps, int flags)
Compute codec id for 'lpcm' tag.
Definition: isom.h:379
AVFormatContext
Format I/O context.
Definition: avformat.h:1106
internal.h
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:979
NULL
#define NULL
Definition: coverity.c:32
AVERROR_PATCHWELCOME
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
read_probe
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
read_header
static int read_header(AVFormatContext *s)
Definition: cafdec.c:248
isom.h
ALAC_PREAMBLE
#define ALAC_PREAMBLE
avio_rb64
uint64_t avio_rb64(AVIOContext *s)
Definition: aviobuf.c:885
CafContext::data_start
int64_t data_start
data start position, in bytes
Definition: cafdec.c:47
AVProbeData
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
read_kuki_chunk
static int read_kuki_chunk(AVFormatContext *s, int64_t size)
Read magic cookie chunk.
Definition: cafdec.c:102
CafContext::num_bytes
int64_t num_bytes
total number of bytes in stream
Definition: cafdec.c:42
AVCodecParameters::sample_rate
int sample_rate
Audio only.
Definition: codec_par.h:170
AVStream::nb_frames
int64_t nb_frames
number of frames in this stream if known or 0
Definition: avformat.h:877
AV_WB32
#define AV_WB32(p, v)
Definition: intreadwrite.h:419
AV_CODEC_ID_AAC
@ AV_CODEC_ID_AAC
Definition: codec_id.h:423
read_seek
static int read_seek(AVFormatContext *s, int stream_index, int64_t timestamp, int flags)
Definition: cafdec.c:427
avio_rl32
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:733
ALAC_NEW_KUKI
#define ALAC_NEW_KUKI
AVIOContext
Bytestream IO Context.
Definition: avio.h:161
AVPacket::size
int size
Definition: packet.h:366
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:117
ff_codec_get_id
enum AVCodecID ff_codec_get_id(const AVCodecTag *tags, unsigned int tag)
Definition: utils.c:3078
AVIOContext::seekable
int seekable
A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
Definition: avio.h:260
av_clipd
#define av_clipd
Definition: common.h:173
CafContext::bytes_per_packet
int bytes_per_packet
bytes in a packet, or 0 if variable
Definition: cafdec.c:40
FFMAX
#define FFMAX(a, b)
Definition: common.h:103
avpriv_set_pts_info
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:4799
avio_get_str
int avio_get_str(AVIOContext *pb, int maxlen, char *buf, int buflen)
Read a string from pb into buf.
Definition: aviobuf.c:843
size
int size
Definition: twinvq_data.h:10344
CafContext::frames_per_packet
int frames_per_packet
frames in a packet, or 0 if variable
Definition: cafdec.c:41
AV_RB32
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:96
MKBETAG
#define MKBETAG(a, b, c, d)
Definition: common.h:479
AV_CODEC_ID_OPUS
@ AV_CODEC_ID_OPUS
Definition: codec_id.h:481
AVStreamInternal::nb_index_entries
int nb_index_entries
Definition: internal.h:252
AVPacket::dts
int64_t dts
Decompression timestamp in AVStream->time_base units; the time at which the packet is decompressed.
Definition: packet.h:364
FFMIN
#define FFMIN(a, b)
Definition: common.h:105
AVStreamInternal::index_entries
AVIndexEntry * index_entries
Only used if the format does not support seeking natively.
Definition: internal.h:250
ff_mp4_read_descr_len
int ff_mp4_read_descr_len(AVIOContext *pb)
Definition: isom.c:282
CafContext
Definition: cafdec.c:39
i
int i
Definition: input.c:407
AVPacket::pts
int64_t pts
Presentation timestamp in AVStream->time_base units; the time at which the decompressed packet will b...
Definition: packet.h:358
AVCodecParameters::block_align
int block_align
Audio only.
Definition: codec_par.h:177
value
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this just let it vf default value
Definition: writing_filters.txt:86
ff_codec_caf_tags
const AVCodecTag ff_codec_caf_tags[]
Known codec tags for CAF.
Definition: caf.c:34
av_get_packet
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:280
mov_chan.h
tag
uint32_t tag
Definition: movenc.c:1594
ret
ret
Definition: filter_design.txt:187
AVStream
Stream structure.
Definition: avformat.h:832
avio_seek
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:243
pos
unsigned int pos
Definition: spdifenc.c:412
avformat.h
dict.h
AV_INPUT_BUFFER_PADDING_SIZE
#define AV_INPUT_BUFFER_PADDING_SIZE
Definition: avcodec.h:192
left
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:386
ff_caf_codec_tags_list
const AVCodecTag *const ff_caf_codec_tags_list[]
Definition: caf.c:81
AVIO_SEEKABLE_NORMAL
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
avio_read
int avio_read(AVIOContext *s, unsigned char *buf, int size)
Read size bytes from AVIOContext into buf.
Definition: aviobuf.c:616
AVIndexEntry::pos
int64_t pos
Definition: avformat.h:763
AVPacket::stream_index
int stream_index
Definition: packet.h:367
avio_skip
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:327
AVCodecParameters::bits_per_coded_sample
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:102
avpriv_request_sample
#define avpriv_request_sample(...)
Definition: tableprint_vlc.h:39
AVCodecParameters::codec_id
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
AVPacket
This structure stores compressed data.
Definition: packet.h:342
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
av_dict_set
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
CafContext::frame_cnt
int64_t frame_cnt
frame counter
Definition: cafdec.c:45
read_packet
static int read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: cafdec.c:371
flags
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVCodecParameters::bit_rate
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
AVERROR_INVALIDDATA
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
AVStream::start_time
int64_t start_time
Decoding: pts of the first frame of the stream in presentation order, in stream time base.
Definition: avformat.h:865
probe
static int probe(const AVProbeData *p)
Definition: cafdec.c:51
ALAC_HEADER
#define ALAC_HEADER
AV_RB16
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:98
av_fourcc2str
#define av_fourcc2str(fourcc)
Definition: avutil.h:348
ff_mov_read_chan
int ff_mov_read_chan(AVFormatContext *s, AVIOContext *pb, AVStream *st, int64_t size)
Read 'chan' tag from the input stream.
Definition: mov_chan.c:547
av_index_search_timestamp
int av_index_search_timestamp(AVStream *st, int64_t timestamp, int flags)
Get the index for a specific timestamp.
Definition: utils.c:2054
ff_alloc_extradata
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:3261
read_pakt_chunk
static int read_pakt_chunk(AVFormatContext *s, int64_t size)
Read packet table chunk.
Definition: cafdec.c:188
avio_feof
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:354