FFmpeg
flacenc.c
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1 /*
2  * raw FLAC muxer
3  * Copyright (c) 2006-2009 Justin Ruggles
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
23 #include "libavutil/opt.h"
24 #include "libavutil/pixdesc.h"
25 #include "libavcodec/flac.h"
26 #include "avformat.h"
27 #include "avio_internal.h"
28 #include "flacenc.h"
29 #include "id3v2.h"
30 #include "internal.h"
31 #include "vorbiscomment.h"
32 #include "libavcodec/bytestream.h"
33 
34 
35 typedef struct FlacMuxerContext {
36  const AVClass *class;
38 
41  /* audio packets are queued here until we get all the attached pictures */
43 
44  /* updated streaminfo sent by the encoder at the end */
46 
47  unsigned attached_types;
49 
50 static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes,
51  int last_block)
52 {
53  avio_w8(pb, last_block ? 0x81 : 0x01);
54  avio_wb24(pb, n_padding_bytes);
55  ffio_fill(pb, 0, n_padding_bytes);
56  return 0;
57 }
58 
60  int last_block, int bitexact)
61 {
62  const char *vendor = bitexact ? "ffmpeg" : LIBAVFORMAT_IDENT;
63  int64_t len;
64  uint8_t *p, *p0;
65 
67 
68  len = ff_vorbiscomment_length(*m, vendor, NULL, 0);
69  if (len >= ((1<<24) - 4))
70  return AVERROR(EINVAL);
71  p0 = av_malloc(len+4);
72  if (!p0)
73  return AVERROR(ENOMEM);
74  p = p0;
75 
76  bytestream_put_byte(&p, last_block ? 0x84 : 0x04);
77  bytestream_put_be24(&p, len);
78  ff_vorbiscomment_write(&p, m, vendor, NULL, 0);
79 
80  avio_write(pb, p0, len+4);
81  av_freep(&p0);
82  p = NULL;
83 
84  return 0;
85 }
86 
88 {
90  AVIOContext *pb = s->pb;
91  const AVPixFmtDescriptor *pixdesc;
92  const CodecMime *mime = ff_id3v2_mime_tags;
94  const char *mimetype = NULL, *desc = "";
95  const AVStream *st = s->streams[pkt->stream_index];
96  int i, mimelen, desclen, type = 0;
97 
98  if (!pkt->data)
99  return 0;
100 
101  while (mime->id != AV_CODEC_ID_NONE) {
102  if (mime->id == st->codecpar->codec_id) {
103  mimetype = mime->str;
104  break;
105  }
106  mime++;
107  }
108  if (!mimetype) {
109  av_log(s, AV_LOG_ERROR, "No mimetype is known for stream %d, cannot "
110  "write an attached picture.\n", st->index);
111  return AVERROR(EINVAL);
112  }
113  mimelen = strlen(mimetype);
114 
115  /* get the picture type */
116  e = av_dict_get(st->metadata, "comment", NULL, 0);
117  for (i = 0; e && i < FF_ARRAY_ELEMS(ff_id3v2_picture_types); i++) {
119  type = i;
120  break;
121  }
122  }
123 
124  if ((c->attached_types & (1 << type)) & 0x6) {
125  av_log(s, AV_LOG_ERROR, "Duplicate attachment for type '%s'\n", ff_id3v2_picture_types[type]);
126  return AVERROR(EINVAL);
127  }
128 
129  if (type == 1 && (st->codecpar->codec_id != AV_CODEC_ID_PNG ||
130  st->codecpar->width != 32 ||
131  st->codecpar->height != 32)) {
132  av_log(s, AV_LOG_ERROR, "File icon attachment must be a 32x32 PNG");
133  return AVERROR(EINVAL);
134  }
135 
136  c->attached_types |= (1 << type);
137 
138  /* get the description */
139  if ((e = av_dict_get(st->metadata, "title", NULL, 0)))
140  desc = e->value;
141  desclen = strlen(desc);
142 
143  avio_w8(pb, 0x06);
144  avio_wb24(pb, 4 + 4 + mimelen + 4 + desclen + 4 + 4 + 4 + 4 + 4 + pkt->size);
145 
146  avio_wb32(pb, type);
147 
148  avio_wb32(pb, mimelen);
149  avio_write(pb, mimetype, mimelen);
150 
151  avio_wb32(pb, desclen);
152  avio_write(pb, desc, desclen);
153 
154  avio_wb32(pb, st->codecpar->width);
155  avio_wb32(pb, st->codecpar->height);
156  if ((pixdesc = av_pix_fmt_desc_get(st->codecpar->format)))
157  avio_wb32(pb, av_get_bits_per_pixel(pixdesc));
158  else
159  avio_wb32(pb, 0);
160  avio_wb32(pb, 0);
161 
162  avio_wb32(pb, pkt->size);
163  avio_write(pb, pkt->data, pkt->size);
164  return 0;
165 }
166 
168 {
169  int i, ret, padding = s->metadata_header_padding;
170  if (padding < 0)
171  padding = 8192;
172  /* The FLAC specification states that 24 bits are used to represent the
173  * size of a metadata block so we must clip this value to 2^24-1. */
174  padding = av_clip_uintp2(padding, 24);
175 
176  for (i = 0; i < s->nb_streams; i++) {
177  AVStream *st = s->streams[i];
178  AVPacket *pkt = st->priv_data;
179  if (!pkt)
180  continue;
181  ret = flac_write_picture(s, pkt);
182  av_packet_unref(pkt);
183  if (ret < 0 && (s->error_recognition & AV_EF_EXPLODE))
184  return ret;
185  }
186 
187  ret = flac_write_block_comment(s->pb, &s->metadata, !padding,
189  if (ret)
190  return ret;
191 
192  /* The command line flac encoder defaults to placing a seekpoint
193  * every 10s. So one might add padding to allow that later
194  * but there seems to be no simple way to get the duration here.
195  * So just add the amount requested by the user. */
196  if (padding)
197  flac_write_block_padding(s->pb, padding, 1);
198 
199  return 0;
200 }
201 
202 static int flac_init(struct AVFormatContext *s)
203 {
204  AVCodecParameters *par;
206  int i;
207 
208  c->audio_stream_idx = -1;
209  for (i = 0; i < s->nb_streams; i++) {
210  AVStream *st = s->streams[i];
211  if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
212  if (c->audio_stream_idx >= 0 || st->codecpar->codec_id != AV_CODEC_ID_FLAC) {
213  av_log(s, AV_LOG_ERROR, "Invalid audio stream. Exactly one FLAC "
214  "audio stream is required.\n");
215  return AVERROR(EINVAL);
216  }
217  par = s->streams[i]->codecpar;
218  c->audio_stream_idx = i;
219  } else if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
221  av_log(s, AV_LOG_WARNING, "Video stream #%d is not an attached picture. Ignoring\n", i);
222  continue;
223  } else if (st->codecpar->codec_id == AV_CODEC_ID_GIF) {
224  av_log(s, AV_LOG_ERROR, "GIF image support is not implemented.\n");
225  return AVERROR_PATCHWELCOME;
226  } else if (!c->write_header) {
227  av_log(s, AV_LOG_ERROR, "Can't write attached pictures without a header.\n");
228  return AVERROR(EINVAL);
229  }
230  c->waiting_pics++;
231  } else {
232  av_log(s, AV_LOG_ERROR, "Only audio streams and pictures are allowed in FLAC.\n");
233  return AVERROR(EINVAL);
234  }
235  }
236  if (c->audio_stream_idx < 0) {
237  av_log(s, AV_LOG_ERROR, "No audio stream present.\n");
238  return AVERROR(EINVAL);
239  }
240 
241  /* add the channel layout tag */
242  if (par->channel_layout &&
243  !(par->channel_layout & ~0x3ffffULL) &&
245  AVDictionaryEntry *chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK",
246  NULL, 0);
247 
248  if (chmask) {
249  av_log(s, AV_LOG_WARNING, "A WAVEFORMATEXTENSIBLE_CHANNEL_MASK is "
250  "already present, this muxer will not overwrite it.\n");
251  } else {
252  uint8_t buf[32];
253  snprintf(buf, sizeof(buf), "0x%"PRIx64, par->channel_layout);
254  av_dict_set(&s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", buf, 0);
255  }
256  }
257 
258  return 0;
259 }
260 
262 {
265  int ret;
266 
267  if (!c->write_header)
268  return 0;
269 
270  ret = ff_flac_write_header(s->pb, par->extradata,
271  par->extradata_size, 0);
272  if (ret < 0)
273  return ret;
274 
275  if (!c->waiting_pics)
276  ret = flac_finish_header(s);
277 
278  return ret;
279 }
280 
282 {
285  int streaminfo_size;
286 
287  /* check for updated streaminfo */
289  &streaminfo_size);
290  if (streaminfo && streaminfo_size == FLAC_STREAMINFO_SIZE) {
291  av_freep(&c->streaminfo);
292 
294  if (!c->streaminfo)
295  return AVERROR(ENOMEM);
296  memcpy(c->streaminfo, streaminfo, FLAC_STREAMINFO_SIZE);
297  }
298 
299  if (pkt->size)
300  avio_write(s->pb, pkt->data, pkt->size);
301  return 0;
302 }
303 
305 {
307  AVPacket pkt;
308  int ret, write = 1;
309 
310  ret = flac_finish_header(s);
311  if (ret < 0)
312  write = 0;
313 
314  while (c->queue) {
315  ff_packet_list_get(&c->queue, &c->queue_end, &pkt);
316  if (write && (ret = flac_write_audio_packet(s, &pkt)) < 0)
317  write = 0;
318  av_packet_unref(&pkt);
319  }
320  return ret;
321 }
322 
324 {
325  AVIOContext *pb = s->pb;
326  int64_t file_size;
330 
331  if (c->waiting_pics) {
332  av_log(s, AV_LOG_WARNING, "No packets were sent for some of the "
333  "attached pictures.\n");
334  flac_queue_flush(s);
335  }
336 
337  if (!c->write_header || !streaminfo)
338  return 0;
339 
340  if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
341  /* rewrite the STREAMINFO header block data */
342  file_size = avio_tell(pb);
343  avio_seek(pb, 8, SEEK_SET);
344  avio_write(pb, streaminfo, FLAC_STREAMINFO_SIZE);
345  avio_seek(pb, file_size, SEEK_SET);
346  avio_flush(pb);
347  } else {
348  av_log(s, AV_LOG_WARNING, "unable to rewrite FLAC header.\n");
349  }
350 
351  av_freep(&c->streaminfo);
352 
353  return 0;
354 }
355 
357 {
359  int ret;
360 
361  if (pkt->stream_index == c->audio_stream_idx) {
362  if (c->waiting_pics) {
363  /* buffer audio packets until we get all the pictures */
365  if (ret < 0) {
366  av_log(s, AV_LOG_ERROR, "Out of memory in packet queue; skipping attached pictures\n");
367  c->waiting_pics = 0;
368  ret = flac_queue_flush(s);
369  if (ret < 0)
370  return ret;
371  return flac_write_audio_packet(s, pkt);
372  }
373  } else
374  return flac_write_audio_packet(s, pkt);
375  } else {
376  AVStream *st = s->streams[pkt->stream_index];
377 
378  if (!c->waiting_pics ||
380  return 0;
381 
382  /* warn only once for each stream */
383  if (st->nb_frames == 1) {
384  av_log(s, AV_LOG_WARNING, "Got more than one picture in stream %d,"
385  " ignoring.\n", pkt->stream_index);
386  }
387  if (st->nb_frames >= 1)
388  return 0;
389 
390  st->priv_data = av_packet_clone(pkt);
391  if (!st->priv_data)
392  av_log(s, AV_LOG_ERROR, "Out of memory queueing an attached picture; skipping\n");
393  c->waiting_pics--;
394 
395  /* flush the buffered audio packets */
396  if (!c->waiting_pics &&
397  (ret = flac_queue_flush(s)) < 0)
398  return ret;
399  }
400 
401  return 0;
402 }
403 
404 static const AVOption flacenc_options[] = {
405  { "write_header", "Write the file header", offsetof(FlacMuxerContext, write_header), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
406  { NULL },
407 };
408 
409 static const AVClass flac_muxer_class = {
410  .class_name = "flac muxer",
411  .item_name = av_default_item_name,
412  .option = flacenc_options,
413  .version = LIBAVUTIL_VERSION_INT,
414 };
415 
417  .name = "flac",
418  .long_name = NULL_IF_CONFIG_SMALL("raw FLAC"),
419  .priv_data_size = sizeof(FlacMuxerContext),
420  .mime_type = "audio/x-flac",
421  .extensions = "flac",
422  .audio_codec = AV_CODEC_ID_FLAC,
423  .video_codec = AV_CODEC_ID_PNG,
424  .init = flac_init,
429  .priv_class = &flac_muxer_class,
430 };
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:689
#define NULL
Definition: coverity.c:32
Bytestream IO Context.
Definition: avio.h:161
const AVPixFmtDescriptor * av_pix_fmt_desc_get(enum AVPixelFormat pix_fmt)
Definition: pixdesc.c:2522
AVOption.
Definition: opt.h:246
int ff_packet_list_put(AVPacketList **head, AVPacketList **tail, AVPacket *pkt, int flags)
Append an AVPacket to the list.
Definition: utils.c:447
static int flac_init(struct AVFormatContext *s)
Definition: flacenc.c:202
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
const char * desc
Definition: nvenc.c:68
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
AVPacketList * queue
Definition: flacenc.c:42
int av_get_bits_per_pixel(const AVPixFmtDescriptor *pixdesc)
Return the number of bits per pixel used by the pixel format described by pixdesc.
Definition: pixdesc.c:2474
static int flac_write_block_padding(AVIOContext *pb, unsigned int n_padding_bytes, int last_block)
Definition: flacenc.c:50
AVOutputFormat ff_flac_muxer
Definition: flacenc.c:416
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3957
int index
stream index in AVFormatContext
Definition: avformat.h:882
int size
Definition: avcodec.h:1478
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:246
const char * av_default_item_name(void *ptr)
Return the context name.
Definition: log.c:191
int ff_flac_is_native_layout(uint64_t channel_layout)
GLint GLenum type
Definition: opengl_enc.c:104
void * priv_data
Definition: avformat.h:896
static AVPacket pkt
This struct describes the properties of an encoded stream.
Definition: avcodec.h:3949
Format I/O context.
Definition: avformat.h:1358
char str[32]
Definition: internal.h:50
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
static int flac_queue_flush(AVFormatContext *s)
Definition: flacenc.c:304
uint8_t
#define av_malloc(s)
int width
Video only.
Definition: avcodec.h:4023
AVOptions.
uint8_t * streaminfo
Definition: flacenc.c:45
Undefined Behavior In the C some operations are like signed integer dereferencing freed accessing outside allocated Undefined Behavior must not occur in a C it is not safe even if the output of undefined operations is unused The unsafety may seem nit picking but Optimizing compilers have in fact optimized code on the assumption that no undefined Behavior occurs Optimizing code based on wrong assumptions can and has in some cases lead to effects beyond the output of computations The signed integer overflow problem in speed critical code Code which is highly optimized and works with signed integers sometimes has the problem that often the output of the computation does not c
Definition: undefined.txt:32
static int flac_write_header(struct AVFormatContext *s)
Definition: flacenc.c:261
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1426
#define FF_PACKETLIST_FLAG_REF_PACKET
Create a new reference for the packet instead of transferring the ownership of the existing one to th...
Definition: internal.h:757
AVDictionaryEntry * av_dict_get(const AVDictionary *m, const char *key, const AVDictionaryEntry *prev, int flags)
Get a dictionary entry with matching key.
Definition: dict.c:40
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1489
uint8_t * data
Definition: avcodec.h:1477
enum AVCodecID id
Definition: internal.h:51
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
static int flac_finish_header(struct AVFormatContext *s)
Definition: flacenc.c:167
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:218
#define AVFMT_FLAG_BITEXACT
When muxing, try to avoid writing any random/volatile data to the output.
Definition: avformat.h:1506
static int flac_write_trailer(struct AVFormatContext *s)
Definition: flacenc.c:323
uint64_t channel_layout
Audio only.
Definition: avcodec.h:4059
#define av_log(a,...)
#define AV_OPT_FLAG_ENCODING_PARAM
a generic parameter which can be set by the user for muxing or encoding
Definition: opt.h:276
static int flac_write_audio_packet(struct AVFormatContext *s, AVPacket *pkt)
Definition: flacenc.c:281
static int flac_write_picture(struct AVFormatContext *s, AVPacket *pkt)
Definition: flacenc.c:87
const AVMetadataConv ff_vorbiscomment_metadata_conv[]
VorbisComment metadata conversion mapping.
Definition: vorbiscomment.c:33
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:259
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
AVDictionary * metadata
Metadata that applies to the whole file.
Definition: avformat.h:1598
AVPacket * av_packet_clone(const AVPacket *src)
Create a new packet that references the same data as src.
Definition: avpacket.c:642
FLAC (Free Lossless Audio Codec) decoder/demuxer common functions.
uint8_t * av_packet_get_side_data(const AVPacket *pkt, enum AVPacketSideDataType type, int *size)
Get side information from packet.
Definition: avpacket.c:350
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:186
enum AVMediaType codec_type
General type of the encoded data.
Definition: avcodec.h:3953
int ff_vorbiscomment_write(uint8_t **p, AVDictionary **m, const char *vendor_string, AVChapter **chapters, unsigned int nb_chapters)
Write a VorbisComment into a buffer.
Definition: vorbiscomment.c:65
int extradata_size
Size of the extradata content in bytes.
Definition: avcodec.h:3975
static const AVOption flacenc_options[]
Definition: flacenc.c:404
const CodecMime ff_id3v2_mime_tags[]
Definition: id3v2.c:131
int write_header
Definition: flacenc.c:37
unsigned attached_types
Definition: flacenc.c:47
unsigned int nb_streams
Number of elements in AVFormatContext.streams.
Definition: avformat.h:1414
#define LIBAVFORMAT_IDENT
Definition: version.h:46
int seekable
A combination of AVIO_SEEKABLE_ flags or 0 when the stream is not seekable.
Definition: avio.h:260
audio channel layout utility functions
void ffio_fill(AVIOContext *s, int b, int count)
Definition: aviobuf.c:204
int av_strcasecmp(const char *a, const char *b)
Locale-independent case-insensitive compare.
Definition: avstring.c:213
static int write_trailer(AVFormatContext *s1)
Definition: v4l2enc.c:94
void avio_wb24(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:490
int64_t ff_vorbiscomment_length(AVDictionary *m, const char *vendor_string, AVChapter **chapters, unsigned int nb_chapters)
Calculate the length in bytes of a VorbisComment.
Definition: vorbiscomment.c:41
const char * name
Definition: avformat.h:505
#define FLAC_STREAMINFO_SIZE
Definition: flac.h:34
int ff_flac_write_header(AVIOContext *pb, uint8_t *extradata, int extradata_size, int last_block)
#define s(width, name)
Definition: cbs_vp9.c:257
#define AV_EF_EXPLODE
abort decoding on minor error detection
Definition: avcodec.h:2705
AVDictionary * metadata
Definition: avformat.h:945
static int flac_write_block_comment(AVIOContext *pb, AVDictionary **m, int last_block, int bitexact)
Definition: flacenc.c:59
#define FF_ARRAY_ELEMS(a)
#define AV_DISPOSITION_ATTACHED_PIC
The stream is stored in the file as an attached picture/"cover art" (e.g.
Definition: avformat.h:849
int metadata_header_padding
Number of bytes to be written as padding in a metadata header.
Definition: avformat.h:1858
Stream structure.
Definition: avformat.h:881
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
#define AVFMT_NOTIMESTAMPS
Format does not need / have any timestamps.
Definition: avformat.h:467
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
The AV_PKT_DATA_NEW_EXTRADATA is used to notify the codec or the format that the extradata buffer was...
Definition: avcodec.h:1199
static const AVClass flac_muxer_class
Definition: flacenc.c:409
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
Descriptor that unambiguously describes how the bits of a pixel are stored in the up to 4 data planes...
Definition: pixdesc.h:81
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:196
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:599
void * buf
Definition: avisynth_c.h:766
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
Describe the class of an AVClass context structure.
Definition: log.h:67
int waiting_pics
Definition: flacenc.c:40
void avio_flush(AVIOContext *s)
Force flushing of buffered data.
Definition: aviobuf.c:238
#define snprintf
Definition: snprintf.h:34
#define flags(name, subs,...)
Definition: cbs_av1.c:561
AVPacketList * queue_end
Definition: flacenc.c:42
static int flac_write_packet(struct AVFormatContext *s, AVPacket *pkt)
Definition: flacenc.c:356
int ff_packet_list_get(AVPacketList **head, AVPacketList **tail, AVPacket *pkt)
Remove the oldest AVPacket in the list and return it.
Definition: utils.c:1550
Main libavformat public API header.
int audio_stream_idx
Definition: flacenc.c:39
int error_recognition
Error recognition; higher values will detect more errors but may misdetect some more or less valid pa...
Definition: avformat.h:1625
int disposition
AV_DISPOSITION_* bit field.
Definition: avformat.h:934
int64_t nb_frames
number of frames in this stream if known or 0
Definition: avformat.h:932
void ff_metadata_conv(AVDictionary **pm, const AVMetadataConv *d_conv, const AVMetadataConv *s_conv)
Definition: metadata.c:26
char * value
Definition: dict.h:87
int len
void * priv_data
Format private data.
Definition: avformat.h:1386
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: avcodec.h:3971
void avio_wb32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:380
#define av_freep(p)
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
const char *const ff_id3v2_picture_types[21]
Definition: id3v2.c:107
int stream_index
Definition: avcodec.h:1479
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
This structure stores compressed data.
Definition: avcodec.h:1454