FFmpeg
mmf.c
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1 /*
2  * Yamaha SMAF format
3  * Copyright (c) 2005 Vidar Madsen
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 "avformat.h"
24 #include "avio_internal.h"
25 #include "internal.h"
26 #include "pcm.h"
27 #include "rawenc.h"
28 #include "riff.h"
29 
30 typedef struct MMFContext {
31  int64_t atrpos, atsqpos, awapos;
32  int64_t data_end;
33  int stereo;
34 } MMFContext;
35 
36 static const int mmf_rates[] = { 4000, 8000, 11025, 22050, 44100 };
37 
38 static int mmf_rate(int code)
39 {
40  if ((code < 0) || (code > 4))
41  return -1;
42  return mmf_rates[code];
43 }
44 
45 #if CONFIG_MMF_MUXER
46 static int mmf_rate_code(int rate)
47 {
48  int i;
49  for (i = 0; i < 5; i++)
50  if (mmf_rates[i] == rate)
51  return i;
52  return -1;
53 }
54 
55 /* Copy of end_tag() from avienc.c, but for big-endian chunk size */
56 static void end_tag_be(AVIOContext *pb, int64_t start)
57 {
58  int64_t pos;
59 
60  pos = avio_tell(pb);
61  avio_seek(pb, start - 4, SEEK_SET);
62  avio_wb32(pb, (uint32_t)(pos - start));
63  avio_seek(pb, pos, SEEK_SET);
64 }
65 
66 static int mmf_write_header(AVFormatContext *s)
67 {
68  MMFContext *mmf = s->priv_data;
69  AVIOContext *pb = s->pb;
70  int64_t pos;
71  int rate;
72  const char *version = s->flags & AVFMT_FLAG_BITEXACT ?
73  "VN:Lavf," :
74  "VN:"LIBAVFORMAT_IDENT",";
75 
76  rate = mmf_rate_code(s->streams[0]->codecpar->sample_rate);
77  if (rate < 0) {
78  av_log(s, AV_LOG_ERROR, "Unsupported sample rate %d, supported are 4000, 8000, 11025, 22050 and 44100\n",
79  s->streams[0]->codecpar->sample_rate);
80  return AVERROR(EINVAL);
81  }
82 
83  mmf->stereo = s->streams[0]->codecpar->channels > 1;
84  if (mmf->stereo &&
86  av_log(s, AV_LOG_ERROR, "Yamaha SMAF stereo is experimental, "
87  "add '-strict %d' if you want to use it.\n",
89  return AVERROR(EINVAL);
90  }
91 
92  ffio_wfourcc(pb, "MMMD");
93  avio_wb32(pb, 0);
94  pos = ff_start_tag(pb, "CNTI");
95  avio_w8(pb, 0); /* class */
96  avio_w8(pb, 1); /* type */
97  avio_w8(pb, 1); /* code type */
98  avio_w8(pb, 0); /* status */
99  avio_w8(pb, 0); /* counts */
100  end_tag_be(pb, pos);
101 
102  pos = ff_start_tag(pb, "OPDA");
103  avio_write(pb, version, strlen(version)); /* metadata ("ST:songtitle,VN:version,...") */
104  end_tag_be(pb, pos);
105 
106  avio_write(pb, "ATR\x00", 4);
107  avio_wb32(pb, 0);
108  mmf->atrpos = avio_tell(pb);
109  avio_w8(pb, 0); /* format type */
110  avio_w8(pb, 0); /* sequence type */
111  avio_w8(pb, (mmf->stereo << 7) | (1 << 4) | rate); /* (channel << 7) | (format << 4) | rate */
112  avio_w8(pb, 0); /* wave base bit */
113  avio_w8(pb, 2); /* time base d */
114  avio_w8(pb, 2); /* time base g */
115 
116  ffio_wfourcc(pb, "Atsq");
117  avio_wb32(pb, 16);
118  mmf->atsqpos = avio_tell(pb);
119  /* Will be filled on close */
120  avio_write(pb, "\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00", 16);
121 
122  mmf->awapos = ff_start_tag(pb, "Awa\x01");
123 
124  avpriv_set_pts_info(s->streams[0], 64, 1, s->streams[0]->codecpar->sample_rate);
125 
126  avio_flush(pb);
127 
128  return 0;
129 }
130 
131 /* Write a variable-length symbol */
132 static void put_varlength(AVIOContext *pb, int val)
133 {
134  if (val < 128)
135  avio_w8(pb, val);
136  else {
137  val -= 128;
138  avio_w8(pb, 0x80 | val >> 7);
139  avio_w8(pb, 0x7f & val);
140  }
141 }
142 
143 static int mmf_write_trailer(AVFormatContext *s)
144 {
145  AVIOContext *pb = s->pb;
146  MMFContext *mmf = s->priv_data;
147  int64_t pos, size;
148  int gatetime;
149 
150  if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
151  /* Fill in length fields */
152  end_tag_be(pb, mmf->awapos);
153  end_tag_be(pb, mmf->atrpos);
154  end_tag_be(pb, 8);
155 
156  pos = avio_tell(pb);
157  size = pos - mmf->awapos;
158 
159  /* Fill Atsq chunk */
160  avio_seek(pb, mmf->atsqpos, SEEK_SET);
161 
162  /* "play wav" */
163  avio_w8(pb, 0); /* start time */
164  avio_w8(pb, (mmf->stereo << 6) | 1); /* (channel << 6) | wavenum */
165  gatetime = size * 500 / s->streams[0]->codecpar->sample_rate;
166  put_varlength(pb, gatetime); /* duration */
167 
168  /* "nop" */
169  put_varlength(pb, gatetime); /* start time */
170  avio_write(pb, "\xff\x00", 2); /* nop */
171 
172  /* "end of sequence" */
173  avio_write(pb, "\x00\x00\x00\x00", 4);
174 
175  avio_seek(pb, pos, SEEK_SET);
176 
177  avio_flush(pb);
178  }
179  return 0;
180 }
181 #endif /* CONFIG_MMF_MUXER */
182 
183 static int mmf_probe(const AVProbeData *p)
184 {
185  /* check file header */
186  if (p->buf[0] == 'M' && p->buf[1] == 'M' &&
187  p->buf[2] == 'M' && p->buf[3] == 'D' &&
188  p->buf[8] == 'C' && p->buf[9] == 'N' &&
189  p->buf[10] == 'T' && p->buf[11] == 'I')
190  return AVPROBE_SCORE_MAX;
191  else
192  return 0;
193 }
194 
195 /* mmf input */
197 {
198  MMFContext *mmf = s->priv_data;
199  unsigned int tag;
200  AVIOContext *pb = s->pb;
201  AVStream *st;
202  int64_t size;
203  int rate, params;
204 
205  tag = avio_rl32(pb);
206  if (tag != MKTAG('M', 'M', 'M', 'D'))
207  return AVERROR_INVALIDDATA;
208  avio_skip(pb, 4); /* file_size */
209 
210  /* Skip some unused chunks that may or may not be present */
211  for (;; avio_skip(pb, size)) {
212  tag = avio_rl32(pb);
213  size = avio_rb32(pb);
214  if (tag == MKTAG('C', 'N', 'T', 'I'))
215  continue;
216  if (tag == MKTAG('O', 'P', 'D', 'A'))
217  continue;
218  break;
219  }
220 
221  /* Tag = "ATRx", where "x" = track number */
222  if ((tag & 0xffffff) == MKTAG('M', 'T', 'R', 0)) {
223  av_log(s, AV_LOG_ERROR, "MIDI like format found, unsupported\n");
224  return AVERROR_PATCHWELCOME;
225  }
226  if ((tag & 0xffffff) != MKTAG('A', 'T', 'R', 0)) {
227  av_log(s, AV_LOG_ERROR, "Unsupported SMAF chunk %08x\n", tag);
228  return AVERROR_PATCHWELCOME;
229  }
230 
231  avio_r8(pb); /* format type */
232  avio_r8(pb); /* sequence type */
233  params = avio_r8(pb); /* (channel << 7) | (format << 4) | rate */
234  rate = mmf_rate(params & 0x0f);
235  if (rate < 0) {
236  av_log(s, AV_LOG_ERROR, "Invalid sample rate\n");
237  return AVERROR_INVALIDDATA;
238  }
239  avio_r8(pb); /* wave base bit */
240  avio_r8(pb); /* time base d */
241  avio_r8(pb); /* time base g */
242 
243  /* Skip some unused chunks that may or may not be present */
244  for (;; avio_skip(pb, size)) {
245  tag = avio_rl32(pb);
246  size = avio_rb32(pb);
247  if (tag == MKTAG('A', 't', 's', 'q'))
248  continue;
249  if (tag == MKTAG('A', 's', 'p', 'I'))
250  continue;
251  break;
252  }
253 
254  /* Make sure it's followed by an Awa chunk, aka wave data */
255  if ((tag & 0xffffff) != MKTAG('A', 'w', 'a', 0)) {
256  av_log(s, AV_LOG_ERROR, "Unexpected SMAF chunk %08x\n", tag);
257  return AVERROR_INVALIDDATA;
258  }
259  mmf->data_end = avio_tell(pb) + size;
260 
261  st = avformat_new_stream(s, NULL);
262  if (!st)
263  return AVERROR(ENOMEM);
264 
267  st->codecpar->sample_rate = rate;
268  st->codecpar->channels = (params >> 7) + 1;
271  st->codecpar->bit_rate = st->codecpar->sample_rate *
273 
274  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
275 
276  return 0;
277 }
278 
279 #define MAX_SIZE 4096
280 
282 {
283  MMFContext *mmf = s->priv_data;
284  int64_t left, size;
285  int ret;
286 
287  left = mmf->data_end - avio_tell(s->pb);
288  size = FFMIN(left, MAX_SIZE);
289  if (avio_feof(s->pb) || size <= 0)
290  return AVERROR_EOF;
291 
292  ret = av_get_packet(s->pb, pkt, size);
293  if (ret < 0)
294  return ret;
295 
296  pkt->stream_index = 0;
297 
298  return ret;
299 }
300 
301 #if CONFIG_MMF_DEMUXER
303  .name = "mmf",
304  .long_name = NULL_IF_CONFIG_SMALL("Yamaha SMAF"),
305  .priv_data_size = sizeof(MMFContext),
310 };
311 #endif
312 
313 #if CONFIG_MMF_MUXER
315  .name = "mmf",
316  .long_name = NULL_IF_CONFIG_SMALL("Yamaha SMAF"),
317  .mime_type = "application/vnd.smaf",
318  .extensions = "mmf",
319  .priv_data_size = sizeof(MMFContext),
320  .audio_codec = AV_CODEC_ID_ADPCM_YAMAHA,
321  .video_codec = AV_CODEC_ID_NONE,
322  .write_header = mmf_write_header,
324  .write_trailer = mmf_write_trailer,
325 };
326 #endif
#define FF_COMPLIANCE_EXPERIMENTAL
Allow nonstandardized experimental things.
Definition: avcodec.h:2629
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:689
#define NULL
Definition: coverity.c:32
const char const char void * val
Definition: avisynth_c.h:863
Bytestream IO Context.
Definition: avio.h:161
#define AVERROR_INVALIDDATA
Invalid data found when processing input.
Definition: error.h:59
int64_t awapos
Definition: mmf.c:31
int64_t ff_start_tag(AVIOContext *pb, const char *tag)
Definition: riffenc.c:31
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:4882
AVInputFormat ff_mmf_demuxer
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: avcodec.h:3953
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:246
Definition: mmf.c:30
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:331
int version
Definition: avisynth_c.h:858
static AVPacket pkt
#define AV_CH_LAYOUT_STEREO
int stereo
Definition: mmf.c:33
int strict_std_compliance
Allow non-standard and experimental extension.
Definition: avformat.h:1666
Format I/O context.
Definition: avformat.h:1358
static int mmf_rate(int code)
Definition: mmf.c:38
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:801
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4455
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1426
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1489
uint32_t tag
Definition: movenc.c:1496
#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:310
ptrdiff_t size
Definition: opengl_enc.c:100
static av_always_inline int64_t avio_tell(AVIOContext *s)
ftell() equivalent for AVIOContext.
Definition: avio.h:557
void avio_write(AVIOContext *s, const unsigned char *buf, int size)
Definition: aviobuf.c:218
#define MAX_SIZE
Definition: mmf.c:279
static av_always_inline void ffio_wfourcc(AVIOContext *pb, const uint8_t *s)
Definition: avio_internal.h:58
#define AVFMT_FLAG_BITEXACT
When muxing, try to avoid writing any random/volatile data to the output.
Definition: avformat.h:1506
uint64_t channel_layout
Audio only.
Definition: avcodec.h:4055
#define av_log(a,...)
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: avcodec.h:3982
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:260
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:176
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:770
#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:3949
GLenum GLint * params
Definition: opengl_enc.c:113
AVOutputFormat ff_mmf_muxer
static int mmf_probe(const AVProbeData *p)
Definition: mmf.c:183
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:639
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:448
#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
int void avio_flush(AVIOContext *s)
Force flushing of buffered data.
Definition: aviobuf.c:238
audio channel layout utility functions
#define FFMIN(a, b)
Definition: common.h:96
int64_t data_end
Definition: mmf.c:32
static int write_trailer(AVFormatContext *s1)
Definition: v4l2enc.c:94
const char * name
Definition: avformat.h:505
internal header for RIFF based (de)muxers do NOT include this in end user applications ...
#define s(width, name)
Definition: cbs_vp9.c:257
int ff_raw_write_packet(AVFormatContext *s, AVPacket *pkt)
Definition: rawenc.c:29
int64_t atsqpos
Definition: mmf.c:31
static int read_header(FFV1Context *f)
Definition: ffv1dec.c:530
Stream structure.
Definition: avformat.h:881
#define AVERROR_PATCHWELCOME
Not yet implemented in FFmpeg, patches welcome.
Definition: error.h:62
static int read_packet(void *opaque, uint8_t *buf, int buf_size)
Definition: avio_reading.c:42
#define AVIO_SEEKABLE_NORMAL
Seeking works like for a local file.
Definition: avio.h:40
AVIOContext * pb
I/O context.
Definition: avformat.h:1400
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:196
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
#define AVFMT_GENERIC_INDEX
Use generic index building code.
Definition: avformat.h:468
static int mmf_read_header(AVFormatContext *s)
Definition: mmf.c:196
This structure contains the data a format has to probe a file.
Definition: avformat.h:446
#define flags(name, subs,...)
Definition: cbs_av1.c:561
and forward the test the status of outputs and forward it to the corresponding return FFERROR_NOT_READY If the filters stores internally one or a few frame for some it can consider them to be part of the FIFO and delay acknowledging a status change accordingly Example code
static const int mmf_rates[]
Definition: mmf.c:36
static int read_probe(const AVProbeData *pd)
Definition: jvdec.c:55
int sample_rate
Audio only.
Definition: avcodec.h:4063
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:458
Main libavformat public API header.
static int mmf_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mmf.c:281
void * priv_data
Format private data.
Definition: avformat.h:1386
static void write_header(FFV1Context *f)
Definition: ffv1enc.c:337
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: avcodec.h:3995
int channels
Audio only.
Definition: avcodec.h:4059
void avio_wb32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:377
void INT64 start
Definition: avisynth_c.h:766
const char * name
A comma separated list of short names for the format.
Definition: avformat.h:654
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition: avformat.h:1028
int avio_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:358
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
#define AV_CH_LAYOUT_MONO
#define MKTAG(a, b, c, d)
Definition: common.h:366
This structure stores compressed data.
Definition: avcodec.h:1454
int64_t atrpos
Definition: mmf.c:31