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  return 0;
127 }
128 
129 /* Write a variable-length symbol */
130 static void put_varlength(AVIOContext *pb, int val)
131 {
132  if (val < 128)
133  avio_w8(pb, val);
134  else {
135  val -= 128;
136  avio_w8(pb, 0x80 | val >> 7);
137  avio_w8(pb, 0x7f & val);
138  }
139 }
140 
141 static int mmf_write_trailer(AVFormatContext *s)
142 {
143  AVIOContext *pb = s->pb;
144  MMFContext *mmf = s->priv_data;
145  int64_t pos, size;
146  int gatetime;
147 
148  if (s->pb->seekable & AVIO_SEEKABLE_NORMAL) {
149  /* Fill in length fields */
150  end_tag_be(pb, mmf->awapos);
151  end_tag_be(pb, mmf->atrpos);
152  end_tag_be(pb, 8);
153 
154  pos = avio_tell(pb);
155  size = pos - mmf->awapos;
156 
157  /* Fill Atsq chunk */
158  avio_seek(pb, mmf->atsqpos, SEEK_SET);
159 
160  /* "play wav" */
161  avio_w8(pb, 0); /* start time */
162  avio_w8(pb, (mmf->stereo << 6) | 1); /* (channel << 6) | wavenum */
163  gatetime = size * 500 / s->streams[0]->codecpar->sample_rate;
164  put_varlength(pb, gatetime); /* duration */
165 
166  /* "nop" */
167  put_varlength(pb, gatetime); /* start time */
168  avio_write(pb, "\xff\x00", 2); /* nop */
169 
170  /* "end of sequence" */
171  avio_write(pb, "\x00\x00\x00\x00", 4);
172 
173  avio_seek(pb, pos, SEEK_SET);
174  }
175  return 0;
176 }
177 #endif /* CONFIG_MMF_MUXER */
178 
179 static int mmf_probe(const AVProbeData *p)
180 {
181  /* check file header */
182  if (p->buf[0] == 'M' && p->buf[1] == 'M' &&
183  p->buf[2] == 'M' && p->buf[3] == 'D' &&
184  p->buf[8] == 'C' && p->buf[9] == 'N' &&
185  p->buf[10] == 'T' && p->buf[11] == 'I')
186  return AVPROBE_SCORE_MAX;
187  else
188  return 0;
189 }
190 
191 /* mmf input */
193 {
194  MMFContext *mmf = s->priv_data;
195  unsigned int tag;
196  AVIOContext *pb = s->pb;
197  AVStream *st;
198  int64_t size;
199  int rate, params;
200 
201  tag = avio_rl32(pb);
202  if (tag != MKTAG('M', 'M', 'M', 'D'))
203  return AVERROR_INVALIDDATA;
204  avio_skip(pb, 4); /* file_size */
205 
206  /* Skip some unused chunks that may or may not be present */
207  for (;; avio_skip(pb, size)) {
208  tag = avio_rl32(pb);
209  size = avio_rb32(pb);
210  if (tag == MKTAG('C', 'N', 'T', 'I'))
211  continue;
212  if (tag == MKTAG('O', 'P', 'D', 'A'))
213  continue;
214  break;
215  }
216 
217  /* Tag = "ATRx", where "x" = track number */
218  if ((tag & 0xffffff) == MKTAG('M', 'T', 'R', 0)) {
219  av_log(s, AV_LOG_ERROR, "MIDI like format found, unsupported\n");
220  return AVERROR_PATCHWELCOME;
221  }
222  if ((tag & 0xffffff) != MKTAG('A', 'T', 'R', 0)) {
223  av_log(s, AV_LOG_ERROR, "Unsupported SMAF chunk %08x\n", tag);
224  return AVERROR_PATCHWELCOME;
225  }
226 
227  avio_r8(pb); /* format type */
228  avio_r8(pb); /* sequence type */
229  params = avio_r8(pb); /* (channel << 7) | (format << 4) | rate */
230  rate = mmf_rate(params & 0x0f);
231  if (rate < 0) {
232  av_log(s, AV_LOG_ERROR, "Invalid sample rate\n");
233  return AVERROR_INVALIDDATA;
234  }
235  avio_r8(pb); /* wave base bit */
236  avio_r8(pb); /* time base d */
237  avio_r8(pb); /* time base g */
238 
239  /* Skip some unused chunks that may or may not be present */
240  for (;; avio_skip(pb, size)) {
241  tag = avio_rl32(pb);
242  size = avio_rb32(pb);
243  if (tag == MKTAG('A', 't', 's', 'q'))
244  continue;
245  if (tag == MKTAG('A', 's', 'p', 'I'))
246  continue;
247  break;
248  }
249 
250  /* Make sure it's followed by an Awa chunk, aka wave data */
251  if ((tag & 0xffffff) != MKTAG('A', 'w', 'a', 0)) {
252  av_log(s, AV_LOG_ERROR, "Unexpected SMAF chunk %08x\n", tag);
253  return AVERROR_INVALIDDATA;
254  }
255  mmf->data_end = avio_tell(pb) + size;
256 
257  st = avformat_new_stream(s, NULL);
258  if (!st)
259  return AVERROR(ENOMEM);
260 
263  st->codecpar->sample_rate = rate;
264  st->codecpar->channels = (params >> 7) + 1;
267  st->codecpar->bit_rate = st->codecpar->sample_rate *
269 
270  avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
271 
272  return 0;
273 }
274 
275 #define MAX_SIZE 4096
276 
278 {
279  MMFContext *mmf = s->priv_data;
280  int64_t left, size;
281  int ret;
282 
283  left = mmf->data_end - avio_tell(s->pb);
284  size = FFMIN(left, MAX_SIZE);
285  if (avio_feof(s->pb) || size <= 0)
286  return AVERROR_EOF;
287 
288  ret = av_get_packet(s->pb, pkt, size);
289  if (ret < 0)
290  return ret;
291 
292  pkt->stream_index = 0;
293 
294  return ret;
295 }
296 
297 #if CONFIG_MMF_DEMUXER
299  .name = "mmf",
300  .long_name = NULL_IF_CONFIG_SMALL("Yamaha SMAF"),
301  .priv_data_size = sizeof(MMFContext),
306 };
307 #endif
308 
309 #if CONFIG_MMF_MUXER
311  .name = "mmf",
312  .long_name = NULL_IF_CONFIG_SMALL("Yamaha SMAF"),
313  .mime_type = "application/vnd.smaf",
314  .extensions = "mmf",
315  .priv_data_size = sizeof(MMFContext),
316  .audio_codec = AV_CODEC_ID_ADPCM_YAMAHA,
317  .video_codec = AV_CODEC_ID_NONE,
318  .write_header = mmf_write_header,
320  .write_trailer = mmf_write_trailer,
321 };
322 #endif
#define FF_COMPLIANCE_EXPERIMENTAL
Allow nonstandardized experimental things.
Definition: avcodec.h:1599
static void write_packet(OutputFile *of, AVPacket *pkt, OutputStream *ost, int unqueue)
Definition: ffmpeg.c:703
#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
int64_t awapos
Definition: mmf.c:31
version
Definition: libkvazaar.c:317
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:4871
AVInputFormat ff_mmf_demuxer
enum AVCodecID codec_id
Specific type of the encoded data (the codec used).
Definition: codec_par.h:60
int64_t avio_seek(AVIOContext *s, int64_t offset, int whence)
fseek() equivalent for AVIOContext.
Definition: aviobuf.c:253
Definition: mmf.c:30
int64_t avio_skip(AVIOContext *s, int64_t offset)
Skip given number of bytes forward.
Definition: aviobuf.c:341
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:1547
Format I/O context.
Definition: avformat.h:1239
static int mmf_rate(int code)
Definition: mmf.c:38
unsigned int avio_rb32(AVIOContext *s)
Definition: aviobuf.c:785
AVStream * avformat_new_stream(AVFormatContext *s, const AVCodec *c)
Add a new stream to a media file.
Definition: utils.c:4453
AVStream ** streams
A list of all streams in the file.
Definition: avformat.h:1307
int flags
Flags modifying the (de)muxer behaviour.
Definition: avformat.h:1370
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
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:225
#define MAX_SIZE
Definition: mmf.c:275
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:1387
uint64_t channel_layout
Audio only.
Definition: codec_par.h:162
#define av_log(a,...)
int64_t bit_rate
The average bitrate of the encoded data (in bits per second).
Definition: codec_par.h:89
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:194
unsigned int avio_rl32(AVIOContext *s)
Definition: aviobuf.c:754
#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
enum AVMediaType codec_type
General type of the encoded data.
Definition: codec_par.h:56
GLenum GLint * params
Definition: opengl_enc.c:113
AVOutputFormat ff_mmf_muxer
static int mmf_probe(const AVProbeData *p)
Definition: mmf.c:179
int avio_r8(AVIOContext *s)
Definition: aviobuf.c:628
unsigned char * buf
Buffer must have AVPROBE_PADDING_SIZE of extra allocated bytes filled with zero.
Definition: avformat.h:443
#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
#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:98
const char * name
Definition: avformat.h:500
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:527
Stream structure.
Definition: avformat.h:880
#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:1281
void avio_w8(AVIOContext *s, int b)
Definition: aviobuf.c:203
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:463
static int mmf_read_header(AVFormatContext *s)
Definition: mmf.c:192
This structure contains the data a format has to probe a file.
Definition: avformat.h:441
#define flags(name, subs,...)
Definition: cbs_av1.c:560
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: codec_par.h:170
#define AVPROBE_SCORE_MAX
maximum score
Definition: avformat.h:453
Main libavformat public API header.
static int mmf_read_packet(AVFormatContext *s, AVPacket *pkt)
Definition: mmf.c:277
void * priv_data
Format private data.
Definition: avformat.h:1267
static void write_header(FFV1Context *f)
Definition: ffv1enc.c:346
int bits_per_coded_sample
The number of bits per sample in the codedwords.
Definition: codec_par.h:102
int channels
Audio only.
Definition: codec_par.h:166
void avio_wb32(AVIOContext *s, unsigned int val)
Definition: aviobuf.c:387
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_feof(AVIOContext *s)
Similar to feof() but also returns nonzero on read errors.
Definition: aviobuf.c:368
int stream_index
Definition: packet.h:365
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:405
static double val(void *priv, double ch)
Definition: aeval.c:76
This structure stores compressed data.
Definition: packet.h:340
int i
Definition: input.c:407
int64_t atrpos
Definition: mmf.c:31