FFmpeg
framesync.c
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1 /*
2  * Copyright (c) 2013 Nicolas George
3  *
4  * This file is part of FFmpeg.
5  *
6  * FFmpeg is free software; you can redistribute it and/or
7  * modify it under the terms of the GNU Lesser General Public License
8  * as published by the Free Software Foundation; either
9  * version 2.1 of the License, or (at your option) any later version.
10  *
11  * FFmpeg is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14  * GNU Lesser General Public License for more details.
15  *
16  * You should have received a copy of the GNU Lesser General Public License
17  * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
18  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
19  */
20 
21 #include "libavutil/avassert.h"
22 #include "libavutil/opt.h"
23 #include "avfilter.h"
24 #include "filters.h"
25 #include "framesync.h"
26 #include "internal.h"
27 
28 #define OFFSET(member) offsetof(FFFrameSync, member)
29 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_FILTERING_PARAM
30 
31 static const char *framesync_name(void *ptr)
32 {
33  return "framesync";
34 }
35 
36 static const AVOption framesync_options[] = {
37  { "eof_action", "Action to take when encountering EOF from secondary input ",
38  OFFSET(opt_eof_action), AV_OPT_TYPE_INT, { .i64 = EOF_ACTION_REPEAT },
39  EOF_ACTION_REPEAT, EOF_ACTION_PASS, .flags = FLAGS, "eof_action" },
40  { "repeat", "Repeat the previous frame.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_REPEAT }, .flags = FLAGS, "eof_action" },
41  { "endall", "End both streams.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_ENDALL }, .flags = FLAGS, "eof_action" },
42  { "pass", "Pass through the main input.", 0, AV_OPT_TYPE_CONST, { .i64 = EOF_ACTION_PASS }, .flags = FLAGS, "eof_action" },
43  { "shortest", "force termination when the shortest input terminates", OFFSET(opt_shortest), AV_OPT_TYPE_BOOL, { .i64 = 0 }, 0, 1, FLAGS },
44  { "repeatlast", "extend last frame of secondary streams beyond EOF", OFFSET(opt_repeatlast), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, FLAGS },
45  { NULL }
46 };
47 static const AVClass framesync_class = {
49  .class_name = "framesync",
50  .item_name = framesync_name,
51  .category = AV_CLASS_CATEGORY_FILTER,
52  .option = framesync_options,
53  .parent_log_context_offset = OFFSET(parent),
54 };
55 
57 {
58  const AVClass *c = *iter ? NULL : &framesync_class;
59  *iter = (void *)(uintptr_t)c;
60  return c;
61 }
62 
63 enum {
67 };
68 
69 static int consume_from_fifos(FFFrameSync *fs);
70 
72 {
73  if (fs->class)
74  return;
75  fs->class = &framesync_class;
77 }
78 
79 int ff_framesync_init(FFFrameSync *fs, AVFilterContext *parent, unsigned nb_in)
80 {
81  /* For filters with several outputs, we will not be able to assume which
82  output is relevant for ff_outlink_frame_wanted() and
83  ff_outlink_set_status(). To be designed when needed. */
84  av_assert0(parent->nb_outputs == 1);
85 
87  fs->parent = parent;
88  fs->nb_in = nb_in;
89 
90  fs->in = av_calloc(nb_in, sizeof(*fs->in));
91  if (!fs->in)
92  return AVERROR(ENOMEM);
93  return 0;
94 }
95 
97 {
98  fs->eof = 1;
99  fs->frame_ready = 0;
100  ff_outlink_set_status(fs->parent->outputs[0], AVERROR_EOF, AV_NOPTS_VALUE);
101 }
102 
104 {
105  unsigned i, level = 0;
106 
107  for (i = 0; i < fs->nb_in; i++)
108  if (fs->in[i].state != STATE_EOF)
109  level = FFMAX(level, fs->in[i].sync);
110  av_assert0(level <= fs->sync_level);
111  if (level < fs->sync_level)
112  av_log(fs, AV_LOG_VERBOSE, "Sync level %u\n", level);
113  if (level)
114  fs->sync_level = level;
115  else
116  framesync_eof(fs);
117 }
118 
120 {
121  unsigned i;
122 
123  if (!fs->opt_repeatlast || fs->opt_eof_action == EOF_ACTION_PASS) {
124  fs->opt_repeatlast = 0;
125  fs->opt_eof_action = EOF_ACTION_PASS;
126  }
127  if (fs->opt_shortest || fs->opt_eof_action == EOF_ACTION_ENDALL) {
128  fs->opt_shortest = 1;
129  fs->opt_eof_action = EOF_ACTION_ENDALL;
130  }
131  if (!fs->opt_repeatlast) {
132  for (i = 1; i < fs->nb_in; i++) {
133  fs->in[i].after = EXT_NULL;
134  fs->in[i].sync = 0;
135  }
136  }
137  if (fs->opt_shortest) {
138  for (i = 0; i < fs->nb_in; i++)
139  fs->in[i].after = EXT_STOP;
140  }
141 
142  if (!fs->time_base.num) {
143  for (i = 0; i < fs->nb_in; i++) {
144  if (fs->in[i].sync) {
145  if (fs->time_base.num) {
146  fs->time_base = av_gcd_q(fs->time_base, fs->in[i].time_base,
148  } else {
149  fs->time_base = fs->in[i].time_base;
150  }
151  }
152  }
153  if (!fs->time_base.num) {
154  av_log(fs, AV_LOG_ERROR, "Impossible to set time base\n");
155  return AVERROR(EINVAL);
156  }
157  av_log(fs, AV_LOG_VERBOSE, "Selected %d/%d time base\n",
158  fs->time_base.num, fs->time_base.den);
159  }
160 
161  for (i = 0; i < fs->nb_in; i++)
162  fs->in[i].pts = fs->in[i].pts_next = AV_NOPTS_VALUE;
163  fs->sync_level = UINT_MAX;
165 
166  return 0;
167 }
168 
170 {
171  unsigned i;
172  int64_t pts;
173  int ret;
174 
175  while (!(fs->frame_ready || fs->eof)) {
177  if (ret <= 0)
178  return ret;
179 
180  pts = INT64_MAX;
181  for (i = 0; i < fs->nb_in; i++)
182  if (fs->in[i].have_next && fs->in[i].pts_next < pts)
183  pts = fs->in[i].pts_next;
184  if (pts == INT64_MAX) {
185  framesync_eof(fs);
186  break;
187  }
188  for (i = 0; i < fs->nb_in; i++) {
189  if (fs->in[i].pts_next == pts ||
190  (fs->in[i].before == EXT_INFINITY &&
191  fs->in[i].state == STATE_BOF)) {
192  av_frame_free(&fs->in[i].frame);
193  fs->in[i].frame = fs->in[i].frame_next;
194  fs->in[i].pts = fs->in[i].pts_next;
195  fs->in[i].frame_next = NULL;
196  fs->in[i].pts_next = AV_NOPTS_VALUE;
197  fs->in[i].have_next = 0;
198  fs->in[i].state = fs->in[i].frame ? STATE_RUN : STATE_EOF;
199  if (fs->in[i].sync == fs->sync_level && fs->in[i].frame)
200  fs->frame_ready = 1;
201  if (fs->in[i].state == STATE_EOF &&
202  fs->in[i].after == EXT_STOP)
203  framesync_eof(fs);
204  }
205  }
206  if (fs->frame_ready)
207  for (i = 0; i < fs->nb_in; i++)
208  if ((fs->in[i].state == STATE_BOF &&
209  fs->in[i].before == EXT_STOP))
210  fs->frame_ready = 0;
211  fs->pts = pts;
212  }
213  return 0;
214 }
215 
216 static int64_t framesync_pts_extrapolate(FFFrameSync *fs, unsigned in,
217  int64_t pts)
218 {
219  /* Possible enhancement: use the link's frame rate */
220  return pts + 1;
221 }
222 
223 static void framesync_inject_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
224 {
225  int64_t pts;
226 
227  av_assert0(!fs->in[in].have_next);
228  av_assert0(frame);
229  pts = av_rescale_q(frame->pts, fs->in[in].time_base, fs->time_base);
230  frame->pts = pts;
231  fs->in[in].frame_next = frame;
232  fs->in[in].pts_next = pts;
233  fs->in[in].have_next = 1;
234 }
235 
236 static void framesync_inject_status(FFFrameSync *fs, unsigned in, int status, int64_t pts)
237 {
238  av_assert0(!fs->in[in].have_next);
239  pts = fs->in[in].state != STATE_RUN || fs->in[in].after == EXT_INFINITY
240  ? INT64_MAX : framesync_pts_extrapolate(fs, in, fs->in[in].pts);
241  fs->in[in].sync = 0;
243  fs->in[in].frame_next = NULL;
244  fs->in[in].pts_next = pts;
245  fs->in[in].have_next = 1;
246 }
247 
248 int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
249  unsigned get)
250 {
251  AVFrame *frame;
252  unsigned need_copy = 0, i;
253  int64_t pts_next;
254  int ret;
255 
256  if (!fs->in[in].frame) {
257  *rframe = NULL;
258  return 0;
259  }
260  frame = fs->in[in].frame;
261  if (get) {
262  /* Find out if we need to copy the frame: is there another sync
263  stream, and do we know if its current frame will outlast this one? */
264  pts_next = fs->in[in].have_next ? fs->in[in].pts_next : INT64_MAX;
265  for (i = 0; i < fs->nb_in && !need_copy; i++)
266  if (i != in && fs->in[i].sync &&
267  (!fs->in[i].have_next || fs->in[i].pts_next < pts_next))
268  need_copy = 1;
269  if (need_copy) {
270  if (!(frame = av_frame_clone(frame)))
271  return AVERROR(ENOMEM);
272  if ((ret = av_frame_make_writable(frame)) < 0) {
274  return ret;
275  }
276  } else {
277  fs->in[in].frame = NULL;
278  }
279  fs->frame_ready = 0;
280  }
281  *rframe = frame;
282  return 0;
283 }
284 
286 {
287  unsigned i;
288 
289  for (i = 0; i < fs->nb_in; i++) {
290  av_frame_free(&fs->in[i].frame);
291  av_frame_free(&fs->in[i].frame_next);
292  }
293 
294  av_freep(&fs->in);
295 }
296 
298 {
299  AVFilterContext *ctx = fs->parent;
300  AVFrame *frame = NULL;
301  int64_t pts;
302  unsigned i, nb_active, nb_miss;
303  int ret, status;
304 
305  nb_active = nb_miss = 0;
306  for (i = 0; i < fs->nb_in; i++) {
307  if (fs->in[i].have_next || fs->in[i].state == STATE_EOF)
308  continue;
309  nb_active++;
310  ret = ff_inlink_consume_frame(ctx->inputs[i], &frame);
311  if (ret < 0)
312  return ret;
313  if (ret) {
314  av_assert0(frame);
316  } else {
318  if (ret > 0) {
320  } else if (!ret) {
321  nb_miss++;
322  }
323  }
324  }
325  if (nb_miss) {
326  if (nb_miss == nb_active && !ff_outlink_frame_wanted(ctx->outputs[0]))
327  return FFERROR_NOT_READY;
328  for (i = 0; i < fs->nb_in; i++)
329  if (!fs->in[i].have_next && fs->in[i].state != STATE_EOF)
330  ff_inlink_request_frame(ctx->inputs[i]);
331  return 0;
332  }
333  return 1;
334 }
335 
337 {
338  int ret;
339 
341  if (ret < 0)
342  return ret;
343  if (fs->eof || !fs->frame_ready)
344  return 0;
345  ret = fs->on_event(fs);
346  if (ret < 0)
347  return ret;
348  fs->frame_ready = 0;
349 
350  return 0;
351 }
352 
354 {
355  int ret;
356 
357  ret = ff_framesync_init(fs, parent, 2);
358  if (ret < 0)
359  return ret;
360  fs->in[0].time_base = parent->inputs[0]->time_base;
361  fs->in[1].time_base = parent->inputs[1]->time_base;
362  fs->in[0].sync = 2;
363  fs->in[0].before = EXT_STOP;
364  fs->in[0].after = EXT_INFINITY;
365  fs->in[1].sync = 1;
366  fs->in[1].before = EXT_NULL;
367  fs->in[1].after = EXT_INFINITY;
368  return 0;
369 }
370 
372 {
373  AVFilterContext *ctx = fs->parent;
374  AVFrame *mainpic = NULL, *secondpic = NULL;
375  int ret;
376 
377  if ((ret = ff_framesync_get_frame(fs, 0, &mainpic, 1)) < 0 ||
378  (ret = ff_framesync_get_frame(fs, 1, &secondpic, 0)) < 0) {
379  av_frame_free(&mainpic);
380  return ret;
381  }
382  av_assert0(mainpic);
383  mainpic->pts = av_rescale_q(fs->pts, fs->time_base, ctx->outputs[0]->time_base);
384  if (ctx->is_disabled)
385  secondpic = NULL;
386  *f0 = mainpic;
387  *f1 = secondpic;
388  return 0;
389 }
390 
392 {
393  int ret;
394 
395  ret = ff_framesync_dualinput_get(fs, f0, f1);
396  if (ret < 0)
397  return ret;
398  ret = ff_inlink_make_frame_writable(fs->parent->inputs[0], f0);
399  if (ret < 0) {
400  av_frame_free(f0);
401  *f1 = NULL;
402  return ret;
403  }
404  return 0;
405 }
ff_framesync_configure
int ff_framesync_configure(FFFrameSync *fs)
Configure a frame sync structure.
Definition: framesync.c:119
status
they must not be accessed directly The fifo field contains the frames that are queued in the input for processing by the filter The status_in and status_out fields contains the queued status(EOF or error) of the link
level
uint8_t level
Definition: svq3.c:204
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
opt.h
av_opt_set_defaults
void av_opt_set_defaults(void *s)
Set the values of all AVOption fields to their default values.
Definition: opt.c:1361
ff_framesync_uninit
void ff_framesync_uninit(FFFrameSync *fs)
Free all memory currently allocated.
Definition: framesync.c:285
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition: error.h:57
FFERROR_NOT_READY
return FFERROR_NOT_READY
Definition: filter_design.txt:204
consume_from_fifos
static int consume_from_fifos(FFFrameSync *fs)
Definition: framesync.c:297
ff_framesync_get_frame
int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe, unsigned get)
Get the current frame in an input.
Definition: framesync.c:248
AV_TIME_BASE_Q
#define AV_TIME_BASE_Q
Internal time base represented as fractional value.
Definition: avutil.h:260
AVClass::version
int version
LIBAVUTIL_VERSION with which this structure was created.
Definition: log.h:92
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
Definition: frame.c:112
AVFrame
This structure describes decoded (raw) audio or video data.
Definition: frame.h:303
av_frame_make_writable
int av_frame_make_writable(AVFrame *frame)
Ensure that the frame data is writable, avoiding data copy if possible.
Definition: frame.c:490
AVFrame::pts
int64_t pts
Presentation timestamp in time_base units (time when frame should be shown to user).
Definition: frame.h:396
AVOption
AVOption.
Definition: opt.h:247
EOF_ACTION_ENDALL
@ EOF_ACTION_ENDALL
Definition: framesync.h:28
AVFilterContext::nb_outputs
unsigned nb_outputs
number of output pads
Definition: avfilter.h:399
AV_LOG_VERBOSE
#define AV_LOG_VERBOSE
Detailed information.
Definition: log.h:196
FFMAX
#define FFMAX(a, b)
Definition: macros.h:47
FFFrameSync
Frame sync structure.
Definition: framesync.h:146
EXT_INFINITY
@ EXT_INFINITY
Extend the frame to infinity.
Definition: framesync.h:75
framesync_advance
static int framesync_advance(FFFrameSync *fs)
Definition: framesync.c:169
ff_inlink_consume_frame
int ff_inlink_consume_frame(AVFilterLink *link, AVFrame **rframe)
Take a frame from the link's FIFO and update the link's stats.
Definition: avfilter.c:1417
EXT_STOP
@ EXT_STOP
Completely stop all streams with this one.
Definition: framesync.h:65
ff_framesync_child_class_iterate
const AVClass * ff_framesync_child_class_iterate(void **iter)
Definition: framesync.c:56
framesync_inject_frame
static void framesync_inject_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
Definition: framesync.c:223
EXT_NULL
@ EXT_NULL
Ignore this stream and continue processing the other ones.
Definition: framesync.h:70
framesync_pts_extrapolate
static int64_t framesync_pts_extrapolate(FFFrameSync *fs, unsigned in, int64_t pts)
Definition: framesync.c:216
pts
static int64_t pts
Definition: transcode_aac.c:653
OFFSET
#define OFFSET(member)
Definition: framesync.c:28
avassert.h
AV_LOG_ERROR
#define AV_LOG_ERROR
Something went wrong and cannot losslessly be recovered.
Definition: log.h:180
FLAGS
#define FLAGS
Definition: framesync.c:29
ff_outlink_set_status
static void ff_outlink_set_status(AVFilterLink *link, int status, int64_t pts)
Set the status field of a link from the source filter.
Definition: filters.h:189
ff_inlink_request_frame
void ff_inlink_request_frame(AVFilterLink *link)
Mark that a frame is wanted on the link.
Definition: avfilter.c:1534
STATE_RUN
@ STATE_RUN
Definition: framesync.c:65
av_assert0
#define av_assert0(cond)
assert() equivalent, that is always enabled.
Definition: avassert.h:37
get
static void get(uint8_t *pixels, int stride, int16_t *block)
Definition: proresenc_anatoliy.c:307
filters.h
ctx
AVFormatContext * ctx
Definition: movenc.c:48
av_frame_clone
AVFrame * av_frame_clone(const AVFrame *src)
Create a new frame that references the same data as src.
Definition: frame.c:424
av_rescale_q
int64_t av_rescale_q(int64_t a, AVRational bq, AVRational cq)
Rescale a 64-bit integer by 2 rational numbers.
Definition: mathematics.c:141
EOF_ACTION_PASS
@ EOF_ACTION_PASS
Definition: framesync.h:29
ff_inlink_make_frame_writable
int ff_inlink_make_frame_writable(AVFilterLink *link, AVFrame **rframe)
Make sure a frame is writable.
Definition: avfilter.c:1461
LIBAVUTIL_VERSION_INT
#define LIBAVUTIL_VERSION_INT
Definition: version.h:85
AVClass
Describe the class of an AVClass context structure.
Definition: log.h:66
NULL
#define NULL
Definition: coverity.c:32
fs
#define fs(width, name, subs,...)
Definition: cbs_vp9.c:259
AVFilterContext::inputs
AVFilterLink ** inputs
array of pointers to input links
Definition: avfilter.h:394
framesync_inject_status
static void framesync_inject_status(FFFrameSync *fs, unsigned in, int status, int64_t pts)
Definition: framesync.c:236
ff_inlink_acknowledge_status
int ff_inlink_acknowledge_status(AVFilterLink *link, int *rstatus, int64_t *rpts)
Test and acknowledge the change of status on the link.
Definition: avfilter.c:1371
c
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
AV_CLASS_CATEGORY_FILTER
@ AV_CLASS_CATEGORY_FILTER
Definition: log.h:36
framesync_sync_level_update
static void framesync_sync_level_update(FFFrameSync *fs)
Definition: framesync.c:103
ff_framesync_init_dualinput
int ff_framesync_init_dualinput(FFFrameSync *fs, AVFilterContext *parent)
Initialize a frame sync structure for dualinput.
Definition: framesync.c:353
AV_NOPTS_VALUE
#define AV_NOPTS_VALUE
Undefined timestamp value.
Definition: avutil.h:248
framesync_options
static const AVOption framesync_options[]
Definition: framesync.c:36
internal.h
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
av_gcd_q
AVRational av_gcd_q(AVRational a, AVRational b, int max_den, AVRational def)
Return the best rational so that a and b are multiple of it.
Definition: rational.c:186
AV_TIME_BASE
#define AV_TIME_BASE
Internal time base represented as integer.
Definition: avutil.h:254
framesync_eof
static void framesync_eof(FFFrameSync *fs)
Definition: framesync.c:96
framesync_class
static const AVClass framesync_class
Definition: framesync.c:47
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:271
ret
ret
Definition: filter_design.txt:187
frame
these buffered frames must be flushed immediately if a new input produces new the filter must not call request_frame to get more It must just process the frame or queue it The task of requesting more frames is left to the filter s request_frame method or the application If a filter has several the filter must be ready for frames arriving randomly on any input any filter with several inputs will most likely require some kind of queuing mechanism It is perfectly acceptable to have a limited queue and to drop frames when the inputs are too unbalanced request_frame For filters that do not use the this method is called when a frame is wanted on an output For a it should directly call filter_frame on the corresponding output For a if there are queued frames already one of these frames should be pushed If the filter should request a frame on one of its repeatedly until at least one frame has been pushed Return or at least make progress towards producing a frame
Definition: filter_design.txt:264
STATE_BOF
@ STATE_BOF
Definition: framesync.c:64
ff_framesync_init
int ff_framesync_init(FFFrameSync *fs, AVFilterContext *parent, unsigned nb_in)
Initialize a frame sync structure.
Definition: framesync.c:79
EOF_ACTION_REPEAT
@ EOF_ACTION_REPEAT
Definition: framesync.h:27
framesync.h
AV_OPT_TYPE_INT
@ AV_OPT_TYPE_INT
Definition: opt.h:224
STATE_EOF
@ STATE_EOF
Definition: framesync.c:66
avfilter.h
framesync_name
static const char * framesync_name(void *ptr)
Definition: framesync.c:31
AVFilterContext
An instance of a filter.
Definition: avfilter.h:386
AV_OPT_TYPE_BOOL
@ AV_OPT_TYPE_BOOL
Definition: opt.h:241
av_freep
#define av_freep(p)
Definition: tableprint_vlc.h:35
av_log
#define av_log(a,...)
Definition: tableprint_vlc.h:28
ff_outlink_frame_wanted
the definition of that something depends on the semantic of the filter The callback must examine the status of the filter s links and proceed accordingly The status of output links is stored in the status_in and status_out fields and tested by the ff_outlink_frame_wanted() function. If this function returns true
ff_framesync_activate
int ff_framesync_activate(FFFrameSync *fs)
Examine the frames in the filter's input and try to produce output.
Definition: framesync.c:336
ff_framesync_dualinput_get
int ff_framesync_dualinput_get(FFFrameSync *fs, AVFrame **f0, AVFrame **f1)
Definition: framesync.c:371
ff_framesync_dualinput_get_writable
int ff_framesync_dualinput_get_writable(FFFrameSync *fs, AVFrame **f0, AVFrame **f1)
Same as ff_framesync_dualinput_get(), but make sure that f0 is writable.
Definition: framesync.c:391
AV_OPT_TYPE_CONST
@ AV_OPT_TYPE_CONST
Definition: opt.h:233
ff_framesync_preinit
void ff_framesync_preinit(FFFrameSync *fs)
Pre-initialize a frame sync structure.
Definition: framesync.c:71