Statistics
| Branch: | Revision:

ffmpeg / libavfilter / avfilter.h @ 006aa1a4

History | View | Annotate | Download (25.9 KB)

1
/*
2
 * filter layer
3
 * copyright (c) 2007 Bobby Bingham
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

    
22
#ifndef AVFILTER_AVFILTER_H
23
#define AVFILTER_AVFILTER_H
24

    
25
#include "libavutil/avutil.h"
26

    
27
#define LIBAVFILTER_VERSION_MAJOR  1
28
#define LIBAVFILTER_VERSION_MINOR 17
29
#define LIBAVFILTER_VERSION_MICRO  0
30

    
31
#define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
32
                                               LIBAVFILTER_VERSION_MINOR, \
33
                                               LIBAVFILTER_VERSION_MICRO)
34
#define LIBAVFILTER_VERSION     AV_VERSION(LIBAVFILTER_VERSION_MAJOR,   \
35
                                           LIBAVFILTER_VERSION_MINOR,   \
36
                                           LIBAVFILTER_VERSION_MICRO)
37
#define LIBAVFILTER_BUILD       LIBAVFILTER_VERSION_INT
38

    
39
#include <stddef.h>
40
#include "libavcodec/avcodec.h"
41

    
42
/**
43
 * Returns the LIBAVFILTER_VERSION_INT constant.
44
 */
45
unsigned avfilter_version(void);
46

    
47
/**
48
 * Returns the libavfilter build-time configuration.
49
 */
50
const char *avfilter_configuration(void);
51

    
52
/**
53
 * Returns the libavfilter license.
54
 */
55
const char *avfilter_license(void);
56

    
57

    
58
typedef struct AVFilterContext AVFilterContext;
59
typedef struct AVFilterLink    AVFilterLink;
60
typedef struct AVFilterPad     AVFilterPad;
61

    
62
/* TODO: look for other flags which may be useful in this structure (interlace
63
 * flags, etc)
64
 */
65
/**
66
 * A reference-counted picture data type used by the filter system. Filters
67
 * should not store pointers to this structure directly, but instead use the
68
 * AVFilterPicRef structure below.
69
 */
70
typedef struct AVFilterPic
71
{
72
    uint8_t *data[4];           ///< picture data for each plane
73
    int linesize[4];            ///< number of bytes per line
74
    enum PixelFormat format;    ///< colorspace
75

    
76
    unsigned refcount;          ///< number of references to this image
77

    
78
    /** private data to be used by a custom free function */
79
    void *priv;
80
    /**
81
     * A pointer to the function to deallocate this image if the default
82
     * function is not sufficient. This could, for example, add the memory
83
     * back into a memory pool to be reused later without the overhead of
84
     * reallocating it from scratch.
85
     */
86
    void (*free)(struct AVFilterPic *pic);
87

    
88
    int w, h;                  ///< width and height of the allocated buffer
89
} AVFilterPic;
90

    
91
/**
92
 * A reference to an AVFilterPic. Since filters can manipulate the origin of
93
 * a picture to, for example, crop image without any memcpy, the picture origin
94
 * and dimensions are per-reference properties. Linesize is also useful for
95
 * image flipping, frame to field filters, etc, and so is also per-reference.
96
 *
97
 * TODO: add anything necessary for frame reordering
98
 */
99
typedef struct AVFilterPicRef
100
{
101
    AVFilterPic *pic;           ///< the picture that this is a reference to
102
    uint8_t *data[4];           ///< picture data for each plane
103
    int linesize[4];            ///< number of bytes per line
104
    int w;                      ///< image width
105
    int h;                      ///< image height
106

    
107
    int64_t pts;                ///< presentation timestamp in units of 1/AV_TIME_BASE
108

    
109
    AVRational pixel_aspect;    ///< pixel aspect ratio
110

    
111
    int perms;                  ///< permissions
112
#define AV_PERM_READ     0x01   ///< can read from the buffer
113
#define AV_PERM_WRITE    0x02   ///< can write to the buffer
114
#define AV_PERM_PRESERVE 0x04   ///< nobody else can overwrite the buffer
115
#define AV_PERM_REUSE    0x08   ///< can output the buffer multiple times, with the same contents each time
116
#define AV_PERM_REUSE2   0x10   ///< can output the buffer multiple times, modified each time
117
} AVFilterPicRef;
118

    
119
/**
120
 * Adds a new reference to a picture.
121
 * @param ref   an existing reference to the picture
122
 * @param pmask a bitmask containing the allowable permissions in the new
123
 *              reference
124
 * @return      a new reference to the picture with the same properties as the
125
 *              old, excluding any permissions denied by pmask
126
 */
127
AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask);
128

    
129
/**
130
 * Removes a reference to a picture. If this is the last reference to the
131
 * picture, the picture itself is also automatically freed.
132
 * @param ref reference to the picture
133
 */
134
void avfilter_unref_pic(AVFilterPicRef *ref);
135

    
136
/**
137
 * A list of supported formats for one end of a filter link. This is used
138
 * during the format negotiation process to try to pick the best format to
139
 * use to minimize the number of necessary conversions. Each filter gives a
140
 * list of the formats supported by each input and output pad. The list
141
 * given for each pad need not be distinct - they may be references to the
142
 * same list of formats, as is often the case when a filter supports multiple
143
 * formats, but will always output the same format as it is given in input.
144
 *
145
 * In this way, a list of possible input formats and a list of possible
146
 * output formats are associated with each link. When a set of formats is
147
 * negotiated over a link, the input and output lists are merged to form a
148
 * new list containing only the common elements of each list. In the case
149
 * that there were no common elements, a format conversion is necessary.
150
 * Otherwise, the lists are merged, and all other links which reference
151
 * either of the format lists involved in the merge are also affected.
152
 *
153
 * For example, consider the filter chain:
154
 * filter (a) --> (b) filter (b) --> (c) filter
155
 *
156
 * where the letters in parenthesis indicate a list of formats supported on
157
 * the input or output of the link. Suppose the lists are as follows:
158
 * (a) = {A, B}
159
 * (b) = {A, B, C}
160
 * (c) = {B, C}
161
 *
162
 * First, the first link's lists are merged, yielding:
163
 * filter (a) --> (a) filter (a) --> (c) filter
164
 *
165
 * Notice that format list (b) now refers to the same list as filter list (a).
166
 * Next, the lists for the second link are merged, yielding:
167
 * filter (a) --> (a) filter (a) --> (a) filter
168
 *
169
 * where (a) = {B}.
170
 *
171
 * Unfortunately, when the format lists at the two ends of a link are merged,
172
 * we must ensure that all links which reference either pre-merge format list
173
 * get updated as well. Therefore, we have the format list structure store a
174
 * pointer to each of the pointers to itself.
175
 */
176
typedef struct AVFilterFormats AVFilterFormats;
177
struct AVFilterFormats
178
{
179
    unsigned format_count;      ///< number of formats
180
    enum PixelFormat *formats;  ///< list of pixel formats
181

    
182
    unsigned refcount;          ///< number of references to this list
183
    AVFilterFormats ***refs;    ///< references to this list
184
};
185

    
186
/**
187
 * Creates a list of supported formats. This is intended for use in
188
 * AVFilter->query_formats().
189
 * @param pix_fmt list of pixel formats, terminated by PIX_FMT_NONE
190
 * @return the format list, with no existing references
191
 */
192
AVFilterFormats *avfilter_make_format_list(const enum PixelFormat *pix_fmts);
193

    
194
/**
195
 * Adds pix_fmt to the list of pixel formats contained in *avff.
196
 * If *avff is NULL the function allocates the filter formats struct
197
 * and puts its pointer in *avff.
198
 *
199
 * @return a non negative value in case of success, or a negative
200
 * value corresponding to an AVERROR code in case of error
201
 */
202
int avfilter_add_colorspace(AVFilterFormats **avff, enum PixelFormat pix_fmt);
203

    
204
/**
205
 * Returns a list of all colorspaces supported by FFmpeg.
206
 */
207
AVFilterFormats *avfilter_all_colorspaces(void);
208

    
209
/**
210
 * Returns a format list which contains the intersection of the formats of
211
 * a and b. Also, all the references of a, all the references of b, and
212
 * a and b themselves will be deallocated.
213
 *
214
 * If a and b do not share any common formats, neither is modified, and NULL
215
 * is returned.
216
 */
217
AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
218

    
219
/**
220
 * Adds *ref as a new reference to formats.
221
 * That is the pointers will point like in the ascii art below:
222
 *   ________
223
 *  |formats |<--------.
224
 *  |  ____  |     ____|___________________
225
 *  | |refs| |    |  __|_
226
 *  | |* * | |    | |  | |  AVFilterLink
227
 *  | |* *--------->|*ref|
228
 *  | |____| |    | |____|
229
 *  |________|    |________________________
230
 */
231
void avfilter_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
232

    
233
/**
234
 * If *ref is non-NULL, removes *ref as a reference to the format list
235
 * it currently points to, deallocates that list if this was the last
236
 * reference, and sets *ref to NULL.
237
 *
238
 *         Before                                 After
239
 *   ________                               ________         NULL
240
 *  |formats |<--------.                   |formats |         ^
241
 *  |  ____  |     ____|________________   |  ____  |     ____|________________
242
 *  | |refs| |    |  __|_                  | |refs| |    |  __|_
243
 *  | |* * | |    | |  | |  AVFilterLink   | |* * | |    | |  | |  AVFilterLink
244
 *  | |* *--------->|*ref|                 | |*   | |    | |*ref|
245
 *  | |____| |    | |____|                 | |____| |    | |____|
246
 *  |________|    |_____________________   |________|    |_____________________
247
 */
248
void avfilter_formats_unref(AVFilterFormats **ref);
249

    
250
/**
251
 *
252
 *         Before                                 After
253
 *   ________                         ________
254
 *  |formats |<---------.            |formats |<---------.
255
 *  |  ____  |       ___|___         |  ____  |       ___|___
256
 *  | |refs| |      |   |   |        | |refs| |      |   |   |   NULL
257
 *  | |* *--------->|*oldref|        | |* *--------->|*newref|     ^
258
 *  | |* * | |      |_______|        | |* * | |      |_______|  ___|___
259
 *  | |____| |                       | |____| |                |   |   |
260
 *  |________|                       |________|                |*oldref|
261
 *                                                             |_______|
262
 */
263
void avfilter_formats_changeref(AVFilterFormats **oldref,
264
                                AVFilterFormats **newref);
265

    
266
/**
267
 * A filter pad used for either input or output.
268
 */
269
struct AVFilterPad
270
{
271
    /**
272
     * Pad name. The name is unique among inputs and among outputs, but an
273
     * input may have the same name as an output. This may be NULL if this
274
     * pad has no need to ever be referenced by name.
275
     */
276
    const char *name;
277

    
278
    /**
279
     * AVFilterPad type. Only video supported now, hopefully someone will
280
     * add audio in the future.
281
     */
282
    enum CodecType type;
283

    
284
    /**
285
     * Minimum required permissions on incoming buffers. Any buffer with
286
     * insufficient permissions will be automatically copied by the filter
287
     * system to a new buffer which provides the needed access permissions.
288
     *
289
     * Input pads only.
290
     */
291
    int min_perms;
292

    
293
    /**
294
     * Permissions which are not accepted on incoming buffers. Any buffer
295
     * which has any of these permissions set will be automatically copied
296
     * by the filter system to a new buffer which does not have those
297
     * permissions. This can be used to easily disallow buffers with
298
     * AV_PERM_REUSE.
299
     *
300
     * Input pads only.
301
     */
302
    int rej_perms;
303

    
304
    /**
305
     * Callback called before passing the first slice of a new frame. If
306
     * NULL, the filter layer will default to storing a reference to the
307
     * picture inside the link structure.
308
     *
309
     * Input video pads only.
310
     */
311
    void (*start_frame)(AVFilterLink *link, AVFilterPicRef *picref);
312

    
313
    /**
314
     * Callback function to get a buffer. If NULL, the filter system will
315
     * use avfilter_default_get_video_buffer().
316
     *
317
     * Input video pads only.
318
     */
319
    AVFilterPicRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
320

    
321
    /**
322
     * Callback called after the slices of a frame are completely sent. If
323
     * NULL, the filter layer will default to releasing the reference stored
324
     * in the link structure during start_frame().
325
     *
326
     * Input video pads only.
327
     */
328
    void (*end_frame)(AVFilterLink *link);
329

    
330
    /**
331
     * Slice drawing callback. This is where a filter receives video data
332
     * and should do its processing.
333
     *
334
     * Input video pads only.
335
     */
336
    void (*draw_slice)(AVFilterLink *link, int y, int height, int slice_dir);
337

    
338
    /**
339
     * Frame poll callback. This returns the number of immediately available
340
     * frames. It should return a positive value if the next request_frame()
341
     * is guaranteed to return one frame (with no delay).
342
     *
343
     * Defaults to just calling the source poll_frame() method.
344
     *
345
     * Output video pads only.
346
     */
347
    int (*poll_frame)(AVFilterLink *link);
348

    
349
    /**
350
     * Frame request callback. A call to this should result in at least one
351
     * frame being output over the given link. This should return zero on
352
     * success, and another value on error.
353
     *
354
     * Output video pads only.
355
     */
356
    int (*request_frame)(AVFilterLink *link);
357

    
358
    /**
359
     * Link configuration callback.
360
     *
361
     * For output pads, this should set the link properties such as
362
     * width/height. This should NOT set the format property - that is
363
     * negotiated between filters by the filter system using the
364
     * query_formats() callback before this function is called.
365
     *
366
     * For input pads, this should check the properties of the link, and update
367
     * the filter's internal state as necessary.
368
     *
369
     * For both input and output filters, this should return zero on success,
370
     * and another value on error.
371
     */
372
    int (*config_props)(AVFilterLink *link);
373
};
374

    
375
/** default handler for start_frame() for video inputs */
376
void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
377
/** default handler for draw_slice() for video inputs */
378
void avfilter_default_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
379
/** default handler for end_frame() for video inputs */
380
void avfilter_default_end_frame(AVFilterLink *link);
381
/** default handler for config_props() for video outputs */
382
int avfilter_default_config_output_link(AVFilterLink *link);
383
/** default handler for config_props() for video inputs */
384
int avfilter_default_config_input_link (AVFilterLink *link);
385
/** default handler for get_video_buffer() for video inputs */
386
AVFilterPicRef *avfilter_default_get_video_buffer(AVFilterLink *link,
387
                                                  int perms, int w, int h);
388
/**
389
 * A helper for query_formats() which sets all links to the same list of
390
 * formats. If there are no links hooked to this filter, the list of formats is
391
 * freed.
392
 */
393
void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
394
/** Default handler for query_formats() */
395
int avfilter_default_query_formats(AVFilterContext *ctx);
396

    
397
/**
398
 * Filter definition. This defines the pads a filter contains, and all the
399
 * callback functions used to interact with the filter.
400
 */
401
typedef struct AVFilter
402
{
403
    const char *name;         ///< filter name
404

    
405
    int priv_size;      ///< size of private data to allocate for the filter
406

    
407
    /**
408
     * Filter initialization function. Args contains the user-supplied
409
     * parameters. FIXME: maybe an AVOption-based system would be better?
410
     * opaque is data provided by the code requesting creation of the filter,
411
     * and is used to pass data to the filter.
412
     */
413
    int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
414

    
415
    /**
416
     * Filter uninitialization function. Should deallocate any memory held
417
     * by the filter, release any picture references, etc. This does not need
418
     * to deallocate the AVFilterContext->priv memory itself.
419
     */
420
    void (*uninit)(AVFilterContext *ctx);
421

    
422
    /**
423
     * Queries formats supported by the filter and its pads, and sets the
424
     * in_formats for links connected to its output pads, and out_formats
425
     * for links connected to its input pads.
426
     *
427
     * @return zero on success, a negative value corresponding to an
428
     * AVERROR code otherwise
429
     */
430
    int (*query_formats)(AVFilterContext *);
431

    
432
    const AVFilterPad *inputs;  ///< NULL terminated list of inputs. NULL if none
433
    const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
434

    
435
    /**
436
     * A description for the filter. You should use the
437
     * NULL_IF_CONFIG_SMALL() macro to define it.
438
     */
439
    const char *description;
440
} AVFilter;
441

    
442
/** An instance of a filter */
443
struct AVFilterContext
444
{
445
    const AVClass *av_class;              ///< needed for av_log()
446

    
447
    AVFilter *filter;               ///< the AVFilter of which this is an instance
448

    
449
    char *name;                     ///< name of this filter instance
450

    
451
    unsigned input_count;           ///< number of input pads
452
    AVFilterPad   *input_pads;      ///< array of input pads
453
    AVFilterLink **inputs;          ///< array of pointers to input links
454

    
455
    unsigned output_count;          ///< number of output pads
456
    AVFilterPad   *output_pads;     ///< array of output pads
457
    AVFilterLink **outputs;         ///< array of pointers to output links
458

    
459
    void *priv;                     ///< private data for use by the filter
460
};
461

    
462
/**
463
 * A link between two filters. This contains pointers to the source and
464
 * destination filters between which this link exists, and the indexes of
465
 * the pads involved. In addition, this link also contains the parameters
466
 * which have been negotiated and agreed upon between the filter, such as
467
 * image dimensions, format, etc.
468
 */
469
struct AVFilterLink
470
{
471
    AVFilterContext *src;       ///< source filter
472
    unsigned int srcpad;        ///< index of the output pad on the source filter
473

    
474
    AVFilterContext *dst;       ///< dest filter
475
    unsigned int dstpad;        ///< index of the input pad on the dest filter
476

    
477
    /** stage of the initialization of the link properties (dimensions, etc) */
478
    enum {
479
        AVLINK_UNINIT = 0,      ///< not started
480
        AVLINK_STARTINIT,       ///< started, but incomplete
481
        AVLINK_INIT             ///< complete
482
    } init_state;
483

    
484
    int w;                      ///< agreed upon image width
485
    int h;                      ///< agreed upon image height
486
    enum PixelFormat format;    ///< agreed upon image colorspace
487

    
488
    /**
489
     * Lists of formats supported by the input and output filters respectively.
490
     * These lists are used for negotiating the format to actually be used,
491
     * which will be loaded into the format member, above, when chosen.
492
     */
493
    AVFilterFormats *in_formats;
494
    AVFilterFormats *out_formats;
495

    
496
    /**
497
     * The picture reference currently being sent across the link by the source
498
     * filter. This is used internally by the filter system to allow
499
     * automatic copying of pictures which do not have sufficient permissions
500
     * for the destination. This should not be accessed directly by the
501
     * filters.
502
     */
503
    AVFilterPicRef *srcpic;
504

    
505
    AVFilterPicRef *cur_pic;
506
    AVFilterPicRef *outpic;
507
};
508

    
509
/**
510
 * Links two filters together.
511
 * @param src    the source filter
512
 * @param srcpad index of the output pad on the source filter
513
 * @param dst    the destination filter
514
 * @param dstpad index of the input pad on the destination filter
515
 * @return       zero on success
516
 */
517
int avfilter_link(AVFilterContext *src, unsigned srcpad,
518
                  AVFilterContext *dst, unsigned dstpad);
519

    
520
/**
521
 * Negotiates the colorspace, dimensions, etc of all inputs to a filter.
522
 * @param filter the filter to negotiate the properties for its inputs
523
 * @return       zero on successful negotiation
524
 */
525
int avfilter_config_links(AVFilterContext *filter);
526

    
527
/**
528
 * Requests a picture buffer with a specific set of permissions.
529
 * @param link  the output link to the filter from which the picture will
530
 *              be requested
531
 * @param perms the required access permissions
532
 * @param w     the minimum width of the buffer to allocate
533
 * @param h     the minimum height of the buffer to allocate
534
 * @return      A reference to the picture. This must be unreferenced with
535
 *              avfilter_unref_pic when you are finished with it.
536
 */
537
AVFilterPicRef *avfilter_get_video_buffer(AVFilterLink *link, int perms,
538
                                          int w, int h);
539

    
540
/**
541
 * Requests an input frame from the filter at the other end of the link.
542
 * @param link the input link
543
 * @return     zero on success
544
 */
545
int avfilter_request_frame(AVFilterLink *link);
546

    
547
/**
548
 * Polls a frame from the filter chain.
549
 * @param  link the input link
550
 * @return the number of immediately available frames, a negative
551
 * number in case of error
552
 */
553
int avfilter_poll_frame(AVFilterLink *link);
554

    
555
/**
556
 * Notifies the next filter of the start of a frame.
557
 * @param link   the output link the frame will be sent over
558
 * @param picref A reference to the frame about to be sent. The data for this
559
 *               frame need only be valid once draw_slice() is called for that
560
 *               portion. The receiving filter will free this reference when
561
 *               it no longer needs it.
562
 */
563
void avfilter_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
564

    
565
/**
566
 * Notifies the next filter that the current frame has finished.
567
 * @param link the output link the frame was sent over
568
 */
569
void avfilter_end_frame(AVFilterLink *link);
570

    
571
/**
572
 * Sends a slice to the next filter.
573
 *
574
 * Slices have to be provided in sequential order, either in
575
 * top-bottom or bottom-top order. If slices are provided in
576
 * non-sequential order the behavior of the function is undefined.
577
 *
578
 * @param link the output link over which the frame is being sent
579
 * @param y    offset in pixels from the top of the image for this slice
580
 * @param h    height of this slice in pixels
581
 * @param slice_dir the assumed direction for sending slices,
582
 *             from the top slice to the bottom slice if the value is 1,
583
 *             from the bottom slice to the top slice if the value is -1,
584
 *             for other values the behavior of the function is undefined.
585
 */
586
void avfilter_draw_slice(AVFilterLink *link, int y, int h, int slice_dir);
587

    
588
/** Initializes the filter system. Registers all builtin filters. */
589
void avfilter_register_all(void);
590

    
591
/** Uninitializes the filter system. Unregisters all filters. */
592
void avfilter_uninit(void);
593

    
594
/**
595
 * Registers a filter. This is only needed if you plan to use
596
 * avfilter_get_by_name later to lookup the AVFilter structure by name. A
597
 * filter can still by instantiated with avfilter_open even if it is not
598
 * registered.
599
 * @param filter the filter to register
600
 * @return 0 if the registration was succesfull, a negative value
601
 * otherwise
602
 */
603
int avfilter_register(AVFilter *filter);
604

    
605
/**
606
 * Gets a filter definition matching the given name.
607
 * @param name the filter name to find
608
 * @return     the filter definition, if any matching one is registered.
609
 *             NULL if none found.
610
 */
611
AVFilter *avfilter_get_by_name(const char *name);
612

    
613
/**
614
 * If filter is NULL, returns a pointer to the first registered filter pointer,
615
 * if filter is non-NULL, returns the next pointer after filter.
616
 * If the returned pointer points to NULL, the last registered filter
617
 * was already reached.
618
 */
619
AVFilter **av_filter_next(AVFilter **filter);
620

    
621
/**
622
 * Creates a filter instance.
623
 * @param filter    the filter to create an instance of
624
 * @param inst_name Name to give to the new instance. Can be NULL for none.
625
 * @return          Pointer to the new instance on success. NULL on failure.
626
 */
627
AVFilterContext *avfilter_open(AVFilter *filter, const char *inst_name);
628

    
629
/**
630
 * Initializes a filter.
631
 * @param filter the filter to initialize
632
 * @param args   A string of parameters to use when initializing the filter.
633
 *               The format and meaning of this string varies by filter.
634
 * @param opaque Any extra non-string data needed by the filter. The meaning
635
 *               of this parameter varies by filter.
636
 * @return       zero on success
637
 */
638
int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
639

    
640
/**
641
 * Destroys a filter.
642
 * @param filter the filter to destroy
643
 */
644
void avfilter_destroy(AVFilterContext *filter);
645

    
646
/**
647
 * Inserts a filter in the middle of an existing link.
648
 * @param link the link into which the filter should be inserted
649
 * @param filt the filter to be inserted
650
 * @param in   the input pad on the filter to connect
651
 * @param out  the output pad on the filter to connect
652
 * @return     zero on success
653
 */
654
int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
655
                           unsigned in, unsigned out);
656

    
657
/**
658
 * Inserts a new pad.
659
 * @param idx Insertion point. Pad is inserted at the end if this point
660
 *            is beyond the end of the list of pads.
661
 * @param count Pointer to the number of pads in the list
662
 * @param padidx_off Offset within an AVFilterLink structure to the element
663
 *                   to increment when inserting a new pad causes link
664
 *                   numbering to change
665
 * @param pads Pointer to the pointer to the beginning of the list of pads
666
 * @param links Pointer to the pointer to the beginning of the list of links
667
 * @param newpad The new pad to add. A copy is made when adding.
668
 */
669
void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
670
                         AVFilterPad **pads, AVFilterLink ***links,
671
                         AVFilterPad *newpad);
672

    
673
/** Inserts a new input pad for the filter. */
674
static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
675
                                         AVFilterPad *p)
676
{
677
    avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
678
                        &f->input_pads, &f->inputs, p);
679
}
680

    
681
/** Inserts a new output pad for the filter. */
682
static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
683
                                          AVFilterPad *p)
684
{
685
    avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
686
                        &f->output_pads, &f->outputs, p);
687
}
688

    
689
#endif  /* AVFILTER_AVFILTER_H */