libavfilter/avfilter.h

   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 #define LIBAVFILTER_VERSION_MAJOR  1
  26 #define LIBAVFILTER_VERSION_MINOR  1
  27 #define LIBAVFILTER_VERSION_MICRO  0
  28
  29 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
  30                                                LIBAVFILTER_VERSION_MINOR, \
  31                                                LIBAVFILTER_VERSION_MICRO)
  32 #define LIBAVFILTER_VERSION     AV_VERSION(LIBAVFILTER_VERSION_MAJOR,   \
  33                                            LIBAVFILTER_VERSION_MINOR,   \
  34                                            LIBAVFILTER_VERSION_MICRO)
  35 #define LIBAVFILTER_BUILD       LIBAVFILTER_VERSION_INT
  36
  37 #include <stddef.h>
  38 #include "libavcodec/avcodec.h"
  39
  40 /**
  41  * Returns the LIBAVFILTER_VERSION_INT constant.
  42  */
  43 unsigned avfilter_version(void);
  44
  45 typedef struct AVFilterContext AVFilterContext;
  46 typedef struct AVFilterLink    AVFilterLink;
  47 typedef struct AVFilterPad     AVFilterPad;
  48
  49 /* TODO: look for other flags which may be useful in this structure (interlace
  50  * flags, etc)
  51  */
  52 /**
  53  * A reference-counted picture data type used by the filter system. Filters
  54  * should not store pointers to this structure directly, but instead use the
  55  * AVFilterPicRef structure below.
  56  */
  57 typedef struct AVFilterPic
  58 {
  59     uint8_t *data[4];           ///< picture data for each plane
  60     int linesize[4];            ///< number of bytes per line
  61     enum PixelFormat format;    ///< colorspace
  62
  63     unsigned refcount;          ///< number of references to this image
  64
  65     /** private data to be used by a custom free function */
  66     void *priv;
  67     /**
  68      * A pointer to the function to deallocate this image if the default
  69      * function is not sufficient. This could, for example, add the memory
  70      * back into a memory pool to be reused later without the overhead of
  71      * reallocating it from scratch.
  72      */
  73     void (*free)(struct AVFilterPic *pic);
  74
  75     int w, h;                  ///< width and height of the allocated buffer
  76 } AVFilterPic;
  77
  78 /**
  79  * A reference to an AVFilterPic. Since filters can manipulate the origin of
  80  * a picture to, for example, crop image without any memcpy, the picture origin
  81  * and dimensions are per-reference properties. Linesize is also useful for
  82  * image flipping, frame to field filters, etc, and so is also per-reference.
  83  *
  84  * TODO: add anything necessary for frame reordering
  85  */
  86 typedef struct AVFilterPicRef
  87 {
  88     AVFilterPic *pic;           ///< the picture that this is a reference to
  89     uint8_t *data[4];           ///< picture data for each plane
  90     int linesize[4];            ///< number of bytes per line
  91     int w;                      ///< image width
  92     int h;                      ///< image height
  93
  94     int64_t pts;                ///< presentation timestamp in units of 1/AV_TIME_BASE
  95
  96     AVRational pixel_aspect;    ///< pixel aspect ratio
  97
  98     int perms;                  ///< permissions
  99 #define AV_PERM_READ     0x01   ///< can read from the buffer
 100 #define AV_PERM_WRITE    0x02   ///< can write to the buffer
 101 #define AV_PERM_PRESERVE 0x04   ///< nobody else can overwrite the buffer
 102 #define AV_PERM_REUSE    0x08   ///< can output the buffer multiple times, with the same contents each time
 103 #define AV_PERM_REUSE2   0x10   ///< can output the buffer multiple times, modified each time
 104 } AVFilterPicRef;
 105
 106 /**
 107  * Adds a new reference to a picture.
 108  * @param ref   an existing reference to the picture
 109  * @param pmask a bitmask containing the allowable permissions in the new
 110  *              reference
 111  * @return      a new reference to the picture with the same properties as the
 112  *              old, excluding any permissions denied by pmask
 113  */
 114 AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask);
 115
 116 /**
 117  * Removes a reference to a picture. If this is the last reference to the
 118  * picture, the picture itself is also automatically freed.
 119  * @param ref reference to the picture
 120  */
 121 void avfilter_unref_pic(AVFilterPicRef *ref);
 122
 123 /**
 124  * A list of supported formats for one end of a filter link. This is used
 125  * during the format negotiation process to try to pick the best format to
 126  * use to minimize the number of necessary conversions. Each filter gives a
 127  * list of the formats supported by each input and output pad. The list
 128  * given for each pad need not be distinct - they may be references to the
 129  * same list of formats, as is often the case when a filter supports multiple
 130  * formats, but will always output the same format as it is given in input.
 131  *
 132  * In this way, a list of possible input formats and a list of possible
 133  * output formats are associated with each link. When a set of formats is
 134  * negotiated over a link, the input and output lists are merged to form a
 135  * new list containing only the common elements of each list. In the case
 136  * that there were no common elements, a format conversion is necessary.
 137  * Otherwise, the lists are merged, and all other links which reference
 138  * either of the format lists involved in the merge are also affected.
 139  *
 140  * For example, consider the filter chain:
 141  * filter (a) --> (b) filter (b) --> (c) filter
 142  *
 143  * where the letters in parenthesis indicate a list of formats supported on
 144  * the input or output of the link. Suppose the lists are as follows:
 145  * (a) = {A, B}
 146  * (b) = {A, B, C}
 147  * (c) = {B, C}
 148  *
 149  * First, the first link's lists are merged, yielding:
 150  * filter (a) --> (a) filter (a) --> (c) filter
 151  *
 152  * Notice that format list (b) now refers to the same list as filter list (a).
 153  * Next, the lists for the second link are merged, yielding:
 154  * filter (a) --> (a) filter (a) --> (a) filter
 155  *
 156  * where (a) = {B}.
 157  *
 158  * Unfortunately, when the format lists at the two ends of a link are merged,
 159  * we must ensure that all links which reference either pre-merge format list
 160  * get updated as well. Therefore, we have the format list structure store a
 161  * pointer to each of the pointers to itself.
 162  */
 163 typedef struct AVFilterFormats AVFilterFormats;
 164 struct AVFilterFormats
 165 {
 166     unsigned format_count;      ///< number of formats
 167     enum PixelFormat *formats;  ///< list of pixel formats
 168
 169     unsigned refcount;          ///< number of references to this list
 170     AVFilterFormats ***refs;    ///< references to this list
 171 };
 172
 173 /**
 174  * Helper function to create a list of supported formats.  This is intended
 175  * for use in AVFilter->query_formats().
 176  * @param len the number of formats supported
 177  * @param ... a list of the supported formats
 178  * @return    the format list, with no existing references
 179  */
 180 AVFilterFormats *avfilter_make_format_list(int len, ...);
 181
 182 /**
 183  * Creates a list of supported formats. This is intended for use in
 184  * AVFilter->query_formats().
 185  * @param pix_fmt list of pixel formats, terminated by PIX_FMT_NONE
 186  * @return the format list, with no existing references
 187  */
 188 AVFilterFormats *avfilter_make_format_list2(enum PixelFormat *pix_fmt);
 189
 190 /**
 191  * Returns a list of all colorspaces supported by FFmpeg.
 192  */
 193 AVFilterFormats *avfilter_all_colorspaces(void);
 194
 195 /**
 196  * Returns a format list which contains the intersection of the formats of
 197  * a and b. Also, all the references of a, all the references of b, and
 198  * a and b themselves will be deallocated.
 199  *
 200  * If a and b do not share any common formats, neither is modified, and NULL
 201  * is returned.
 202  */
 203 AVFilterFormats *avfilter_merge_formats(AVFilterFormats *a, AVFilterFormats *b);
 204
 205 /**
 206  * Adds *ref as a new reference to formats.
 207  * That is the pointers will point like in the ascii art below:
 208  *   ________
 209  *  |formats |<--------.
 210  *  |  ____  |     ____|___________________
 211  *  | |refs| |    |  __|_
 212  *  | |* * | |    | |  | |  AVFilterLink
 213  *  | |* *--------->|*ref|
 214  *  | |____| |    | |____|
 215  *  |________|    |________________________
 216  */
 217 void avfilter_formats_ref(AVFilterFormats *formats, AVFilterFormats **ref);
 218
 219 /**
 220  * Removes *ref as a reference to the format list it currently points to,
 221  * deallocates that list if this was the last reference, and sets *ref to NULL.
 222  *
 223  *         Before                                 After
 224  *   ________                               ________         NULL
 225  *  |formats |<--------.                   |formats |         ^
 226  *  |  ____  |     ____|________________   |  ____  |     ____|________________
 227  *  | |refs| |    |  __|_                  | |refs| |    |  __|_
 228  *  | |* * | |    | |  | |  AVFilterLink   | |* * | |    | |  | |  AVFilterLink
 229  *  | |* *--------->|*ref|                 | |*   | |    | |*ref|
 230  *  | |____| |    | |____|                 | |____| |    | |____|
 231  *  |________|    |_____________________   |________|    |_____________________
 232  */
 233 void avfilter_formats_unref(AVFilterFormats **ref);
 234
 235 /**
 236  *
 237  *         Before                                 After
 238  *   ________                         ________
 239  *  |formats |<---------.            |formats |<---------.
 240  *  |  ____  |       ___|___         |  ____  |       ___|___
 241  *  | |refs| |      |   |   |        | |refs| |      |   |   |   NULL
 242  *  | |* *--------->|*oldref|        | |* *--------->|*newref|     ^
 243  *  | |* * | |      |_______|        | |* * | |      |_______|  ___|___
 244  *  | |____| |                       | |____| |                |   |   |
 245  *  |________|                       |________|                |*oldref|
 246  *                                                             |_______|
 247  */
 248 void avfilter_formats_changeref(AVFilterFormats **oldref,
 249                                 AVFilterFormats **newref);
 250
 251 /**
 252  * A filter pad used for either input or output.
 253  */
 254 struct AVFilterPad
 255 {
 256     /**
 257      * Pad name. The name is unique among inputs and among outputs, but an
 258      * input may have the same name as an output. This may be NULL if this
 259      * pad has no need to ever be referenced by name.
 260      */
 261     const char *name;
 262
 263     /**
 264      * AVFilterPad type. Only video supported now, hopefully someone will
 265      * add audio in the future.
 266      */
 267     enum CodecType type;
 268
 269     /**
 270      * Minimum required permissions on incoming buffers. Any buffer with
 271      * insufficient permissions will be automatically copied by the filter
 272      * system to a new buffer which provides the needed access permissions.
 273      *
 274      * Input pads only.
 275      */
 276     int min_perms;
 277
 278     /**
 279      * Permissions which are not accepted on incoming buffers. Any buffer
 280      * which has any of these permissions set will be automatically copied
 281      * by the filter system to a new buffer which does not have those
 282      * permissions. This can be used to easily disallow buffers with
 283      * AV_PERM_REUSE.
 284      *
 285      * Input pads only.
 286      */
 287     int rej_perms;
 288
 289     /**
 290      * Callback called before passing the first slice of a new frame. If
 291      * NULL, the filter layer will default to storing a reference to the
 292      * picture inside the link structure.
 293      *
 294      * Input video pads only.
 295      */
 296     void (*start_frame)(AVFilterLink *link, AVFilterPicRef *picref);
 297
 298     /**
 299      * Callback function to get a buffer. If NULL, the filter system will
 300      * handle buffer requests.
 301      *
 302      * Input video pads only.
 303      */
 304     AVFilterPicRef *(*get_video_buffer)(AVFilterLink *link, int perms, int w, int h);
 305
 306     /**
 307      * Callback called after the slices of a frame are completely sent. If
 308      * NULL, the filter layer will default to releasing the reference stored
 309      * in the link structure during start_frame().
 310      *
 311      * Input video pads only.
 312      */
 313     void (*end_frame)(AVFilterLink *link);
 314
 315     /**
 316      * Slice drawing callback. This is where a filter receives video data
 317      * and should do its processing.
 318      *
 319      * Input video pads only.
 320      */
 321     void (*draw_slice)(AVFilterLink *link, int y, int height);
 322
 323     /**
 324      * Frame poll callback. This returns the number of immediately available
 325      * frames. It should return a positive value if the next request_frame()
 326      * is guaranteed to return one frame (with no delay).
 327      *
 328      * Defaults to just calling the source poll_frame() method.
 329      *
 330      * Output video pads only.
 331      */
 332     int (*poll_frame)(AVFilterLink *link);
 333
 334     /**
 335      * Frame request callback. A call to this should result in at least one
 336      * frame being output over the given link. This should return zero on
 337      * success, and another value on error.
 338      *
 339      * Output video pads only.
 340      */
 341     int (*request_frame)(AVFilterLink *link);
 342
 343     /**
 344      * Link configuration callback.
 345      *
 346      * For output pads, this should set the link properties such as
 347      * width/height. This should NOT set the format property - that is
 348      * negotiated between filters by the filter system using the
 349      * query_formats() callback before this function is called.
 350      *
 351      * For input pads, this should check the properties of the link, and update
 352      * the filter's internal state as necessary.
 353      *
 354      * For both input and output filters, this should return zero on success,
 355      * and another value on error.
 356      */
 357     int (*config_props)(AVFilterLink *link);
 358 };
 359
 360 /** default handler for start_frame() for video inputs */
 361 void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
 362 /** default handler for draw_slice() for video inputs */
 363 void avfilter_default_draw_slice(AVFilterLink *link, int y, int h);
 364 /** default handler for end_frame() for video inputs */
 365 void avfilter_default_end_frame(AVFilterLink *link);
 366 /** default handler for config_props() for video outputs */
 367 int avfilter_default_config_output_link(AVFilterLink *link);
 368 /** default handler for config_props() for video inputs */
 369 int avfilter_default_config_input_link (AVFilterLink *link);
 370 /** default handler for get_video_buffer() for video inputs */
 371 AVFilterPicRef *avfilter_default_get_video_buffer(AVFilterLink *link,
 372                                                   int perms, int w, int h);
 373 /**
 374  * A helper for query_formats() which sets all links to the same list of
 375  * formats. If there are no links hooked to this filter, the list of formats is
 376  * freed.
 377  */
 378 void avfilter_set_common_formats(AVFilterContext *ctx, AVFilterFormats *formats);
 379 /** Default handler for query_formats() */
 380 int avfilter_default_query_formats(AVFilterContext *ctx);
 381
 382 /**
 383  * Filter definition. This defines the pads a filter contains, and all the
 384  * callback functions used to interact with the filter.
 385  */
 386 typedef struct
 387 {
 388     const char *name;         ///< filter name
 389
 390     int priv_size;      ///< size of private data to allocate for the filter
 391
 392     /**
 393      * Filter initialization function. Args contains the user-supplied
 394      * parameters. FIXME: maybe an AVOption-based system would be better?
 395      * opaque is data provided by the code requesting creation of the filter,
 396      * and is used to pass data to the filter.
 397      */
 398     int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
 399
 400     /**
 401      * Filter uninitialization function. Should deallocate any memory held
 402      * by the filter, release any picture references, etc. This does not need
 403      * to deallocate the AVFilterContext->priv memory itself.
 404      */
 405     void (*uninit)(AVFilterContext *ctx);
 406
 407     /**
 408      * Query formats supported by the filter and its pads. Should set the
 409      * in_formats for links connected to its output pads, and out_formats
 410      * for links connected to its input pads.
 411      *
 412      * Should return zero on success.
 413      */
 414     int (*query_formats)(AVFilterContext *);
 415
 416     const AVFilterPad *inputs;  ///< NULL terminated list of inputs. NULL if none
 417     const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
 418 } AVFilter;
 419
 420 /** An instance of a filter */
 421 struct AVFilterContext
 422 {
 423     const AVClass *av_class;              ///< needed for av_log()
 424
 425     AVFilter *filter;               ///< the AVFilter of which this is an instance
 426
 427     char *name;                     ///< name of this filter instance
 428
 429     unsigned input_count;           ///< number of input pads
 430     AVFilterPad   *input_pads;      ///< array of input pads
 431     AVFilterLink **inputs;          ///< array of pointers to input links
 432
 433     unsigned output_count;          ///< number of output pads
 434     AVFilterPad   *output_pads;     ///< array of output pads
 435     AVFilterLink **outputs;         ///< array of pointers to output links
 436
 437     void *priv;                     ///< private data for use by the filter
 438 };
 439
 440 /**
 441  * A link between two filters. This contains pointers to the source and
 442  * destination filters between which this link exists, and the indexes of
 443  * the pads involved. In addition, this link also contains the parameters
 444  * which have been negotiated and agreed upon between the filter, such as
 445  * image dimensions, format, etc.
 446  */
 447 struct AVFilterLink
 448 {
 449     AVFilterContext *src;       ///< source filter
 450     unsigned int srcpad;        ///< index of the output pad on the source filter
 451
 452     AVFilterContext *dst;       ///< dest filter
 453     unsigned int dstpad;        ///< index of the input pad on the dest filter
 454
 455     /** stage of the initialization of the link properties (dimensions, etc) */
 456     enum {
 457         AVLINK_UNINIT = 0,      ///< not started
 458         AVLINK_STARTINIT,       ///< started, but incomplete
 459         AVLINK_INIT             ///< complete
 460     } init_state;
 461
 462     int w;                      ///< agreed upon image width
 463     int h;                      ///< agreed upon image height
 464     enum PixelFormat format;    ///< agreed upon image colorspace
 465
 466     /**
 467      * Lists of formats supported by the input and output filters respectively.
 468      * These lists are used for negotiating the format to actually be used,
 469      * which will be loaded into the format member, above, when chosen.
 470      */
 471     AVFilterFormats *in_formats;
 472     AVFilterFormats *out_formats;
 473
 474     /**
 475      * The picture reference currently being sent across the link by the source
 476      * filter. This is used internally by the filter system to allow
 477      * automatic copying of pictures which do not have sufficient permissions
 478      * for the destination. This should not be accessed directly by the
 479      * filters.
 480      */
 481     AVFilterPicRef *srcpic;
 482
 483     AVFilterPicRef *cur_pic;
 484     AVFilterPicRef *outpic;
 485 };
 486
 487 /**
 488  * Links two filters together.
 489  * @param src    the source filter
 490  * @param srcpad index of the output pad on the source filter
 491  * @param dst    the destination filter
 492  * @param dstpad index of the input pad on the destination filter
 493  * @return       zero on success
 494  */
 495 int avfilter_link(AVFilterContext *src, unsigned srcpad,
 496                   AVFilterContext *dst, unsigned dstpad);
 497
 498 /**
 499  * Negotiates the colorspace, dimensions, etc of all inputs to a filter.
 500  * @param filter the filter to negotiate the properties for its inputs
 501  * @return       zero on successful negotiation
 502  */
 503 int avfilter_config_links(AVFilterContext *filter);
 504
 505 /**
 506  * Requests a picture buffer with a specific set of permissions.
 507  * @param link  the output link to the filter from which the picture will
 508  *              be requested
 509  * @param perms the required access permissions
 510  * @param w     the minimum width of the buffer to allocate
 511  * @param h     the minimum height of the buffer to allocate
 512  * @return      A reference to the picture. This must be unreferenced with
 513  *              avfilter_unref_pic when you are finished with it.
 514  */
 515 AVFilterPicRef *avfilter_get_video_buffer(AVFilterLink *link, int perms,
 516                                           int w, int h);
 517
 518 /**
 519  * Requests an input frame from the filter at the other end of the link.
 520  * @param link the input link
 521  * @return     zero on success
 522  */
 523 int avfilter_request_frame(AVFilterLink *link);
 524
 525 /**
 526  * Polls a frame from the filter chain.
 527  * @param  link the input link
 528  * @return the number of immediately available frames, a negative
 529  * number in case of error
 530  */
 531 int avfilter_poll_frame(AVFilterLink *link);
 532
 533 /**
 534  * Notifies the next filter of the start of a frame.
 535  * @param link   the output link the frame will be sent over
 536  * @param picref A reference to the frame about to be sent. The data for this
 537  *               frame need only be valid once draw_slice() is called for that
 538  *               portion. The receiving filter will free this reference when
 539  *               it no longer needs it.
 540  */
 541 void avfilter_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
 542
 543 /**
 544  * Notifies the next filter that the current frame has finished.
 545  * @param link the output link the frame was sent over
 546  */
 547 void avfilter_end_frame(AVFilterLink *link);
 548
 549 /**
 550  * Sends a slice to the next filter.
 551  * @param link the output link over which the frame is being sent
 552  * @param y    offset in pixels from the top of the image for this slice
 553  * @param h    height of this slice in pixels
 554  */
 555 void avfilter_draw_slice(AVFilterLink *link, int y, int h);
 556
 557 /** Initialize the filter system. Registers all builtin filters */
 558 void avfilter_register_all(void);
 559
 560 /** Uninitialize the filter system. Unregisters all filters */
 561 void avfilter_uninit(void);
 562
 563 /**
 564  * Registers a filter. This is only needed if you plan to use
 565  * avfilter_get_by_name later to lookup the AVFilter structure by name. A
 566  * filter can still by instantiated with avfilter_open even if it is not
 567  * registered.
 568  * @param filter the filter to register
 569  */
 570 void avfilter_register(AVFilter *filter);
 571
 572 /**
 573  * Gets a filter definition matching the given name.
 574  * @param name the filter name to find
 575  * @return     the filter definition, if any matching one is registered.
 576  *             NULL if none found.
 577  */
 578 AVFilter *avfilter_get_by_name(const char *name);
 579
 580 /**
 581  * Creates a filter instance.
 582  * @param filter    the filter to create an instance of
 583  * @param inst_name Name to give to the new instance. Can be NULL for none.
 584  * @return          Pointer to the new instance on success. NULL on failure.
 585  */
 586 AVFilterContext *avfilter_open(AVFilter *filter, const char *inst_name);
 587
 588 /**
 589  * Initializes a filter.
 590  * @param filter the filter to initialize
 591  * @param args   A string of parameters to use when initializing the filter.
 592  *               The format and meaning of this string varies by filter.
 593  * @param opaque Any extra non-string data needed by the filter. The meaning
 594  *               of this parameter varies by filter.
 595  * @return       zero on success
 596  */
 597 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
 598
 599 /**
 600  * Destroys a filter.
 601  * @param filter the filter to destroy
 602  */
 603 void avfilter_destroy(AVFilterContext *filter);
 604
 605 /**
 606  * Inserts a filter in the middle of an existing link.
 607  * @param link the link into which the filter should be inserted
 608  * @param filt the filter to be inserted
 609  * @param in   the input pad on the filter to connect
 610  * @param out  the output pad on the filter to connect
 611  * @return     zero on success
 612  */
 613 int avfilter_insert_filter(AVFilterLink *link, AVFilterContext *filt,
 614                            unsigned in, unsigned out);
 615
 616 /**
 617  * Inserts a new pad.
 618  * @param idx Insertion point. Pad is inserted at the end if this point
 619  *            is beyond the end of the list of pads.
 620  * @param count Pointer to the number of pads in the list
 621  * @param padidx_off Offset within an AVFilterLink structure to the element
 622  *                   to increment when inserting a new pad causes link
 623  *                   numbering to change
 624  * @param pads Pointer to the pointer to the beginning of the list of pads
 625  * @param links Pointer to the pointer to the beginning of the list of links
 626  * @param newpad The new pad to add. A copy is made when adding.
 627  */
 628 void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
 629                          AVFilterPad **pads, AVFilterLink ***links,
 630                          AVFilterPad *newpad);
 631
 632 /** Inserts a new input pad for the filter. */
 633 static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
 634                                          AVFilterPad *p)
 635 {
 636     avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
 637                         &f->input_pads, &f->inputs, p);
 638 }
 639
 640 /** Inserts a new output pad for the filter. */
 641 static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
 642                                           AVFilterPad *p)
 643 {
 644     avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
 645                         &f->output_pads, &f->outputs, p);
 646 }
 647
 648 #endif  /* AVFILTER_AVFILTER_H */