Allow filters to set the requirements on permissions for incoming buffers.
[libav.git] / 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 FFMPEG_AVFILTER_H
23 #define FFMPEG_AVFILTER_H
24
25 #include <stddef.h>
26 #include "avcodec.h"
27
28 typedef struct AVFilterContext AVFilterContext;
29 typedef struct AVFilterLink AVFilterLink;
30 typedef struct AVFilterPad AVFilterPad;
31
32 /* TODO: look for other flags which may be useful in this structure (interlace
33 * flags, etc)
34 */
35 /**
36 * A reference-counted picture data type used by the filter system. Filters
37 * should not store pointers to this structure directly, but instead use the
38 * AVFilterPicRef structure below
39 */
40 typedef struct AVFilterPic
41 {
42 uint8_t *data[4]; ///< picture data for each plane
43 int linesize[4]; ///< number of bytes per line
44 enum PixelFormat format; ///< colorspace
45
46 unsigned refcount; ///< number of references to this image
47
48 /** private data to be used by a custom free function */
49 void *priv;
50 /**
51 * A pointer to the function to deallocate this image if the default
52 * function is not sufficient. This could, for example, add the memory
53 * back into a memory pool to be reused later without the overhead of
54 * reallocating it from scratch.
55 */
56 void (*free)(struct AVFilterPic *pic);
57 } AVFilterPic;
58
59 /**
60 * A reference to an AVFilterPic. Since filters can manipulate the origin of
61 * a picture to, for example, crop image without any memcpy, the picture origin
62 * and dimensions are per-reference properties. Linesize is also useful for
63 * image flipping, frame to field filters, etc, and so is also per-reference.
64 *
65 * TODO: add anything necessary for frame reordering
66 */
67 typedef struct AVFilterPicRef
68 {
69 AVFilterPic *pic; ///< the picture that this is a reference to
70 uint8_t *data[4]; ///< picture data for each plane
71 int linesize[4]; ///< number of bytes per line
72 int w; ///< image width
73 int h; ///< image height
74
75 int64_t pts; ///< presentation timestamp in milliseconds
76
77 int perms; ///< permissions
78 #define AV_PERM_READ 0x01 ///< can read from the buffer
79 #define AV_PERM_WRITE 0x02 ///< can write to the buffer
80 #define AV_PERM_PRESERVE 0x04 ///< nobody else can overwrite the buffer
81 #define AV_PERM_REUSE 0x08 ///< can output the buffer multiple times
82 } AVFilterPicRef;
83
84 /**
85 * Add a new reference to a picture.
86 * @param ref An existing reference to the picture
87 * @param pmask A bitmask containing the allowable permissions in the new
88 * reference
89 * @return A new reference to the picture with the same properties as the
90 * old, excluding any permissions denied by pmask
91 */
92 AVFilterPicRef *avfilter_ref_pic(AVFilterPicRef *ref, int pmask);
93
94 /**
95 * Remove a reference to a picture. If this is the last reference to the
96 * picture, the picture itself is also automatically freed.
97 * @param ref Reference to the picture.
98 */
99 void avfilter_unref_pic(AVFilterPicRef *ref);
100
101 /**
102 * A filter pad used for either input or output
103 */
104 struct AVFilterPad
105 {
106 /**
107 * Pad name. The name is unique among inputs and among outputs, but an
108 * input may have the same name as an output. This may be NULL if this
109 * pad has no need to ever be referenced by name.
110 */
111 char *name;
112
113 /**
114 * AVFilterPad type. Only video supported now, hopefully someone will
115 * add audio in the future.
116 */
117 int type;
118 #define AV_PAD_VIDEO 0 ///< video pad
119
120 /**
121 * Minimum required permissions on incoming buffers. Any buffers with
122 * insufficient permissions will be automatically copied by the filter
123 * system to a new buffer which provides the needed access permissions.
124 *
125 * Input pads only.
126 */
127 int min_perms;
128
129 /**
130 * Permissions which are not accepted on incoming buffers. Any buffer
131 * which has any of these permissions set be automatically copied by the
132 * filter system to a new buffer which does not have those permissions.
133 * This can be used to easily disallow buffers with AV_PERM_REUSE.
134 *
135 * Input pads only.
136 */
137 int rej_perms;
138
139 /**
140 * Callback to get a list of supported formats. The returned list should
141 * be terminated by -1 (see avfilter_make_format_list for an easy way to
142 * create such a list).
143 *
144 * This is used for both input and output pads. If ommitted from an output
145 * pad, it is assumed that the only format supported is the same format
146 * that is being used for the filter's first input. If the filter has no
147 * inputs, then this may not be ommitted for its output pads.
148 */
149 int *(*query_formats)(AVFilterLink *link);
150
151 /**
152 * Callback called before passing the first slice of a new frame. If
153 * NULL, the filter layer will default to storing a reference to the
154 * picture inside the link structure.
155 *
156 * Input video pads only.
157 */
158 void (*start_frame)(AVFilterLink *link, AVFilterPicRef *picref);
159
160 /**
161 * Callback function to get a buffer. If NULL, the filter system will
162 * handle buffer requests.
163 *
164 * Input video pads only.
165 */
166 AVFilterPicRef *(*get_video_buffer)(AVFilterLink *link, int perms);
167
168 /**
169 * Callback called after the slices of a frame are completely sent. If
170 * NULL, the filter layer will default to releasing the reference stored
171 * in the link structure during start_frame().
172 *
173 * Input video pads only.
174 */
175 void (*end_frame)(AVFilterLink *link);
176
177 /**
178 * Slice drawing callback. This is where a filter receives video data
179 * and should do its processing.
180 *
181 * Input video pads only.
182 */
183 void (*draw_slice)(AVFilterLink *link, int y, int height);
184
185 /**
186 * Frame request callback. A call to this should result in at least one
187 * frame being output over the given link. This should return zero on
188 * success, and another value on error.
189 *
190 * Output video pads only.
191 */
192 int (*request_frame)(AVFilterLink *link);
193
194 /**
195 * Link configuration callback.
196 *
197 * For output pads, this should set the link properties such as
198 * width/height. This should NOT set the format property - that is
199 * negotiated between filters by the filter system using the
200 * query_formats() callback before this function is called.
201 *
202 * For input pads, this should check the properties of the link, and update
203 * the filter's internal state as necessary.
204 *
205 * For both input and output filters, this should return zero on success,
206 * and another value on error.
207 */
208 int (*config_props)(AVFilterLink *link);
209 };
210
211 /** Default handler for start_frame() for video inputs */
212 void avfilter_default_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
213 /** Default handler for end_frame() for video inputs */
214 void avfilter_default_end_frame(AVFilterLink *link);
215 /** Default handler for config_props() for video outputs */
216 int avfilter_default_config_output_link(AVFilterLink *link);
217 /** Default handler for config_props() for video inputs */
218 int avfilter_default_config_input_link (AVFilterLink *link);
219 /** Default handler for query_formats() for video outputs */
220 int *avfilter_default_query_output_formats(AVFilterLink *link);
221 /** Default handler for get_video_buffer() for video inputs */
222 AVFilterPicRef *avfilter_default_get_video_buffer(AVFilterLink *link,
223 int perms);
224
225 /**
226 * Filter definition. This defines the pads a filter contains, and all the
227 * callback functions used to interact with the filter.
228 */
229 typedef struct
230 {
231 char *name; ///< filter name
232 char *author; ///< filter author
233
234 int priv_size; ///< size of private data to allocate for the filter
235
236 /**
237 * Filter initialization function. Args contains the user-supplied
238 * parameters. FIXME: maybe an AVOption-based system would be better?
239 * opaque is data provided by the code requesting creation of the filter,
240 * and is used to pass data to the filter.
241 */
242 int (*init)(AVFilterContext *ctx, const char *args, void *opaque);
243
244 /**
245 * Filter uninitialization function. Should deallocate any memory held
246 * by the filter, release any picture references, etc. This does not need
247 * to deallocate the AVFilterContext->priv memory itself.
248 */
249 void (*uninit)(AVFilterContext *ctx);
250
251 const AVFilterPad *inputs; ///< NULL terminated list of inputs. NULL if none
252 const AVFilterPad *outputs; ///< NULL terminated list of outputs. NULL if none
253 } AVFilter;
254
255 /** An instance of a filter */
256 struct AVFilterContext
257 {
258 AVClass *av_class; ///< Needed for av_log()
259
260 AVFilter *filter; ///< The AVFilter of which this is an instance
261
262 char *name; ///< name of this filter instance
263
264 unsigned input_count; ///< number of input pads
265 AVFilterPad *input_pads; ///< array of input pads
266 AVFilterLink **inputs; ///< array of pointers to input links
267
268 unsigned output_count; ///< number of output pads
269 AVFilterPad *output_pads; ///< array of output pads
270 AVFilterLink **outputs; ///< array of pointers to output links
271
272 void *priv; ///< private data for use by the filter
273 };
274
275 /**
276 * A links between two filters. This contains pointers to the source and
277 * destination filters between which this link exists, and the indices of
278 * the pads involved. In addition, this link also contains the parameters
279 * which have been negotiated and agreed upon between the filter, such as
280 * image dimensions, format, etc
281 */
282 struct AVFilterLink
283 {
284 AVFilterContext *src; ///< source filter
285 unsigned int srcpad; ///< index of the output pad on the source filter
286
287 AVFilterContext *dst; ///< dest filter
288 unsigned int dstpad; ///< index of the input pad on the dest filter
289
290 int w; ///< agreed upon image width
291 int h; ///< agreed upon image height
292 enum PixelFormat format; ///< agreed upon image colorspace
293
294 /**
295 * The picture reference currently being sent across the link by the source
296 * filter. This is used internally by the filter system to allow
297 * automatic copying of pictures which d not have sufficient permissions
298 * for the destination. This should not be accessed directly by the
299 * filters.
300 */
301 AVFilterPicRef *srcpic;
302
303 AVFilterPicRef *cur_pic;
304 AVFilterPicRef *outpic;
305 };
306
307 /**
308 * Link two filters together
309 * @param src The source filter
310 * @param srcpad Index of the output pad on the source filter
311 * @param dst The destination filter
312 * @param dstpad Index of the input pad on the destination filter
313 * @return Zero on success
314 */
315 int avfilter_link(AVFilterContext *src, unsigned srcpad,
316 AVFilterContext *dst, unsigned dstpad);
317
318 /**
319 * Negotiate the colorspace, dimensions, etc of a link
320 * @param link The link to negotiate the properties of
321 * @return Zero on successful negotiation
322 */
323 int avfilter_config_link(AVFilterLink *link);
324
325 /**
326 * Request a picture buffer with a specific set of permissions
327 * @param link The output link to the filter from which the picture will
328 * be requested
329 * @param perms The required access permissions
330 * @return A reference to the picture. This must be unreferenced with
331 * avfilter_unref_pic when you are finished with it.
332 */
333 AVFilterPicRef *avfilter_get_video_buffer(AVFilterLink *link, int perms);
334
335 /**
336 * Request an input frame from the filter at the other end of the link.
337 * @param link The input link
338 * @return Zero on success
339 */
340 int avfilter_request_frame(AVFilterLink *link);
341
342 /**
343 * Notify the next filter of the start of a frame.
344 * @param link The output link the frame will be sent over
345 * @param picref A reference to the frame about to be sent. The data for this
346 * frame need only be valid once draw_slice() is called for that
347 * portion. The receiving filter will free this reference when
348 * it no longer needs it.
349 */
350 void avfilter_start_frame(AVFilterLink *link, AVFilterPicRef *picref);
351
352 /**
353 * Notify the next filter that the current frame has finished
354 * @param link The output link the frame was sent over
355 */
356 void avfilter_end_frame(AVFilterLink *link);
357
358 /**
359 * Send a slice to the next filter
360 * @param link The output link over which the frame is being sent
361 * @param y Offset in pixels from the top of the image for this slice
362 * @param h Height of this slice in pixels
363 */
364 void avfilter_draw_slice(AVFilterLink *link, int y, int h);
365
366 /** Initialize the filter system. Registers all builtin filters */
367 void avfilter_init(void);
368
369 /** Uninitialize the filter system. Unregisters all filters */
370 void avfilter_uninit(void);
371
372 /**
373 * Register a filter. This is only needed if you plan to create an instance of
374 * this filter by name later with avfilter_create_by_name. A filter can still
375 * by created with acfilter_create even if it is not registered.
376 * @param filter The filter to register
377 */
378 void avfilter_register(AVFilter *filter);
379
380 /**
381 * Gets a filter definition matching the given name
382 * @param name The filter name to find
383 * @return The filter definition, if any matching one is registered.
384 * NULL if none found.
385 */
386 AVFilter *avfilter_get_by_name(char *name);
387
388 /**
389 * Create a filter instance
390 * @param filter The filter to create an instance of
391 * @param inst_name Name to give to the new instance. Can be NULL for none.
392 * @return Pointer to the new instance on success. NULL on failure.
393 */
394 AVFilterContext *avfilter_create(AVFilter *filter, char *inst_name);
395
396 /**
397 * Creates a filter instace
398 * @param name The name of the filter type which is to be instantiated
399 * @param inst_name Name to give to the new instance. Can be NULL for none.
400 * @return Pointer to the new instance on success. NULL in failure.
401 */
402 AVFilterContext *avfilter_create_by_name(char *name, char *inst_name);
403
404 /**
405 * Initialize a filter
406 * @param filter The filter to initialize
407 * @param args A string of parameters to use when initializing the filter.
408 * The format and meaning of this string varies by filter.
409 * @param opaque Any extra non-string data needed by the filter. The meaning
410 * of this parameter varies by filter.
411 * @return Zero on success
412 */
413 int avfilter_init_filter(AVFilterContext *filter, const char *args, void *opaque);
414
415 /**
416 * Destroy a filter
417 * @param filter The filter to destroy
418 */
419 void avfilter_destroy(AVFilterContext *filter);
420
421 /**
422 * Helper function to create a list of supported formats. This is intended
423 * for use in AVFilterPad->query_formats().
424 * @param len The number of formats supported
425 * @param ... A list of the supported formats
426 * @return The format list in a form suitable for returning from
427 * AVFilterPad->query_formats()
428 */
429 int *avfilter_make_format_list(int len, ...);
430
431 /**
432 * Insert a new pad
433 * @param idx Insertion point. Pad is inserted at the end if this point
434 * is beyond the end of the list of pads.
435 * @param count Pointer to the number of pads in the list
436 * @param padidx_off Offset within an AVFilterLink structure to the element
437 * to increment when inserting a new pad causes link
438 * numbering to change
439 * @param pads Pointer to the pointer to the beginning of the list of pads
440 * @param links Pointer to the pointer to the beginning of the list of links
441 * @param newpad The new pad to add. A copy is made when adding.
442 */
443 void avfilter_insert_pad(unsigned idx, unsigned *count, size_t padidx_off,
444 AVFilterPad **pads, AVFilterLink ***links,
445 AVFilterPad *newpad);
446
447 /** insert a new input pad for the filter */
448 static inline void avfilter_insert_inpad(AVFilterContext *f, unsigned index,
449 AVFilterPad *p)
450 {
451 avfilter_insert_pad(index, &f->input_count, offsetof(AVFilterLink, dstpad),
452 &f->input_pads, &f->inputs, p);
453 }
454
455 /** insert a new output pad for the filter */
456 static inline void avfilter_insert_outpad(AVFilterContext *f, unsigned index,
457 AVFilterPad *p)
458 {
459 avfilter_insert_pad(index, &f->output_count, offsetof(AVFilterLink, srcpad),
460 &f->output_pads, &f->outputs, p);
461 }
462
463 #endif /* FFMPEG_AVFILTER_H */