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avfiltergraph.h
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1 /*
2  * Filter graphs
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_AVFILTERGRAPH_H
23 #define AVFILTER_AVFILTERGRAPH_H
24 
25 #include "avfilter.h"
26 #include "libavutil/log.h"
27 
28 typedef struct AVFilterGraph {
29  const AVClass *av_class;
30  unsigned filter_count;
32 
33  char *scale_sws_opts; ///< sws options to use for the auto-inserted scale filters
34  char *resample_lavr_opts; ///< libavresample options to use for the auto-inserted resample filters
35  char *aresample_swr_opts; ///< swr options to use for the auto-inserted aresample filters, Access ONLY through AVOptions
36 
37  /**
38  * Private fields
39  *
40  * The following fields are for internal use only.
41  * Their type, offset, number and semantic can change without notice.
42  */
43 
46 
49 
50 /**
51  * Allocate a filter graph.
52  */
54 
55 /**
56  * Get a filter instance with name name from graph.
57  *
58  * @return the pointer to the found filter instance or NULL if it
59  * cannot be found.
60  */
62 
63 /**
64  * Add an existing filter instance to a filter graph.
65  *
66  * @param graphctx the filter graph
67  * @param filter the filter to be added
68  */
70 
71 /**
72  * Create and add a filter instance into an existing graph.
73  * The filter instance is created from the filter filt and inited
74  * with the parameters args and opaque.
75  *
76  * In case of success put in *filt_ctx the pointer to the created
77  * filter instance, otherwise set *filt_ctx to NULL.
78  *
79  * @param name the instance name to give to the created filter instance
80  * @param graph_ctx the filter graph
81  * @return a negative AVERROR error code in case of failure, a non
82  * negative value otherwise
83  */
85  const char *name, const char *args, void *opaque,
86  AVFilterGraph *graph_ctx);
87 
88 /**
89  * Enable or disable automatic format conversion inside the graph.
90  *
91  * Note that format conversion can still happen inside explicitly inserted
92  * scale and aconvert filters.
93  *
94  * @param flags any of the AVFILTER_AUTO_CONVERT_* constants
95  */
97 
98 enum {
99  AVFILTER_AUTO_CONVERT_ALL = 0, /**< all automatic conversions enabled */
100  AVFILTER_AUTO_CONVERT_NONE = -1, /**< all automatic conversions disabled */
101 };
102 
103 /**
104  * Check validity and configure all the links and formats in the graph.
105  *
106  * @param graphctx the filter graph
107  * @param log_ctx context used for logging
108  * @return 0 in case of success, a negative AVERROR code otherwise
109  */
110 int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx);
111 
112 /**
113  * Free a graph, destroy its links, and set *graph to NULL.
114  * If *graph is NULL, do nothing.
115  */
116 void avfilter_graph_free(AVFilterGraph **graph);
117 
118 /**
119  * A linked-list of the inputs/outputs of the filter chain.
120  *
121  * This is mainly useful for avfilter_graph_parse() / avfilter_graph_parse2(),
122  * where it is used to communicate open (unlinked) inputs and outputs from and
123  * to the caller.
124  * This struct specifies, per each not connected pad contained in the graph, the
125  * filter context and the pad index required for establishing a link.
126  */
127 typedef struct AVFilterInOut {
128  /** unique name for this input/output in the list */
129  char *name;
130 
131  /** filter context associated to this input/output */
133 
134  /** index of the filt_ctx pad to use for linking */
135  int pad_idx;
136 
137  /** next input/input in the list, NULL if this is the last */
139 } AVFilterInOut;
140 
141 /**
142  * Allocate a single AVFilterInOut entry.
143  * Must be freed with avfilter_inout_free().
144  * @return allocated AVFilterInOut on success, NULL on failure.
145  */
147 
148 /**
149  * Free the supplied list of AVFilterInOut and set *inout to NULL.
150  * If *inout is NULL, do nothing.
151  */
152 void avfilter_inout_free(AVFilterInOut **inout);
153 
154 /**
155  * Add a graph described by a string to a graph.
156  *
157  * @param graph the filter graph where to link the parsed graph context
158  * @param filters string to be parsed
159  * @param inputs pointer to a linked list to the inputs of the graph, may be NULL.
160  * If non-NULL, *inputs is updated to contain the list of open inputs
161  * after the parsing, should be freed with avfilter_inout_free().
162  * @param outputs pointer to a linked list to the outputs of the graph, may be NULL.
163  * If non-NULL, *outputs is updated to contain the list of open outputs
164  * after the parsing, should be freed with avfilter_inout_free().
165  * @return non negative on success, a negative AVERROR code on error
166  */
167 int avfilter_graph_parse(AVFilterGraph *graph, const char *filters,
169  void *log_ctx);
170 
171 /**
172  * Add a graph described by a string to a graph.
173  *
174  * @param[in] graph the filter graph where to link the parsed graph context
175  * @param[in] filters string to be parsed
176  * @param[out] inputs a linked list of all free (unlinked) inputs of the
177  * parsed graph will be returned here. It is to be freed
178  * by the caller using avfilter_inout_free().
179  * @param[out] outputs a linked list of all free (unlinked) outputs of the
180  * parsed graph will be returned here. It is to be freed by the
181  * caller using avfilter_inout_free().
182  * @return zero on success, a negative AVERROR code on error
183  *
184  * @note the difference between avfilter_graph_parse2() and
185  * avfilter_graph_parse() is that in avfilter_graph_parse(), the caller provides
186  * the lists of inputs and outputs, which therefore must be known before calling
187  * the function. On the other hand, avfilter_graph_parse2() \em returns the
188  * inputs and outputs that are left unlinked after parsing the graph and the
189  * caller then deals with them. Another difference is that in
190  * avfilter_graph_parse(), the inputs parameter describes inputs of the
191  * <em>already existing</em> part of the graph; i.e. from the point of view of
192  * the newly created part, they are outputs. Similarly the outputs parameter
193  * describes outputs of the already existing filters, which are provided as
194  * inputs to the parsed filters.
195  * avfilter_graph_parse2() takes the opposite approach -- it makes no reference
196  * whatsoever to already existing parts of the graph and the inputs parameter
197  * will on return contain inputs of the newly parsed part of the graph.
198  * Analogously the outputs parameter will contain outputs of the newly created
199  * filters.
200  */
201 int avfilter_graph_parse2(AVFilterGraph *graph, const char *filters,
204 
205 
206 /**
207  * Send a command to one or more filter instances.
208  *
209  * @param graph the filter graph
210  * @param target the filter(s) to which the command should be sent
211  * "all" sends to all filters
212  * otherwise it can be a filter or filter instance name
213  * which will send the command to all matching filters.
214  * @param cmd the command to sent, for handling simplicity all commands must be alphanumeric only
215  * @param arg the argument for the command
216  * @param res a buffer with size res_size where the filter(s) can return a response.
217  *
218  * @returns >=0 on success otherwise an error code.
219  * AVERROR(ENOSYS) on unsupported commands
220  */
221 int avfilter_graph_send_command(AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, char *res, int res_len, int flags);
222 
223 /**
224  * Queue a command for one or more filter instances.
225  *
226  * @param graph the filter graph
227  * @param target the filter(s) to which the command should be sent
228  * "all" sends to all filters
229  * otherwise it can be a filter or filter instance name
230  * which will send the command to all matching filters.
231  * @param cmd the command to sent, for handling simplicity all commands must be alphanummeric only
232  * @param arg the argument for the command
233  * @param ts time at which the command should be sent to the filter
234  *
235  * @note As this executes commands after this function returns, no return code
236  * from the filter is provided, also AVFILTER_CMD_FLAG_ONE is not supported.
237  */
238 int avfilter_graph_queue_command(AVFilterGraph *graph, const char *target, const char *cmd, const char *arg, int flags, double ts);
239 
240 
241 /**
242  * Dump a graph into a human-readable string representation.
243  *
244  * @param graph the graph to dump
245  * @param options formatting options; currently ignored
246  * @return a string, or NULL in case of memory allocation failure;
247  * the string must be freed using av_free
248  */
249 char *avfilter_graph_dump(AVFilterGraph *graph, const char *options);
250 
251 /**
252  * Request a frame on the oldest sink link.
253  *
254  * If the request returns AVERROR_EOF, try the next.
255  *
256  * Note that this function is not meant to be the sole scheduling mechanism
257  * of a filtergraph, only a convenience function to help drain a filtergraph
258  * in a balanced way under normal circumstances.
259  *
260  * Also note that AVERROR_EOF does not mean that frames did not arrive on
261  * some of the sinks during the process.
262  * When there are multiple sink links, in case the requested link
263  * returns an EOF, this may cause a filter to flush pending frames
264  * which are sent to another sink link, although unrequested.
265  *
266  * @return the return value of ff_request_frame(),
267  * or AVERROR_EOF if all links returned AVERROR_EOF
268  */
270 
271 #endif /* AVFILTER_AVFILTERGRAPH_H */