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[paraslash.git] / filter.h
1 /*
2 * Copyright (C) 2005-2007 Andre Noll <maan@systemlinux.org>
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA.
17 */
18
19 /** \file filter.h filter-related structures and exported symbols from filter_chain.c */
20
21 /**
22 * describes one running instance of a chain of filters
23 *
24 */
25 struct filter_chain {
26 /**
27 *
28 *
29 * the number of channels of the current stream
30 *
31 * Set by the decoding filter
32 */
33 unsigned int channels;
34 /**
35 *
36 *
37 * current samplerate in Hz
38 *
39 * Set by the decoding filter
40 */
41 unsigned int samplerate;
42 /**
43 *
44 *
45 * the list containing all filter nodes in this filter chain
46 */
47 struct list_head filters;
48 /**
49 *
50 *
51 * the input buffer of the filter chain
52 *
53 * This is set to point to the output buffer of the receiving application (the
54 * buffer used to read from stdin for para_filter; the output buffer of the
55 * current receiver for para_audiod)
56 */
57 char *inbuf;
58 /**
59 *
60 *
61 * the output buffer of the filter chain
62 *
63 * Points to the output buffer of the last filter in the filter chain
64 **/
65 char *outbuf;
66 /**
67 *
68 *
69 * pointer to variable containing the number of bytes loaded in the input buffer
70 */
71 size_t *in_loaded;
72 /**
73 *
74 *
75 * pointer to variable containing the number of bytes loaded in the output buffer
76 */
77 size_t *out_loaded;
78 /** non-zero if this filter wont' produce any more output */
79 int eof;
80 /** pointer to the eof flag of the receiving application */
81 int *input_eof;
82 /** pointer to the eof flag of the writing application */
83 int *output_eof;
84 /** the task associated with the filter chain */
85 struct task task;
86 };
87
88 /**
89 * describes one running instance of a filter
90 */
91 struct filter_node {
92 /**
93 *
94 *
95 * a pointer to the corresponding filter struct
96 */
97 struct filter *filter;
98 /**
99 *
100 *
101 * the filter chain this filter node belongs to
102 */
103 struct filter_chain *fc;
104 /**
105 *
106 *
107 * the position of the filter in the corresponding filter chain
108 *
109 * all filters that make up the filter chains are organized in a doubly
110 * linked list.
111 */
112 struct list_head node;
113 /**
114 *
115 *
116 * each filter may store any filter-specific information about the particular
117 * instance of the filter here.
118 */
119 void *private_data;
120 /**
121 *
122 *
123 * the output buffer
124 */
125 char *buf;
126 /**
127 * the size of the output buffer
128 */
129 size_t bufsize;
130 /**
131 *
132 *
133 * the number of bytes currently loaded in \a buf
134 */
135 size_t loaded;
136 /**
137 *
138 *
139 * the list of registered callbacks
140 */
141 struct list_head callbacks;
142 /**
143 *
144 * a pointer to the configuration of this instance
145 */
146 void *conf;
147 };
148
149 /**
150 * used to manage grab clients
151 *
152 * An application using paraslash's filter subsystem may register any number of
153 * callbacks for each filter_node. It is possible to attach a filter callback
154 * while the filter is running. This is used for stream grabbing in
155 * para_audiod: Whenever a client sends the 'grab' command, para_audiod adds a
156 * filter callback to the list of callbacks for the filter node specified in
157 * the grab command.
158 */
159 struct filter_callback {
160 /**
161 *
162 *
163 * all callbacks are organized in a doubly linked list
164 */
165 struct list_head node;
166 /**
167 *
168 *
169 * private data
170 *
171 * May be initialized by the application before registering the callback. This
172 * pointer is not used by the filter subsystem. It is provided for use within
173 * the input/ouput/close callback functions.
174 */
175 void *data;
176 /**
177 *
178 *
179 * the input callback
180 *
181 * In not \p NULL, the filter subsystem calls this function whenever the filter
182 * consumed some or all of its input buffer. A pointer to the buffer of consumed
183 * data, its length and a pointer to the own \a filter_callback structure are passed
184 * to \a input_cb. The input callback is expected to return a negative value on errors.
185 */
186 int (*input_cb)(char *buf, size_t len, struct filter_callback *fc);
187 /**
188 *
189 *
190 * the output callback
191 *
192 * If not NULL, this is called whenever the filter produces output. A pointer
193 * to the output data, its length and a pointer to the own \a filter_callback
194 * structure are passed to \a output_cb. Like the input callback, the output
195 * callback is expected to return a negative value on errors.
196 */
197 int (*output_cb)(char *buf, size_t len, struct filter_callback *fc);
198 /**
199 *
200 *
201 * the callback close function
202 *
203 * This gets called whenever the input/ouput callback returned an error, or if
204 * the filter chain is going to be destroyed, e.g. because the end of the
205 * stream was encounterd. It is assumed to succeed.
206 */
207 void (*close)(struct filter_callback *fc);
208 };
209
210
211 void close_filters(struct filter_chain *fc);
212 void filter_init(struct filter *all_filters);
213 int check_filter_arg(char *filter_arg, void **conf);
214 void filter_pre_select(__a_unused struct sched *s, struct task *t);
215
216 /**
217 * the structure associated with a paraslash filter
218 *
219 * Paraslash filters are "modules" which are used to transform an audio stream.
220 * struct filter contains pointers to functions that must be supplied by the
221 * filter code in order to be used by the driving application (currently
222 * para_audiod and para_filter).
223 *
224 * Note: As several instances of the same filter may be running at the same
225 * time, all these filter functions must be reentrant; no static non-constant
226 * variables may be used.
227 * \sa mp3dec.c, oggdec.c, wav.c, compress.c, filter_node
228 */
229 struct filter {
230 /**
231 *
232 *
233 * the name of the filter
234 */
235 const char *name;
236 /**
237 *
238 *
239 * pointer to the filter init routine
240 *
241 * This function is only called once at startup. It must initialize the
242 * other non-optional function pointers of \a f.
243 */
244 void (*init)(struct filter *f);
245 /**
246 *
247 *
248 * open one instance of this filter
249 *
250 * This should allocate the output buffer of the given filter node and do any
251 * other filter-specific preparations like initializing the private_data member
252 * of \a fn suitably. The open function is assumed to succeed.
253 */
254 void (*open)(struct filter_node *fn);
255 /**
256 *
257 *
258 * convert (filter) the given data
259 *
260 * Pointer to the converting function of the filter. It should convert the
261 * given input buffer \a inbuf which is of length \a len to the previoulsy
262 * reserved output buffer of \a fn. On success, it must return the number of
263 * bytes it consumed from \a inbuf. On errors, a negative number indicating the
264 * kind of the error must be returned.
265 *
266 * A zero return value just means that nothing was converted (probably because
267 * the input buffer was too small). This is not interpreted as an error.
268 */
269 ssize_t (*convert)(char *inbuf, size_t len, struct filter_node *fn);
270 /**
271 *
272 *
273 * close one instance of this filter
274 *
275 * Free all resources of associated with \a fn that were previously allocated
276 * by the open() function.
277 */
278 void (*close)(struct filter_node *fn);
279 /**
280 *
281 *
282 * print the help text for this filter and exit
283 *
284 * This is optional and it is not necessary to initialize this pointer if
285 * the filter does not have a help text.
286 */
287 void (*print_help)(void);
288 /**
289 *
290 *
291 * a pointer to the filter's command line parser
292 *
293 * If this optional function pointer is not NULL, any filter options are passed
294 * from the main propgram to this command line parser once at application
295 * startup. The command line parser should check its command line options given
296 * by \a argc and \a argv and abort on errors. On success, it should return a
297 * pointer to the filter-specific configuration data determined by \a argc and
298 * \a argv.
299 */
300 void *(*parse_config)(int argc, char **argv);
301 };
302 /** \cond */
303 extern struct filter filters[];
304 #define DECLARE_EXTERN_FILTER_INIT(name) \
305 extern void name ## _init(struct filter *f)
306
307 #define FILTER_INIT(filter) { \
308 .name = #filter, \
309 .init = filter ## _init, \
310 .parse_config = NULL, \
311 .print_help = NULL \
312 },
313
314 /* filters that are always present */
315 DECLARE_EXTERN_FILTER_INIT(wav);
316 /* wav is always the first filter */
317 #define WAV_FILTER_NUM 0
318 DECLARE_EXTERN_FILTER_INIT(compress);
319
320 /* next the optional filters */
321 #ifdef HAVE_MAD
322 DECLARE_EXTERN_FILTER_INIT(mp3dec);
323 #define MP3DEC_FILTER FILTER_INIT(mp3dec)
324 #else
325 #define MP3DEC_FILTER
326 #endif
327
328 #ifdef HAVE_FAAD
329 DECLARE_EXTERN_FILTER_INIT(aacdec);
330 #define AACDEC_FILTER FILTER_INIT(aacdec)
331 #else
332 #define AACDEC_FILTER
333 #endif
334
335 #ifdef HAVE_OGGVORBIS
336 DECLARE_EXTERN_FILTER_INIT(oggdec);
337 #define OGGDEC_FILTER FILTER_INIT(oggdec)
338 #else
339 #define OGGDEC_FILTER
340 #endif
341 /** \endcond */
342
343 /** define an array of all available filters */
344 #define DEFINE_FILTER_ARRAY(filters) struct filter filters[] = { \
345 FILTER_INIT(wav) \
346 FILTER_INIT(compress) \
347 MP3DEC_FILTER \
348 AACDEC_FILTER \
349 OGGDEC_FILTER \
350 { .name = NULL } };