Implement check for invalid playlist entries.
[paraslash.git] / filter.h
1 /*
2 * Copyright (C) 2005-2007 Andre Noll <maan@systemlinux.org>
3 *
4 * Licensed under the GPL v2. For licencing details see COPYING.
5 */
6
7 /** \file filter.h filter-related structures and exported symbols from filter_chain.c */
8
9 /**
10 * describes one running instance of a chain of filters
11 *
12 */
13 struct filter_chain {
14 /**
15 *
16 *
17 * the number of channels of the current stream
18 *
19 * Set by the decoding filter
20 */
21 unsigned int channels;
22 /**
23 *
24 *
25 * current samplerate in Hz
26 *
27 * Set by the decoding filter
28 */
29 unsigned int samplerate;
30 /**
31 *
32 *
33 * the list containing all filter nodes in this filter chain
34 */
35 struct list_head filters;
36 /**
37 *
38 *
39 * the input buffer of the filter chain
40 *
41 * This is set to point to the output buffer of the receiving application (the
42 * buffer used to read from stdin for para_filter; the output buffer of the
43 * current receiver for para_audiod)
44 */
45 char *inbuf;
46 /**
47 *
48 *
49 * the output buffer of the filter chain
50 *
51 * Points to the output buffer of the last filter in the filter chain
52 **/
53 char *outbuf;
54 /**
55 *
56 *
57 * pointer to variable containing the number of bytes loaded in the input buffer
58 */
59 size_t *in_loaded;
60 /**
61 *
62 *
63 * pointer to variable containing the number of bytes loaded in the output buffer
64 */
65 size_t *out_loaded;
66 /** non-zero if this filter wont' produce any more output */
67 int eof;
68 /** pointer to the eof flag of the receiving application */
69 int *input_eof;
70 /** pointer to the eof flag of the writing application */
71 int *output_eof;
72 /** the task associated with the filter chain */
73 struct task task;
74 };
75
76 /**
77 * describes one running instance of a filter
78 */
79 struct filter_node {
80 /**
81 *
82 *
83 * a pointer to the corresponding filter struct
84 */
85 struct filter *filter;
86 /**
87 *
88 *
89 * the filter chain this filter node belongs to
90 */
91 struct filter_chain *fc;
92 /**
93 *
94 *
95 * the position of the filter in the corresponding filter chain
96 *
97 * all filters that make up the filter chains are organized in a doubly
98 * linked list.
99 */
100 struct list_head node;
101 /**
102 *
103 *
104 * each filter may store any filter-specific information about the particular
105 * instance of the filter here.
106 */
107 void *private_data;
108 /**
109 *
110 *
111 * the output buffer
112 */
113 char *buf;
114 /**
115 * the size of the output buffer
116 */
117 size_t bufsize;
118 /**
119 *
120 *
121 * the number of bytes currently loaded in \a buf
122 */
123 size_t loaded;
124 /**
125 *
126 *
127 * the list of registered callbacks
128 */
129 struct list_head callbacks;
130 /**
131 *
132 * a pointer to the configuration of this instance
133 */
134 void *conf;
135 };
136
137 /**
138 * used to manage grab clients
139 *
140 * An application using paraslash's filter subsystem may register any number of
141 * callbacks for each filter_node. It is possible to attach a filter callback
142 * while the filter is running. This is used for stream grabbing in
143 * para_audiod: Whenever a client sends the 'grab' command, para_audiod adds a
144 * filter callback to the list of callbacks for the filter node specified in
145 * the grab command.
146 */
147 struct filter_callback {
148 /**
149 *
150 *
151 * all callbacks are organized in a doubly linked list
152 */
153 struct list_head node;
154 /**
155 *
156 *
157 * private data
158 *
159 * May be initialized by the application before registering the callback. This
160 * pointer is not used by the filter subsystem. It is provided for use within
161 * the input/ouput/close callback functions.
162 */
163 void *data;
164 /**
165 *
166 *
167 * the input callback
168 *
169 * In not \p NULL, the filter subsystem calls this function whenever the filter
170 * consumed some or all of its input buffer. A pointer to the buffer of consumed
171 * data, its length and a pointer to the own \a filter_callback structure are passed
172 * to \a input_cb. The input callback is expected to return a negative value on errors.
173 */
174 int (*input_cb)(char *buf, size_t len, struct filter_callback *fc);
175 /**
176 *
177 *
178 * the output callback
179 *
180 * If not NULL, this is called whenever the filter produces output. A pointer
181 * to the output data, its length and a pointer to the own \a filter_callback
182 * structure are passed to \a output_cb. Like the input callback, the output
183 * callback is expected to return a negative value on errors.
184 */
185 int (*output_cb)(char *buf, size_t len, struct filter_callback *fc);
186 /**
187 *
188 *
189 * the callback close function
190 *
191 * This gets called whenever the input/ouput callback returned an error, or if
192 * the filter chain is going to be destroyed, e.g. because the end of the
193 * stream was encounterd. It is assumed to succeed.
194 */
195 void (*close)(struct filter_callback *fc);
196 };
197
198
199 void close_filters(struct filter_chain *fc);
200 void filter_init(struct filter *all_filters);
201 int check_filter_arg(char *filter_arg, void **conf);
202 void filter_pre_select(__a_unused struct sched *s, struct task *t);
203
204 /**
205 * the structure associated with a paraslash filter
206 *
207 * Paraslash filters are "modules" which are used to transform an audio stream.
208 * struct filter contains pointers to functions that must be supplied by the
209 * filter code in order to be used by the driving application (currently
210 * para_audiod and para_filter).
211 *
212 * Note: As several instances of the same filter may be running at the same
213 * time, all these filter functions must be reentrant; no static non-constant
214 * variables may be used.
215 * \sa mp3dec.c, oggdec.c, wav.c, compress.c, filter_node
216 */
217 struct filter {
218 /**
219 *
220 *
221 * the name of the filter
222 */
223 const char *name;
224 /**
225 *
226 *
227 * pointer to the filter init routine
228 *
229 * This function is only called once at startup. It must initialize the
230 * other non-optional function pointers of \a f.
231 */
232 void (*init)(struct filter *f);
233 /**
234 *
235 *
236 * open one instance of this filter
237 *
238 * This should allocate the output buffer of the given filter node and do any
239 * other filter-specific preparations like initializing the private_data member
240 * of \a fn suitably. The open function is assumed to succeed.
241 */
242 void (*open)(struct filter_node *fn);
243 /**
244 *
245 *
246 * convert (filter) the given data
247 *
248 * Pointer to the converting function of the filter. It should convert the
249 * given input buffer \a inbuf which is of length \a len to the previoulsy
250 * reserved output buffer of \a fn. On success, it must return the number of
251 * bytes it consumed from \a inbuf. On errors, a negative number indicating the
252 * kind of the error must be returned.
253 *
254 * A zero return value just means that nothing was converted (probably because
255 * the input buffer was too small). This is not interpreted as an error.
256 */
257 ssize_t (*convert)(char *inbuf, size_t len, struct filter_node *fn);
258 /**
259 *
260 *
261 * close one instance of this filter
262 *
263 * Free all resources of associated with \a fn that were previously allocated
264 * by the open() function.
265 */
266 void (*close)(struct filter_node *fn);
267 /**
268 *
269 *
270 * print the help text for this filter and exit
271 *
272 * This is optional and it is not necessary to initialize this pointer if
273 * the filter does not have a help text.
274 */
275 void (*print_help)(void);
276 /**
277 *
278 *
279 * a pointer to the filter's command line parser
280 *
281 * If this optional function pointer is not NULL, any filter options are passed
282 * from the main propgram to this command line parser once at application
283 * startup. The command line parser should check its command line options given
284 * by \a argc and \a argv and abort on errors. On success, it should return a
285 * pointer to the filter-specific configuration data determined by \a argc and
286 * \a argv.
287 */
288 void *(*parse_config)(int argc, char **argv);
289 };
290
291
292 static inline void write_int16_host_endian(char *buf, int val)
293 {
294 #ifdef WORDS_BIGENDIAN
295 *buf = val >> 8;
296 *(buf + 1) = val & 0xff;
297 #else
298 *buf = val & 0xff;
299 *(buf + 1) = val >> 8;
300 #endif
301 }
302
303
304 /** \cond */
305 extern struct filter filters[];
306 #define DECLARE_EXTERN_FILTER_INIT(name) \
307 extern void name ## _init(struct filter *f)
308
309 #define FILTER_INIT(filter) { \
310 .name = #filter, \
311 .init = filter ## _init, \
312 .parse_config = NULL, \
313 .print_help = NULL \
314 },
315
316 /* filters that are always present */
317 DECLARE_EXTERN_FILTER_INIT(wav);
318 /* wav is always the first filter */
319 #define WAV_FILTER_NUM 0
320 DECLARE_EXTERN_FILTER_INIT(compress);
321
322 /* next the optional filters */
323 #ifdef HAVE_MAD
324 DECLARE_EXTERN_FILTER_INIT(mp3dec);
325 #define MP3DEC_FILTER FILTER_INIT(mp3dec)
326 #else
327 #define MP3DEC_FILTER
328 #endif
329
330 #ifdef HAVE_FAAD
331 DECLARE_EXTERN_FILTER_INIT(aacdec);
332 #define AACDEC_FILTER FILTER_INIT(aacdec)
333 #else
334 #define AACDEC_FILTER
335 #endif
336
337 #ifdef HAVE_OGGVORBIS
338 DECLARE_EXTERN_FILTER_INIT(oggdec);
339 #define OGGDEC_FILTER FILTER_INIT(oggdec)
340 #else
341 #define OGGDEC_FILTER
342 #endif
343 /** \endcond */
344
345 /** define an array of all available filters */
346 #define DEFINE_FILTER_ARRAY(filters) struct filter filters[] = { \
347 FILTER_INIT(wav) \
348 FILTER_INIT(compress) \
349 MP3DEC_FILTER \
350 AACDEC_FILTER \
351 OGGDEC_FILTER \
352 { .name = NULL } };
353
354