2 * Copyright (C) 2005-2009 Andre Noll <maan@systemlinux.org>
4 * Licensed under the GPL v2. For licencing details see COPYING.
7 /** \file filter.h Filter-related structures and exported symbols from filter_common.c. */
9 /** The list of supported filters. */
10 enum filter_enum {FILTER_ENUM};
13 * Describes one running instance of a filter.
16 /** The number in the array of available filters. */
18 /** The filter chain this filter node belongs to. */
19 struct filter_chain *fc;
21 * Each filter may store any filter-specific information about the particular
22 * instance of the filter here.
25 /** The output buffer. */
27 /** The size of the output buffer. */
29 /** The number of bytes currently loaded in \a buf. */
31 /** The list of registered callbacks. */
32 struct list_head callbacks;
33 /** A pointer to the configuration of this instance. */
35 struct btr_node *btrn;
40 /** Describes one running instance of a chain of filters */
42 /** The length of the filter chain. */
43 unsigned int num_filters;
45 * The number of channels of the current stream.
47 * Set by the decoding filter.
49 unsigned int channels;
51 * Current sample rate in Hz.
53 * Set by the decoding filter.
55 unsigned int samplerate;
56 /** The list containing all filter nodes in this filter chain. */
57 struct filter_node *filter_nodes;
59 * The input buffer of the filter chain.
61 * This is set to point to the output buffer of the receiving application (the
62 * buffer used to read from stdin for para_filter; the output buffer of the
63 * current receiver for para_audiod).
67 * The output buffer of the filter chain.
69 * Points to the output buffer of the last filter in the filter chain.
72 /** Contains the number of bytes loaded in the input buffer. */
74 /** Contains the number of bytes loaded in the output buffer. */
76 /** Pointer to the error variable of the receiving application. */
78 /** Pointer to the error variable of the writing application. */
80 /** The task associated with the filter chain. */
84 #define FOR_EACH_FILTER_NODE(fn, fc, i) for (i = 0; i < (fc)->num_filters \
85 && (fn = (fc)->filter_nodes + i); i++)
88 * The structure associated with a paraslash filter.
90 * Paraslash filters are "modules" which are used to transform an audio stream.
91 * struct filter contains pointers to functions that must be supplied by the
92 * filter code in order to be used by the driving application (currently
93 * para_audiod and para_filter).
95 * Note: As several instances of the same filter may be running at the same
96 * time, all these filter functions must be reentrant; no static non-constant
97 * variables may be used.
98 * \sa mp3dec_filter.c, oggdec_filter.c, wav_filter.c, compress_filter.c, filter_node
101 /** The name of the filter. */
104 * Pointer to the filter init routine.
106 * This function is only called once at startup. It must initialize the
107 * other non-optional function pointers of this structure.
109 void (*init)(struct filter *f);
111 * Open one instance of this filter.
113 * This should allocate the output buffer of the given filter node and do any
114 * other filter-specific preparations like initializing the private_data member
115 * of \a fn suitably. The open function is assumed to succeed.
117 void (*open)(struct filter_node *fn);
119 * Close one instance of this filter.
121 * Free all resources of associated with \a fn that were previously allocated
122 * by the open() function.
124 void (*close)(struct filter_node *fn);
126 * A pointer to the filter's command line parser.
128 * If this optional function pointer is not NULL, any filter options
129 * are passed from the main program to this command line parser once at
130 * application startup. The command line parser should check its
131 * command line options given by \a argc and \a argv and abort on
132 * errors. Success must be indicated by a non-negative return value. In
133 * this case the function should return a pointer to the
134 * filter-specific configuration data determined by \a argc and \a
135 * argv. On failure, a negative paraslash error code must be returned.
137 int (*parse_config)(int argc, char **argv, void **config);
138 void (*free_config)(void *conf);
140 /** The help texts for this filter. */
141 struct ggo_help help;
142 void (*pre_select)(struct sched *s, struct task *t);
144 * Convert (filter) the given data.
146 * Pointer to the converting function of the filter. It should convert as
147 * input data as possible. On errors, the post_select function is supposed
148 * to set t->error to a (negative) error code.
150 void (*post_select)(struct sched *s, struct task *t);
151 btr_command_handler execute;
154 void filter_init(void);
155 int check_filter_arg(char *filter_arg, void **conf);
156 void print_filter_helps(int detailed);
157 void generic_filter_pre_select(struct sched *s, struct task *t);
159 static inline void write_int16_host_endian(char *buf, int val)
161 #ifdef WORDS_BIGENDIAN
163 *(buf + 1) = val & 0xff;
166 *(buf + 1) = val >> 8;
172 #define FOR_EACH_SUPPORTED_FILTER(j) for (j = 0; j < NUM_SUPPORTED_FILTERS; j++)
174 /** The filter array, one structure for each supported filter. */
175 extern struct filter filters[NUM_SUPPORTED_FILTERS];