paraslash 0.7.3

[paraslash.git] / filter.h

diff --git a/filter.h b/filter.h
index ab98c2442b9d13ae5158716fc2fe7f24904685e6..77057e6a7d2b9a997219d907b3ddd459716283ad 100644 (file)
--- a/filter.h
+++ b/filter.h
@@ -1,8 +1,4 @@
-/*
- * Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>
- *
- * Licensed under the GPL v2. For licencing details see COPYING.
- */
+/* Copyright (C) 2005 Andre Noll <maan@tuebingen.mpg.de>, see file COPYING. */
 
 /** \file filter.h Filter-related structures and exported symbols from filter_common.c. */
 
@@ -32,16 +28,18 @@ struct filter_node {
 };
 
 /**
- * The structure associated with a paraslash filter.
+ * Describes a method to convert audio data.
  *
- * Paraslash filters are "modules" which transform an audio stream. struct
- * filter contains methods which are implemented by each filter.
+ * Paraslash filters are "modules" which transform the data of an audio stream.
+ * This structure contains the methods which have to be implemented by each
+ * filter.
  *
- * Note: As several instances of the same filter may be running at the same
- * time, all these filter functions must be reentrant; no static non-constant
- * variables may be used.
+ * As several instances of the same filter may be running at the same time, all
+ * filter methods must be reentrant and no static non-constant variables must
+ * be used.
  *
- * \sa \ref filter_node.
+ * \sa \ref filter_node, struct \ref receiver, struct \ref writer, struct \ref
+ * sched.
  */
 struct filter {
        /**
@@ -85,24 +83,10 @@ struct filter {
         * This should free whatever ->setup() has allocated.
         */
        void (*teardown)(const struct lls_parse_result *lpr, void *conf);
-       /**
-        * Set scheduler timeout and add file descriptors to fd sets.
-        *
-        * This function controls the timeout value for the next call to
-        * select(2). It may decrease the current timeout but shall never
-        * increase it. The second purpose of this function is to add file
-        * descriptors to the two fd sets of the sched structure. The
-        * descriptors in these sets will be watched by the subsequent
-        * select(2) call.
-        */
-       void (*pre_select)(struct sched *s, void *context);
-       /**
-        * Convert (filter) the given data.
-        *
-        * Pointer to the converting function of the filter. On errors, the
-        * post_select function is supposed to return a negative error code.
-        */
-       int (*post_select)(struct sched *s, void *context);
+       /** Force a zero timeout if data is available in the buffer tree. */
+       void (*pre_monitor)(struct sched *s, void *context);
+       /** Convert (filter) input data into output data. */
+       int (*post_monitor)(struct sched *s, void *context);
        /**
         * Answer a buffer tree query.
         *
@@ -128,7 +112,7 @@ int filter_setup(const char *fa, void **conf, struct lls_parse_result **lprp);
 #define FILTER_CMD_OPT_STRING_VAL(_cmd, _opt, _lpr) \
        (lls_string_val(0, FILTER_CMD_OPT_RESULT(_cmd, _opt, _lpr)))
 
-void generic_filter_pre_select(struct sched *s, void *context);
+void generic_filter_pre_monitor(struct sched *s, void *context);
 int decoder_execute(const char *cmd, unsigned sample_rate, unsigned channels,
                char **result);