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control: remap plugin - add docs

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Signed-off-by: Jaroslav Kysela <perex@perex.cz>
This commit is contained in:
Jaroslav Kysela 2021-04-06 12:57:54 +02:00
parent 7371ac9aad
commit 493a41bcad
3 changed files with 100 additions and 1 deletions
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3
include/Makefile.am
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@ -7,6 +7,9 @@ alsainclude_HEADERS = asoundlib.h asoundef.h \
version.h global.h input.h output.h error.h \
conf.h control.h
if BUILD_CTL_PLUGIN
alsainclude_HEADERS += control_plugin.h
endif
if BUILD_CTL_PLUGIN_EXT
alsainclude_HEADERS += control_external.h
endif

9
include/control_plugin.h
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@ -42,7 +42,14 @@
* Control HW
*/
int snd_ctl_hw_open(snd_ctl_t **handle, const char *name, int card, int mode);
int _snd_ctl_hw_open(snd_ctl_t **handlep, char *name, snd_config_t *root ATTRIBUTE_UNUSED, snd_config_t *conf, int mode);
int _snd_ctl_hw_open(snd_ctl_t **handlep, char *name, snd_config_t *root, snd_config_t *conf, int mode);
/*
* Control Remap & Map
*/
int snd_ctl_remap_open(snd_ctl_t **handlep, const char *name, snd_config_t *remap,
snd_config_t *map, snd_ctl_t *child, int mode);
int _snd_ctl_remap_open(snd_ctl_t **handlep, char *name, snd_config_t *root, snd_config_t *conf, int mode);
/** \} */

89
src/control/control_remap.c
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@ -1,3 +1,9 @@
/**
* \file control/control_remap.c
* \brief CTL Remap Plugin Interface
* \author Jaroslav Kysela <perex@perex.cz>
* \date 2021
*/
/*
* Control - Remap Controls
* Copyright (c) 2021 by Jaroslav Kysela <perex@perex.cz>
@ -1127,6 +1133,18 @@ static int parse_map(snd_ctl_remap_t *priv, snd_config_t *conf)
return 0;
}
/**
* \brief Creates a new remap & map control handle
* \param handlep Returns created control handle
* \param name Name of control device
* \param remap Remap configuration
* \param map Map configuration
* \param mode Control handle mode
* \retval zero on success otherwise a negative error code
* \warning Using of this function might be dangerous in the sense
* of compatibility reasons. The prototype might be freely
* changed in future.
*/
int snd_ctl_remap_open(snd_ctl_t **handlep, const char *name, snd_config_t *remap,
snd_config_t *map, snd_ctl_t *child, int mode ATTRIBUTE_UNUSED)
{
@ -1176,6 +1194,77 @@ int snd_ctl_remap_open(snd_ctl_t **handlep, const char *name, snd_config_t *rema
return result;
}
/*! \page control_plugins
\section control_plugins_remap Plugin: Remap & map
This plugin can remap (rename) identifiers (except the numid part) for
a child control to another. The plugin can also merge the multiple
child controls to one or split one control to more.
\code
ctl.name {
type remap # Route & Volume conversion PCM
child STR # Slave name
# or
child { # Slave definition
type STR
...
}
remap {
# the ID strings are parsed in the amixer style like 'name="Headphone Playback Switch",index=2'
SRC_ID1_STR DST_ID1_STR
SRC_ID2_STR DST_ID2_STR
...
}
map {
# join two stereo controls to one
CREATE_ID1_STR {
SRC_ID1_STR {
vindex.0 0 # source channel 0 to merged channel 0
vindex.1 1
}
SRC_ID2_STR {
vindex.2 0
vindex.3 1 # source channel 1 to merged channel 3
}
}
# split stereo to mono
CREATE_ID2_STR {
SRC_ID3_STR {
vindex.0 0 # stereo to mono (first channel)
}
}
CREATE_ID3_STR {
SRC_ID4_STR {
vindex.0 1 # stereo to mono (second channel)
}
}
}
}
\endcode
\subsection control_plugins_route_funcref Function reference
<UL>
<LI>snd_ctl_remap_open()
<LI>_snd_ctl_remap_open()
</UL>
*/
/**
* \brief Creates a new remap & map control plugin
* \param handlep Returns created control handle
* \param name Name of control
* \param root Root configuration node
* \param conf Configuration node with Route & Volume PCM description
* \param mode Control handle mode
* \retval zero on success otherwise a negative error code
* \warning Using of this function might be dangerous in the sense
* of compatibility reasons. The prototype might be freely
* changed in future.
*/
int _snd_ctl_remap_open(snd_ctl_t **handlep, char *name, snd_config_t *root, snd_config_t *conf, int mode)
{
snd_config_iterator_t i, next;