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/*
* Copyright (C) 2003-2009 The Music Player Daemon Project
* http://www.musicpd.org
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifndef MPD_OUTPUT_PLUGIN_H
#define MPD_OUTPUT_PLUGIN_H
#include <stdbool.h>
#include <stddef.h>
struct audio_output;
struct config_param;
struct audio_format;
struct tag;
/**
* A plugin which controls an audio output device.
*/
struct audio_output_plugin {
/**
* the plugin's name
*/
const char *name;
/**
* Test if this plugin can provide a default output, in case
* none has been configured. This method is optional.
*/
bool (*test_default_device)(void);
/**
* Configure and initialize the device, but do not open it
* yet.
*
* @param ao an opaque pointer to the audio_output structure
* @param audio_format the configured audio format, or NULL if
* none is configured
* @param param the configuration section, or NULL if there is
* no configuration
* @return NULL on error, or an opaque pointer to the plugin's
* data
*/
void *(*init)(struct audio_output *ao,
const struct audio_format *audio_format,
const struct config_param *param);
/**
* Free resources allocated by this device.
*/
void (*finish)(void *data);
/**
* Really open the device.
* @param audio_format the audio format in which data is going
* to be delivered; may be modified by the plugin
*/
bool (*open)(void *data, struct audio_format *audio_format);
/**
* Play a chunk of audio data.
*/
bool (*play)(void *data, const char *playChunk, size_t size);
/**
* Pause the device. If supported, it may perform a special
* action, which keeps the device open, but does not play
* anything. Output plugins like "shout" might want to play
* silence during pause, so their clients won't be
* disconnected. Plugins which do not support pausing will
* simply be closed, and have to be reopened when unpaused.
*
* @return false on error (output will be closed then), true
* for continue to pause
*/
bool (*pause)(void *data);
/**
* Try to cancel data which may still be in the device's
* buffers.
*/
void (*cancel)(void *data);
/**
* Close the device.
*/
void (*close)(void *data);
/**
* Control the device. Usualy used for implementing
* set and get mixer levels
*/
bool (*control)(void *data, int cmd, void *arg);
/**
* Display metadata for the next chunk. Optional method,
* because not all devices can display metadata.
*/
void (*send_tag)(void *data, const struct tag *tag);
};
#endif
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