/* the Music Player Daemon (MPD) * Copyright (C) 2003-2007 by Warren Dukes (warren.dukes@gmail.com) * Copyright (C) 2008 Max Kellermann <max@duempel.org> * This project's homepage is: 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_API_H #define MPD_OUTPUT_API_H #include "../config.h" #include "audio_format.h" #include "tag.h" #include "conf.h" #include <stdbool.h> #define DISABLED_AUDIO_OUTPUT_PLUGIN(plugin) const struct audio_output_plugin plugin; struct audio_output; /** * 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, 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. */ void (*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); }; enum audio_output_command { AO_COMMAND_NONE = 0, AO_COMMAND_OPEN, AO_COMMAND_CLOSE, AO_COMMAND_PLAY, AO_COMMAND_PAUSE, AO_COMMAND_CANCEL, AO_COMMAND_SEND_TAG, AO_COMMAND_KILL }; enum audio_control_command { AC_MIXER_GETVOL = 0, AC_MIXER_SETVOL, AC_MIXER_CONFIGURE, }; struct audio_output; const char *audio_output_get_name(const struct audio_output *ao); void audio_output_closed(struct audio_output *ao); /** * Returns true if there is a command pending. */ bool audio_output_is_pending(const struct audio_output *ao); #endif