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Diffstat (limited to 'src/output/OutputPlugin.hxx')
| -rw-r--r-- | src/output/OutputPlugin.hxx | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/src/output/OutputPlugin.hxx b/src/output/OutputPlugin.hxx new file mode 100644 index 000000000..7d77c92b2 --- /dev/null +++ b/src/output/OutputPlugin.hxx @@ -0,0 +1,202 @@ +/* + * Copyright (C) 2003-2014 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., + * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. + */ + +#ifndef MPD_OUTPUT_PLUGIN_HXX +#define MPD_OUTPUT_PLUGIN_HXX + +#include "Compiler.h" + +#include <stddef.h> + +struct config_param; +struct AudioFormat; +struct Tag; +class Error; + +/** + * 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 param the configuration section, or nullptr if there is + * no configuration + * @return nullptr on error, or an opaque pointer to the plugin's + * data + */ + struct audio_output *(*init)(const config_param ¶m, + Error &error); + + /** + * Free resources allocated by this device. + */ + void (*finish)(struct audio_output *data); + + /** + * Enable the device. This may allocate resources, preparing + * for the device to be opened. Enabling a device cannot + * fail: if an error occurs during that, it should be reported + * by the open() method. + * + * @return true on success, false on error + */ + bool (*enable)(struct audio_output *data, Error &error); + + /** + * Disables the device. It is closed before this method is + * called. + */ + void (*disable)(struct audio_output *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)(struct audio_output *data, AudioFormat &audio_format, + Error &error); + + /** + * Close the device. + */ + void (*close)(struct audio_output *data); + + /** + * Returns a positive number if the output thread shall delay + * the next call to play() or pause(). This should be + * implemented instead of doing a sleep inside the plugin, + * because this allows MPD to listen to commands meanwhile. + * + * @return the number of milliseconds to wait + */ + unsigned (*delay)(struct audio_output *data); + + /** + * Display metadata for the next chunk. Optional method, + * because not all devices can display metadata. + */ + void (*send_tag)(struct audio_output *data, const Tag *tag); + + /** + * Play a chunk of audio data. + * + * @return the number of bytes played, or 0 on error + */ + size_t (*play)(struct audio_output *data, + const void *chunk, size_t size, + Error &error); + + /** + * Wait until the device has finished playing. + */ + void (*drain)(struct audio_output *data); + + /** + * Try to cancel data which may still be in the device's + * buffers. + */ + void (*cancel)(struct audio_output *data); + + /** + * 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)(struct audio_output *data); + + /** + * The mixer plugin associated with this output plugin. This + * may be nullptr if no mixer plugin is implemented. When + * created, this mixer plugin gets the same #config_param as + * this audio output device. + */ + const struct mixer_plugin *mixer_plugin; +}; + +static inline bool +ao_plugin_test_default_device(const struct audio_output_plugin *plugin) +{ + return plugin->test_default_device != nullptr + ? plugin->test_default_device() + : false; +} + +gcc_malloc +struct audio_output * +ao_plugin_init(const struct audio_output_plugin *plugin, + const config_param ¶m, + Error &error); + +void +ao_plugin_finish(struct audio_output *ao); + +bool +ao_plugin_enable(struct audio_output *ao, Error &error); + +void +ao_plugin_disable(struct audio_output *ao); + +bool +ao_plugin_open(struct audio_output *ao, AudioFormat &audio_format, + Error &error); + +void +ao_plugin_close(struct audio_output *ao); + +gcc_pure +unsigned +ao_plugin_delay(struct audio_output *ao); + +void +ao_plugin_send_tag(struct audio_output *ao, const Tag *tag); + +size_t +ao_plugin_play(struct audio_output *ao, const void *chunk, size_t size, + Error &error); + +void +ao_plugin_drain(struct audio_output *ao); + +void +ao_plugin_cancel(struct audio_output *ao); + +bool +ao_plugin_pause(struct audio_output *ao); + +#endif |