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/*
* Copyright 2003-2021 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_PLAYER_OUTPUT_INTERFACE_HXX
#define MPD_PLAYER_OUTPUT_INTERFACE_HXX
#include "MusicChunkPtr.hxx"
#include "Chrono.hxx"
#include "util/Compiler.h"
struct AudioFormat;
struct MusicChunk;
/**
* An interface for the player thread to control all outputs. This
* interface is implemented only by #MultipleOutputs, and exists only
* to decouple the player code from the output code, to be able to
* unit-test the player code.
*/
class PlayerOutputs {
public:
/**
* Checks the "enabled" flag of all audio outputs, and if one has
* changed, commit the change.
*
* Throws on error.
*/
virtual void EnableDisable() = 0;
/**
* Opens all audio outputs which are not disabled.
*
* Throws on error.
*
* @param audio_format the preferred audio format
*/
virtual void Open(const AudioFormat audio_format) = 0;
/**
* Closes all audio outputs.
*/
virtual void Close() noexcept = 0;
/**
* Closes all audio outputs. Outputs with the "always_on"
* flag are put into pause mode.
*/
virtual void Release() noexcept = 0;
/**
* Enqueue a #MusicChunk object for playing, i.e. pushes it to a
* #MusicPipe.
*
* Throws on error (all closed then).
*
* @param chunk the #MusicChunk object to be played
*/
virtual void Play(MusicChunkPtr chunk) = 0;
/**
* Checks if the output devices have drained their music pipe, and
* returns the consumed music chunks to the #music_buffer.
*
* @return the number of chunks to play left in the #MusicPipe
*/
virtual unsigned CheckPipe() noexcept = 0;
/**
* Puts all audio outputs into pause mode. Most implementations will
* simply close it then.
*/
virtual void Pause() noexcept = 0;
/**
* Drain all audio outputs.
*/
virtual void Drain() noexcept = 0;
/**
* Try to cancel data which may still be in the device's buffers.
*/
virtual void Cancel() noexcept = 0;
/**
* Indicate that a new song will begin now.
*/
virtual void SongBorder() noexcept = 0;
/**
* Returns the "elapsed_time" stamp of the most recently finished
* chunk. A negative value is returned when no chunk has been
* finished yet.
*/
gcc_pure
virtual SignedSongTime GetElapsedTime() const noexcept = 0;
};
#endif
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