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/* ScummVM - Graphic Adventure Engine
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
* 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
* 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.
* $URL: $
* $Id: mixer_intern.h 48637 2010-04-12 09:14:17Z fingolfin $
#include "common/scummsys.h"
#include "common/mutex.h"
#include "sound/mixer.h"
namespace Audio {
* The (default) implementation of the ScummVM audio mixing subsystem.
* Backends are responsible for allocating (and later releasing) an instance
* of this class, which engines can access via OSystem::getMixer().
* Initialisation of instances of this class usually happens as follows:
* 1) Creat a new Audio::MixerImpl instance.
* 2) Set the hardware output sample rate via the setSampleRate() method.
* 3) Hook up the mixCallback() in a suitable audio processing thread/callback.
* 4) Change the mixer into ready mode via setReady(true).
* 5) Start audio processing (e.g. by resuming the audio thread, if applicable).
* In the future, we might make it possible for backends to provide
* (partial) alternative implementations of the mixer, e.g. to make
* better use of native sound mixing support on low-end devices.
* @see OSystem::getMixer()
class MixerImpl : public Mixer {
enum {
OSystem *_syst;
Common::Mutex _mutex;
const uint _sampleRate;
bool _mixerReady;
uint32 _handleSeed;
int _volumeForSoundType[4];
Channel *_channels[NUM_CHANNELS];
MixerImpl(OSystem *system, uint sampleRate);
virtual bool isReady() const { return _mixerReady; }
virtual void playStream(
SoundType type,
SoundHandle *handle,
AudioStream *input,
int id, byte volume, int8 balance,
DisposeAfterUse::Flag autofreeStream,
bool permanent,
bool reverseStereo);
virtual void stopAll();
virtual void stopID(int id);
virtual void stopHandle(SoundHandle handle);
virtual void pauseAll(bool paused);
virtual void pauseID(int id, bool paused);
virtual void pauseHandle(SoundHandle handle, bool paused);
virtual bool isSoundIDActive(int id);
virtual int getSoundID(SoundHandle handle);
virtual bool isSoundHandleActive(SoundHandle handle);
virtual void setChannelVolume(SoundHandle handle, byte volume);
virtual void setChannelBalance(SoundHandle handle, int8 balance);
virtual uint32 getSoundElapsedTime(SoundHandle handle);
virtual Timestamp getElapsedTime(SoundHandle handle);
virtual bool hasActiveChannelOfType(SoundType type);
virtual void setVolumeForSoundType(SoundType type, int volume);
virtual int getVolumeForSoundType(SoundType type) const;
virtual uint getOutputRate() const;
void insertChannel(SoundHandle *handle, Channel *chan);
* The mixer callback function, to be called at regular intervals by
* the backend (e.g. from an audio mixing thread). All the actual mixing
* work is done from here.
void mixCallback(byte *samples, uint len);
* Set the internal 'is ready' flag of the mixer.
* Backends should invoke Mixer::setReady(true) once initialisation of
* their audio system has been completed.
void setReady(bool ready);
} // End of namespace Audio
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