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148 lines
4.5 KiB
C++
148 lines
4.5 KiB
C++
/* ScummVM - Graphic Adventure Engine
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*
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* ScummVM is the legal property of its developers, whose names
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* are too numerous to list here. Please refer to the COPYRIGHT
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* file distributed with this source distribution.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
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*
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*/
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#ifndef AUDIO_MIXER_INTERN_H
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#define AUDIO_MIXER_INTERN_H
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#include "common/scummsys.h"
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#include "common/mutex.h"
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#include "audio/mixer.h"
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namespace Audio {
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/**
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* The (default) implementation of the ScummVM audio mixing subsystem.
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*
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* Backends are responsible for allocating (and later releasing) an instance
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* of this class, which engines can access via OSystem::getMixer().
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*
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* Initialisation of instances of this class usually happens as follows:
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* 1) Creat a new Audio::MixerImpl instance.
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* 2) Set the hardware output sample rate via the setSampleRate() method.
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* 3) Hook up the mixCallback() in a suitable audio processing thread/callback.
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* 4) Change the mixer into ready mode via setReady(true).
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* 5) Start audio processing (e.g. by resuming the audio thread, if applicable).
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*
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* In the future, we might make it possible for backends to provide
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* (partial) alternative implementations of the mixer, e.g. to make
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* better use of native sound mixing support on low-end devices.
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*
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* @see OSystem::getMixer()
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*/
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class MixerImpl : public Mixer {
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private:
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enum {
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NUM_CHANNELS = 32
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};
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Common::Mutex _mutex;
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const uint _sampleRate;
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bool _mixerReady;
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uint32 _handleSeed;
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struct SoundTypeSettings {
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SoundTypeSettings() : mute(false), volume(kMaxMixerVolume) {}
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bool mute;
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int volume;
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};
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SoundTypeSettings _soundTypeSettings[4];
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Channel *_channels[NUM_CHANNELS];
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public:
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MixerImpl(uint sampleRate);
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~MixerImpl();
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virtual bool isReady() const { Common::StackLock lock(_mutex); return _mixerReady; }
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virtual void playStream(
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SoundType type,
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SoundHandle *handle,
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AudioStream *input,
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int id, byte volume, int8 balance,
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DisposeAfterUse::Flag autofreeStream,
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bool permanent,
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bool reverseStereo);
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virtual void stopAll();
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virtual void stopID(int id);
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virtual void stopHandle(SoundHandle handle);
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virtual void pauseAll(bool paused);
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virtual void pauseID(int id, bool paused);
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virtual void pauseHandle(SoundHandle handle, bool paused);
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virtual bool isSoundIDActive(int id);
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virtual int getSoundID(SoundHandle handle);
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virtual bool isSoundHandleActive(SoundHandle handle);
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virtual void muteSoundType(SoundType type, bool mute);
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virtual bool isSoundTypeMuted(SoundType type) const;
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virtual void setChannelVolume(SoundHandle handle, byte volume);
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virtual byte getChannelVolume(SoundHandle handle);
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virtual void setChannelBalance(SoundHandle handle, int8 balance);
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virtual int8 getChannelBalance(SoundHandle handle);
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virtual uint32 getSoundElapsedTime(SoundHandle handle);
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virtual Timestamp getElapsedTime(SoundHandle handle);
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virtual bool hasActiveChannelOfType(SoundType type);
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virtual void setVolumeForSoundType(SoundType type, int volume);
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virtual int getVolumeForSoundType(SoundType type) const;
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virtual uint getOutputRate() const;
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protected:
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void insertChannel(SoundHandle *handle, Channel *chan);
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public:
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/**
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* The mixer callback function, to be called at regular intervals by
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* the backend (e.g. from an audio mixing thread). All the actual mixing
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* work is done from here.
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*
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* @param samples Sample buffer, in which stereo 16-bit samples will be stored.
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* @param len Length of the provided buffer to fill (in bytes, should be divisible by 4).
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* @return number of sample pairs processed (which can still be silence!)
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*/
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int mixCallback(byte *samples, uint len);
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/**
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* Set the internal 'is ready' flag of the mixer.
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* Backends should invoke Mixer::setReady(true) once initialisation of
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* their audio system has been completed.
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*/
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void setReady(bool ready);
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};
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} // End of namespace Audio
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#endif
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