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arts/flow/audiosubsys.h

237 lines
6.1 KiB

/*
Copyright (C) 2000 Stefan Westerfeld
stefan@space.twc.de
This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public
License as published by the Free Software Foundation; either
version 2 of the License, or (at your option) any later version.
This library 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
Library General Public License for more details.
You should have received a copy of the GNU Library General Public License
along with this library; see the file COPYING.LIB. If not, write to
the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
Boston, MA 02110-1301, USA.
*/
#ifndef AUDIOSUBSYS_H
#define AUDIOSUBSYS_H
#include <string>
#include "arts_export.h"
#include "pipebuffer.h"
#include "startupmanager.h"
/*
* BC - tqStatus (2002-03-08): AudioSubSystem, ASProducer, ASConsumer.
*
* These classes are kept binary compatible. You can rely on them.
* AudioSubSystem has a private data pointer to do so. Even if ports to
* other architectures or hardware will require different organization
* (i.e. no fragments, direct memory access via mmap), the data members
* and functions exported here MAY NOT BE CHANGED. Use the private data
* pointer for adding data members.
*
* If ASProducer/ASConsumer doesn't suit the needs any longer, do NOT
* change them. Add new classes instead.
*/
namespace Arts {
class ASProducer {
public:
virtual void needMore() = 0;
};
// FIXME: haveMore won't be called currently
class ASConsumer {
public:
virtual void haveMore() = 0;
};
class ARTS_EXPORT AudioSubSystemStart :public StartupClass {
protected:
class AudioSubSystem *_instance;
public:
inline AudioSubSystem *the() { return _instance; };
void startup();
void shutdown();
};
class AudioSubSystemPrivate;
class ARTS_EXPORT AudioSubSystem {
class AudioSubSystemPrivate *d;
std::string _error;
char *fragment_buffer;
int _fragmentCount;
int _fragmentSize;
bool _running;
PipeBuffer wBuffer, rBuffer;
ASConsumer *consumer;
ASProducer *producer;
friend class AudioSubSystemStart;
AudioSubSystem();
~AudioSubSystem();
void close();
void initAudioIO();
/**
* checks that full duplex doesn't go out of sync
*/
void adjustDuplexBuffers();
/**
* creates count empty fragments of input in rBuffer if count > 0
* removes count fragments of input from rBuffer if count < 0
*/
void adjustInputBuffer(int count);
public:
enum { ioRead=1, ioWrite=2, ioExcept=4 };
// singleton
static AudioSubSystem *the();
/*
* Currently, if you want to use the AudioSubSystem, you need to
*
* 1. - attach one producer
* - attach one consumer (only for full duplex)
* - open the audio subsystem using open (watch the fd)
* (in any order)
*
* 2. react on the callbacks you get for the producer
*
* 3. if you don't need the audio subsystem any longer, call detach
* both, the producer and the cosumer.
*
* Be careful that you don't read/write from/to the audio subsystem
* when running() is not true.
*/
bool attachProducer(ASProducer *producer);
bool attachConsumer(ASConsumer *consumer);
void detachProducer();
void detachConsumer();
/*
* can be used to select the AudioIO class to use, reasonable choices
* may be "oss" or "alsa" at this point in time - you need to choose
* this before doing anything else
*/
void audioIO(const std::string& audioIO);
std::string audioIO();
// which device to use for audio output (default /dev/dsp)
void deviceName(const std::string& deviceName);
std::string deviceName();
void fragmentSize(int size);
int fragmentSize();
void fragmentCount(int fragments);
int fragmentCount();
void samplingRate(int samplingrate);
int samplingRate();
void channels(int channels);
int channels();
void format(int format);
int format();
/**
* As opposed to format(), this one returns the number of bits used per
* sample. Thats sometimes a difference, for instance 16bit big endian
* encoding has the format() 17, whereas bits() would return 16.
*/
int bits();
void fullDuplex(bool newFullDuplex);
bool fullDuplex();
bool check();
/**
* Opens the audio device.
*
* After opening, you must check selectReadFD() and selectWriteFD() to
* select() on the appropriate file descriptors. Whenever select()ing is
* successful, handleIO needs to be called.
*
* The type for handleIO must be set to ioRead if fd is ready for
* reading, ioWrite if fd is ready for writing, ioExcept if something
* special happend or any combination of these using bitwise or.
*
* @returns true if audio device has been opened successfully,
* false otherwise
*/
bool open();
/**
* human readable error message that descibes why opening the audio device
* failed
*/
const char *error();
/**
* File descriptor to select on for reading (@see open()), -1 if there is
* none.
*/
int selectReadFD();
/**
* File descriptor to select on for writing (@see open()), -1 if there is
* none.
*/
int selectWriteFD();
/**
* Needs to be called to handle I/O on the filedescriptors given by
* selectReadFD() and selectWriteFD() (@see open()).
*/
void handleIO(int type);
void read(void *buffer, int size);
void write(void *buffer, int size);
/**
* this returns the time in seconds it will take until everything written
* to the AudioSubSystem so far will be played - in other words, it returns
* the time it will take until the next sample written by the application
* will be heard by the user
*/
float outputDelay();
/**
* returns true as long as the audio subsystem is opened and active (that
* is, between successful opening, with attaching producer, and the first
* detachConsumer/detachProducer)
*/
bool running();
/**
* called during crashes, to release the opened device (and other resources)
* don't use this method for other purposes than emergencies
*/
void emergencyCleanup();
};
}
#endif /* AUDIOSUBSYS_H */