lbajardsilogic@0: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
lbajardsilogic@0: 
lbajardsilogic@0: /*
lbajardsilogic@0:     Sonic Visualiser
lbajardsilogic@0:     An audio file viewer and annotation editor.
lbajardsilogic@0:     Centre for Digital Music, Queen Mary, University of London.
lbajardsilogic@0:     This file copyright 2006 Chris Cannam.
lbajardsilogic@0:     
lbajardsilogic@0:     This program is free software; you can redistribute it and/or
lbajardsilogic@0:     modify it under the terms of the GNU General Public License as
lbajardsilogic@0:     published by the Free Software Foundation; either version 2 of the
lbajardsilogic@0:     License, or (at your option) any later version.  See the file
lbajardsilogic@0:     COPYING included with this distribution for more information.
lbajardsilogic@0: */
lbajardsilogic@0: 
lbajardsilogic@0: #ifndef _AUDIO_PLAY_SOURCE_H_
lbajardsilogic@0: #define _AUDIO_PLAY_SOURCE_H_
lbajardsilogic@0: 
lbajardsilogic@0: /**
lbajardsilogic@0:  * Simple interface for audio playback.  This should be all that the
lbajardsilogic@0:  * ViewManager needs to know about to synchronise with playback by
lbajardsilogic@0:  * sample frame, but it doesn't provide enough to determine what is
lbajardsilogic@0:  * actually being played or how.  See the audioio directory for a
lbajardsilogic@0:  * concrete subclass.
lbajardsilogic@0:  */
lbajardsilogic@0: 
lbajardsilogic@0: class AudioPlaySource
lbajardsilogic@0: {
lbajardsilogic@0: public:
lbajardsilogic@0:     virtual ~AudioPlaySource() { }
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Start playing from the given frame.  If playback is already
lbajardsilogic@0:      * under way, reseek to the given frame and continue.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual void play(size_t startFrame) = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Stop playback.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual void stop() = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Return whether playback is currently supposed to be happening.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual bool isPlaying() const = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Return the frame number that is currently expected to be coming
lbajardsilogic@0:      * out of the speakers.  (i.e. compensating for playback latency.)
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual size_t getCurrentPlayingFrame() = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Return the current (or thereabouts) output levels in the range
lbajardsilogic@0:      * 0.0 -> 1.0, for metering purposes.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual bool getOutputLevels(float &left, float &right) = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Return the sample rate of the source material -- any material
lbajardsilogic@0:      * that wants to play at a different rate will sound wrong.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual size_t getSourceSampleRate() const = 0;
lbajardsilogic@0: 
lbajardsilogic@0:     /**
lbajardsilogic@0:      * Return the sample rate set by the target audio device (or the
lbajardsilogic@0:      * source sample rate if the target hasn't set one).  If the
lbajardsilogic@0:      * source and target sample rates differ, resampling will occur.
lbajardsilogic@0:      */
lbajardsilogic@0:     virtual size_t getTargetSampleRate() const = 0;
lbajardsilogic@0:      
lbajardsilogic@0: };
lbajardsilogic@0: 
lbajardsilogic@0: #endif