comparison base/AudioPlaySource.h @ 0:fc9323a41f5a

start base : Sonic Visualiser sv1-1.0rc1

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