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1 /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */
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2
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3 /*
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4 Sonic Visualiser
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5 An audio file viewer and annotation editor.
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6 Centre for Digital Music, Queen Mary, University of London.
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7 This file copyright 2006 Chris Cannam.
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8
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9 This program is free software; you can redistribute it and/or
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10 modify it under the terms of the GNU General Public License as
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11 published by the Free Software Foundation; either version 2 of the
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12 License, or (at your option) any later version. See the file
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13 COPYING included with this distribution for more information.
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14 */
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15
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16 #ifndef _AUDIO_PLAY_SOURCE_H_
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17 #define _AUDIO_PLAY_SOURCE_H_
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18
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19 /**
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20 * Simple interface for audio playback. This should be all that the
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21 * ViewManager needs to know about to synchronise with playback by
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22 * sample frame, but it doesn't provide enough to determine what is
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23 * actually being played or how. See the audioio directory for a
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24 * concrete subclass.
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25 */
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26
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27 class AudioPlaySource
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28 {
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29 public:
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30 virtual ~AudioPlaySource() { }
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31
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32 /**
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33 * Start playing from the given frame. If playback is already
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34 * under way, reseek to the given frame and continue.
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35 */
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36 virtual void play(size_t startFrame) = 0;
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37
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38 /**
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39 * Stop playback.
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40 */
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41 virtual void stop() = 0;
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42
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43 /**
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44 * Return whether playback is currently supposed to be happening.
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45 */
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46 virtual bool isPlaying() const = 0;
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47
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48 /**
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49 * Return the frame number that is currently expected to be coming
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50 * out of the speakers. (i.e. compensating for playback latency.)
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51 */
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52 virtual size_t getCurrentPlayingFrame() = 0;
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53
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54 /**
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55 * Return the current (or thereabouts) output levels in the range
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56 * 0.0 -> 1.0, for metering purposes.
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57 */
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58 virtual bool getOutputLevels(float &left, float &right) = 0;
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59
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60 /**
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61 * Return the sample rate set by the target audio device (or the
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62 * source sample rate if the target hasn't set one).
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63 */
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64 virtual size_t getTargetSampleRate() const = 0;
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65 };
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66
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67 #endif
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