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1 /* -*- c-basic-offset: 4 -*- vi:set ts=8 sts=4 sw=4: */
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2
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3 /*
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4 A waveform viewer and audio annotation editor.
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5 Chris Cannam, Queen Mary University of London, 2005
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6
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7 This is experimental software. Not for distribution.
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8 */
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9
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10 #ifndef _AUDIO_PLAY_SOURCE_H_
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11 #define _AUDIO_PLAY_SOURCE_H_
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12
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13 /**
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14 * Simple interface for audio playback. This should be all that the
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15 * ViewManager needs to know about to synchronise with playback by
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16 * sample frame, but it doesn't provide enough to determine what is
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17 * actually being played or how. See the audioio directory for a
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18 * concrete subclass.
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19 */
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20
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21 class AudioPlaySource
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22 {
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23 public:
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24 /**
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25 * Start playing from the given frame. If playback is already
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26 * under way, reseek to the given frame and continue.
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27 */
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28 virtual void play(size_t startFrame) = 0;
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29
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30 /**
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31 * Stop playback.
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32 */
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33 virtual void stop() = 0;
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34
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35 /**
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36 * Return whether playback is currently supposed to be happening.
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37 */
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38 virtual bool isPlaying() const = 0;
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39
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40 /**
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41 * Return the frame number that is currently expected to be coming
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42 * out of the speakers. (i.e. compensating for playback latency.)
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43 */
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44 virtual size_t getCurrentPlayingFrame() = 0;
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45
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46 /**
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47 * Return the current (or thereabouts) output levels in the range
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48 * 0.0 -> 1.0, for metering purposes.
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49 */
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50 virtual bool getOutputLevels(float &left, float &right) = 0;
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51 };
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52
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53 #endif
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