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71 lines
3.0 KiB
71 lines
3.0 KiB
8 years ago
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<script type="text/x-red" data-help-name="AudioPlaySdWav">
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<h3>Summary</h3>
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<div class=tooltipinfo>
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<p>Play a WAV file, stored on a SD card.</p>
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</div>
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<h3>Audio Connections</h3>
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<table class=doc align=center cellpadding=3>
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<tr class=top><th>Port</th><th>Purpose</th></tr>
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<tr class=odd><td align=center>Out 0</td><td>Left Channel Output</td></tr>
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<tr class=odd><td align=center>Out 1</td><td>Right Channel Output</td></tr>
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</table>
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<h3>Functions</h3>
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<p class=func><span class=keyword>play</span>(filename);</p>
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<p class=desc>Begin playing a WAV file. If a file is already playing,
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it is stopped and this file starts playing from the beginning.
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</p>
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<p class=func><span class=keyword>stop</span>();</p>
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<p class=desc>Stop playing. If not playing, this function has no effect.
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</p>
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<p class=func><span class=keyword>isPlaying</span>();</p>
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<p class=desc>Return true (non-zero) if playing, or false (zero)
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when not playing. See the note below about delayed start.
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</p>
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<p class=func><span class=keyword>positionMillis</span>();</p>
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<p class=desc>While playing, return the current time offset, in
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milliseconds. When not playing, the return from this function
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is undefined.
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</p>
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<p class=func><span class=keyword>lengthMillis</span>();</p>
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<p class=desc>Return the total length of the current sound clip,
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in milliseconds. When not playing, the return from this function
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is undefined.
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</p>
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<h3>Examples</h3>
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<p class=exam>File > Examples > Audio > WavFilePlayer
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</p>
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<h3>Notes</h3>
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<p>Only 16 bit PCM, 44100 Hz WAV files are supported. When mono
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files are played, both output ports transmit a copy of the
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single sound. Of course, stereo WAV files play with the left
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channel on port 0 and the right channel on port 1.
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</p>
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<p>A brief delay after calling play() will usually occur before
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isPlaying() returns true and positionMillis() returns valid
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time offset. WAV files have a header at the beginning of the
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file, which the audio library must read and parse before
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playing can begin.
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</p>
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<p>While playing, the audio library accesses the SD card automatically.
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If card access is required, you must
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<a href="http://www.pjrc.com/teensy/td_libs_AudioProcessorUsage.html" target="_blank">use AudioNoInterrupts()</a>
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to prevent the library from accessing the SD card while you use it.
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Disabling the audio library interrupt for too long may cause audible
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dropouts or glitches.
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</p>
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<p>An experimental SD library optimization exists, which can remove these
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SD library restrictions. It also allows reliable playback of more
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files at the same time. To enable this special code, find and edit
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the SD_t3.h file within your Arduino folder. See the comments within
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that file for details.
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</p>
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</script>
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<script type="text/x-red" data-template-name="AudioPlaySdWav">
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<div class="form-row">
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<label for="node-input-name"><i class="fa fa-tag"></i> Name</label>
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<input type="text" id="node-input-name" placeholder="Name">
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</div>
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</script>
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