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<p>
Next: <a href="Sources.html" accesskey="n" rel="next">Sources</a>, Up: <a href="Audio.html" accesskey="u" rel="up">Audio</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p>
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<hr />
<span id="Audio-Files-1"></span><h4 class="subsection">5.4.1 Audio Files</h4>
<p>Sound data is represented by a special <code><audio></code> data type that
stores not only the audio samples themselves, but metadata such as
sample rate, number of channels, and how many bits are used for each
sample.
</p>
<dl>
<dt id="index-load_002daudio">Procedure: <strong>load-audio</strong> <em>file-name [#:mode <code>static</code>]</em></dt>
<dd><p>Load audio within <var>file-name</var>. The following file formats are
currently supported:
</p>
<ul>
<li> WAV
</li><li> MP3
</li><li> Ogg Vorbis
</li></ul>
<p>Audio files can be loaded in two different ways, as indicated by
<var>mode</var>:
</p>
<ul>
<li> static:
Load the entire audio file into memory.
</li><li> stream:
Load chunks of the audio file as needed.
</li></ul>
<p>Generally speaking, sound effects don’t take up much space and should
be loaded statically, but music files are much larger and should use
streaming. Static loading is the default.
</p></dd></dl>
<dl>
<dt id="index-audio_003f">Procedure: <strong>audio?</strong> <em><var>obj</var></em></dt>
<dd><p>Return <code>#t</code> if <var>obj</var> is an audio object.
</p></dd></dl>
<dl>
<dt id="index-streaming_002daudio_003f">Procedure: <strong>streaming-audio?</strong> <em><var>audio</var></em></dt>
<dd><p>Return <code>#t</code> if <var>audio</var> uses stream loading.
</p></dd></dl>
<dl>
<dt id="index-static_002daudio_003f">Procedure: <strong>static-audio?</strong></dt>
<dd><p>Return <code>#t</code> if <var>audio</var> uses static loading.
</p></dd></dl>
<dl>
<dt id="index-audio_002dmode">Procedure: <strong>audio-mode</strong> <em>audio</em></dt>
<dd><p>Return the loading mode for <var>audio</var>, either <code>static</code> or
<code>stream</code>.
</p></dd></dl>
<dl>
<dt id="index-audio_002dduration">Procedure: <strong>audio-duration</strong> <em>audio</em></dt>
<dd><p>Return the duration of <var>audio</var> in seconds.
</p></dd></dl>
<dl>
<dt id="index-audio_002dbits_002dper_002dsample">Procedure: <strong>audio-bits-per-sample</strong> <em>audio</em></dt>
<dd><p>Return the number of bits per sample in <var>audio</var>.
</p></dd></dl>
<dl>
<dt id="index-audio_002dchannels">Procedure: <strong>audio-channels</strong> <em>audio</em></dt>
<dd><p>Return the number of channels in <var>audio</var>.
</p></dd></dl>
<dl>
<dt id="index-audio_002dsample_002drate">Procedure: <strong>audio-sample-rate</strong> <em>audio</em></dt>
<dd><p>Return the sample rate of <var>audio</var>.
</p></dd></dl>
<dl>
<dt id="index-audio_002dplay">Procedure: <strong>audio-play</strong> <em>audio [#:pitch 1.0] [#:volume 1.0] [#:min-volume 0.0] [#:max-volume 1.0] [#:max-distance] [#:reference-distance 0.0] [#:rolloff-factor 1.0] [#:cone-outer-volume 0.0] [#:cone-inner-angle 0.0] [#:cone-outer-angle] [#:position <code>(vec3 0.0 0.0 0.0)</code>] [#:velocity <code>(vec3 0.0 0.0 0.0)</code>] [#:direction <code>(vec3 0.0 0.0 0.0)</code>] [#:relative? <code>#f</code>]</em></dt>
<dd>
<p>Play <var>audio</var>. There are many, many knobs to tweak that will
affect the sound that comes out of the player’s speakers.:
</p>
<ul>
<li> <var>pitch</var>:
Pitch multiplier. The default value of 1.0 means no change in pitch.
</li><li> <var>volume</var>:
Volume multiplier. The default value of 1.0 means no change in volume.
</li><li> <var>min-volume</var>:
Minimum volume.
</li><li> <var>max-volume</var>:
Maximum volume.
</li><li> <var>max-distance</var>:
Used with the inverse clamped distance model (the default model) to
set the distance where there will no longer be any attenuation of the
source.
</li><li> <var>reference-distance</var>:
The distance where the volume for the audio would drop by half (before
being influenced by the rolloff factor or maximum distance.)
</li><li> <var>rolloff-factor</var>:
For slowing down or speeding up the rate of attenuation. The default
of 1.0 means no attenuation adjustment is made.
</li><li> <var>cone-outer-volume</var>:
The volume when outside the oriented cone.
</li><li> <var>cone-inner-angle</var>:
Inner angle of the sound cone, in radians. The default value is 0.
</li><li> <var>cone-outer-angle</var>:
Outer angle of the sound cone, in radians. The default value is 2pi
radians, or 360 degrees.
</li><li> <var>position</var>:
The source of the sound emitter in 3D space.
</li><li> <var>velocity</var>:
The velocity of the sound emitter in 3D space.
</li><li> <var>direction</var>:
The direction of the sound emitter in 3D space.
</li><li> <var>relative?</var>:
A flag that determines whether the position is in absolute coordinates
or relative to the listener’s location. Absolute coordinates are used
by default.
</li></ul>
<p>For games with basic sound needs (that is to say they don’t need 3D
sound modeling), the only things that really matter are <var>volume</var>
and <var>pitch</var>.
</p>
</dd></dl>
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