File: CastleSoundFile.TSoundOggVorbis.html

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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
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<title>Castle Game Engine: CastleSoundFile: Class TSoundOggVorbis</title>
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<h2>Castle Game Engine</h2><p><a href="introduction.html" class="navigation">Introduction</a></p><p><a href="AllUnits.html" class="navigation">Units</a></p><p><a href="ClassHierarchy.html" class="navigation">Class Hierarchy</a></p><p><a href="AllClasses.html" class="navigation">Classes, Interfaces, Objects and Records</a></p><p><a href="AllTypes.html" class="navigation">Types</a></p><p><a href="AllVariables.html" class="navigation">Variables</a></p><p><a href="AllConstants.html" class="navigation">Constants</a></p><p><a href="AllFunctions.html" class="navigation">Functions and Procedures</a></p><p><a href="AllIdentifiers.html" class="navigation">Identifiers</a></p></td><td class="content">
<a name="TSoundOggVorbis"></a><h1 class="cio">Class TSoundOggVorbis</h1>
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<td><a class="section" href="#PasDoc-Description">Description</a></td><td><a class="section" href="#PasDoc-Hierarchy">Hierarchy</a></td><td>Fields</td><td><a class="section" href="#PasDoc-Methods">Methods</a></td><td>Properties</td></tr></table>
<a name="PasDoc-Description"></a><h2 class="unit">Unit</h2>
<p class="unitlink">
<a  href="CastleSoundFile.html">CastleSoundFile</a></p>
<h2 class="declaration">Declaration</h2>
<p class="declaration">
<code>type TSoundOggVorbis = class(<a class="normal" href="CastleSoundFile.TSoundFile.html">TSoundFile</a>)</code></p>
<h2 class="description">Description</h2>
<p>
OggVorbis file loader.

<p>Internally we can use two implementations of OggVorbis handling:

<p></p>

<ol class="paragraph_spacing">
  <li value="1"><p>If AL_EXT_vorbis extension is available, then we will use this.

<p>The advantage of using AL_EXT_vorbis extension is that OpenAL does all the work, so 1. it's easy for us 2. OpenAL does it in a best way (uses streaming inside, so the OggVorbis data in decoded partially, on as-needed basis).

<p>The disadvantage is obviously that AL_EXT_vorbis must be present... And on Windows there doesn't seem a way to get the extension working anymore with new OpenAL. This hilarious message [<a  href="http://opensource.creative.com/pipermail/openal/2006-April/009488.html">http://opensource.creative.com/pipermail/openal/2006-April/009488.html</a>] basically says that Creative will not fix AL_EXT_vorbis extension in Windows, because it's <i>too easy</i> to do.</p></li>
  <li value="2"><p>If AL_EXT_vorbis extension is not available but we have vorbisfile library available then we use vorbisfile functions to decode the file.

<p>While this works OK, the disadvantages of our current approach are that we decode the whole OggVorbis file in one go. This means that 1. we waste potentially a lot of memory to keep the whole uncompressed data &mdash; 5 MB OggVorbis file can easily take 50 MB in memory after decoding 2. whole decoding is done in one go, so there is a noticeable time delay when this takes place. </p></li>
</ol>

<p>

<p>The check for AL_EXT_vorbis extension and eventual decompression using vorbisfile directly take place in the first <a class="normal" href="CastleSoundFile.TSoundOggVorbis.html#DataFormat">DataFormat</a> call. You can also call method <a class="normal" href="CastleSoundFile.TSoundOggVorbis.html#VorbisMethod">VorbisMethod</a> to check which approach (if any) will be used.

<p>Note that both approaches require vorbisfile library to be installed (OpenAL AL_EXT_vorbis extension also works using vorbisfile library). If vorbisfile is not available, we cannot load OggVorbis sounds.</p>
<a name="PasDoc-Hierarchy"></a><h2 class="hierarchy">Hierarchy</h2>
<ul class="hierarchy"><li class="ancestor">TObject</li>
<li class="ancestor"><a class="normal" href="CastleSoundFile.TSoundFile.html">TSoundFile</a></li>
<li class="thisitem">TSoundOggVorbis</li></ul><h2 class="overview">Overview</h2>
<a name="PasDoc-Methods"></a><h3 class="summary">Methods</h3>
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<td class="itemcode"><code>constructor <b><a  href="CastleSoundFile.TSoundOggVorbis.html#CreateFromStream">CreateFromStream</a></b>(Stream: TStream); override;</code></td>
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<td class="itemcode"><code>destructor <b><a  href="CastleSoundFile.TSoundOggVorbis.html#Destroy">Destroy</a></b>; override;</code></td>
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<td class="itemcode"><code>procedure <b><a  href="CastleSoundFile.TSoundOggVorbis.html#PrepareOpenAL">PrepareOpenAL</a></b>; override;</code></td>
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<td class="itemcode"><code>function <b><a  href="CastleSoundFile.TSoundOggVorbis.html#Data">Data</a></b>: Pointer; override;</code></td>
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<td class="itemcode"><code>function <b><a  href="CastleSoundFile.TSoundOggVorbis.html#DataSize">DataSize</a></b>: LongWord; override;</code></td>
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<td class="itemcode"><code>function <b><a  href="CastleSoundFile.TSoundOggVorbis.html#DataFormat">DataFormat</a></b>: TALuint; override;</code></td>
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<td class="itemcode"><code>function <b><a  href="CastleSoundFile.TSoundOggVorbis.html#Frequency">Frequency</a></b>: LongWord; override;</code></td>
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<td class="itemcode"><code>class function <b><a  href="CastleSoundFile.TSoundOggVorbis.html#VorbisMethod">VorbisMethod</a></b>: string;</code></td>
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<h2 class="description">Description</h2>
<h3 class="detail">Methods</h3>
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<td class="itemcode"><a name="CreateFromStream"></a><code>constructor <b>CreateFromStream</b>(Stream: TStream); override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="Destroy"></a><code>destructor <b>Destroy</b>; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="PrepareOpenAL"></a><code>procedure <b>PrepareOpenAL</b>; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="Data"></a><code>function <b>Data</b>: Pointer; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="DataSize"></a><code>function <b>DataSize</b>: LongWord; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="DataFormat"></a><code>function <b>DataFormat</b>: TALuint; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="Frequency"></a><code>function <b>Frequency</b>: LongWord; override;</code></td>
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&nbsp;</td></tr>
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<td class="itemcode"><a name="VorbisMethod"></a><code>class function <b>VorbisMethod</b>: string;</code></td>
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&nbsp;</td></tr>
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