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<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>The Be Book - System Overview - The Media Kit</title><link rel="stylesheet" href="be_book.css" type="text/css" media="all" /><link rel="shortcut icon" type="image/vnd.microsoft.icon" href="./images/favicon.ico" /><!--[if IE]>
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<![endif]--><meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /><meta name="keywords" content="Access, BeOS, BeBook, API" /><link rel="start" href="index.html" title="The Be Book" /><link rel="up" href="TheMediaKit_Overview.html" title="The Media Kit" /><link rel="prev" href="BMediaTheme_Overview.html" title="BMediaTheme" /><link rel="next" href="BNullParameter_Overview.html" title="BNullParameter" /></head><body><div id="header"><div id="headerT"><div id="headerTL"><a accesskey="p" href="BMediaTheme_Overview.html" title="BMediaTheme"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a accesskey="u" href="TheMediaKit_Overview.html" title="The Media Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a accesskey="n" href="BNullParameter_Overview.html" title="BNullParameter"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="headerTR"><div id="navigpeople"><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div><div class="navigboxed" id="navigindex"><a accesskey="i" href="ClassIndex.html" title="Index">I</a></div><div class="navigboxed" id="naviglang" title="English">en</div></div><div id="headerTC">The Be Book - System Overview - The Media Kit</div></div><div id="headerB">Prev: <a href="BMediaTheme_Overview.html">BMediaTheme</a>  Up: <a href="TheMediaKit_Overview.html">The Media Kit</a>  Next: <a href="BNullParameter_Overview.html">BNullParameter</a></div><hr /></div><div class="section"><div xmlns="" xmlns:d="http://docbook.org/ns/docbook" class="titlepage"><div><div xmlns:d="http://docbook.org/ns/docbook"><h2 xmlns="http://www.w3.org/1999/xhtml" class="title"><a id="BMediaTrack_Overview"></a>BMediaTrack</h2></div></div></div><a id="id590292" class="indexterm"></a><p>The <a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
class provides access to a particular track in a media
file. It's always instantiated using the
<a class="link" href="BMediaFile.html#BMediaFile_TrackAt" title="TrackAt()"><code class="methodname">BMediaFile::TrackAt()</code></a> or
<a class="link" href="BMediaFile.html#BMediaFile_CreateTrack" title="CreateTrack()"><code class="methodname">BMediaFile::CreateTrack()</code></a>
function.</p><p>The <a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
constructor searches for a codec that can handle the
encoded data in the track; once that's been done, the track is ready to
be used.</p><p>If you opened the file for writing, you can write data into the track. If
you specified the <code class="constant">B_MEDIA_FILE_REPLACE_MODE</code> flag when constructing the
<a class="link" href="BMediaFile.html" title="BMediaFile"><code class="classname">BMediaFile</code></a>,
you can both read and write from the file. If no decoder is
available for the track, you can still use
<a class="link" href="BMediaTrack.html#BMediaTrack_ReadChunk" title="ReadChunk()"><code class="methodname">ReadChunk()</code></a>
to access the encoded data directly.</p><p>After instantiating the
<a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>, using the
<a class="link" href="BMediaFile.html" title="BMediaFile"><code class="classname">BMediaFile</code></a>
functions for doing so, you should call
<a class="link" href="BMediaTrack.html#BMediaTrack_InitCheck" title="InitCheck()"><code class="methodname">InitCheck()</code></a>
to be sure the track is valid. You can then use
<a class="link" href="BMediaTrack.html#BMediaTrack_ReadFrames" title="ReadFrames()"><code class="methodname">ReadFrames()</code></a> and
<a class="link" href="BMediaTrack.html#BMediaTrack_WriteFrames" title="WriteFrames()"><code class="methodname">WriteFrames()</code></a>
to read and write data to the
file, as appropriate. For video data, you should work one frame at a time.</p><p>You can also seek particular times or frames using
<a class="link" href="BMediaTrack.html#BMediaTrack_SeekToTime"><code class="methodname">SeekToTime()</code></a> or
<a class="link" href="BMediaTrack.html#BMediaTrack_SeekToFrame" title="SeekToFrame(), SeekToTime()"><code class="methodname">SeekToFrame()</code></a>.</p><p>For an example of how to use
<a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
to read and write tracks in media files, see
"<a class="xref" href="TheMediaKit_Overview_ReadingWriting.html" title="Reading and Writing Media Files">Reading and Writing Media Files</a>"</p><div class="admonition note"><div class="title">Note</div><div class="graphic"><img class="icon" alt="Note" width="32" src="./images/admonitions/Info_32.png" /><div class="text"><p>As a general rule, you can't use wildcards in any structures used by
<a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
functions. You tell
<a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
what format you have, and
<a class="link" href="BMediaTrack.html" title="BMediaTrack"><code class="classname">BMediaTrack</code></a>
will simply tell you whether or not that format is supported.</p></div></div></div></div><div id="footer"><hr /><div id="footerT">Prev: <a href="BMediaTheme_Overview.html">BMediaTheme</a>  Up: <a href="TheMediaKit_Overview.html">The Media Kit</a>  Next: <a href="BNullParameter_Overview.html">BNullParameter</a> </div><div id="footerB"><div id="footerBL"><a href="BMediaTheme_Overview.html" title="BMediaTheme"><img src="./images/navigation/prev.png" alt="Prev" /></a> <a href="TheMediaKit_Overview.html" title="The Media Kit"><img src="./images/navigation/up.png" alt="Up" /></a> <a href="BNullParameter_Overview.html" title="BNullParameter"><img src="./images/navigation/next.png" alt="Next" /></a></div><div id="footerBR"><div><a href="http://www.haiku-os.org"><img src="./images/People_24.png" alt="haiku-os.org" title="Visit The Haiku Website" /></a></div><div class="navighome" title="Home"><a accesskey="h" href="index.html"><img src="./images/navigation/home.png" alt="Home" /></a></div></div><div id="footerBC"><a href="http://www.access-company.com/home.html" title="ACCESS Co."><img alt="Access Company" src="./images/access_logo.png" /></a></div></div></div><div id="licenseFooter"><div id="licenseFooterBL"><a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/" title="Creative Commons License"><img alt="Creative Commons License" style="border-width:0" src="https://licensebuttons.net/l/by-nc-nd/3.0/88x31.png" /></a></div><div id="licenseFooterBR"><a href="./LegalNotice.html">Legal Notice</a></div><div id="licenseFooterBC"><span id="licenseText">This work is licensed under a
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