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<pre>
Basename: ?? please check the spelling for me!
Title: HOWTO play and record sound
Author: Thomas.Holme
Email: thomas.holme@openmpeg4.org
Environment: VC++ 6.0, win2k
Keywords: mmsystem, sound, play, record
Level: Beginner
Description: Howto record and play sound
Section Multimedia
SubSection Audio
</pre>
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<ul>
<li class=download><a href="fister.zip">Download source + demo
200 Kb</a></li>
<p><img border="0" src="wpe5.gif" width="152" height="136"></p>
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<h2>Introduction</h2>
<p>This is a simple application that show you how to play and record sound under windows.
<br>It uses the old multimedia API. A better solution may be to use DirectSound.
</p>
<p><img border="0" src="UML.gif" width="427" height="327">
</p>
<h3>HOWTO read the code fast
</h3>
<p>Start with the two functions in <code>CFisterDlg</code> called <i>OnPlay</i>
and <i>OnRecord</i>. Follow them down to the depth you need to use the
classes.
</p>
<h3>Short description</h3>
<p><code>CSoundIn</code> is a wrapper class that will let you retreive sound
from the soundcard. Main functions is Start() and Stop()<p><code>CSoundOut</code>
is a wrapper class that will let you play sound on the soundcard. Main
functions is Start() and Stop()<p><code>CSoundFile</code> is a wrapper class
of a single wave file, it can either be a file reader or a file writer object.
See the constructor.<p><code>CSoundBase</code> is a very small class that
encapsulate the wave format.<p><code>CBuffer</code> is a very small class that
encapsulates a simple one dimentional buffer.<p>The project has a number of
different callback functions:
</ul>
<blockquote>
<ul>
<li>One callback function make the Play button change it's lable to stop
when it has finished playing the file. <code>CDialogDlg </code>enherits <code>CPipe
</code>and overload a function that <code>CPipe </code>can call when it
has finished playing the wave file. <code> </code></li>
<li>Another callback function make it possible for <code>CSoundIn</code> to
callback to <code>CPipe</code> when it has filled the input buffer. Thus <code>CPipe</code>
can give <code>CSoundIn</code> a new buffer to fill. </li>
<li>A clone of the above principle is also used in <code>CSoundOut</code>,
which enables it to callback to the owner when it is finished playing the
sound in a given buffer. </li>
</ul>
</blockquote>
<ul>
<h3>Problems that I encountered</h3>
<p>I have spend almost 2 days debugging the following stupid problem. When <code>CSoundIn</code>
and <code>CSoundOut</code> inherit from <code>CSoundBase</code> and <code>CWinThread</code>
the order in which they are listed MUST be as shown below. If not the callback
functions, which are started by the WinThread message handler, will not be
able to access the member variables of the <code>CSoundIn</code> object.
<pre>
class CSoundIn : public CWinThread, public CSoundBase
</pre>
<p>During these two days of fustration I also tried to implement the callback
as regular callback functions called by the device driver. This is possible
using ::waveInOpen(...). But since the this callback function is not allowed
to call any of the ::waveInXXX(...) functions it is not of much use.</p>
<p> </p>
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