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| 16 | <title>14.11 ossaudiodev -- Access to OSS-compatible audio devices</title> | |
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| 53 | ||
| 54 | <H1><A NAME="SECTION00161100000000000000000"> | |
| 55 | 14.11 <tt class="module">ossaudiodev</tt> -- | |
| 56 | Access to OSS-compatible audio devices</A> | |
| 57 | </H1> | |
| 58 | ||
| 59 | <P> | |
| 60 | <A NAME="module-ossaudiodev"></A> | |
| 61 | <p class="availability">Availability: <span | |
| 62 | class="platform">Linux, FreeBSD</span>.</p> | |
| 63 | ||
| 64 | <P> | |
| 65 | ||
| 66 | <span class="versionnote">New in version 2.3.</span> | |
| 67 | ||
| 68 | <P> | |
| 69 | This module allows you to access the OSS (Open Sound System) audio | |
| 70 | interface. OSS is available for a wide range of open-source and | |
| 71 | commercial Unices, and is the standard audio interface for Linux and | |
| 72 | recent versions of FreeBSD. | |
| 73 | ||
| 74 | <P> | |
| 75 | <div class="seealso"> | |
| 76 | <p class="heading">See Also:</p> | |
| 77 | ||
| 78 | <dl compact="compact" class="seetitle"> | |
| 79 | <dt><em class="citetitle"><a href="http://www.opensound.com/pguide/oss.pdf" | |
| 80 | >Open Sound System Programmer's Guide</a></em></dt> | |
| 81 | <dd>the official | |
| 82 | documentation for the OSS C API</dd> | |
| 83 | </dl> | |
| 84 | <div class="seetext"><p>The module defines a large number of constants supplied by | |
| 85 | the OSS device driver; see <code><sys/soundcard.h></code> on either | |
| 86 | Linux or FreeBSD for a listing .</p></div> | |
| 87 | </div> | |
| 88 | ||
| 89 | <P> | |
| 90 | <tt class="module">ossaudiodev</tt> defines the following variables and functions: | |
| 91 | ||
| 92 | <P> | |
| 93 | <dl><dt><b><span class="typelabel">exception</span> <tt id='l2h-4770' xml:id='l2h-4770' class="exception">OSSAudioError</tt></b></dt> | |
| 94 | <dd> | |
| 95 | This exception is raised on certain errors. The argument is a string | |
| 96 | describing what went wrong. | |
| 97 | ||
| 98 | <P> | |
| 99 | (If <tt class="module">ossaudiodev</tt> receives an error from a system call such as | |
| 100 | <tt class="cfunction">open()</tt>, <tt class="cfunction">write()</tt>, or <tt class="cfunction">ioctl()</tt>, it | |
| 101 | raises <tt class="exception">IOError</tt>. Errors detected directly by | |
| 102 | <tt class="module">ossaudiodev</tt> result in <tt class="exception">OSSAudioError</tt>.) | |
| 103 | ||
| 104 | <P> | |
| 105 | (For backwards compatibility, the exception class is also available as | |
| 106 | <code>ossaudiodev.error</code>.) | |
| 107 | </dd></dl> | |
| 108 | ||
| 109 | <P> | |
| 110 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> | |
| 111 | <td><nobr><b><tt id='l2h-4771' xml:id='l2h-4771' class="function">open</tt></b>(</nobr></td> | |
| 112 | <td><var></var><big>[</big><var>device, </var><big>]</big><var>mode</var>)</td></tr></table></dt> | |
| 113 | <dd> | |
| 114 | Open an audio device and return an OSS audio device object. This | |
| 115 | object supports many file-like methods, such as <tt class="method">read()</tt>, | |
| 116 | <tt class="method">write()</tt>, and <tt class="method">fileno()</tt> (although there are subtle | |
| 117 | differences between conventional Unix read/write semantics and those of | |
| 118 | OSS audio devices). It also supports a number of audio-specific | |
| 119 | methods; see below for the complete list of methods. | |
| 120 | ||
| 121 | <P> | |
| 122 | <var>device</var> is the audio device filename to use. If it is not | |
| 123 | specified, this module first looks in the environment variable | |
| 124 | <a class="envvar" id='l2h-4773' xml:id='l2h-4773'>AUDIODEV</a> for a device to use. If not found, it falls back to | |
| 125 | <span class="file">/dev/dsp</span>. | |
| 126 | ||
| 127 | <P> | |
| 128 | <var>mode</var> is one of <code>'r'</code> for read-only (record) access, | |
| 129 | <code>'w'</code> for write-only (playback) access and <code>'rw'</code> for both. | |
| 130 | Since many sound cards only allow one process to have the recorder or | |
| 131 | player open at a time, it is a good idea to open the device only for the | |
| 132 | activity needed. Further, some sound cards are half-duplex: they can be | |
| 133 | opened for reading or writing, but not both at once. | |
| 134 | ||
| 135 | <P> | |
| 136 | Note the unusual calling syntax: the <em>first</em> argument is optional, | |
| 137 | and the second is required. This is a historical artifact for | |
| 138 | compatibility with the older <tt class="module">linuxaudiodev</tt> module which | |
| 139 | <tt class="module">ossaudiodev</tt> supersedes. </dl> | |
| 140 | ||
| 141 | <P> | |
| 142 | <dl><dt><table cellpadding="0" cellspacing="0"><tr valign="baseline"> | |
| 143 | <td><nobr><b><tt id='l2h-4772' xml:id='l2h-4772' class="function">openmixer</tt></b>(</nobr></td> | |
| 144 | <td><var></var><big>[</big><var>device</var><big>]</big><var></var>)</td></tr></table></dt> | |
| 145 | <dd> | |
| 146 | Open a mixer device and return an OSS mixer device object. | |
| 147 | <var>device</var> is the mixer device filename to use. If it is | |
| 148 | not specified, this module first looks in the environment variable | |
| 149 | <a class="envvar" id='l2h-4774' xml:id='l2h-4774'>MIXERDEV</a> for a device to use. If not found, it falls back to | |
| 150 | <span class="file">/dev/mixer</span>. | |
| 151 | ||
| 152 | <P> | |
| 153 | </dl> | |
| 154 | ||
| 155 | <P> | |
| 156 | ||
| 157 | <p><br /></p><hr class='online-navigation' /> | |
| 158 | <div class='online-navigation'> | |
| 159 | <!--Table of Child-Links--> | |
| 160 | <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a> | |
| 161 | ||
| 162 | <UL CLASS="ChildLinks"> | |
| 163 | <LI><A href="ossaudio-device-objects.html">14.11.1 Audio Device Objects</a> | |
| 164 | <LI><A href="mixer-device-objects.html">14.11.2 Mixer Device Objects</a> | |
| 165 | </ul> | |
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| 199 | <a class="sectref" rel="next" href="ossaudio-device-objects.html">14.11.1 Audio Device Objects</A> | |
| 200 | </div> | |
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| 202 | <hr /> | |
| 203 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> | |
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