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  193.   <section id="module-ossaudiodev">

  194. <span id="ossaudiodev-access-to-oss-compatible-audio-devices"></span><h1><a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> — Access to OSS-compatible audio devices<a class="headerlink" href="#module-ossaudiodev" title="Link to this heading">¶</a></h1>

  195. <div class="deprecated-removed">

  196. <p><span class="versionmodified">Deprecated since version 3.11, will be removed in version 3.13: </span>The <a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> module is deprecated

  197. (see <span class="target" id="index-0"></span><a class="pep reference external" href="https://peps.python.org/pep-0594/#ossaudiodev"><strong>PEP 594</strong></a> for details).</p>

  198. </div>

  199. <hr class="docutils" />

  200. <p>This module allows you to access the OSS (Open Sound System) audio interface.

  201. OSS is available for a wide range of open-source and commercial Unices, and is

  202. the standard audio interface for Linux and recent versions of FreeBSD.</p>

  203. <div class="versionchanged">

  204. <p><span class="versionmodified changed">Changed in version 3.3: </span>Operations in this module now raise <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a> where <a class="reference internal" href="exceptions.html#IOError" title="IOError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">IOError</span></code></a>

  205. was raised.</p>

  206. </div>

  207. <div class="admonition seealso">

  208. <p class="admonition-title">See also</p>

  209. <dl class="simple">

  210. <dt><a class="reference external" href="http://www.opensound.com/pguide/oss.pdf">Open Sound System Programmer’s Guide</a></dt><dd><p>the official documentation for the OSS C API</p>

  211. </dd>

  212. </dl>

  213. <p>The module defines a large number of constants supplied by the OSS device

  214. driver; see <code class="docutils literal notranslate"><span class="pre">&lt;sys/soundcard.h&gt;</span></code> on either Linux or FreeBSD for a listing.</p>

  215. </div>

  216. <p><a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> defines the following variables and functions:</p>

  217. <dl class="py exception">

  218. <dt class="sig sig-object py" id="ossaudiodev.OSSAudioError">

  219. <em class="property"><span class="pre">exception</span><span class="w"> </span></em><span class="sig-prename descclassname"><span class="pre">ossaudiodev.</span></span><span class="sig-name descname"><span class="pre">OSSAudioError</span></span><a class="headerlink" href="#ossaudiodev.OSSAudioError" title="Link to this definition">¶</a></dt>

  220. <dd><p>This exception is raised on certain errors.  The argument is a string describing

  221. what went wrong.</p>

  222. <p>(If <a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> receives an error from a system call such as

  223. <code class="xref c c-func docutils literal notranslate"><span class="pre">open()</span></code>, <code class="xref c c-func docutils literal notranslate"><span class="pre">write()</span></code>, or <code class="xref c c-func docutils literal notranslate"><span class="pre">ioctl()</span></code>, it raises <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a>.

  224. Errors detected directly by <a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> result in <a class="reference internal" href="#ossaudiodev.OSSAudioError" title="ossaudiodev.OSSAudioError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSSAudioError</span></code></a>.)</p>

  225. <p>(For backwards compatibility, the exception class is also available as

  226. <code class="docutils literal notranslate"><span class="pre">ossaudiodev.error</span></code>.)</p>

  227. </dd></dl>

  228. 

  229. <dl class="py function">

  230. <dt class="sig sig-object py" id="ossaudiodev.open">

  231. <span class="sig-prename descclassname"><span class="pre">ossaudiodev.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">mode</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.open" title="Link to this definition">¶</a></dt>

  232. <dt class="sig sig-object py">

  233. <span class="sig-prename descclassname"><span class="pre">ossaudiodev.</span></span><span class="sig-name descname"><span class="pre">open</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">device</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">mode</span></span></em><span class="sig-paren">)</span></dt>

  234. <dd><p>Open an audio device and return an OSS audio device object.  This object

  235. supports many file-like methods, such as <code class="xref py py-meth docutils literal notranslate"><span class="pre">read()</span></code>, <code class="xref py py-meth docutils literal notranslate"><span class="pre">write()</span></code>, and

  236. <code class="xref py py-meth docutils literal notranslate"><span class="pre">fileno()</span></code> (although there are subtle differences between conventional Unix

  237. read/write semantics and those of OSS audio devices).  It also supports a number

  238. of audio-specific methods; see below for the complete list of methods.</p>

  239. <p><em>device</em> is the audio device filename to use.  If it is not specified, this

  240. module first looks in the environment variable <span class="target" id="index-1"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">AUDIODEV</span></code> for a device

  241. to use.  If not found, it falls back to <code class="file docutils literal notranslate"><span class="pre">/dev/dsp</span></code>.</p>

  242. <p><em>mode</em> is one of <code class="docutils literal notranslate"><span class="pre">'r'</span></code> for read-only (record) access, <code class="docutils literal notranslate"><span class="pre">'w'</span></code> for

  243. write-only (playback) access and <code class="docutils literal notranslate"><span class="pre">'rw'</span></code> for both. Since many sound cards

  244. only allow one process to have the recorder or player open at a time, it is a

  245. good idea to open the device only for the activity needed.  Further, some

  246. sound cards are half-duplex: they can be opened for reading or writing, but

  247. not both at once.</p>

  248. <p>Note the unusual calling syntax: the <em>first</em> argument is optional, and the

  249. second is required.  This is a historical artifact for compatibility with the

  250. older <code class="xref py py-mod docutils literal notranslate"><span class="pre">linuxaudiodev</span></code> module which <a class="reference internal" href="#module-ossaudiodev" title="ossaudiodev: Access to OSS-compatible audio devices. (deprecated) (Linux, FreeBSD)"><code class="xref py py-mod docutils literal notranslate"><span class="pre">ossaudiodev</span></code></a> supersedes.</p>

  251. </dd></dl>

  252. 

  253. <dl class="py function">

  254. <dt class="sig sig-object py" id="ossaudiodev.openmixer">

  255. <span class="sig-prename descclassname"><span class="pre">ossaudiodev.</span></span><span class="sig-name descname"><span class="pre">openmixer</span></span><span class="sig-paren">(</span><span class="optional">[</span><em class="sig-param"><span class="n"><span class="pre">device</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.openmixer" title="Link to this definition">¶</a></dt>

  256. <dd><p>Open a mixer device and return an OSS mixer device object.   <em>device</em> is the

  257. mixer device filename to use.  If it is not specified, this module first looks

  258. in the environment variable <span class="target" id="index-2"></span><code class="xref std std-envvar docutils literal notranslate"><span class="pre">MIXERDEV</span></code> for a device to use.  If not

  259. found, it falls back to <code class="file docutils literal notranslate"><span class="pre">/dev/mixer</span></code>.</p>

  260. </dd></dl>

  261. 

  262. <section id="audio-device-objects">

  263. <span id="ossaudio-device-objects"></span><h2>Audio Device Objects<a class="headerlink" href="#audio-device-objects" title="Link to this heading">¶</a></h2>

  264. <p>Before you can write to or read from an audio device, you must call three

  265. methods in the correct order:</p>

  266. <ol class="arabic simple">

  267. <li><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">setfmt()</span></code> to set the output format</p></li>

  268. <li><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">channels()</span></code> to set the number of channels</p></li>

  269. <li><p><code class="xref py py-meth docutils literal notranslate"><span class="pre">speed()</span></code> to set the sample rate</p></li>

  270. </ol>

  271. <p>Alternately, you can use the <code class="xref py py-meth docutils literal notranslate"><span class="pre">setparameters()</span></code> method to set all three audio

  272. parameters at once.  This is more convenient, but may not be as flexible in all

  273. cases.</p>

  274. <p>The audio device objects returned by <a class="reference internal" href="#ossaudiodev.open" title="ossaudiodev.open"><code class="xref py py-func docutils literal notranslate"><span class="pre">open()</span></code></a> define the following methods

  275. and (read-only) attributes:</p>

  276. <dl class="py method">

  277. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.close">

  278. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.close" title="Link to this definition">¶</a></dt>

  279. <dd><p>Explicitly close the audio device.  When you are done writing to or reading from

  280. an audio device, you should explicitly close it.  A closed device cannot be used

  281. again.</p>

  282. </dd></dl>

  283. 

  284. <dl class="py method">

  285. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.fileno">

  286. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.fileno" title="Link to this definition">¶</a></dt>

  287. <dd><p>Return the file descriptor associated with the device.</p>

  288. </dd></dl>

  289. 

  290. <dl class="py method">

  291. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.read">

  292. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">read</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">size</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.read" title="Link to this definition">¶</a></dt>

  293. <dd><p>Read <em>size</em> bytes from the audio input and return them as a Python string.

  294. Unlike most Unix device drivers, OSS audio devices in blocking mode (the

  295. default) will block <a class="reference internal" href="#ossaudiodev.oss_audio_device.read" title="ossaudiodev.oss_audio_device.read"><code class="xref py py-func docutils literal notranslate"><span class="pre">read()</span></code></a> until the entire requested amount of data is

  296. available.</p>

  297. </dd></dl>

  298. 

  299. <dl class="py method">

  300. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.write">

  301. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">write</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.write" title="Link to this definition">¶</a></dt>

  302. <dd><p>Write a <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> <em>data</em> to the audio device and return the

  303. number of bytes written.  If the audio device is in blocking mode (the

  304. default), the entire data is always written (again, this is different from

  305. usual Unix device semantics).  If the device is in non-blocking mode, some

  306. data may not be written—see <a class="reference internal" href="#ossaudiodev.oss_audio_device.writeall" title="ossaudiodev.oss_audio_device.writeall"><code class="xref py py-meth docutils literal notranslate"><span class="pre">writeall()</span></code></a>.</p>

  307. <div class="versionchanged">

  308. <p><span class="versionmodified changed">Changed in version 3.5: </span>Writable <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> is now accepted.</p>

  309. </div>

  310. </dd></dl>

  311. 

  312. <dl class="py method">

  313. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.writeall">

  314. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">writeall</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">data</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.writeall" title="Link to this definition">¶</a></dt>

  315. <dd><p>Write a <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> <em>data</em> to the audio device: waits until

  316. the audio device is able to accept data, writes as much data as it will

  317. accept, and repeats until <em>data</em> has been completely written. If the device

  318. is in blocking mode (the default), this has the same effect as

  319. <a class="reference internal" href="#ossaudiodev.oss_audio_device.write" title="ossaudiodev.oss_audio_device.write"><code class="xref py py-meth docutils literal notranslate"><span class="pre">write()</span></code></a>; <a class="reference internal" href="#ossaudiodev.oss_audio_device.writeall" title="ossaudiodev.oss_audio_device.writeall"><code class="xref py py-meth docutils literal notranslate"><span class="pre">writeall()</span></code></a> is only useful in non-blocking mode.  Has

  320. no return value, since the amount of data written is always equal to the

  321. amount of data supplied.</p>

  322. <div class="versionchanged">

  323. <p><span class="versionmodified changed">Changed in version 3.5: </span>Writable <a class="reference internal" href="../glossary.html#term-bytes-like-object"><span class="xref std std-term">bytes-like object</span></a> is now accepted.</p>

  324. </div>

  325. </dd></dl>

  326. 

  327. <div class="versionchanged">

  328. <p><span class="versionmodified changed">Changed in version 3.2: </span>Audio device objects also support the context management protocol, i.e. they can

  329. be used in a <a class="reference internal" href="../reference/compound_stmts.html#with"><code class="xref std std-keyword docutils literal notranslate"><span class="pre">with</span></code></a> statement.</p>

  330. </div>

  331. <p>The following methods each map to exactly one <code class="xref c c-func docutils literal notranslate"><span class="pre">ioctl()</span></code> system call.  The

  332. correspondence is obvious: for example, <code class="xref py py-meth docutils literal notranslate"><span class="pre">setfmt()</span></code> corresponds to the

  333. <code class="docutils literal notranslate"><span class="pre">SNDCTL_DSP_SETFMT</span></code> ioctl, and <code class="xref py py-meth docutils literal notranslate"><span class="pre">sync()</span></code> to <code class="docutils literal notranslate"><span class="pre">SNDCTL_DSP_SYNC</span></code> (this can

  334. be useful when consulting the OSS documentation).  If the underlying

  335. <code class="xref c c-func docutils literal notranslate"><span class="pre">ioctl()</span></code> fails, they all raise <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a>.</p>

  336. <dl class="py method">

  337. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.nonblock">

  338. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">nonblock</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.nonblock" title="Link to this definition">¶</a></dt>

  339. <dd><p>Put the device into non-blocking mode.  Once in non-blocking mode, there is no

  340. way to return it to blocking mode.</p>

  341. </dd></dl>

  342. 

  343. <dl class="py method">

  344. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.getfmts">

  345. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">getfmts</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.getfmts" title="Link to this definition">¶</a></dt>

  346. <dd><p>Return a bitmask of the audio output formats supported by the soundcard.  Some

  347. of the formats supported by OSS are:</p>

  348. <table class="docutils align-default">

  349. <thead>

  350. <tr class="row-odd"><th class="head"><p>Format</p></th>

  351. <th class="head"><p>Description</p></th>

  352. </tr>

  353. </thead>

  354. <tbody>

  355. <tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_MU_LAW</span></code></p></td>

  356. <td><p>a logarithmic encoding (used by Sun <code class="docutils literal notranslate"><span class="pre">.au</span></code>

  357. files and <code class="file docutils literal notranslate"><span class="pre">/dev/audio</span></code>)</p></td>

  358. </tr>

  359. <tr class="row-odd"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_A_LAW</span></code></p></td>

  360. <td><p>a logarithmic encoding</p></td>

  361. </tr>

  362. <tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_IMA_ADPCM</span></code></p></td>

  363. <td><p>a 4:1 compressed format defined by the

  364. Interactive Multimedia Association</p></td>

  365. </tr>

  366. <tr class="row-odd"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_U8</span></code></p></td>

  367. <td><p>Unsigned, 8-bit audio</p></td>

  368. </tr>

  369. <tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_S16_LE</span></code></p></td>

  370. <td><p>Signed, 16-bit audio, little-endian byte

  371. order (as used by Intel processors)</p></td>

  372. </tr>

  373. <tr class="row-odd"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_S16_BE</span></code></p></td>

  374. <td><p>Signed, 16-bit audio, big-endian byte order

  375. (as used by 68k, PowerPC, Sparc)</p></td>

  376. </tr>

  377. <tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_S8</span></code></p></td>

  378. <td><p>Signed, 8 bit audio</p></td>

  379. </tr>

  380. <tr class="row-odd"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_U16_LE</span></code></p></td>

  381. <td><p>Unsigned, 16-bit little-endian audio</p></td>

  382. </tr>

  383. <tr class="row-even"><td><p><code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_U16_BE</span></code></p></td>

  384. <td><p>Unsigned, 16-bit big-endian audio</p></td>

  385. </tr>

  386. </tbody>

  387. </table>

  388. <p>Consult the OSS documentation for a full list of audio formats, and note that

  389. most devices support only a subset of these formats.  Some older devices only

  390. support <code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_U8</span></code>; the most common format used today is

  391. <code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_S16_LE</span></code>.</p>

  392. </dd></dl>

  393. 

  394. <dl class="py method">

  395. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.setfmt">

  396. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">setfmt</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">format</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.setfmt" title="Link to this definition">¶</a></dt>

  397. <dd><p>Try to set the current audio format to <em>format</em>—see <a class="reference internal" href="#ossaudiodev.oss_audio_device.getfmts" title="ossaudiodev.oss_audio_device.getfmts"><code class="xref py py-meth docutils literal notranslate"><span class="pre">getfmts()</span></code></a> for a

  398. list.  Returns the audio format that the device was set to, which may not be the

  399. requested format.  May also be used to return the current audio format—do this

  400. by passing an “audio format” of <code class="xref py py-const docutils literal notranslate"><span class="pre">AFMT_QUERY</span></code>.</p>

  401. </dd></dl>

  402. 

  403. <dl class="py method">

  404. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.channels">

  405. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">channels</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">nchannels</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.channels" title="Link to this definition">¶</a></dt>

  406. <dd><p>Set the number of output channels to <em>nchannels</em>.  A value of 1 indicates

  407. monophonic sound, 2 stereophonic.  Some devices may have more than 2 channels,

  408. and some high-end devices may not support mono. Returns the number of channels

  409. the device was set to.</p>

  410. </dd></dl>

  411. 

  412. <dl class="py method">

  413. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.speed">

  414. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">speed</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">samplerate</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.speed" title="Link to this definition">¶</a></dt>

  415. <dd><p>Try to set the audio sampling rate to <em>samplerate</em> samples per second.  Returns

  416. the rate actually set.  Most sound devices don’t support arbitrary sampling

  417. rates.  Common rates are:</p>

  418. <table class="docutils align-default">

  419. <thead>

  420. <tr class="row-odd"><th class="head"><p>Rate</p></th>

  421. <th class="head"><p>Description</p></th>

  422. </tr>

  423. </thead>

  424. <tbody>

  425. <tr class="row-even"><td><p>8000</p></td>

  426. <td><p>default rate for <code class="file docutils literal notranslate"><span class="pre">/dev/audio</span></code></p></td>

  427. </tr>

  428. <tr class="row-odd"><td><p>11025</p></td>

  429. <td><p>speech recording</p></td>

  430. </tr>

  431. <tr class="row-even"><td><p>22050</p></td>

  432. <td></td>

  433. </tr>

  434. <tr class="row-odd"><td><p>44100</p></td>

  435. <td><p>CD quality audio (at 16 bits/sample and 2

  436. channels)</p></td>

  437. </tr>

  438. <tr class="row-even"><td><p>96000</p></td>

  439. <td><p>DVD quality audio (at 24 bits/sample)</p></td>

  440. </tr>

  441. </tbody>

  442. </table>

  443. </dd></dl>

  444. 

  445. <dl class="py method">

  446. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.sync">

  447. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">sync</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.sync" title="Link to this definition">¶</a></dt>

  448. <dd><p>Wait until the sound device has played every byte in its buffer.  (This happens

  449. implicitly when the device is closed.)  The OSS documentation recommends closing

  450. and re-opening the device rather than using <a class="reference internal" href="#ossaudiodev.oss_audio_device.sync" title="ossaudiodev.oss_audio_device.sync"><code class="xref py py-meth docutils literal notranslate"><span class="pre">sync()</span></code></a>.</p>

  451. </dd></dl>

  452. 

  453. <dl class="py method">

  454. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.reset">

  455. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">reset</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.reset" title="Link to this definition">¶</a></dt>

  456. <dd><p>Immediately stop playing or recording and return the device to a state where it

  457. can accept commands.  The OSS documentation recommends closing and re-opening

  458. the device after calling <a class="reference internal" href="#ossaudiodev.oss_audio_device.reset" title="ossaudiodev.oss_audio_device.reset"><code class="xref py py-meth docutils literal notranslate"><span class="pre">reset()</span></code></a>.</p>

  459. </dd></dl>

  460. 

  461. <dl class="py method">

  462. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.post">

  463. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">post</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.post" title="Link to this definition">¶</a></dt>

  464. <dd><p>Tell the driver that there is likely to be a pause in the output, making it

  465. possible for the device to handle the pause more intelligently.  You might use

  466. this after playing a spot sound effect, before waiting for user input, or before

  467. doing disk I/O.</p>

  468. </dd></dl>

  469. 

  470. <p>The following convenience methods combine several ioctls, or one ioctl and some

  471. simple calculations.</p>

  472. <dl class="py method">

  473. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.setparameters">

  474. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">setparameters</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">format</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">nchannels</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">samplerate</span></span></em><span class="optional">[</span>, <em class="sig-param"><span class="n"><span class="pre">strict=False</span></span></em><span class="optional">]</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.setparameters" title="Link to this definition">¶</a></dt>

  475. <dd><p>Set the key audio sampling parameters—sample format, number of channels, and

  476. sampling rate—in one method call.  <em>format</em>,  <em>nchannels</em>, and <em>samplerate</em>

  477. should be as specified in the <a class="reference internal" href="#ossaudiodev.oss_audio_device.setfmt" title="ossaudiodev.oss_audio_device.setfmt"><code class="xref py py-meth docutils literal notranslate"><span class="pre">setfmt()</span></code></a>, <a class="reference internal" href="#ossaudiodev.oss_audio_device.channels" title="ossaudiodev.oss_audio_device.channels"><code class="xref py py-meth docutils literal notranslate"><span class="pre">channels()</span></code></a>, and

  478. <a class="reference internal" href="#ossaudiodev.oss_audio_device.speed" title="ossaudiodev.oss_audio_device.speed"><code class="xref py py-meth docutils literal notranslate"><span class="pre">speed()</span></code></a>  methods.  If <em>strict</em> is true, <a class="reference internal" href="#ossaudiodev.oss_audio_device.setparameters" title="ossaudiodev.oss_audio_device.setparameters"><code class="xref py py-meth docutils literal notranslate"><span class="pre">setparameters()</span></code></a> checks to

  479. see if each parameter was actually set to the requested value, and raises

  480. <a class="reference internal" href="#ossaudiodev.OSSAudioError" title="ossaudiodev.OSSAudioError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSSAudioError</span></code></a> if not.  Returns a tuple (<em>format</em>, <em>nchannels</em>,

  481. <em>samplerate</em>) indicating the parameter values that were actually set by the

  482. device driver (i.e., the same as the return values of <a class="reference internal" href="#ossaudiodev.oss_audio_device.setfmt" title="ossaudiodev.oss_audio_device.setfmt"><code class="xref py py-meth docutils literal notranslate"><span class="pre">setfmt()</span></code></a>,

  483. <a class="reference internal" href="#ossaudiodev.oss_audio_device.channels" title="ossaudiodev.oss_audio_device.channels"><code class="xref py py-meth docutils literal notranslate"><span class="pre">channels()</span></code></a>, and <a class="reference internal" href="#ossaudiodev.oss_audio_device.speed" title="ossaudiodev.oss_audio_device.speed"><code class="xref py py-meth docutils literal notranslate"><span class="pre">speed()</span></code></a>).</p>

  484. <p>For example,</p>

  485. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="p">(</span><span class="n">fmt</span><span class="p">,</span> <span class="n">channels</span><span class="p">,</span> <span class="n">rate</span><span class="p">)</span> <span class="o">=</span> <span class="n">dsp</span><span class="o">.</span><span class="n">setparameters</span><span class="p">(</span><span class="n">fmt</span><span class="p">,</span> <span class="n">channels</span><span class="p">,</span> <span class="n">rate</span><span class="p">)</span>

  486. </pre></div>

  487. </div>

  488. <p>is equivalent to</p>

  489. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">fmt</span> <span class="o">=</span> <span class="n">dsp</span><span class="o">.</span><span class="n">setfmt</span><span class="p">(</span><span class="n">fmt</span><span class="p">)</span>

  490. <span class="n">channels</span> <span class="o">=</span> <span class="n">dsp</span><span class="o">.</span><span class="n">channels</span><span class="p">(</span><span class="n">channels</span><span class="p">)</span>

  491. <span class="n">rate</span> <span class="o">=</span> <span class="n">dsp</span><span class="o">.</span><span class="n">rate</span><span class="p">(</span><span class="n">rate</span><span class="p">)</span>

  492. </pre></div>

  493. </div>

  494. </dd></dl>

  495. 

  496. <dl class="py method">

  497. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.bufsize">

  498. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">bufsize</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.bufsize" title="Link to this definition">¶</a></dt>

  499. <dd><p>Returns the size of the hardware buffer, in samples.</p>

  500. </dd></dl>

  501. 

  502. <dl class="py method">

  503. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.obufcount">

  504. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">obufcount</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.obufcount" title="Link to this definition">¶</a></dt>

  505. <dd><p>Returns the number of samples that are in the hardware buffer yet to be played.</p>

  506. </dd></dl>

  507. 

  508. <dl class="py method">

  509. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.obuffree">

  510. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">obuffree</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_audio_device.obuffree" title="Link to this definition">¶</a></dt>

  511. <dd><p>Returns the number of samples that could be queued into the hardware buffer to

  512. be played without blocking.</p>

  513. </dd></dl>

  514. 

  515. <p>Audio device objects also support several read-only attributes:</p>

  516. <dl class="py attribute">

  517. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.closed">

  518. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">closed</span></span><a class="headerlink" href="#ossaudiodev.oss_audio_device.closed" title="Link to this definition">¶</a></dt>

  519. <dd><p>Boolean indicating whether the device has been closed.</p>

  520. </dd></dl>

  521. 

  522. <dl class="py attribute">

  523. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.name">

  524. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">name</span></span><a class="headerlink" href="#ossaudiodev.oss_audio_device.name" title="Link to this definition">¶</a></dt>

  525. <dd><p>String containing the name of the device file.</p>

  526. </dd></dl>

  527. 

  528. <dl class="py attribute">

  529. <dt class="sig sig-object py" id="ossaudiodev.oss_audio_device.mode">

  530. <span class="sig-prename descclassname"><span class="pre">oss_audio_device.</span></span><span class="sig-name descname"><span class="pre">mode</span></span><a class="headerlink" href="#ossaudiodev.oss_audio_device.mode" title="Link to this definition">¶</a></dt>

  531. <dd><p>The I/O mode for the file, either <code class="docutils literal notranslate"><span class="pre">&quot;r&quot;</span></code>, <code class="docutils literal notranslate"><span class="pre">&quot;rw&quot;</span></code>, or <code class="docutils literal notranslate"><span class="pre">&quot;w&quot;</span></code>.</p>

  532. </dd></dl>

  533. 

  534. </section>

  535. <section id="mixer-device-objects">

  536. <span id="id1"></span><h2>Mixer Device Objects<a class="headerlink" href="#mixer-device-objects" title="Link to this heading">¶</a></h2>

  537. <p>The mixer object provides two file-like methods:</p>

  538. <dl class="py method">

  539. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.close">

  540. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">close</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.close" title="Link to this definition">¶</a></dt>

  541. <dd><p>This method closes the open mixer device file.  Any further attempts to use the

  542. mixer after this file is closed will raise an <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a>.</p>

  543. </dd></dl>

  544. 

  545. <dl class="py method">

  546. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.fileno">

  547. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">fileno</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.fileno" title="Link to this definition">¶</a></dt>

  548. <dd><p>Returns the file handle number of the open mixer device file.</p>

  549. </dd></dl>

  550. 

  551. <div class="versionchanged">

  552. <p><span class="versionmodified changed">Changed in version 3.2: </span>Mixer objects also support the context management protocol.</p>

  553. </div>

  554. <p>The remaining methods are specific to audio mixing:</p>

  555. <dl class="py method">

  556. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.controls">

  557. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">controls</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.controls" title="Link to this definition">¶</a></dt>

  558. <dd><p>This method returns a bitmask specifying the available mixer controls (“Control”

  559. being a specific mixable “channel”, such as <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_PCM</span></code> or

  560. <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_SYNTH</span></code>).  This bitmask indicates a subset of all available

  561. mixer controls—the <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_*</span></code> constants defined at module level.

  562. To determine if, for example, the current mixer object supports a PCM mixer, use

  563. the following Python code:</p>

  564. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">mixer</span><span class="o">=</span><span class="n">ossaudiodev</span><span class="o">.</span><span class="n">openmixer</span><span class="p">()</span>

  565. <span class="k">if</span> <span class="n">mixer</span><span class="o">.</span><span class="n">controls</span><span class="p">()</span> <span class="o">&amp;</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">ossaudiodev</span><span class="o">.</span><span class="n">SOUND_MIXER_PCM</span><span class="p">):</span>

  566.     <span class="c1"># PCM is supported</span>

  567.     <span class="o">...</span> <span class="n">code</span> <span class="o">...</span>

  568. </pre></div>

  569. </div>

  570. <p>For most purposes, the <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_VOLUME</span></code> (master volume) and

  571. <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_PCM</span></code> controls should suffice—but code that uses the mixer

  572. should be flexible when it comes to choosing mixer controls.  On the Gravis

  573. Ultrasound, for example, <code class="xref py py-const docutils literal notranslate"><span class="pre">SOUND_MIXER_VOLUME</span></code> does not exist.</p>

  574. </dd></dl>

  575. 

  576. <dl class="py method">

  577. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.stereocontrols">

  578. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">stereocontrols</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.stereocontrols" title="Link to this definition">¶</a></dt>

  579. <dd><p>Returns a bitmask indicating stereo mixer controls.  If a bit is set, the

  580. corresponding control is stereo; if it is unset, the control is either

  581. monophonic or not supported by the mixer (use in combination with

  582. <a class="reference internal" href="#ossaudiodev.oss_mixer_device.controls" title="ossaudiodev.oss_mixer_device.controls"><code class="xref py py-meth docutils literal notranslate"><span class="pre">controls()</span></code></a> to determine which).</p>

  583. <p>See the code example for the <a class="reference internal" href="#ossaudiodev.oss_mixer_device.controls" title="ossaudiodev.oss_mixer_device.controls"><code class="xref py py-meth docutils literal notranslate"><span class="pre">controls()</span></code></a> function for an example of getting

  584. data from a bitmask.</p>

  585. </dd></dl>

  586. 

  587. <dl class="py method">

  588. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.reccontrols">

  589. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">reccontrols</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.reccontrols" title="Link to this definition">¶</a></dt>

  590. <dd><p>Returns a bitmask specifying the mixer controls that may be used to record.  See

  591. the code example for <a class="reference internal" href="#ossaudiodev.oss_mixer_device.controls" title="ossaudiodev.oss_mixer_device.controls"><code class="xref py py-meth docutils literal notranslate"><span class="pre">controls()</span></code></a> for an example of reading from a bitmask.</p>

  592. </dd></dl>

  593. 

  594. <dl class="py method">

  595. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.get">

  596. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">get</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">control</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.get" title="Link to this definition">¶</a></dt>

  597. <dd><p>Returns the volume of a given mixer control.  The returned volume is a 2-tuple

  598. <code class="docutils literal notranslate"><span class="pre">(left_volume,right_volume)</span></code>.  Volumes are specified as numbers from 0

  599. (silent) to 100 (full volume).  If the control is monophonic, a 2-tuple is still

  600. returned, but both volumes are the same.</p>

  601. <p>Raises <a class="reference internal" href="#ossaudiodev.OSSAudioError" title="ossaudiodev.OSSAudioError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSSAudioError</span></code></a> if an invalid control is specified, or

  602. <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a> if an unsupported control is specified.</p>

  603. </dd></dl>

  604. 

  605. <dl class="py method">

  606. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.set">

  607. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">set</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">control</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">(left</span></span></em>, <em class="sig-param"><span class="n"><span class="pre">right)</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.set" title="Link to this definition">¶</a></dt>

  608. <dd><p>Sets the volume for a given mixer control to <code class="docutils literal notranslate"><span class="pre">(left,right)</span></code>. <code class="docutils literal notranslate"><span class="pre">left</span></code> and

  609. <code class="docutils literal notranslate"><span class="pre">right</span></code> must be ints and between 0 (silent) and 100 (full volume).  On

  610. success, the new volume is returned as a 2-tuple. Note that this may not be

  611. exactly the same as the volume specified, because of the limited resolution of

  612. some soundcard’s mixers.</p>

  613. <p>Raises <a class="reference internal" href="#ossaudiodev.OSSAudioError" title="ossaudiodev.OSSAudioError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSSAudioError</span></code></a> if an invalid mixer control was specified, or if the

  614. specified volumes were out-of-range.</p>

  615. </dd></dl>

  616. 

  617. <dl class="py method">

  618. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.get_recsrc">

  619. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">get_recsrc</span></span><span class="sig-paren">(</span><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.get_recsrc" title="Link to this definition">¶</a></dt>

  620. <dd><p>This method returns a bitmask indicating which control(s) are currently being

  621. used as a recording source.</p>

  622. </dd></dl>

  623. 

  624. <dl class="py method">

  625. <dt class="sig sig-object py" id="ossaudiodev.oss_mixer_device.set_recsrc">

  626. <span class="sig-prename descclassname"><span class="pre">oss_mixer_device.</span></span><span class="sig-name descname"><span class="pre">set_recsrc</span></span><span class="sig-paren">(</span><em class="sig-param"><span class="n"><span class="pre">bitmask</span></span></em><span class="sig-paren">)</span><a class="headerlink" href="#ossaudiodev.oss_mixer_device.set_recsrc" title="Link to this definition">¶</a></dt>

  627. <dd><p>Call this function to specify a recording source.  Returns a bitmask indicating

  628. the new recording source (or sources) if successful; raises <a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal notranslate"><span class="pre">OSError</span></code></a> if an

  629. invalid source was specified.  To set the current recording source to the

  630. microphone input:</p>

  631. <div class="highlight-python3 notranslate"><div class="highlight"><pre><span></span><span class="n">mixer</span><span class="o">.</span><span class="n">setrecsrc</span> <span class="p">(</span><span class="mi">1</span> <span class="o">&lt;&lt;</span> <span class="n">ossaudiodev</span><span class="o">.</span><span class="n">SOUND_MIXER_MIC</span><span class="p">)</span>

  632. </pre></div>

  633. </div>

  634. </dd></dl>

  635. 

  636. </section>

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