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dsp - Open Sound System audio devices
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/dev/dsp is the default audio device in the system. It's connected to the
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main speakers and the primary recording source (such as microphone). The system
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administrator can set /dev/dsp to be a symbolic link to the desired default
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device. The ossinfo utility can be used to list the available audio devices
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/dev/dsp_mmap, /dev/dsp_ac3, /dev/dsp_multich and /dev/dsp_spdifout are
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default audio devices for specific applications such as games or media (DVD)
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DIRECT ACCESS AUDIO DEVICE FILES
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OSS 4.0 (and later) will create audio devices under /dev/oss/<device> directory.
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For example /dev/oss/sblive0/pcm0 is the first audio device that belongs to the
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first Sound Blaster Live! or Audigy card in the system. These direct devices
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are used when an application needs to access specific audio device (instead of
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You can use the ossinfo(1) utility with the -a option to get a list of the
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available audio devices in the system.
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LEGACY AUDIO DEVICE FILES
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Traditionally OSS has created device files like /dev/dsp0 to /dev/dspN for
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each audio device in the system. OSS 4.0 still supports this legacy naming.
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These files are symbolic links to the actual device files located under
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/dev/oss. The ossdevlinks(8) utility is used to manage these links and it
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will be automatically invoked when OSS is started.
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o The /dev/dsp (default() audio device file will be supported by all OSS
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implementations and versions.
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o The special purpose audio default devices (such as /dev/dsp_mmap) are only
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supported by OSS 4.0 and later.
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o The legacy audio device files (such as /dev/dsp1) are supported by all OSS
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versions and implementations.
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o New style audio device files (under /dev/oss) are only supported by OSS 4.0
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and later. However some independent OSS implementations may only support
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the legacy naming even they are otherwise OSS 4.0 compatible.
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o /dev/dsp0 doesn't exist in all Linux systems which use /dev/dsp for the same
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purpose. In such systems /dev/dsp points to the first audio device and
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/dev/dsp1 to the second.
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PROGRAMMING INFORMATION
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See the Audio Programming section of the OSS Programmer's Guide (DSP(2)) for
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o /dev/dsp Default audio device
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o /dev/dsp_mmap Default audio device for applications using mmap(2)
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o /dev/dsp_ac3 Default audio device for applications sending Dolby
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Digital (AC3) audio to an external receiver.
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o /dev/dsp_multich Default multichannel (4.0-7.1) audio output device
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o /dev/dsp_spdifout Default digital audio (S/PDIF) output device
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o /dev/oss/<driver>/pcmN Direct access device files for individual audio
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o /dev/dsp0 to /dev/dspN Legacy style direct access audio device files.