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dsp(2) [debian man page]

7(16 December 2012)													       7(16 December 2012)

dsp - Open Sound System audio devices DESCRIPTION
/dev/dsp is the default audio device in the system. It's connected to the main speakers and the primary recording source (such as micro- phone). The system administrator can set /dev/dsp to be a symbolic link to the desired default device. The ossinfo utility can be used to list the available audio devices in the system. /dev/dsp_mmap, /dev/dsp_ac3, /dev/dsp_multich and /dev/dsp_spdifout are default audio devices for specific applications such as games or media (DVD) players. DIRECT ACCESS AUDIO DEVICE FILES
OSS 4.0 (and later) will create audio devices under /dev/oss/<device> directory. For example /dev/oss/sblive0/pcm0 is the first audio device that belongs to the first Sound Blaster Live! or Audigy card in the system. These direct devices are used when an application needs to access specific audio device (instead of the default one). You can use the ossinfo(1) utility with the -a option to get a list of the available audio devices in the system. LEGACY AUDIO DEVICE FILES
Traditionally OSS has created device files like /dev/dsp0 to /dev/dspN for each audio device in the system. OSS 4.0 still supports this legacy naming. These files are symbolic links to the actual device files located under /dev/oss. The ossdevlinks(8) utility is used to manage these links and it will be automatically invoked when OSS is started. COMPATIBILITY
o The /dev/dsp (default() audio device file will be supported by all OSS implementations and versions. o The special purpose audio default devices (such as /dev/dsp_mmap) are only supported by OSS 4.0 and later. o The legacy audio device files (such as /dev/dsp1) are supported by all OSS versions and implementations. o New style audio device files (under /dev/oss) are only supported by OSS 4.0 and later. However some independent OSS implementations may only support the legacy naming even they are otherwise OSS 4.0 compatible. o /dev/dsp0 doesn't exist in all Linux systems which use /dev/dsp for the same purpose. In such systems /dev/dsp points to the first audio device and /dev/dsp1 to the second. PROGRAMMING INFORMATION
See the Audio Programming section of the OSS Programmer's Guide (DSP(2)) for more info. OPTIONS
o /dev/dsp Default audio device o /dev/dsp_mmap Default audio device for applications using mmap(2) o /dev/dsp_ac3 Default audio device for applications sending Dolby Digital (AC3) audio to an external receiver. o /dev/dsp_multich Default multichannel (4.0-7.1) audio output device o /dev/dsp_spdifout Default digital audio (S/PDIF) output device o /dev/oss/<driver>/pcmN Direct access device files for individual audio devices. o /dev/dsp0 to /dev/dspN Legacy style direct access audio device files. AUTHOR
4Front Technologies OSS Devices 7(16 December 2012)

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7(16 December 2012)													       7(16 December 2012)

sndstat - Open Sound System status device DESCRIPTION
/dev/sndstat is a text formatted device special file that returns information about available (OSS) sound devices. This device file is obsolete and the ossinfo(1) utility should be used instead. Notice that the device numbering used in this file is different that the official numbering used by ossinfo(1) and some other utilities. /dev/sndstat uses device numbers that match the "legacy" /dev/dspN, /dev/midiN and /dev/mixerN device files. Application programs should not use /dev/sndstat to obtain information about the sound devices. The format of this file may change in the future and /dev/sndstat may even be removed from OSS in distant future. OSS 4.0 and later has an ioctl interface for getting detailed and reliable information about the devices. AUDIO USAGE HISTORY
/dev/sndstat reports some history information about previously run audio applications. This section is a debugging aid for application developers and it will be moved to the ossinfo program in the future. For example: History: /dev/oss/hdaudio0/pcm0.10: pid 6326 cmd 'error_test' OUT Play events:01009:2 Rec events:01002:0 /dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT /dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT /dev/oss/hdaudio0/pcm0.10: pid 6329 cmd 'mpg123' OUT Each line will show the the device name, PID and name of the application (if known) and access mode (IN and/or OUT). There may also be additional info about buffer underruns/overruns and other recording and playback related events. Each Play and rec events consist of 5-6 digit event code and a parameter separated by a colon. A list of defined event codes and their explanations can be found from Purpose of these events is to inform applica- tion developers by potential problems in their code. COMPATIBILITY
/dev/sndstat has been available in all OSS versions. However in OSS 4.0 and later this device file should only be used by applications written for earlier OSS versions. OPTIONS
Some applications use /dev/sndstat to find the audio devices available in the system. This method is no longer recommended. Applications should use the SNDCTL_AUDIOINFO(2) ioctl call to find the devices. SEE ALSO
o dsp(7) - Audio device files o mixer(7) - Mixer (control panel) device files o midi(7) - MIDI device files FILES
/dev/sndstat AUTHOR
4Front Technologies OSS Devices 7(16 December 2012)
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