MIXERCTL.CONF(5)          OpenBSD Programmer's Manual         MIXERCTL.CONF(5)

NAME
     mixerctl.conf - mixerctl configuration file

DESCRIPTION
     mixerctl.conf is the configuration file for mixerctl(1).  It allows the
     user to specify settings for the audio mixer at system startup.  The ex-
     act set of variables available are largely dependent on the audio device
     driver, and vary from device to device.  The format of these variables is
     described more fully in the mixerctl(1) manual page.

     Some audio devices have _sense variables which can help identify connec-
     tors.  The connectors' state will be one of plugged or unplugged, depend-
     ing on whether a jack is inserted.

     The connectors on audio cards are generally as follows:

        pink       Microphone in.  Used to record from a microphone.
        green      Line out.  Used for stereo speakers or headphones.
        blue       Line in.  Used to record from an external source.
        orange     Speaker out; subwoofer.
        brown      Speaker out; rear speakers.
        S/PDIF     Optical connector; TOSLink, RCA, or 1/8" mini stereo.

PLAYBACK
     Most devices have a number of digital to analogue converters (DACs), used
     for sound playback, and each DAC has a corresponding output mixer.  The
     mixers are labelled ``mix'' or ``sel''.  Each DAC represents two channels
     of playback.

     Verify that playback works by playing an audio file (see aucat(1)) or CD
     (see cdio(1)).  Check that any relevant inputs.* variables are unmuted
     and set to a high enough value to permit playback.  For example, if play-
     ing a CD, grep(1) for cd variables to adjust.  Check also that the vari-
     able governing the general audio level, such as outputs.master, is set to
     a sufficiently high value.

     Some cards are capable of multi-channel sound.  In some cases _dir vari-
     ables detail the direction (input or output) of the various connectors.
     Check that the direction of the corresponding connectors is set to
     output.  Other devices may need to set _source variables to work correct-
     ly.  The maximum possible value of the audioctl(1) variable play.channels
     shows the number of channels available.

RECORDING
     Most devices have a number of analogue to digital converters (ADCs), used
     for recording sound, and each ADC has a corresponding input mixer.  The
     mixers are labelled ``mix'' or ``sel''.  Each ADC represents two channels
     of recording.

     Connect line in on the audio card to an audio source, such as an amplifi-
     er.  Many devices have an auxiliary connector (``aux'') available for
     recording, or a headphone socket could be used.

     Check that the variable that determines recording volume, such as
     record.volume, is set high enough to provide a high enough sound level,
     but not so high as to distort the sound being recorded.  It is also a
     good idea to mute any record.* variables not being used for recording.
     Obviously the recording source itself will have to be unmuted.

     A simple test that recording works may be done using aucat(1) whilst
     playing back audio from an external source.  The example below creates a
     .wav file of any audio being played.  The file can then be played back to
     determine quality.

           $ aucat -o test.wav

FILES
     /dev/mixer             Default audio mixing device.
     /etc/mixerctl.conf     mixerctl(1) configuration file.

SEE ALSO
     aucat(1), audioctl(1), mixerctl(1)

OpenBSD 4.5                    December 2, 2008                              2