100 lines
4.1 KiB
Groff
100 lines
4.1 KiB
Groff
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." Automatically generated text
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.TH 8 "August 31, 2006" "OSS" "System Administration Commands"
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.SH NAME
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vmixctl - Open Sound System utility to control the vmix subsystem.
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.SH SYNOPSIS
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o vmixctl attach [attach_options...] audiodev [inputdev]
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o vmixctl detach [attach_options...] audiodev
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o vmixctl rate audiodev samplerate
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.SH DESCRIPTION
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The vmixctl program can be used to attach or detach the virtual mixer subsystem
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(vmix) to/from audio devices. In addition it can be used to control vmix
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related parameters such as the sampling rate to be used with the device.
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By default most OSS drivers will attach virtual mixer to the primary audio device
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of the sound card (or motherboard audio chip) when the device is attached.
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However possible secondary audio devices (engines) will not have vmix
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attached by default. In additional professional audio devices will be
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attached without vmix because mixing may cause some unwanted distortion
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to the signal.
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.SH ATTACHING VMIX TO AN AUDIO DEVICE
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There are two forms of vmixctl attach command:
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o vmixctl attach audiodev
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This alternative is to be used with devices that support only output or
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have a single audio device file that supports full duplex.
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o vmixctl attach audiodev inputdev
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The second form is to be used with devices that have separate output and
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input device files. The "audiodev" parameter defines the output device and
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the "inputdev" parameter is the device file to be used for input direction.
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Note that both device files must belong to the same "physical" sound card.
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In some cases it might be possible to use one sound card for playback and
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another for recording. However this configuration is not supported and the
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result may not be functional.
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To find out the right device file names (audiodev and inputdev) you can use
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the "ossinfo -a" command.
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.SH ATTACH OPTIONS
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o -r Disable recording functionality. By default vmix will suppor
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recording if the master device(s) support it.
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o -p Do not preallocate client engines. By default vmix will
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preallocate first 4 (out of 8) client engines when attaching
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to the device. The remaining engines will be allocated
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on-demand if there are more concurrent applications that
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use the device.
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o -V Make client devices visible (have private device nodes under /dev).
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o -c <n> Preallocate <n> client engines instead of 4. However -p
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option makes this option ineffective.
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.SH EXAMPLES
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o vmixctl attach /dev/oss/oss_envy240/pcm0
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o vmixctl attach /dev/oss/oss_envy240/pcm0 /dev/oss/oss_envy240/pcmin0
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.SH SETTING THE SAMPLING RATE USED BY VMIX
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The virtual mixer subsystem will set the physical audio devce(s) to use
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fixed sampling rate that is 48000 Hz by default. It is possible to use
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"vmixctl rate audiodev" to switch vmix to use some different rate with this
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device (pair). You should use "ossinfo -a -v2" to verify that the sampling rate
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is actually supported by the device. Otherwise the actual device may enforce
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vmix to use the nearest supported rate (or some default rate).
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The "audiodev" parameter is the device file name (see ossinfo -a) that is
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used for playback. The input device name doesn't need to be specified.
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Note that some professional audio devices may be locked to external sampling
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rate or some fixed rate (defined in ossmix/ossxmis). In such case the rate is
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not changeable by vmixctl.
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.SH EXAMPLE
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o vmixctl rate /dev/oss/oss_envy240/pcm0
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.SH DETACHING VMIX FROM AN AUDIO DEVICE
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It is possible to detach vmix from an audio device if it causes problems
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with applications by using "vmix detach audiodev".
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It is not possible to detach and (re)attach vmix to the same device more
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than few times. Use the vmix-enable setting in the control panel
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(ossxmix or ossmix) to disable/re-enable vmix if you need to do it
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repeatedly. Use vmix detach only if you need to attach virtual mixer using
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different parameters.
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.SH EXAMPLE
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o vmix detach /dev/oss/oss_envy240/pcm0
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.SH POSSIBLE BUGS
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o The control panel elements related with vmix are not removed from the
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mixer API when vmix is detached. This may be somehow confusing.
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.SH SEE ALSO
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soundoff(1), soundon(1), ossmix(1), ossxmix(1)
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.SH FILES
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/usr/sbin/vmixct
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.SH AUTHOR
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4Front Technologies
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