osscore(7) OSS Devices osscore(7)
NAME
osscore - Open Sound Sytem core audio framework.
DESCRIPTION
Open Sound System core audio support psudo driver. This driver implements the core Open
Sound System API for audio, midi, mixer and synth functions. This driver also implements
the OS driver interface as well as device configuration and setup. More information on
programming on the OSS API is avaialable at: http://manuals.opensound.com/
OPTIONS
o ac97_recselect
When set to 1 this option enables independent recording source selection for the
left and the right channel on AC97 devices. In this way it's possible to record
audio streams so that (for example) the left channel signal comes from the micro‐
phone and the right channel signal from line-in. However when this option is
enabled it's only possible to select the recording source by using a fully OSS 4.0
compatible mixer program such as ossxmix. Default: 0 - recording source is common
to both channels.
o ac97_amplifier
When set to 1 this option enables the speaker power amplifier feature of AC97 codec
(if available). Some boards have this inverted, so this feature can be disabled by
setting this option to 0. Affects all AC97 based audio devices in the system.
Default: -1=autodetect correct setting.
o cooked_enable
By default OSS will let applications to use sampling rates and formats that are not
supported by the hardware. Instead OSS performs the necessary format conversions
in software. Applications that don't tolerate this kind of conversions usually dis‐
able them by using features of the OSS API (SNDCTL_DSP_COOKEDMODE). If this option
is set to 0 then the format conversions will be disabled for all applications and
devices unless the application explicitly enables them. Default: 1 - conversions
are enabled. This option should not be changed without very strong reasons.
o detect_trace
Internal debugging (do not change). Default: 0
o dma_buffsize
By default OSS will allocate audio DMA buffers with some system dependent default
size (usually 64k but sometimes smaller). It is possible to change this default
allocation by setting this option. Value of 0 means that the default size will be
used. Value between 16 and 128 (kilobytes) can be used if the default size is not
suitable for some reason. Default: 0 - system dependent buffsize. This option
mustn't be changed unless it's absolutely necessary.
o max_intrate
Set the maximum number of interrupts per second. A value of 0 means the number is
unlimited. Default: 100 interrupts per second which equals to about 10 msec mini‐
mum latencies.
o vmix_disabled
The virtual mixer subsystem can be disabled by setting this configuration option to
1. Default: 0 - virtual mixer is enabled.
o vmix_loopdevs
Optionally the virtual mixer subsystem can create special loopback audio devices
that can be used to record the output mix sent to the device. This option tells how
many loopback devices will be created (0, 1 or 2). If there are multiple audio
devices in the system the all of them will have the same number of loopback
devices. Default: 0 - no loopback devices are created. This setting should be
left to 0 unless there are specific reasons to enable the loopback devices.
o vmix_no_autoattach
By default (0) the low level drivers for most sound cards will automatically attach
virtual mixer (vmix) to the primary audio devices of the cards. In some situations
it may be necessary to attach virtual mixer using nonstandard parameters. If
vmix_no_autoattach is set to 1 then user can use vmixctl attach command to attach
virtual mixer manually to the device(s). Default: 0 - Automatically attach virtual
mixer.
o excl_policy
The O_EXCL open() flag can be used by programs to bypass the virtual mixer. Setting
excl_policy to 1 or 2 makes OSS ignore O_EXCL. A setting of 1 ignores O_EXCL from
all but root processes, while a setting of 2 always ignores O_EXCL. Default: 0 -
Do not ignore O_EXCL.
o mixer_muted
By default OSS will set most volume controls to audible level. If this causes
problems then it's possible to ask OSS to set the levels to zero when the drivers
are loaded. However the levels saved with the savemixer utility will get loaded few
moments later when all OSS drivers have been started. Note that just some of the
OSS drivers honor this setting. Values: 0 (default) - Use audible volumes, 1 - Set
volumes to low.
FILES
/usr/lib/oss/conf/osscore.conf Device configuration file
AUTHOR
4Front Technologies
21 November 2019 osscore(7)