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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE. .\" SUCH DAMAGE.
.\" .\"
.Dd March 24, 2024 .Dd December 4, 2024
.Dt SOUND 4 .Dt SOUND 4
.Os .Os
.Sh NAME .Sh NAME
.Nm sound , .Nm sound ,
.Nm pcm , .Nm pcm ,
.Nm snd .Nm snd
.Nd .Nd
.Fx .Fx
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Possible values range between 0 (lowest latency) and 10 (highest latency). Possible values range between 0 (lowest latency) and 10 (highest latency).
.It Va hw.snd.latency_profile .It Va hw.snd.latency_profile
Define sets of buffering latency conversion tables for the Define sets of buffering latency conversion tables for the
.Va hw.snd.latency .Va hw.snd.latency
tunable. tunable.
A value of 0 will use a low and aggressive latency profile which can result A value of 0 will use a low and aggressive latency profile which can result
in possible underruns if the application cannot keep up with a rapid irq in possible underruns if the application cannot keep up with a rapid irq
rate, especially during high workload. rate, especially during high workload.
The default value is 1, which is considered a moderate/safe latency profile. The default value is 1, which is considered a moderate/safe latency profile.
.It Va hw.snd.maxautovchans .It Va hw.snd.vchans_enable
christosAuthorUnsubmitted
Done
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@emaste @markj Is this more appropriate for RELNOTES or UPDATING? This patch will probably be MFC'd to stable/14 along with the other patches.

christos: @emaste @markj Is this more appropriate for RELNOTES or UPDATING? This patch will probably be…
markjUnsubmitted
Not Done
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RELNOTES makes more sense. UPDATING is for documenting issues that specifically affect users upgrading from source, as opposed to using freebsd-update, say.

markj: RELNOTES makes more sense. UPDATING is for documenting issues that specifically affect users…
Global VCHAN setting that only affects devices with at least one playback or Global VCHAN setting to enable (1) or disable (0) VCHANs.
recording channel available. This setting can be overridden for an individual device by using the
dev_submerge.chUnsubmitted
Done
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"overridden"

dev_submerge.ch: "overridden"
The sound system will dynamically create up to this many VCHANs. .Va dev.pcm.%d.[play|rec].vchans
Set to tunables.
.Dq 0 Default is enabled.
if no VCHANs are desired.
Maximum value is 256.
.It Va hw.snd.report_soft_formats .It Va hw.snd.report_soft_formats
dev_submerge.chUnsubmitted
Done
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We should mention here that it can be overridden. Also the explanation for dev.pcm.X.vchans needs an update regarding that.

dev_submerge.ch: We should mention here that it can be overridden. Also the explanation for `dev.pcm.X.vchans`…
Controls the internal format conversion if it is Controls the internal format conversion if it is
available transparently to the application software. available transparently to the application software.
When disabled or not available, the application will When disabled or not available, the application will
only be able to select formats the device natively supports. only be able to select formats the device natively supports.
.It Va hw.snd.report_soft_matrix .It Va hw.snd.report_soft_matrix
Enable seamless channel matrixing even if the hardware does not support it. Enable seamless channel matrixing even if the hardware does not support it.
Makes it possible to play multichannel streams even with a simple stereo Makes it possible to play multichannel streams even with a simple stereo
sound card. sound card.
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.Nm .Nm
stream will be fed directly to the hardware. stream will be fed directly to the hardware.
If VCHANs are enabled, the bitperfect mode will use the VCHAN format/rate as If VCHANs are enabled, the bitperfect mode will use the VCHAN format/rate as
the definitive format/rate target. the definitive format/rate target.
The recommended way to use bitperfect mode is to disable VCHANs and enable this The recommended way to use bitperfect mode is to disable VCHANs and enable this
sysctl. sysctl.
Default is disabled. Default is disabled.
.It Va dev.pcm.%d.[play|rec].vchans .It Va dev.pcm.%d.[play|rec].vchans
The current number of VCHANs allocated per device. Enable (1) or disable (0) VCHANs.
This can be set to preallocate a certain number of VCHANs. Default is enabled.
Setting this value to
.Dq 0
will disable VCHANs for this device.
.It Va dev.pcm.%d.[play|rec].vchanformat .It Va dev.pcm.%d.[play|rec].vchanformat
Format for VCHAN mixing. Format for VCHAN mixing.
All playback paths will be converted to this format before the mixing All playback paths will be converted to this format before the mixing
process begins. process begins.
By default only 2 channels are enabled. By default only 2 channels are enabled.
Available options include: Available options include:
.Bl -tag -width 2n .Bl -tag -width 2n
.It s16le:1.0 .It s16le:1.0
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