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Document recent improvements to the sound infrastructure (virtual recording

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channels, changed sysctl's and device nodes etc).

Reviewed by:	ariff
This commit is contained in:
joel 2007-05-31 20:26:39 +00:00
parent 663d795614
commit 2e12909782
1 changed files with 20 additions and 9 deletions
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29
share/man/man4/pcm.4
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@ -25,7 +25,7 @@
.\"
.\" $FreeBSD$
.\"
.Dd November 29, 2006
.Dd May 31, 2007
.Dt SOUND 4
.Os
.Sh NAME
@ -152,7 +152,7 @@ set the channel to the preferred value using hints, e.g.:
.Va hint.pcm.0.line Ns = Ns Qq Li 0 .
This will mute the input channel per default.
.Ss VCHANs
Each device can optionally support more playback channels
Each device can optionally support more playback and recording channels
than physical hardware provides by using
.Dq virtual channels
or
@ -226,7 +226,7 @@ Various messages intended for debugging.
.It Va hw.snd.maxautovchans
Global
.Tn VCHAN
setting that only affects devices with only one playback channel available.
setting that only affects devices with at least one playback or recording channel available.
The sound system will dynamically create up this many
.Tn VCHANs .
Set to
@ -234,7 +234,7 @@ Set to
if no
.Tn VCHANS
are desired.
Maximum value is 255.
Maximum value is 256.
.It Va hw.snd.default_unit
Default sound card for systems with multiple sound cards.
When using
@ -245,7 +245,7 @@ Equivalent to a symlink from
.Pa /dev/dsp
to
.Pa /dev/dsp Ns Va ${hw.snd.default_unit} .
.It Va dev.pcm.%d.vchans
.It Va dev.pcm.%d.[play|rec].vchans
The current number of
.Tn VCHANs
allocated per device.
@ -256,13 +256,13 @@ Setting this value to
will disable
.Tn VCHANs
for this device.
.It Va dev.pcm.%d.vchanrate
.It Va dev.pcm.%d.[play|rec].vchanrate
Sample rate speed for
.Tn VCHAN
mixing.
All playback paths will be converted to this sample rate before the mixing
process begins.
.It Va dev.pcm.%d.vchanformat
.It Va dev.pcm.%d.[play|rec].vchanformat
Format for
.Tn VCHAN
mixing.
@ -322,8 +322,10 @@ but 16 bits per sample.
Playback channel.
.It Pa /dev/dsp%d.r%d
Record channel.
.It Pa /dev/dsp%d.v%d
Virtual channel.
.It Pa /dev/dsp%d.vp%d
Virtual playback channel.
.It Pa /dev/dsp%d.vr%d
Virtual recording channel.
.It Pa /dev/sndstat
Current
.Nm
@ -343,6 +345,15 @@ Additional messages are sometimes recorded when the
device is probed and attached, these messages can be viewed with the
.Xr dmesg 8
utility.
.Pp
The above device nodes are only created on demand through the dynamic
.Xr devfs 5
clone handler.
Users are strongly discouraged to access them directly.
For specific sound card access, please instead use
.Pa /dev/dsp
or
.Pa /dev/dsp%d .
.Sh DIAGNOSTICS
.Bl -diag
.It pcm%d:play:%d:dsp%d.p%d: play interrupt timeout, channel dead