Date: Mon, 6 Jul 2009 19:32:13 +0000 (UTC) From: Joel Dahl <joel@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r195417 - head/share/man/man4 Message-ID: <200907061932.n66JWD41090516@svn.freebsd.org>
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Author: joel (doc committer) Date: Mon Jul 6 19:32:13 2009 New Revision: 195417 URL: http://svn.freebsd.org/changeset/base/195417 Log: Document the new EQ and VPC features along with a few loader tunables. Reviewed by: ariff Approved by: re (blanket) Modified: head/share/man/man4/pcm.4 Modified: head/share/man/man4/pcm.4 ============================================================================== --- head/share/man/man4/pcm.4 Mon Jul 6 18:43:42 2009 (r195416) +++ head/share/man/man4/pcm.4 Mon Jul 6 19:32:13 2009 (r195417) @@ -25,7 +25,7 @@ .\" .\" $FreeBSD$ .\" -.Dd June 23, 2009 +.Dd July 6, 2009 .Dt SOUND 4 .Os .Sh NAME @@ -141,6 +141,15 @@ To define default values for the differe 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 EQ +The Parametric Software Equlizer (EQ) enables the use of +.Dq tone +controls (bass and treble). +Commonly used for ear-candy or frequency compensation due to the vast +difference in hardware quality. +EQ is disabled by default, but can be enabled with the +.Va hint.pcm. Ns Ao Ar X Ac Ns Va .eq +tunable. .Ss VCHANs Each device can optionally support more playback and recording channels than physical hardware provides by using @@ -151,15 +160,55 @@ or options can be configured via the .Xr sysctl 8 interface but can only be manipulated while the device is inactive. +.Ss VPC +FreeBSD supports independent and individual volume controls for each active +application, without touching the master +.Nm +volume. +This is sometimes referred to as Volume Per Channel (VPC). +The +.Tn VPC +feature is enabled by default. +.Ss Loader Tunables +The following loader tunables are used to set driver configuration at the +.Xr loader 8 +prompt before booting the kernel, or they can be stored in +.Pa /boot/loader.conf +in order to automatically set them before booting the kernel. +It is also possible to use +.Xr kenv 1 +to change these tunables before loading the +.Nm +driver. +The following tunables can not be changed during runtime using +.Xr sysctl 8 . +.Bl -tag -width indent +.It Va hint.pcm. Ns Ao Ar X Ac Ns Va .eq +Set to 1 or 0 to explicitly enable (1) or disable (0) the equalizer. +Requires a driver reload if changed. +Enabling this will make bass and treble controls appear in mixer applications. +This tunable is undefined by default. +Equalizing is disabled by default. +.It Va hint.pcm. Ns Ao Ar X Ac Ns Va .vpc +Set to 1 or 0 to explicitly enable (1) or disable (0) the +.Tn VPC +feature. +This tunable is undefined by default. +.Tn VPC +is however enabled by default. +.El .Ss Runtime Configuration There are a number of .Xr sysctl 8 -variables available. +variables available which can be modified during runtime. +These values can also be stored in +.Pa /etc/sysctl.conf +in order to automatically set them during the boot process. .Va hw.snd.* -tunables are global settings and +are global settings and .Va dev.pcm.* are device specific. -.Bl -tag -width ".Va hw.snd.report_soft_formats" -offset indent +.Bl -tag -width indent .It Va hw.snd.compat_linux_mmap Enable to allow PROT_EXEC page mappings. All Linux applications using sound and @@ -299,7 +348,9 @@ This means that any changes to the volum Enabling this will preserve the volume, at the cost of possible confusion when applications tries to re-open the same device. .It Va hw.snd.vpc_mixer_bypass -The recommended way to use the vpc feature is to teach applications to use +The recommended way to use the +.Tn VPC +feature is to teach applications to use the correct .Fn ioctl : .Dv SNDCTL_DSP_GETPLAYVOL, SNDCTL_DSP_SETPLAYVOL,
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