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author | joel <joel@FreeBSD.org> | 2009-07-06 19:32:13 +0000 |
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committer | joel <joel@FreeBSD.org> | 2009-07-06 19:32:13 +0000 |
commit | 0f4464a41365e0dec0a78d122dbc3156c0058bca (patch) | |
tree | 7f13cf733341ae266e39b1ea7fc4d5aff54586a7 | |
parent | c9ef1e01042ca2bf24cdc667b8706fa633692304 (diff) | |
download | FreeBSD-src-0f4464a41365e0dec0a78d122dbc3156c0058bca.zip FreeBSD-src-0f4464a41365e0dec0a78d122dbc3156c0058bca.tar.gz |
Document the new EQ and VPC features along with a few loader tunables.
Reviewed by: ariff
Approved by: re (blanket)
-rw-r--r-- | share/man/man4/pcm.4 | 61 |
1 files changed, 56 insertions, 5 deletions
diff --git a/share/man/man4/pcm.4 b/share/man/man4/pcm.4 index 5f46444..dbb1437 100644 --- a/share/man/man4/pcm.4 +++ b/share/man/man4/pcm.4 @@ -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 different mixer channels, 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 volume will be lost. 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, |