Date: Tue, 15 Jul 2003 01:36:52 -0400 (EDT) From: Stuart Barkley <stuartb@4gh.net> To: =?ISO-8859-1?Q?Joachim_Str=F6mbergson?= <watchman@ludd.luth.se> Cc: freebsd-multimedia@freebsd.org Subject: Re: Problems recording sound in FreeBSD 5.1 Message-ID: <20030715005046.R74615@freeman.4gh.net> In-Reply-To: <3F131802.9040301@ludd.luth.se>
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On Mon, 14 Jul 2003 at 22:52 +0200, Joachim Strömbergson wrote:
> Hardware wise, I've got an Asus A7V8X motherboard with built in AC97
> sound. I'm running FreeBSD 5.1 and KDE3.
>
> Is there ar simple way to directly verify that the mic input works?
> Has anybody experienced similar problems? Anybody knows what might
> be the problem?
You should be able to bring up the microphone volume in the mixer and
hear it in your speakers or headphones:
% mixer mic 100
Setting the mixer mic to 100:100.
%
For recording from the microphone, I normally select the recording
source with mixer and set the record level with the rec device:
% mixer =rec mic mic 100
Setting the mixer mic to 100:100.
Recording source: mic
%
As a test you can copy from /dev/audio to a file and vice-versa for
playback:
% cp /dev/audio test.au
^C [after several seconds of recording]
% cp test.au /dev/audio
%
Are you sure you are going into a microphone input and not a line-in
input? If you have a line-in input, are you able to record from that
input when feeding it a signal from a cd player or something similar?
Are you sure you are going into an input and not an output? I've seen
some newer motherboards replace the line-in and microphone in jacks
with output jacks for 5.1 sound systems.
Two other things come to mind for AC97 recording:
- AC97 specifies a control register bit which enables a 20dB
microphone input gain. For the microphones I use, I seem to always
need the boost. I apply the following patch (to 4.7, I'm not sure if
it applies to 5.1 at all).
--- ../src_dist/sys/dev/sound/pcm/ac97.c Mon Aug 26 20:25:55 2002
+++ ./sys/dev/sound/pcm/ac97.c Tue Jan 7 20:47:36 2003
@@ -332,6 +332,12 @@
int cur = rdcd(codec, e->reg);
val |= cur & ~(max << e->ofs);
}
+ /* stuartb: Enable 20dB mic channel gain boost */
+ /* TODO: Add ioctl or something else to control this */
+ /* Do ALL AC97 chips support this? */
+ if (channel == SOUND_MIXER_MIC)
+ val |= 0x40;
+
}
if (left == 0 && right == 0 && e->mute == 1)
val = AC97_MUTE;
- The AC97 specification also has support for an alternate mic input.
I think this controls selection between a front panel and a rear panel
microphone jack. You might need to set bit 0x0100 (MS) in the General
Purpose Register 0x20. I have not created a patch for this function.
If you have Windows XP or similar running on your system you can see
these options as advanced setting on the microphone channel.
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