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To: multimedia@freebsd.org
Subject: GUSMAX is 1/2 volume with /dev/dsp0 compared to /dev/dsp2?
Date: Wed, 07 Feb 1996 15:43:56 -0800
Message-ID: <7821.823736636@time.cdrom.com>
From: "Jordan K. Hubbard" <jkh@time.cdrom.com>
Sender: owner-multimedia@freebsd.org
Precedence: bulk

2.1-STABLE:

jkh@time-> ls -l /dev/dsp*
lrwxr-xr-x  1 root  wheel         4 Feb  6 00:05 /dev/dsp -> dsp0
crw-rw-rw-  1 root  wheel   30,   3 Feb  7 15:30 /dev/dsp0
crw-rw-rw-  1 root  wheel   30,  19 Feb  2 18:08 /dev/dsp1
crw-rw-rw-  1 root  wheel   30,  35 Feb  2 18:08 /dev/dsp2
jkh@time-> maplay ~/MPEGAudio/stereo-Angels.mp2

<turn volume knob way up in order to be able to hear it - noise is similarly
 amplified.  Yuck>

root@time> cd /dev && ./MAKEDEV gusmax
jkh@time-> ls -l /dev/dsp*
lrwxr-xr-x  1 root  wheel         4 Feb  6 00:05 /dev/dsp -> dsp0
crw-rw-rw-  1 root  wheel   30,   3 Feb  7 15:30 /dev/dsp0
crw-rw-rw-  1 root  wheel   30,  19 Feb  2 18:08 /dev/dsp1
crw-rw-rw-  1 root  wheel   30,  35 Feb  2 18:08 /dev/dsp2
jkh@time-> maplay ~/MPEGAudio/stereo-Angels.mp2

<YOW!  Jump for the volume knob!  Ah, yes, that sounds much better!>


Now the way I understand it (and that may be utterly wrong), in
2.1-STABLE the /dev/dsp2 device points to an actual hardware DSP
(CS4321?) and it somehow assists in the decoding process.  It must,
since the maplay program eats only 35% of the CPU time while running
against /dev/dsp2 and a full 60% of the CPU time while running against
/dev/dsp0.  Even so, the volume levels should be the same, no?

Is there any reason NOT to use /dev/dsp2?  It's certainly a major win
for me with maplay, and playing MPEG audio is probably my #1 use of
the card (I have a large collection of favorites from IUMA which often
replace my CD player for hours at a time! :-).

					Jordan