More ICE1712 hassles (was Re: [linux-audio-user] Minidisk question)

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Subject: More ICE1712 hassles (was Re: [linux-audio-user] Minidisk question)
From: Andrew Nesbit (
Date: Sun May 19 2002 - 18:51:35 EEST

Frank Barknecht <> writes:

> > and that using the monitor mixer with outputs set to "0dB" gives a
> > harsh clipping-like effect.
> The monitor mixer is H/W In 1 and 2, isn't it?

No. You have a choice of three signals to send to the output of the
card, which can be selected in the patchbay:

1. PCM output from some "player" application;
2. the signal which arrives on the "H/W In" jacks on the card;
3. a mix of the above classes of signals, where the output levels are
   defined by the mixer levels in the monitor mixer panel of envy24control.

> I don't hear a clipping
> here, but PD shows me that the ADC seems to clip, but it does this
> regardless of the settings in envy24control. I'm not sure, how PD reads
> it's ADC information, though.

Here is what I've experienced: i fire up envy24control. All the
sliders in the monitor mixer are set to 0dB. I have PCM being output
by aplay/XMMS/whatever. If I set the patchbay to "digital mix", and
unmute the "PCM Out 1 & 2" channels (all other channels muted), then
the output signal is (incorrectly, IMHO) hotter than if I select "PCM
Out 1 & 2" for "HW Out 1 & 2" in the patchbay. This leads to
clipping. Analogously for having "H/W In 1/2" signals pass through
the monitor mixer instead of the "PCM Out 1 & 2" signals.

I have not done any "real" scientific analyses of this; this is based
on what I /hear/, and it is a very significant difference and is not
hard to notice.

My benchmark for how envy24control should operate is the M-Audio
Control Panel under Windows because it behaves how /I/ expect, that
is, no nasty clipping: whether I select "PCM Out" or "Monitor mixer"
in the patchbay, I seem to get exactly the same effect (unitary

> > I also get a short burst of noise at the very start and end of
> > playback (but I don't know if this is peculiar to this driver or
> > card).
> Now this is serious: I get the same, and I always thought it somehow
> was my fault. But this is only a small and short clickish sound.
> OTOH I remember, that my SBLive showed te same behaviour, but I can't
> test this right now.

These problems, including the lack of OSS Mixer emulation, and a few
other problems, are things that I have resolved to try to rectify by
the end of this year, at the latest. I am still working my way
through Rubini & Corbet's "Linux Device Drivers" 2nd ed. and trying to
understand the ALSA source code and the ICE1712 programming specs. On
top of this, my main priority is all my university work. I am still
trying to formulate my ideas for improvement in ICE1712 drivers and
ALSA in general, and when I do, will post a request for comments on
alsa-devel. Then I can get cracking. I feel bad about mentioning
this before anything has yet come to fruition; all talk and no action
is a bad thing in anybody's opinion, but this is probably the
appropriate time to mention it.


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