[alsa-devel] [LAD] [LAU] mudita24 1.02 -- improved envy24control mixer/router for ice1712-based sound-cards

Niels Mayer nielsmayer at gmail.com
Tue Aug 10 16:08:51 CEST 2010

On Tue, Aug 10, 2010 at 1:14 AM,  <fons at kokkinizita.net> wrote:
> - The meters are there to show levels at the AD/DA converters,
>  i.e. to allow you to check you are using those in a sensible
>  way. They happen to be on the same window as the mixer, which
>  can be useful as they suggest to the user which signal is
>  being controlled by a fader. But otherwise they are not part
>  of the mixer, and a better place for them would be with the
>  HW gain controls.

The meters show the levels at the A/D&D/A's but also at other things
that don't necessarily end up being routed to the analog I/O.

See the "Peak" labels on
http://nielsmayer.com/envy24control/envy24mixer-architecture.png ...
* 10 channels of hardware peak-levels of inputs (including an SPDIF pair).
* 10 channels of hardware peak-level outputs (including an SPDIF pair).
* 2 channels for the digital mixer output.

So in reality (assuming reality==documentation==
http://alsa.cybermirror.org/manuals/icensemble/envy24.pdf )
the peak meters are part of the mixer. However, the peak meter
information is most useful in the "Analog Volume" panel, but that
would  miss four-six channels + spdif-pair of outputs. As a stopgap, I
put the dBFS value alongside each channel, since adding the full
meters to this panel was a much larger and more radical change than my
initial patches.

A better design overall, IMHO would be to combine all 20 input and
output faders feeding the digital-summer into a single panel. Instead
of two faders per channel, just one fader and a panpot, which would
normally be swung hard-left or hard-right, but should also have a
detent or page-position at center mix. The panpot would also  indicate
inactive and set at center-mix when "L/R Gang" is selected. Each
channel would have the numeric dbFS input value displayed as a
"button", which when selected, expands a meter that fills the column
vertically; and deselected, it goes back to being a text display of
the peak levels. That mechanism of dynamically adding a meter per
channel could also be used in the "Analog Volumes" section to
optionally allow meter info to be displayed alongside each slider.

> - The post-fader signals in the mixer are not available anywhere,
>  they just get summed to the bus.

They are "available" in that the output of the digital mixer is
metered and that meter is always displayed in envy24control. If you
want to see the resulting level of any particular channels'
attenuation, "solo" it (by manually muting the other incoming
channels) and observe the resulting levels under the "Digital Mixer"
meters. (Actually, a "Channel Solo" option-menu would be a useful
addition to the digital mixer GUI: "off", "solo left" "solo right"
"solo center".

-- Niels

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