[LAD] FIxed alsa-tools' envy24control missing peak level meters and "Reset Peaks"

[fons at kokkinizita.net]

On Mon, Jul 12, 2010 at 06:18:29PM -0700, Niels Mayer wrote:

> On Mon, Jul 12, 2010 at 4:40 PM,  <fons at kokkinizita.net> wrote:
> > That comment is still true. A K-meter is for signals
> > that are in a sense the 'end result' you listen to.
> > For monitoring 'technical' levels in digital audio
> > the peak digital level is all you need.
> 
> As I mentioned, the main use would be for the "digital mixer" meter --
> which is a single meter -- always visible on the left hand side no
> matter which tab-panel selected -- representing the output of all the
> inputs to the 36 bit wide digital mixer. The inputs feeding the
> meter&mixer can include audio from 8 PCM outs + 2 SPDIF outs, as well
> as 4 inputs, and 2 SPDIF inputs. Very much the "end result" you listen
> to. It is normally used for "zero latency monitoring" of analog inputs
> -- in which case the digital mix out is routed to the headphones. You
> can also use it as an internal digital mix/route before going to hard
> disk or DAW input -- very convenient as such.

Yes, if the mixer is used for monitoring you'd want a good ides
of the level you send to the musician's headphones.

But the output mixer is available on two PCM ins as well, so you can 
measure it there using the real thing.

> If anybody wants to contribute a mapping of 0-255 in db as the "9
> msb's" of a 36bit deep mixer -- I'll add peak levels.

That is easy enough. L dB (L < 0) corresponds to 255 * (10 ^ L / 20).

> And fons, if you
> have any suggestions for displaying averaged, rms'd or "k-system'd"
> versions of these 0-255 loudness values from the hardware metering,
> that would be helpful too -- all I'm really looking for is "average
> listening level/perceptual level". But the hardware metering may not
> be able to provide that in a meaninful fashion.

Indeed it's not possible. You can't derive average or RMS levels
from peak levels. Basically you need all samples.

> Speaking of making my brain hurt -- I really would not have done the
> meters as done in envy24control. I really hate the concept of
> emulating the look of real gear down to the level that you have to
> "quantize" to individual LED's...

That is indeed quite absurd.

Ciao,

-- 
Je veux que la mort me trouve plantant mes choux, mais
nonchalant d’elle, et encore plus de mon jardin imparfait.
(Michel de Montaigne)