[arch-general] OT: [arch-dev-public] polkit package upgrade patch

["Jérôme M. Berger"]

Ralf Mardorf wrote:
> On Sun, 2012-08-12 at 19:38 +0200, "Jérôme M. Berger" wrote:
>> 	Actually, that's one point where PA is right (even though it's
>> wrong on a lot of other points): doing it like (2) avoids amplifying
>> the quantification noise if the sound card applies the master gain
>> in analog (or uses higher bit depths internally before the DACs as
>> some do).
>>
>> 	When cascading amplifiers, it is always better to put the highest
>> possible gain on the first stages (always leaving enough headroom to
>> avoid clipping/distortion) so that later stages will not amplify the
>> noise from the first stages (or so that they will reduce it along
>> with the signal). The only case when this rule does not hold is when
>> doing digital processing in floating point (because then the
>> quantification noise is defined as a proportion of the actual signal
>> instead of its potential maximum).
>>
>> 		Jerome
> 
> If you do a mix you should keep the first stages within a good level
> that fits to the operating points of the op-amps, when ever possible,
> but you do the mix at that point, followed by sub groups followed by the
> master, the earlier the stage, the more you'll work with levels, you do
> less work for the sub groups and the most less work for for the master.
> You won't readjust the master continuous, especially not for a live
> stream.
>  
	Two points:

- You don't readjust the master continuously, but you don't
add/remove sources on the fly either. You adjust the master in the
beginning when you setup your system, but the reason you can do that
is because you know exactly what sources you will have and what
kinds of levels those sources generate.

- "Keep the first stages within a good level that fits the operating
points of the op-amps". In practice, this is done by using the
maximum level that does not produce distortion. When talking digital
signals, this means keep the level at 0dB for as long as possible.

		Jerome
-- 
mailto:jeberger at free.fr
http://jeberger.free.fr
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