linuxaudio.org

On Fri, Jul 16, 2010 at 03:57:20PM -0700, Niels Mayer wrote:
> On a completely different "note"  the envy 24 manual (

quoted text
> http://alsa.cybermirror.org/manuals/icensemble/envy24.pdf )

> has interesting info on the envy24 digital mixer that I've snapshotted:

>

> Diagram: http://nielsmayer.com/npm/envy24mixer-architecture.png

>

> Note the way it truncates in the mixer: the more inputs you "mix" at

> once, the fewer bits each input source gets,

It has to be, as the sum is limited. No signal can use the full

range if another signal is present at the same time. The mixer

permits 0 dB gain, so if you do have a single signal it can pass

through untouched.
> and it's not clear what

quoted text
> kind of dither, or it's a straight truncate of 24... 

Truncating 24 bit doesn't need dithering, as the error will

be below thermal noise of the analog parts anyway. Assuming

you keep sane levels.
> ultimately the

quoted text
> envy24 seems oriented towards producing a 16 bit, and not 24 bit

> master (which makes sense given that the chip is well over a decade

> old and HD audio production for "prosumer" was rare):

I see no reason at all to arrive at that conclusion. The card

as a whole is limited by the performance of the converters, and

nothing else.
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)

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