Re: [LAD] FULL audio-signal path

Hi,

Am Samstag, 21. Juli 2007 schrieb Andrew Gaydenko:
> The questions are:
> - what is full strict list of "audio-entities" steps in such
> roughly-presented chain? - which formats (float/integer, bitdepth) are used
> on each step?
> 1. analogue source (say, mic-amp),

This one doesn't use either double nor float :-) But you want to keep this
part of the chain as high-quality or at least as short as possible.

> 2. sound card's line input (let sound card be rme hdsp9632),

Even if the drivers would expose it as doubles, it is still quantified which
is best represented as integers. Most (all?) drivers present the soundcard io
as integers.

> 3. JackRack (or some other JACKified LADSPA host) with the only LADSPA
> plugin, let last one be a simple aplifier,

With jack the internal processing is done in floating point numbers. This
leaves some quantification-steps but these are _much_ smaller than any
soundcard can reproduce and only affect you when you do some very serious
amplification or something like that...

> 4.1. sound card SPDIF output.
> 4.2. sound card analogue output,

This is integer again with fixed bit-depth. Again you will want to keep the
path from your soundcard to the speakers as short and high-quality as
possible.

> - which format convertions between steps may be treated as lossless and
> whcih as "lossness"?

The AD/DA-steps are lossy. Depending on the quality of the converters and the
used samplingrate and bitdepth it is sometimes more lossy and sometimes less.
And there is always the question of improvements being better than the human
ear can hear (see the ongoing discussions about 48/96/192).

> And more generally: are there common rules for keeping sound quality
> intact?

Use integer calculations as few as possible (unless you know exactly what you
are doing).

Arnold

-- 
visit http://www.arnoldarts.de/
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