Sound cards (Was: Re: no sound

[Ralf Mardorf]

On Fri, 2011-05-20 at 15:00 +0200, Hartmut Noack wrote:
> Am 20.05.2011 14:37, schrieb Ralf Mardorf:
> > On Fri, 2011-05-20 at 14:04 +0200, Thomas Orgis wrote:
> >> Am Fri, 20 May 2011 13:54:57 +0200
> >> schrieb Ralf Mardorf<ralf.mardorf at alice-dsl.net>:
> >>
> >>> When recording soft synth just by
> >>> JACK, without the sound cards being involved, there's a loss for the
> >>> sound quality too!
> >>
> >> Wait a minute... could you explain that? You have a loss of quality compared to live playback of the soft synths (using JACK?) when playing back a recording taken from JACK? A recording that preserves 32 bit floating point sample format (heck, or 24 bit integer) and the sample rate, of course?
> >
> > Yes and other people who can't hear it, do have it too.
> 
> I do not.
> 
> > You can see it
> > by watching the waves spectral by Audacity. I did this regarding to a
> > zero-copy issue, that appears if a Jack client is connected directly to
> > itself, e.g. to do the mastering. 48 and 96 KHz, 32-bit wav 32-bit
> > float.
> 
> If a synth has dynamic filters it will never produce the exactly same 
> stream twice. But if you think about yourself you will find out, that 
> given you use the same settings for Jack on a HDA or a HDSP you will get 
> exactly the same quality.

I'm an expert for audio engineering. I did work for Brauner microphones
development and others, hence I know a little bit about how to do
tests ;).
No dynamic filters are involved!

It's very simple, there's a natural sounding drum set as example drum
kit for Hydrogen. Play a rhythm, record this Rhythm and then record this
recording and compare both recordings. They should be equal, but they
aren't equal. I can here a !clear! loss and it's visible by spectral
waves.

> 
> Simply because a synth-software only delivers, what it renders to Jack 
> and Jack does *not* change anything in that rendered data. There is 
> simply not soundcard and not even a driver involved in the rendering 
> itself. DSPs only do the very same thing faster as cheap chips.
> 
> All difference in sound quality is related to DAC/ADC period

No! Before any converter is involved, there at least could be rounding
errors, if you don't use 32-bit float all the times.

And by the way, the sound card will effect the original and the digital
copy in the same way, even with a bad sound card both recordings
shouldn't differ.

Hey, do a recording of a recording and then run the diff command to
compare them ;)!

> 
> >
> >> I have to wonder what you did there to alter the data from the soft synth. I mean ... we're talking bit-exact copy here, aren't we? Can you present a test setup to observe that issue?
> >
> > Any Linux install I know, e.g. 64 Studio 64-bit 3.0, 3.3, Suse 64-bit
> > 11.2 and Edubuntu 32-bit Maverick + Ubuntu Studio meta packages and
> > others! If you can't here it, try to see it. If you don't have this
> > issue too, some people claim that they get 100% correct digital copies,
> > then something on my machine might cause a software issue, but I don't
> > think so.
> >
> > Ralf
> >
> >>
> >> Alrighty then,
> >>
> >> Thomas.
> >
> >
> 
>