Sound cards (Was: Re: no sound

[Hartmut Noack]

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.

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

>
>> 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.
>
>