[mdlug] Vinyl to digital

[Paul]

"Ingles, Raymond" <Raymond.Ingles at compuware.com>, on Tue Mar 20, 2007 [12:17:02 PM] said:
> 
> > From: Dan Pritts
> 
> > If i were doing this i'd probably have 
> >  a) used a hardware preamp rather than doing it in software 
> 
>  I dunno. The only preamp I have is... well... not in the best of
> condition, and wasn't the greatest item when new either. So I figured
> I'd get the best capture by eliminating as many analog steps as
> possible. Within my meager needs it seems to have worked out okay.
> 
	Hi;

	Ratshack used to sell a phono pre-amp for not much, if you
really dont have a home amplifier with a phono pre-amp. Recording
such a low signal would I imagine, reduce the real dynamic range
of the signal, (eg. if you are sampling at 16 bits but your highest
sample never gets above 8 bits, you are essentially recording in
8 bit quality) and then dramaticly amplify the floor of whatever
noise exists in the path thru the card.

> >  b) sampled at 44.1KHz - although my understanding is that your
> >     basic consumer sound card (including some that cost $200) will
> >     always sample at 48KHz and resample in software - so i dunno
> >     that it makes any difference in the standard case.
> 
	Well, if your card doesnt resample or doesnt resample and ALSA
does it, thats probably not ideal. The only reason to sample at 44.1
is if you are going to burn the wave to a cd, or you want to reduce
the file size. If its going to ogg or mp3, then it might as well be
at the native rate, no resampling required.

>  That was my reasoning. I figured I'd stick with the native hardware
> sample rate, and if I need to do resampling later, I can do it in
> software at high quality. (Tools like sox do a very good job, at the
> cost of a lot of CPU.) I vaguely remember hearing that consumer
> soundcards didn't always do a good job at that...
> 

	Btw. AFAIK libsamplerate aka Secret Rabbit Code is the best
thing for resampling out there. Ive heard that sox uses more primative
techniques. (maybe that has changed) Anything that links to libsamplerate
should do a good job, and it also comes with a stand alone 'sndfile-resample'.
	Also there are some other denoising utils, like GWC or Gnome Wave
Cleaner, which can depop, and also denoise based upon a sample of the
offending noise.

Paul
set at pobox.com

>  Sincerely,
> 
>  Ray Ingles                                                  (313) 227-2317