Re: Re: sound APIs/programming

Just something to keep in mind, I've noticed the audiostix is very
noisy when using the usb interface, but gets much quieter if you don't
use it.

Craig Casey

On 7/11/05, Craig Hughes <craig@xxxxxxxxxxx> wrote:
> On Jul 10, 2005, at 5:24 PM, Seth Cameron wrote:
> 
> > I do not think that separate left volume/right volume control
> > (balance) is
> > possible using aumix without the ncurses interface. Is that true?
> 
> I believe it is -- certainly I implemented left/right balance, bass/
> treble boost and I think maybe one or two other similar things in the
> ucb1400 driver, and the only way I had to test was using aumix -- so
> I think it is possible.
> 
> > Also, recording using brec should be done stereo even though the
> > mic is
> > mono. Mono settings with brec will write an incorrect .wav header
> > and only
> > record for 1/2 as long as requested.
> 
> Yeah, ucb1400 seems to be doing something "special" with the duped
> mic input or something, and I think it confuses brec somehow.  Not
> sure what's going on exactly.
> 
> > This brings me back my original query about decent quality microphone
> > recordings.  I've been able to make reasonable recordings from line
> > in CD
> > sources, but all of my attempts at microphone recordings have
> > significant
> > hiss and poor gain. (Similar to the type of voice recordings one
> > can make
> > with, for example, an IPAQ using the built-in mic.)
> >
> > Has anyone had success making good S/N microphone recordings?
> >
> > If not, my conclusion at this point is the that the preamp on the
> > UCB1400 is
> > crap, or significant digital noise is creeping into the audio
> > circuitry,
> > probably both.
> 
> Hmm, testing I was doing sounded OK -- not audiophile OK since I
> wasn't listening for that, but "sounds at least as good as I'd expect
> from my $10 microphone" OK.  It wouldn't substantially surprise me if
> the pre-amp were lousy on the usb1400, which seems like the most
> likely problem if you say line-in input is OK.  Might be useful to
> look at a sonogram of the noise though, to see if it looks like
> there's a dominant frequency which might point to noise leaking.
> 
> > I'm looking at using a separate battery powered mic preamp, but the
> > smallest
> > I can find is bigger than gumstix and requires 9 V. :-) So much for
> > miniaturization....
> 
> I think while I was looking around at mics for testing, that I saw
> some reasonably small powered mics.  Could easily be that the
> websites I was looking at though were just showing the mic head and
> not showing the giant battery pack box...  I'll see if I can find
> those sites again to provide links when I get back online here...
> 
> C
> 
> 
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