[PD] FreeBSD 4.8, pd 0.35 - and distortion
pix at test.at
Thu Aug 14 18:14:29 CEST 2003
a possible problem:
some audio cards under linux (and likely under most unixen), have crappier
audio drivers than their windows counterparts. i know because the card in
my laptop (the maestro m3) loads a quick-and-dirty sample rate converter
into the dsp chip on the card, as opposed to the all-singing-all-dancing
version that is included in the windows driver. the upshot of this is that
the normal pre-filtering that happens when doing sample rate conversion
doesn't happen, and so frequencies that some frequencies higher than 50%
volume will distort. on this particular card you can just output at 48k to
avoid having to use the samplerate converter.
err, but this probably isn't your problem because the value you have found
is suspiciously close to 1/256. making me thing that it's some kind of
signed/unsigned value problem in the way that pd is talking to your sound
card. your best bet is to say what kind of sound card you have, and
whether you are using alsa, oss, or whatever.
try using jack too.
report on your success, and it might inspire a response.
On Fri, 15 Aug 2003 00:29:09 +0930
Nick Morrison <nickm at internode.com.au> wrote:
> Hello list,
> I asked a similar question a while back, so apologies for repeating
> If I have a patch like so:
> [osc~ 440]
> Should I get a clean output signal from my speakers?
> At the moment, the only way for me to get a signal without distortion is
> to do this:
> [osc~ 440]
> [*~ 0.0038] <- found through trial and error :-)
> The above patch makes a clear sound for me.
> My mixer settings are nominal. Other audio apps - xmms, play, mplayer,
> etc work properly.
> My question: Is there a "hidden" gain control I can tweak on the pd
> command line? Is this behaviour normal? It's as if pd is setting the
> sound card's gain to a very high level, causing distortion - but mixer
> tells me everything is nominal.
> I would simply upgrade to the latest version instead of troubling the
> list, but it's proving to be troublesome to compile under FreeBSD 4.8.
> There is a ports version, but it is still at 0.35. I'm on the verge of
> replacing my FreeBSD with Linux just for the sake of pd :-)
> Nick Morrison | Email: nickm at internode.com.au
> CCNA, CCDA, WLAN-SE, BCRAN | Phone: (08) 8228 2999
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