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.

pix.

On Fri, 15 Aug 2003 00:29:09 +0930 Nick Morrison nickm@internode.com.au wrote:

Hello list,

I asked a similar question a while back, so apologies for repeating myself.

If I have a patch like so:

[osc~ 440] | | [dac~]

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 :-) | | [dac~]

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 :-)

Cheers,

Nick!

-- Nick Morrison | Email: nickm@internode.com.au CCNA, CCDA, WLAN-SE, BCRAN | Phone: (08) 8228 2999 Corporate Support and Provisioning | Fax: (08) 8235 6921 Internode Systems Pty Ltd | WWW:
http://www.internode.on.net/

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On Fri, Aug 15, 2003 at 12:29:09AM +0930, Nick Morrison said:

Hello list,

I asked a similar question a while back, so apologies for repeating myself.

If I have a patch like so:

[osc~ 440] | | [dac~]

Should I get a clean output signal from my speakers?

Thankyou to all who responded.

In the end, Jonas saved me with a freebsd port of version 0.37 TEST 6 - there are some good changes. The gui is a lot faster, and my annoying [*~ 0.0038] bug is gone :-)

So, I put it down to a bug in 0.35 that was resolved somewhere after 0.35.

Thanks again!

Nick