[ale] Sound question

JK jknapka at kneuro.net
Wed Feb 10 13:24:48 EST 2010


Hi folks,

I'm trying to use the Csound software sythesizer to do real-time audio
processing on Ubuntu 9.10 (specifically, I want to use it to process
live guitar signals, so minimizing latency is critical).  Getting this
working is turning out to be a huge hassle

I got it basically working, with one serious issue: even for Csound
to merely copy the raw signal from input to output was taking over
100ms, which is a   L    O    N    G  time when you're trying to play
live. Asking the Csound community the possible reasons for this,
it seems PulseAudio is the likely culprit -- it introduces massive
latencies which are not noticeable unless synchronization between
input and output is important.

So I un-installed PulseAudio, but now Csound cannot seem to read any
audio input, or render any audio output.  I guess PulseAudio must've
had its tentacles insinuated into the sound architecture in ways that
I don't begin to comprehend.

So my question is, WTF is up with sound on Linux?  In the old days,
one would simply read audio from /dev/dsp and write audio to
/dev/audio, and that worked fine.  Now there are so many acronyms
and packages involved that I have absolutely no idea what they're
all doing.  Is there an overview document somewhere?  Or is anyone
here doing realtime audio processing on a Linux box?

BTW: switching distros is not on the table for me, right now.  I
might consider it if there were serious advantages to be gained,
but I like Ubuntu, and I've got a bunch of other stuff going on on
this machine that I'd rather not have to re-construct after a
re-install.

Thanks,

-- JK


-- 
We Americans are a freedom-loving people, and nothing says "freedom"
like Getting Away With It. -- Guy Forsyth, "Long Long Time"


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