[ale] Sound question

[Ryan Marshall]

> 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
>
>


Well, I've got more questions than answers, really.

First, are you using a realtime kernel?  Secondly, why aren't you
using jack?  IIRC, I usually pull between 40 and 60 ms of latency and
that's a mostly vanilla setup.  I know it can get much lower with the
right tweaks and hardware.

Also, Jack may be a mess when it comes to the UI and config, but once
you figure it out, it really is a wonderful tool.