guenter geiger geiger at xdv.org
Mon Dec 16 21:04:51 CET 2002

On Sat, 14 Dec 2002, Thomas Grill wrote:
> Hi all,
> i did some experiments with version 0.36 and i'm a bit disappointed that the
> audio (asio) part hasn't improved yet.
> I don't know if it's a PortAudio issue but i find it quite lame that under
> Windows (with a RME HDSP Multiface, digital loopback) i can't get stable
> audio with effective latencies under 30 ms. That may be ok for just playing
> sounds but it's not for live processing of instruments (for example
> percussion). The other thing is that using 18 in/18 out channels without any
> dsp load costs 16-20% of cpu (PIII 800) - that's just for audio IO!
> Has anyone had more success? How can the situation by improved?

There are two things, AFAIK with portaudio.
One is, that portaudio is a callback based library.  PD uses it in
write/read mode, which is definitely not optimal.

The second thing is that I headr rumours that portaudio by default
is configured to have a pretty high latency. You might be able to
change this in some portaudio file.
(This is really only a guess).

Under Linux, callback based JACK API, the minimum latency that is
achievable with pd is 10 ms. This is due to the imprecise linux
timers, it can be changed by recompiling your kernel.


> It would also be less confusing if the devices listed with the -listdev flag
> (now one-based) would exactly correspond with those specified by
> the -audiodev flag (zero-based)
> best greetings,
> Thomas
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