[PD] PD ASIO

[Thomas Grill]

> 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).

Hi Guenter, these the results of my test with a quickly sketched PortAudio
test program (it might not be too clean....)

Portaudio latency (with ASIO - RME HDSP digital loopback):
hdsp buffer = 256 samples -> latency 516 samples (= 11.1 ms)
hdsp buffer = 128 samples -> latency 260 samples (= 5.9 ms)
hdsp buffer = 64 samples -> latency 132 samples (= 3.0 ms)

The choice of the portaudio buffer size doesn't seem to have an influence
(tested with 16,32,64).
D/A and A/D conversion (RME Multiface) adds another
60 samples (what surprises me a lot).


best greetings,
Thomas