Weird, weird weird, but solved it seems.
Roman Haefeli escribió:
i think, the samplingrate, that pd thinks it is using and the one that it is actually using, are differnt. try an [osc~ 440], it will sound like a d.
First I tried by using -noaudio and the timing issue disappeared, suggesting the diagnostic made by Roman was correct.
Then I switched to ASIO mode and the timing issue disappeared. I don't have absolute ear nor a diapason (nor any tuned musical instrument at home), but the tone in "test Audio and Midi" sounds exactly equal to the one in my older computer with XP which I know to be a reliable reference.
Also, with ASIO I was able to use the default 70ms latency settings without glitches, while in default MMIO mode I had to use 200ms or so.
Now the WEIRD WEIRD thing is that I switched back to MMIO mode, and now it still works fine, the timing is still correct.
I never made any "save all setting", so I restarted the computer (Windows Vista, the one previously presenting the issue), I opened PD with its default settings (MMIO) and opened the time test patch, changed only the latency setting to 200 in order to avoid glitches, and everything still works fine, with correct timing and correct pitch. Even changing sampling rate to different values, everything works as expected. In MMIO mode. And of course if I switch to ASIO it also works fine (and with lower latency).
I assure you that when I wrote I had tested the issue more than once and also after restarting the computer at least once.
I can only guess that the simultaneous use of some other application accessing the soundcard (IExplorer through Flash or Silverlight plugins, quicktime player, winamp, etc) may have messed something up, and probably even if I tested more than once even restarting the computer, I always had one of such applications running (often I listen to music or see stream TV programs and then leave winamp or the browser open and minimized and idle without closing it - bad habits).
So the problem seems gone and seems to be related to some sound card driver mess, possibly not related to any PD bug.
Thank Roman for the suggestions.
Bye m.