obviously it doesn't have to be FFTs, in block-glitch1.pd I replaced the FFTs with square roots. But it's neither related to the number of block~ objects or subpatches. In block-glitch2.pd, I have a single blocked subpatch with lots of square roots and I get the same result. Again, the CPU load is not the problem. It seems the problem is merely related to reblocking, overlap and upsampling.
> Gesendet: Montag, 31. Oktober 2016 um 14:38 Uhr
> Von: "Christof Ressi" <
christof.ressi@gmx.at>
> An: pd-list <
pd-list@iem.at>
> Betreff: [PD] Weird issue: need to increase Pd latency in FFT patches, otherwise Pd sound output glitches and clocks are slowing down!!!
>
> Hi,
>
> I have the following issue with Pd 0.47.1 on Win 7 (onboard soundcard + ASIO4ALL and also Focusrite Scarlett 6i6 + Focusrite ASIO Driver):
>
> When I use more than just a few FFTs anywhere in my patch, I get a staggering sound output + clicks from Pd unless I increase the Pd latency... Apparently, it's only the playback because I couldn't hear it in a recording I made with [writesf~]. Therefore I made a recording in Reaper to show you what I'm hearing.
>
> The more FFTs and the larger the FFT blocksize, the larger I have to set the latency. This even happens if the CPU load is as little as 5% (where 25% would be the maximum for one hardware thread on my laptop).
>
> In my test patch, I put a couple of FFT subpatches and a single sine wave with a volume control to check the sound output. Usually, I can play a sine wave without artifacts as long as the CPU load is not peeking. But here, the FFTs seem to magically disturb the audio output of the whole patch...
>
> I think there's something going wrong with the scheduler because also objects like [metro] and [line] start to go slower - sometimes up to 50%!
>
> What is going on!?
>
> Christof_______________________________________________
>
Pd-list@lists.iem.at mailing list
> UNSUBSCRIBE and account-management ->
https://lists.puredata.info/listinfo/pd-list>