[PD] no more sound on iOS with biquad~ and libpd

IOhannes m zmoelnig zmoelnig at iem.at
Tue Jul 14 16:53:16 CEST 2015

On 2015-07-14 16:11, Jack wrote:
> Hello,
> Jumping fast to certain coefficient (for frequency around 40/50 Hz and
> Q around 0.7) cut sound on iOS (iPad) when i use libpd (it seems to be
> OK with MacOSX).
> I need to restart the iOS after.
> Do you know what I have to do to solve this issue ?

provide a test-patch.

two ideas:
- the quick jump causes some very high sample values. the iOS system
limiter~ mutes the signal and takes ages to recover (too long to wait).
a quick fix would be to use [clip~] just before the [dac~]s

- the quick jump might cause a NaN to be introduced in the signal
vector; due to the recursive nature of [biquad~] all successive samples
become NaNs. no quick fix for this.
try to get the sample values after muting. e.g. using [print~], or even
just [env~]...


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