Re: samplerate~ race condition?

IOhannes m zmölnig <[email protected]> Fri, 10 Jan 2025 12:45:51 +0100
Newsgroups	gmane.comp.multimedia.puredata.general
Message-ID	<[email protected]>
On 10/01/2025 00:13, Peter P. wrote:
> Hi list,
> 
> on Debian Linux with jackd running at 44100 it seems that [samplerate~] when [loadbang]ed will report a rate of
> 48000. But if this loadbang is [delay]ed by 1msec it will report the
> correct rate of 44100.

i can reproduce this. (and btw, a [delay 0] is sufficient to get the 
correct samplerate)

i wouldn't call it a "race condition" though, it's just that Pd 
initializes the audio backend after sending out the loadbangs.

christof's PR will probably fix this.

in general, the audio backend might impose a samplerate different from 
what you (or Pd) expected.
that could lead to a behaviour similar to what you describe, though 
totally expected. e.g. if you have two fixed-samplerate soundcards, one 
of them running at 48k and the other at 44.1k, and you switch from one 
to the other; then [samplerate~] should report different rates depending 
on when you bang it.
in order to work around this, you should probably query [samplerate~] 
when the DSP gets (re)started, rather than with loadbang.


however, the the really weird thing about this is actually that the 
samplerate passed via the preferences (and cmdline-flags) is ignored.
i would expect Pd to honour those settings in the first place 
(defaulting to 48000), and only change it if the audio backend demands 
otherwise.

using your settings-file (which sets 44100) and starting Pd *without* 
sound, but with (or without) an explicit "-r44100" i get:

```
pd -nosound -r 44100
```

i get:
@loadbang: 48000
@loadbang+0: 48000
@loadbang+1: 48000

hecking the audio-settings, i see that Pd claims to still use JACK as 
the backend (though - as expected - there's no sound), even if no JACK 
is actually running¹.


so yes, there are things to be fixed.

gmsadr
IOhannes




¹ all my JACK experiments now are a bit complicated, as i have PipeWire 
running and it's the default JACK implementation. but uisng 
LD_LIBRARY_PATH= to force the "real" JACK onto Pd (and jackd), seems to 
work OK.

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