[PD] metro slow down + audio drop-outs

[Giulio Moro]

Pd messages get processed in the audio thread in a sample-accurate fashion. This means that if you are sending many messages within the time of the audio callback, then your callback will take longer to execute. If the time it takes to execute exceeds the time available for it to complete, then you are going to get a dropout in the audio. I then believe that Pd's internal "logical time" will slow down compared to system time as a consequence of dropping one (or more) audio callback.
So you get both glitches and slower metro.

Solution is to throttle your messages: do not send them all at once but add a few ms delay between them.

Giulio

________________________________
From: Nicola Pandini <nicola.pandini at gmail.com>
To: pd-list at lists.iem.at 
Sent: Friday, 16 June 2017, 11:47
Subject: [PD] metro slow down + audio drop-outs



Hi list,

I have a patch that acts as MIDI master, that sends MTC and other data 

via udpsend to 4 udp ports.

It happens that sometime the patch's audio metronome begin to slow down 

for a bunch of seconds. I also hear cracklings in metronome sound (the 

metronome patch is based on a simple [metro] object).


I don't see any xrun, so I'm starting to think it's a problem of the 

patch. Maybe the buffer of udpsend? Because it seems to happen when I'm 

sending more data than usual (not everytime, though).

Can you give me some hints? I'm using pd-extended on Debian Jessie.


     Thanks


-- 

Nicola



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