[PD] PD and latency on kernel 2.6.14.2-lsm

Tim Blechmann TimBlechmann at gmx.net
Sat Nov 19 01:37:43 CET 2005


> For my personal education Tim, what are the "design decisions" that
> will never allow Pd to become a very good latency system?

pd is written as a single threaded application, if you read the pd
code, you can see this everywhere ... the main pd thread does
everything ... audio io, dsp computation, soundfile loading, object
generation, gui communication, midi io, messaging ... basically
everything.

but this is the contrary, how the audio hardware of all modern audio
apis (jack, asio, coreaudio, portaudio, possibly alsa) works. the sound
card sends an interrupt to the os, the driver calls a function in the
program that should send/receive the audio data...

my approach for devel was to use this callback to drive the dsp
computation, but to keep the system in sync, i have to lock the global
pd mutex. 
so basically all functions that are run, while the global pd mutex is
locked, should be executed, without locking the system for a too long
time ...

cheers ... tim

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