[PD] looking for a circular buffer for dsp blocks or similar.

[Martin Schied]

Hi!

is there already something like a 'circular buffer' external or 
abstraction for dsp blocks?

I want to detect onsets / attacks of 512 sample long signals using 
[fiddle~ 1024] and write them in arrays of 1024 samples.

for now my patch looks like this:

the signal is going to [fiddle~ 1024] and to a [delay~] with 576 samples 
(512 + 64) which is going to tabwrite~.
after fiddle~ detects an attack it starts a recording of tabwrite. (see 
also attached patch)

Altogether this process needs 33ms (1024 + 512 + 64 samples) after an 
attack has happened to record a signal of 22ms. (1024 samples)

My idea was, to use a kind of delayline which is big enough to contain 
the whole signal and then copy the entire content of this delayline "in 
one moment", so in effect no time has been wasted for delaying the 
signal. It could save 11ms in this example.

I'm also open for other suggestions. I already thought of 
"pre-recording" blocks with multiple delay~ + tabsend~ and copying them 
together after a bang from fiddle~, but felt not well by thinking this...
also some concerns for this:
-using big blocks (1024) there's an additional uncertainity to match 
analysis windows of fiddle~ so their offset to fiddle~ must be known.
-using small blocks (64) this becomes unhandy for long delays when not 
using dynamic patching (at least with my knowledge of pd)

btw. can somebody explain where those additional 64 frames (1 Block) 
delay are coming from? Is fiddle's (and also bonk's) output delayed by 
one audio block? attached is an example showing this. (and also the 
above mentioned)

cheers,
Martin



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