[PD-dev] [ pure-data-Bugs-3568989 ] subpatch-audio (reblocked) out of sync

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Bugs item #3568989, was opened at 2012-09-18 08:38
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Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Nobody/Anonymous (nobody)
Summary: subpatch-audio (reblocked) out of sync

Initial Comment:
Hello,
I think I've found a rather fundamental (vanilla) bug.
Imagine the following (as the title says): One has a (subpatch with) blocksize=64. Inside there are 2 more subpatches with a blocksize=128. Now it can happen, that both are in sync to eachother, because both are in sync to the 1st 64 samples of the parent-patch. Or they are not in sync, because one sticks to the 1st 64, tho other one sticks to the 2nd 64 samples.
It would look like this:

Out of sync:
Parent: =_=_=_=_=_=_=_=_=_=_... <-BS=64
Sub1..: ===_===_===_===_===_... <-BS=128
Sub2..: =_===_===_===_===_==... <-BS=128

Sync:
Parent: =_=_=_=_=_=_=_=_=_=_... <-BS=64
Sub1..: ===_===_===_===_===_... <-BS=128
Sub2..: ===_===_===_===_===_... <-BS=128

I won't paint it, but one can imagine that there is even more potential chaos if the blocksize-ratio is biger than 2 (=128/64).

This is the only part in pd, that really is not deterministic! Because this behavior, the "relative block-position" ("sync/no sync") can change with each dsp-switching. ..At least I couldn't find a way to make it do what I want..

To think of a more complicated version: Imagine one wants to sync subpatches, which are not in the same parent...

I don't know what it would be good for to have blocks not be synced, but there may even be an application for that.
So wouldn't it be a good idea to let the user decide how they sync??
...Maybe via some initial subpatch-parameters... Something like "1/2 or 2/2" for a BS-ratio=2. (1/8, 2/8, 3/8,..., 7/8, 8/8 for a BS-ratio=8) ...just as with a sequencer...

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