[PD] maximum "control rate" in Pd

[Alexandre Torres Porres]

since it was mentioned here, what's the behaviour and deal with
[vnsapshot~]? Cause there's no help file for ir yet.

thanks

2015-03-12 19:14 GMT-03:00 Charles Z Henry <czhenry at gmail.com>:

> On Thu, Mar 12, 2015 at 5:01 PM, David Medine <dmedine at ucsd.edu> wrote:
> > @Charles: None of those five sentences is a misconception. When I said
> 'DSP
> > functions' I meant the functions of the form 'whatever_tilde_perform',
> not
> > the dsp tick function. I see how this might lead to a misunderstanding.
>
> Sorry if I was unclear as well.  We *are* trying to split hairs here,
> of course, just to have an accurate description.
>
> It's not *all* of the dsp functions.  I thought this was unclear and
> tried to clarify: rather than scheduling them more often, it actually
> just loops over the sub-graphs multiple times when the block size is
> low.  There is always a parent function which is being run once every
> 64 samples (the default).
>
> > Also, I see that suseconds_t (which is the type of now.tv_usec)  is an
> > integer, as I had previously thought, so I am really perplexed as to how
> > [delay] can apparently deliver bangs within less than 1us. I would love
> for
> > someone to explain this to me. It is a small detail and it doesn't really
> > matter in practice, but I am annoyed when my inferences are not correct
> --
> > especially when I send them to the Pd list!
> >
> >
> > On 3/12/2015 1:58 PM, Charles Z Henry wrote:
> >>
> >> On Thu, Mar 12, 2015 at 3:18 PM, David Medine <dmedine at ucsd.edu> wrote:
> >>>
> >>> Yeah, of course. Block size 1 and high sampling rate will make the
> timing
> >>> between control and audio super tight (ChucK does this, for example).
> It
> >>> will also eat the hell out of your CPU. It's a trade off. This is
> because
> >>> you start calling all the DSP functions once every 1/192k seconds
> instead
> >>> of
> >>> once every 1.45ms.
> >>
> >> This last sentence is also a misconception--the dsp tick function is
> >> called every 64 samples, as commonly defined.
> >>
> >>      sys_time_per_dsp_tick = (TIMEUNITPERSECOND) *
> >>          ((double)sys_schedblocksize) / sys_dacsr;
> >>
> >> sys_schedblocksize gets set from DEFDACBLKSIZE
> >>
> >> So, the dsp_tick gets called, and when there is a sub-patch with
> >> [block~ 1], it loops over the graph generated from the sub-patch 64
> >> times.
> >>
> >> You'd find this behavior coded with the block prologue and epilogue
> >> functions.
>
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