[PD] lower limit on control to signal

[Roman Haefeli]

On Wed, 2010-12-08 at 14:33 -0800, Jonathan Wilkes wrote:
> Hi List,
>      I have a question about converting control messages to signal 
> messages that I thought about after reading a recent thread about 
> triggering sounds made from [osc~].
>      I recently tried a simple test to see if I could generate audio 
> using a [del] metronome, a counter, and [sin] in a subpatch with 
> [block~ 1].  However, I ended up with a kind of staircase signal that 
> resembles a sine wave, where each step is 64 samples long.
>      Does this mean it's not possible in Pd to  
> convert control messages to audio faster than however long it takes to 
> play a 64-sample block?  I (think) I understand why this is true for a 
> normal canvas with the default blocksize 64, but not for the subpatch 
> where I've reset the block size to be smaller.

Yeah, it is possible and no, you don't need to adjust the  block size of
the canvas. Setting the block size can be useful for implementing short
audio signal feedbacks and for FFT operations where you sometimes need
even bigger block size. 
The case you describe here is about message to signal conversion which
should generally work without adjustments to block size. First, you need
a metro that is faster than the 1ms-limited [metro], so your [del] based
metro should do. [del] and [metro], both are able to schedule messages
in between of blocks, but not all object classes with control inlets and
signal outlets take that scheduled timing into account. For instance,
[sig~] updates the audio signal only at block boundaries. OTOH, [vline~]
uses this timing information to create sub-sample accurate signals
(sub-sample accurate means here that a ramp might start and end between
samples).
I assume, you're now using a [sig~] for the conversion. Try replacing it
with a [vline~] and it should do.

I am too lazy to test right now, so I hope everything I said is correct.

Roman