[PD] Simple Subtractive Synth filter envelope

Jonathan Wilkes jancsika at yahoo.com
Tue Nov 23 00:57:14 CET 2010


--- On Mon, 11/22/10, Claude Heiland-Allen <claudiusmaximus at goto10.org> wrote:

> From: Claude Heiland-Allen <claudiusmaximus at goto10.org>
> Subject: Re: [PD] Simple Subtractive Synth filter envelope
> To: pd-list at iem.at
> Date: Monday, November 22, 2010, 11:09 PM
> On 22/11/10 21:48, samuel rowe
> wrote:
> > an envelope generator with ADSR
> 
> vline~ is your friend here:
> 
> "1 10, 0.5 100 10, 0 1000 2000"
>  |
> [vline~]
>  |
> [*~]\[osc~ 666]
>  |
> [dac~]
> 
> > the output will not feed into the argument for a
> filter cutoff value.
> 
> right. you can't connect signal outlets to message inlets:
> http://www-crca.ucsd.edu/~msp/Pd_documentation/x2.htm#s4.2

Big problems with the text you are quoting:
1. 3rd paragraph, sentence one contradicts 3rd paragraph, sentence 
two.
2. The whole section is outdated because it doesn't mention the 
automatic conversion from float to signal.
3. The last paragraph/sentence of that section doesn't specify that 
the leftmost inlet of an abstraction cannot take both messages and 
audio (which is implied by paragraph 2, last sentence).
4. It is generally confusing to read in the first sentence that an 
xlet is either _for_ x or y, with y xlets accepting x some of the 
time.  It might be clearer to just name the xlets: say xlets are 
_either_ control or signal xlets, then explain the difference (and 
that they are visually distinct).

Here's a first attempt at a revision:

'There are two types of inlets and outlets in Pd: control and 
signal.  Control inlets only accept messages, just as control outlets 
only output messages.  Signal inlets accept audio, and may also 
accept messages; signal outlets, however, only output audio.
Thus, it's an error to connect a signal outlet to a control inlet; 
usually this error is detected when the user tries to make the 
connection with the mouse (which will be prevented).  Otherwise it is 
detected at "sort time" when audio is started or the network changed with audio running.

For convenience, float messages arriving at a signal inlet will be converted to audio. Additionally, an object's leftmost signal inlet may accept other messages as well.  Signal inlets/outlets, as well 
as signal connections, are visually distinct from control 
inlets/outlets.'

-Jonathan

> 
> and most of pd's filters (lop~, hip~, bp~, ...) expect
> messages for the parameters.  the workaround is to use
> the "raw filter objects" to build more complex filters from
> poles and zeros.
> 
> I made a resonant low pass filter using that method:
> http://lists.puredata.info/pipermail/pd-list/2007-11/056858.html
> [PD] pd filter with pole and zero
> Sat Nov 24 19:00:13 CET 2007
> 
> There are also externals with more filters (iemlib has
> many) and some abstractions out there somewhere.
> 
> Good luck!
> 
> 
> Claude
> -- http://claudiusmaximus.goto10.org
> 
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