[PD] How's Pd limited?

Wed Feb 24 22:54:20 CET 2016

The issue with blocking is that you don't have fine-grained control of an
audio, process, right? If you want that level of fine-grained control, you
either need to explicitly set the blocksize to 1 in your patch/sub-patch,
or you need to actually dig into the C code for the externals and change
the logic there (which requires you write C code, recompile things, restart
Pd...).

Theoretically, there could be a way to swap out the code for an external
while Pd is running, rather than restarting Pd. Still, you'd have to write
C and pray that you didn't introduce some terrible bug.

But theoretically, instead of writing externals in C, couldn't we come up
with a high-level representation of a Pd external in a visual programming
environment similar to Pd? Then we could compile that down to an external,
and actually use it in our Pd patch, without actually reloading Pd. It
sounds very difficult, but I imagine gen~ does something like that.

For reference, I believe Extempore provides the ability to edit and replace
a low-level audio process while the program is running (I'll have to
rewatch some conference videos to confirm that).

On Wed, Feb 24, 2016 at 3:41 PM, Matt Barber <brbrofsvl at gmail.com> wrote:

> OK, now I'm having trouble even imagining how an unblocked audio model
> could possibly behave (at least, as David points out, in a real-time
> context).
>
> On Wed, Feb 24, 2016 at 2:58 PM, David Medine <dmedine at ucsd.edu> wrote:
>
>> This doesn't answer Matt's question at all (apologies), but just as a
>> clarification, ChucK *does *block audio. It's just that ChucK always
>> blocks at the minimum size of 1 sample per block. 1 is still a block size
>> though, and it still implies the same problems associated with order of
>> operations, feedback, interpolating control input, and parallelization that
>> a block size of 64 does.
>>
>> Also, maybe this has already been pointed out on this thread, but block 1
>> is super slow because it means that you have to load all your DSP functions
>> onto the CPU cache every 1/SR seconds instead of 64/SR seconds. Blocking by
>> 64 buys a lot. Having a locally adjustable block size is a great feature
>> (that ChucK lacks) because you can do it for special needs cases (like
>> variable delay patches, for example).
>>
>> Anyway, in my opinion, the block thing isn't a limit to Pd, but a limit
>> to real-time digital signal processing.
>>
>>
>>
>> On 2/24/2016 11:27 AM, Matt Barber wrote:
>>
>> Are there any other DSP environments besides ChucK that don't block
>> audio? Last time I tried ChucK (2012?) its efficiency was still abysmal.
>> [block~ 1] definitely takes a hit, but it's usually possible to minimize
>> how much of the DSP chain is actually blocked at 1. I guess with Csound you
>> can specify a k-rate equal to the sample rate which is also effectively a
>> single sample block. I haven't ever used Csound in a real-time context, and
>> most of what I do with it compiles much more slowly than real time in any
>> case.
>>
>> On Wed, Feb 24, 2016 at 1:44 PM, peiman khosravi <
>> peimankhosravi at gmail.com> wrote:
>>
>>> You can do this with MSP's poly~ too but I'm guessing that the CPU costs
>>> are quite heavy. Moreover, there are operators in gen that are designed for
>>> low-level operations.
>>>
>>>
>>> *www.peimankhosravi.co.uk <http://www.peimankhosravi.co.uk> *
>>>
>>> On 24 February 2016 at 16:15, cyrille henry < <ch at chnry.net>ch at chnry.net
>>> > wrote:
>>>
>>>>
>>>>
>>>> Le 24/02/2016 16:50, peiman khosravi a écrit :
>>>>
>>>>> One great advantage of maxmsp is gen, which gives you sample-level
>>>>> patching with the possibility of a one-sample delay.
>>>>>
>>>>>
>>>> you can use [block~ 1 1 1] in a pd subpatch.
>>>>
>>>> cheers
>>>> c
>>>>
>>>>
>>>> P
>>>>>
>>>>> On Tuesday, February 23, 2016, Samuel Burt <
>>>>> composer.samuel.burt at gmail.com <mailto:composer.samuel.burt at gmail.com>>
>>>>> wrote:
>>>>>
>>>>>     David,
>>>>>
>>>>>     One thing I attempted and couldn't find a solution for was the
>>>>> following, mostly owing to the limitation of interfacing with a 64 sample
>>>>> block size.
>>>>>
>>>>>     I wanted to have a directory of hundreds of audio recordings. Each
>>>>> one would be a single wavelength from an interesting sound, like a bass
>>>>> clarinet, marimba, harpsichord, tambourine, etc. Each would begin and end
>>>>> at a zero crossing so you could chain them together to make complex
>>>>> timbres. They could be chained in sequence, randomized, or loaded in
>>>>> meta-data-matched chunks. I ran into a problem figuring out how to trigger
>>>>> the next sound based on the ending of the last sound in a sample accurate
>>>>> way. Sound file loading or even buffer playback triggering waits until the
>>>>> start of the next block size before it updates. If you have a waveform that
>>>>> lasts 205 samples (64+64+64+13), you have a gap of 51 silent samples before
>>>>> the next waveform would start. Not only do you not get the continuous sound
>>>>> you want, this winds up creating a periodic pattern with a frequency of 689
>>>>> Hz (44100/64).
>>>>>
>>>>>     David, I like your idea "what (if anything) someone tried to do in
>>>>> Pd, but couldn't given its limitations". I think this could be a wonderful
>>>>> challenge if we could have a monthly thread like this where the best minds
>>>>> among us come up with solutions to some of the hardest conceptual
>>>>> challenges in Pd.
>>>>>
>>>>>     I'm still struggling with loading dozens of files, audio dropouts,
>>>>> and other similar problems. Someone else expressed frustration about Pd's
>>>>> single-threaded status. I too have feared upgrading my computer based on
>>>>> the limitations of current multicore processors (although realistically I
>>>>> think we can all look at the "turbo-boost" level or whatever Intel calls it
>>>>> to determine where our processor might run with a demanding patch. I
>>>>> understand the fact that you can't run your audio process on multiple
>>>>> cores, because it is a linear process. It would be great if the GUI could
>>>>> run on a second core, a process that loads audio into memory could run on
>>>>> third core, while GEM could automatically run on a fourth core. I don't
>>>>> have any concept of how feasible that would be, though. Does the GUI in
>>>>> pd-l2orc run on a separate core?
>>>>>
>>>>>     Sam
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>         Message: 4
>>>>>         Date: Tue, 23 Feb 2016 09:01:06 -0800
>>>>>         From: david medine < <dmedine at ucsd.edu>dmedine at ucsd.edu <
>>>>> javascript:_e(%7B%7D,'cvml',' <dmedine at ucsd.edu>dmedine at ucsd.edu');>>
>>>>>
>>>>>         One thing I'd be interested in knowing about is what (if
>>>>> anything)
>>>>>         someone tried to do in Pd, but couldn't given its limitations
>>>>> (apart
>>>>>         from look/feel/convenience issues).
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>>
>>>>> *www.peimankhosravi.co.uk <http://www.peimankhosravi.co.uk> <
>>>>> http://peimankhosravi.co.uk/miscposts.rss><
>>>>> <http://spectralkimia.wordpress.com/>
>>>>> http://spectralkimia.wordpress.com/>*
>>>>>
>>>>>
>>>>>
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