[PD] How's Pd limited?

peiman khosravi peimankhosravi at gmail.com
Thu Feb 25 10:49:09 CET 2016 

Two example I can think of. One-sample delay/feedback for filter design
etc. And real-time zero-crossing detection with sample-rate precision.

On Wednesday, February 24, 2016, Matt Barber <brbrofsvl at gmail.com> wrote:

> How fine-grained does it need to be? As long as all the parameters are
> known at the beginning of the block, you have everything you need. As far
> as human interaction is concerned, 64-sample blocks are extremely
> fine-grained. The individual cycles of the pitches at the beginning of
> Beethoven's 5th are coarser grained. For computer generated events, there
> are ways to schedule events to begin in the middle of a block.
>
> The idea of a kind of Pd JIT compiler is interesting, though.
>
> On Wed, Feb 24, 2016 at 4:54 PM, Brian Fay <ovaltinevortex at gmail.com
> <javascript:_e(%7B%7D,'cvml','ovaltinevortex at gmail.com');>> wrote:
>
>> 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
>> <javascript:_e(%7B%7D,'cvml','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
>>> <javascript:_e(%7B%7D,'cvml','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
>>>> <javascript:_e(%7B%7D,'cvml','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 <
>>>>> <javascript:_e(%7B%7D,'cvml','ch at chnry.net');>ch at chnry.net
>>>>> <javascript:_e(%7B%7D,'cvml','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
>>>>>>> <javascript:_e(%7B%7D,'cvml','composer.samuel.burt at gmail.com');>
>>>>>>> <mailto:composer.samuel.burt at gmail.com
>>>>>>> <javascript:_e(%7B%7D,'cvml','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 <
>>>>>>> <javascript:_e(%7B%7D,'cvml','dmedine at ucsd.edu');>dmedine at ucsd.edu
>>>>>>> <javascript:_e(%7B%7D,'cvml','dmedine at ucsd.edu');> <
>>>>>>> javascript:_e(%7B%7D,'cvml','
>>>>>>> <javascript:_e(%7B%7D,'cvml','dmedine at ucsd.edu');>dmedine at ucsd.edu
>>>>>>> <javascript:_e(%7B%7D,'cvml','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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-- 

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