[PD] [GEM-dev] Timing and PD....

Hans-Christoph Steiner hans at eds.org
Thu Oct 30 15:32:24 CET 2008

I agree.  I think for any indeterminate operation, like anything in a  
separate thread, there should be a bang when that operation is  
complete.  That way you can guarantee that things are ready when you  
run a process.  If you want to make sure that things will be there on  
time, then these threaded/indeterminate operations should run well in  
advance.  Using guesswork and delays is not a real solution...


On Oct 30, 2008, at 4:25 AM, cyrille henry wrote:

> helo,
> i'm also having this kind of problem.
> specially when loading a picture in pix_image.
> i think the best would be the have a bang when things are ready...
> C
> B. Bogart a écrit :
>> Hey all,
>> I'm having more and more problems with sync in PD. By sync I mean  
>> that
>> parts of my patches have processing delays that mess up timing. In
>> general I've been using buffers and delays to keep things working.
>> This approach is not very scalable.
>> I find myself using the "timer" object all the time to see if  
>> there is a
>> processing delay I have to worry about. That is in cases where  
>> there is
>> a bang saying an operation is done.
>> Two examples I'm working on now (in Gem):
>> First there is a delay between sending a message and the  
>> pix_buffer to
>> store, and then again for pix_buffer_read to read the pixels. The  
>> delay
>> is long enough that trigger does not work, there needs to be a  
>> delay to
>> make sure the image in the buffer is the right one. (sometimes as  
>> much
>> as 200ms)
>> A second example is that I'm using pix_share and and second PD  
>> instance
>> to offload some CPU usage. Making sure the image sent to that PD
>> instance and the image received later in the chain is difficult.
>> I'm not writing for specific advice, hence the generalities, but  
>> wanted
>> to start a discussion on the issue.
>> What is the long-term solution for PD to solve these issues?  
>> Should all
>> objects that introduce a delay send a bang when they are complete?  
>> (for
>> example pix_buffer? Of course an additional delay occurs when when  
>> the
>> pix_buffer is written to memory and when it gets to the gfx card for
>> display.
>> I'm banging my head over these issues a lot lately and wonder if  
>> there
>> is a better approach.
>> Back to attempting kludging a solution.
>> .b.
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