[Clam-devel] clam and max

[David García Garzón]

On Dimecres 30 Gener 2008, Greg Kellum wrote:
> Hi all,
>
> I tried to create a clam object for Max/MSP so that one could CLAM
> classes within the Max/MSP environment, but it seems that this isn't
> possible. The problem lies in the fact that Max doesn't allow you to
> allocate memory when audio processing is running.
>
> Typically, a Max object is supposed to allocate all of the memory it
> needs when the object is created, and then, when one turns on audio
> processing, the object just uses this preallocated memory. This is
> part of what makes Max fast. Max was for instance one of the first
> applications that were able to do a real time FFT on a desktop. (That
> was over ten years ago...)
>
> Due to this constraint, I knew that it wouldn't be possible to run
> CLAM networks in Max. The networks are allocating new memory every
> time something is passed from one CLAM object to another over a
> network connection. But I had hoped that by simply preallocating all
> of the objects I needed beforehand and calling them with their public
> methods that I could avoid having new memory being allocated during
> audio processing. I tried this, and Max crashed. I opened it up again
> in a debugger to see what happened.  And within CLAM's processing
> objects, objects are being copied by assignment, and Max was crashing
> in the middle of a call to an object's copy constructor where it was
> calling new.
>
> So, I've given up on the idea of running CLAM inside of Max, because
> this would only be possible by making some major changes to CLAM.

Hi, Greg, nice to read you again despite those are sad news.

By design, to be real-time safe, CLAM should avoid allocations after Start but 
can allow them while before (module creation, port binding, 
configuration...). I know that, currently, running time is not alloc free, 
but all those allocs are bugs that should be fixed.

In summary, if Max do not allow doing allocations during network setup i agree 
with you that Max integration, as we thought it, is not going to be feasible, 
but if Max allows doing allocation during setup, clearing running time 
allocation is a common but hard way we should take anyway: Preallocations of 
objects, allocation free copy, or no copy at all...

What i don't understand is why the allocation crashes. Does Max interfere with 
the standard library heap? Does a simpler Max module crash too doing an 
allocation?


-- 
David García Garzón
(Work) dgarcia at iua dot upf anotherdot es
http://www.iua.upf.edu/~dgarcia
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