Hi,
I suppose that many of you are or might be using fftw for real-time audio processing, and I think the following information may be of your interest.
I just came to realize that fftw_execute calls malloc. This happens even though you create a 'plan' where you pass fftw_malloc preallocated input and output buffers.
It goes without saying that calling malloc is bad practice for audio callbacks, but as a reference I quote the jack_set_process_callback documentation:
The code in the supplied function must be suitable for real-time execution.
That means that it cannot call functions that might block for a long time.
This includes malloc, free, printf, pthread_mutex_lock, sleep, wait, poll,
select, pthread_join, pthread_cond_wait, etc, etc.
I wrote the fftw developers and they confirmed the memory allocation takes place. They suggested the following:
> Try planning with the undocumented flag FFTW_NO_BUFFERING, which will
> prevent the use of malloc() in common cases. This is not
> foolproof---some transforms are very hard to do without additional
> buffers, but if all you are trying to do is vanilla out-of-place 1D
> transforms without large prime factors it should work.
Maarten
Dear all,
I'm collaborating with a lecturer on creating tests to
deliver to users for research purposes. His idea is to
deliver them using mobile devices like the iPhone and
I'd like to use one of the OS devices like the Neo FR,
Pandora or even Indamixx. The problem is that, if it
all goes well, we'd need a lots of them (50/100), so
I'm looking for something cheaper at the moment.
Do you have any idea/suggestions? Of course I
prefer OS devices.
Thanks all, as always!
Marco
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hi...
jacksession stuff is merged into jack1 svn.
here is a rough explanation what needs to be done for apps to support
it: http://trac.jackaudio.org/wiki/WalkThrough/Dev/JackSession
please let me know what is unclear.
--
torben Hohn
> One part of my income I make as
> a IPhone developer so let me tell you, deploying on IPhone/Ipod is pain. Its
> very likely that your app is rejected by Apple because of the limited use so
> you have to deploy on your own. With the developer account you can only
> deploy on up to 99 devices and the app is time limited, cant be started
> after some months. Without it (and a Mac) nothing.
That's why I want to stay away from Apple, at least for the moment.
> You already suggested game handhelds so possibly a Dingoo A320 would be
> enough. Input is limited to joypad and some buttons but for a simple
> multiple choice test its enough. Results could be stored on miniSD card.
> The Dingoo costs around $60-$80.
This is really interesting, looks like a small DS.
> The next would be a GPH Wiz which offers pen input, its the successor of
> GP2X, setting you back with $120-$140
And this one is even better. I like the idea of having stylus input.
> Or get one of these for $99 with keyboard
> http://www.engadget.com/2010/03/15/qi-hardwares-tiny-hackable-ben-nanonote-…
You're the second one suggesting this one. It's not too far from
Pandora, but it's cheaper and closer to a smartphone from a
dimension point of view. Do you have experience developing for
these? Is it difficult or it's like any other Linux based system?
>Cheers,
> Malte
Thanks,
Marco
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