[PD] webcam problem in Gem with Ubuntu Intrepid/Pd-extended 0.41.4-rc3
IOhannes m zmölnig
zmoelnig at iem.at
Mon Jun 1 17:10:40 CEST 2009
> and for the next session
> echo "export LD_PRELOAD=/usr/local/lib/libv4l1/v4l1compat.so" >> ~/.bashrc
actually i would not recommend this.
LD_PRELOAD seriously interferes with how application linking works (and
is therefore usually discouraged); the sole purpose of it is to allow
library calls be intercepted and provided by a different backend,
something useful when doing debugging or swapping a backend for a single
application (like chromium does with openGL apps; or libv4l-compat in
otoh, the only thing that libv4l compat can actually intercept is calls
to ioctl(), which is deep on the kernel-side. overriding ioctl for each
and every application is probably really not what you want.
apart from slowing everything down (as it wraps a system call!), you
might turn otu seeing your harddisk as a webcam. probably nice pictures,
but bad data.
(surely libv4l-devs are trying to do everything to not do any harm when
wrapping system calls; but they will most likely have bugs in their code
thus the way to go, is to compile an application with native libv4l support.
anyhow, i just wanted to point out, that people here are lately
suggesting a log of brute force "solutions", which might work fine but
nevertheless i think it would be proper to warn anybody that they might
just grill their cat.
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