Hello,
Recently, Linus committed a patch from Alan Cox that removes the
controversial decompressors of the PWC module from the kernel. The
commit log [1] suggests to reimplement the decompression code in userspace.
I'm wondering how this could work. Webcam drivers are supposed to offer
to userspace a V4L-compatible API, in order to work with programs such
as xawtv or gnomemeeting. If the decompression code is not made in
kernel space, how can the kernel offer a V4L-compatible API for the PWC
webcams ? Having a library called by the user programs doesn't seem to
be an option, because it would require an adaptation of all user
programs, adaptation which would specific to a particular webcam type.
Should the compressed frame be sent to a userspace daemon which
decompress it and then sends it back to the kernel, which could offer a
V4L-compatible API ? Isn't it a bit overkilled ?
I just wanted your opinion and ideas about this subject, just for
curiosity. I'm not saying I will try to do the horrible reverse
engineering stuff, I just want to understand how it _could_ work.
Thanks !
Thomas
[1]
http://www.kernel.org/git/gitweb.cgi?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=88c1834633341bbb94e315433067496338bff4ad
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Thomas Petazzoni
thomas.petazzoni@xxxxxxxx
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