[Bug 576023] Review Request: libwebcam - user-space configuration of the uvcvideo driver

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https://bugzilla.redhat.com/show_bug.cgi?id=576023

Hans de Goede <hdegoede at redhat.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
         AssignedTo|nobody at fedoraproject.org    |hdegoede at redhat.com
               Flag|                            |fedora-review?

--- Comment #10 from Hans de Goede <hdegoede at redhat.com> 2010-07-12 06:00:36 EDT ---
Hi Michael,

I accidentally stumbled over this review request, which is good as I was
planning on packaging libwebcam myself :)

Self Intro
----------

Short self intro I'm a long time Fedora contributor who has packaged and
maintains many many packages (and I'm also a sponsor). Lately I've been mainly
working on improving webcam support under Fedora, see:
https://fedoraproject.org/wiki/Features/BetterWebcamSupport
https://fedoraproject.org/wiki/Features/BetterWebcamSupportF12
https://fedoraproject.org/wiki/Features/BetterWebcamSupportF13

Oh and since circa 2 years I work for RedHat now, but that is of little
relevance in this case, this is me with my Fedora hat firmly on :)

On libwebcam
------------

So back to libwebcam, I'm afraid that with libwebcam you've chosen an
interesting (but also very useful) first package. I've been working together
with Paulo Assis (guvcview author and Debian libwebcam packager), Laurent
Pinchart (uvcvideo kernel driver author) and libwebcam upstream to fix a number
of problems / shortcomings of libwebcam.

As Stefan mentioned in comment #9, the most important bit of libwebcam (at
least for me) is uvcdynctrl. You probably already know this, but uvcdynctrl +
libwebcam  use xml files with descriptions for various manufacturer specific
controls on uvc webcams (currently only Logitech), and tells the uvcvideo
kernel driver how to map various custom uvc level "controls" to standard v4l2
controls, so that they can be changed using a v4l2 control panel application
like v4l2ucp or gtk-v4l.

We want the libwebcam package to install udev rules to automatically run
uvcdynctrl to tell the driver about these controls when a relevant webcam gets
plugged in (or is plugged in wen the system boots up). I see that you're
current package is missing uvcdynctrl and the udev rules, so that will be a
first thing to fix. It is probably best to base your work for this on top of
the work Paulo has done for Debian, instead of:
# svn export -r 90 http://svn.quickcamteam.net/svn/qct/webcam-tools/trunk/
libwebcam-0.2.0
do:
# svn export -r 90
http://svn.quickcamteam.net/svn/qct/webcam-tools/branches/deb libwebcam-0.2.0

Also the current version of libwebcam lacks the ability to add button and menu
type v4l2 controls, which make it not work very well for the logitech camera
LED controls for example. I've worked together with Laurent Pinchart to add
support for this to the kernel API used by uvcdynctrl, the patches for the
kernel for this are in Laurents tree:
http://git.linuxtv.org/pinchartl/uvcvideo.git?a=commitdiff;h=2bd47ad4894bfaf1a97660b821cbc46439a614d6
http://git.linuxtv.org/pinchartl/uvcvideo.git?a=commitdiff;h=4930f2662e47d33e5baedac620da401a225bc3a8

And I have matching patches for libwebcam / uvcdynctrl for this. I've send
these to libwebcam upstream, but unfortunately libwebcam upstream is not really
fast with processing these, so we will need to add these to the Fedora
libwebcam package for now.

Hmm, too much information I'm afraid, as said with libwebcam you've chosen an
interesting first package.

Summarizing:
1) You should add uvcdynctrl + udev rules to the libwebcam package, it is best
to base your work on the Debian branch for this, to get the Debian branch do:
svn export -r 90 http://svn.quickcamteam.net/svn/qct/webcam-tools/branches/deb
libwebcam-0.2.0

2) I would like to see some patches added to the Fedora package which add
support for menu and button controls, but lets first just tackle 1). If you can
provide an updated spec file and srpm with 1) fixed I'll do a more thorough
review of that.

About getting sponsored
-----------------------

An important part of the getting sponsored process is showing that you've got
the necessary packaging skills and knowledge of the packaging guidelines as
mentioned already in comment #8 one way of doing this is doing reviews of other
packages which are awaiting review (when you do this please add a note you are
not doing an official review).

An other option is to show your skills by creating a couple of packages. Given
that your current libwebcam package only packages the library itself, I'm
guessing that you are packaging libwebcam because it is needed by something
else you plan to package. You could for example also submit that for review (it
is ok to have multiple review requests outstanding while waiting for
sponsoring). Or if I may suggest something you could package v4l-utils, the
successor of libv4l:
http://www.linuxtv.org/downloads/v4l-utils/
http://cvs.fedoraproject.org/viewvc/devel/libv4l/libv4l.spec?view=co

Regards,

Hans

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