Inclusion of libv4l into Debian
Hi,
First, let me indroduce libv4l[1]. It's an userspace Video4Linux helper
library as libasound is for ALSA. Currently it consists of four parts:
1. libv4lconvert:
libv4lconvert offers functions to convert from any (known) pixelformat
like MJPEG or some obscure Bayer pattern formats to YUV or RGB.
2. libv4l1:
This offers functions like v4l1_open, v4l1_ioctl, etc. which can by used
to quickly make v4l1 applications work with v4l2 devices.
3. libv4l2
This offers functions like v4l2_open, v4l2_ioctl, etc. which can by used
to quickly make v4l2 applications work with v4l2 devices with weird formats.
4. wrappers
The functionality provided by libv4l1 and libv4l2 can also be used by
existing apps without modifying them. For this purpose two wrapper
libraries are provided which can be preloaded using the LD_PRELOAD
environment variable.
Rationale for inclusion:
Most currently sold webcams only provide these obscure, sometimes camera
specific image formats and won't work with most V4L applications
expecting YUV or at least RGB. A prominent webcam driver which delivers
such formats is the gspca driver, available in Linux 2.6.27. The "Right
Thing" to do for the apps would be the usage of libv4l as a shared
library. But until all apps are converted the wrappers will do a good job.
Of course I'd like to see libv4l as soon as possible in Debian. As it
currently has no rdepends, inclusion in Lenny won't hurt at all. And if
you upgrade the Linux kernel in Etch + 1/2 the gspca driver have his
companion already in the archive. The con side is, that libv4l is only
(widely) tested on i386 and amd64. I don't know if it even compiles on
mips, et. al.
In a perfect world, a lib4vl update would be available via volatile
and/or proposed-updates as soon as a new camera format is available.
I've got a mail from Otavio Salvador <otavio@debian.org>, a potential
sponsor:
My opinion about that is for me to upload it I'd need an ack from
RT. Lenny is frozen and we're really near of release and then it is
your turn to try to convince them. Otherwise it could be uploaded for
experimental until we sort the release out.
So are you ok with uploading libv4l to unstable to get a wider testing
audience and see how to proceed?
Thanks,
Gregor
[1]
http://mentors.debian.net/cgi-bin/maintainer-packages?action=details;package=libv4l
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