[轉貼自]
http://tpurch-blog.blogspot.com/2010/02/webcam-upside-down.html
Suffering from upside down Webcam?
Well your not the only one. It appears that its a common problem!
Some manufacturers mount the webcam upside down...In Windows the
software detects the problem and flips the image automatically. Linux
handles the problem differently. Most (but not all) Linux software that
makes use of the webcam via a a collection of userspace libraries
called libv4l.
libv4l adds a thin abstraction layer on top of video4linux2 devices. The
purpose of this layer is to make it easy for application writers to
support a wide variety of devices without
having to write separate code for different devices in the same class.
If your webcam is running upside down, download the latest libv4l. Then
run your webcam app with following proceeding it:
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so
For example, if you want to run Kopete instant messenger you would run:
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so kopete
if your webcam is still upside down then you should run the following commands:
lsusb > lsusb.log
dmidecode > dmi.log
then email Hans de Goede (hdegoede@redhat.com) explaining you have a
webcam with upside down image and attaching the two log files you have
just created (lsusb.log & dmi.log).
Hans will update libv4l and send instructions back on how to install it.
For ASUS X5DC users, I have already asked Hans to update so this should work(thanks Hans!)
You can download the new version here:
http://people.fedoraproject.org/~jwrdegoede/libv4l-0.6.5-test.tar.gz1. Install
===========
Howto install and test libv4l depends on your system. There are
different instructions for if you have a 32 bit system or a 64 bit system.
which is using multilib. A 64 bit system without multilib is the same as
a 32 bit system.
To find out what you have do:
ls -d /usr/lib64
If this command gives a "No such file or directory" error, use the Non
multilib instructions, if the second command is successful, you have
multilib, to find out which version (dubbed Fedora and Ubuntu multilib,
because those are the most well known examples, do):
ls -d /usr/lib32
If this command gives a "No such file or directory" error, use the
Fedora multilib instructions. If this command succeeds use the Ubuntu
multilib instructions. Note the ubuntu multilib instructions also apply
to gentoo.
Non multilib instructions:
-------------------------------
tar xvfz libv4l-0.6.5-test.tar.gz
cd libv4l-0.6.5
make PREFIX=/usr
sudo make install PREFIX=/usr
Fedora Multilib instructions:
-----------------------------------
Basic 64 bit install:
tar xvfz libv4l-0.6.5-test.tar.gz
cd libv4l-0.6.5
make PREFIX=/usr LIBDIR=/usr/lib64
sudo make install PREFIX=/usr LIBDIR=/usr/lib64
If you also want to use 32 bit apps (such as skype), you
will need to have the 32 bit libc headers installed, on Fedora
this can be done like this:
Fedora 10-: "sudo yum install glibc-devel.i386"
Fedora 11: "sudo yum install glibc-devel.i586"
Fedora 12+: "sudo yum install glibc-devel.i686"
Then do:
make clean
make PREFIX=/usr CFLAGS=-m32 LDFLAGS=-m32
sudo make install PREFIX=/usr
Ubuntu Multilib instructions:
-----------------------------------
tar xvfz libv4l-0.6.5-test.tar.gz
cd libv4l-0.6.5
make PREFIX=/usr
sudo make install PREFIX=/usr
If you also want to use 32 bit apps (such as skype), you will need to
have the 32 bit libc headers installed, on Ubuntu this can be done like
this:
sudo apt-get install libc6-dev-i386
On gentoo this can be done like this:
sudo emerge -v app-emulation/emul-linux-x86-compat
Then do:
make clean
make PREFIX=/usr CFLAGS=-m32 LDFLAGS=-m32 LIBDIR=/usr/lib32
sudo make install PREFIX=/usr LIBDIR=/usr/lib32
2. Testing
========
You have a chance that your webcam app use libv4l or have an appropriate
script starting it. In that case you don't have to do anything. Just
run the application. This is the most common situation with Ubuntu and
Fedora packages. If your problem remains unsolved, then your app might
not use libv4l.
In that case start the application from a terminal like this:
Non multilib:
----------------
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so
Note on Ubuntu sometimes skype is using a wrapper script, so if skype
does not work try:
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so skype.real
Fedora multilib:
--------------------
For 64 bit applications (almost all apps):
LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so
For 32 bit applications (you only need it for proprietary softwares, which don't have a 64 bit version, like skype):
LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so skype
Ubuntu multilib:
--------------------
For 64 bit applications (almost all apps):
LD_PRELOAD=/usr/lib64/libv4l/v4l1compat.so skype
For 32 bit applications (you only need it for proprietary softwares, which
don't have a 64 bit version, like skype):
LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so skype
Note on Ubuntu sometimes skype is using a wrapper script, so if skype does not work try:
LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so skype.real
=====================================================================================================================================
The only problem is that everytime you want to use Skype webcam, you have to key in the command "LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so skype" to open Skype to
make the webcam normal.
