为了在Android上使用v4l2-ctl,fork了该项目。目前支持了rk3588(使用ndk 21b),要支持其它平台,改下utils/v4l2-ctl/rk3588.android.arm64v8a.cmake
即可
具体改动见commit
编译前需要修改-DCMAKE_ANDROID_NDK
指向自己的NDK路径
编译:
cd utils/v4l2-ctl
./build.sh
在Android上使用:
首先需要取得ROOT权限,或者固件为所有用户提供了/dev/video*的读写权限。
然后确定接入的摄像头是/dev/video的编号,一种方法是拔插后观察/dev/video增减情况,需要人工看。
另一种是根据usb端口号查看。比如对于我的板子,可以预先知道要接入的U口(指定了)是5-1,那么:
ls $(find /sys/bus/usb/devices/5-1/ -name "video4linux")
得到:video19 video20
用v4l2-ctl -d /dev/video19 -l
和v4l2-ctl -d /dev/video20 -l
确认下,有输出可控参数的节点就是目标节点。
最后,设置亮度:./v4l2-ctl -d /dev/video19 -c brightness=255
Linux utilities and libraries to handle media devices (TV devices, capture devices, radio devices, remote controllers).
You can always find the latest development v4l-utils in the git repo: http://git.linuxtv.org/v4l-utils.git.
Those utilities follow the latest Linux Kernel media API, as documented at: http://linuxtv.org/downloads/v4l-dvb-apis/.
Any questions/remarks/patches can be sent to the linux-media mailinglist. See https://linuxtv.org/lists.php for more information about the mailinglist.
There is also a wiki page for the v4l-utils: https://linuxtv.org/wiki/index.php/V4l-utils.
v4l-utils uses the meson build system.
A number of packages is required to fully build v4l-utils. The first step is to install those packages. The package names are different on each distro.
On Debian and derivated distributions, you need to install the following
packages with apt-get
or aptitude
:
debhelper doxygen gcc git graphviz libasound2-dev libjpeg-dev
libqt5opengl5-dev libudev-dev libx11-dev meson pkg-config
qtbase5-dev udev libsdl2-dev libbpf-dev llvm clang
On Fedora, the package list for a minimal install with dnf
or yum
is:
gcc gcc-c++ gettext-devel git meson perl which
(git is only requiried if you're cloning from the main git repository at linuxtv.org).
And, to be able to compile it with all usual functionality with qt5, you'll need also:
alsa-lib-devel doxygen libjpeg-turbo-devel qt5-qtbase-devel libudev-devel
mesa-libGLU-devel
The v4l2-tracer also needs the json-c library. On Debian: libjson-c-dev' ; on Fedora:
json-c-devel`.
After downloading and installing the needed packages on your distribution, you should run:
meson build/
ninja -C build/
And, to install on your system:
sudo ninja -C build/ install
Please notice that there's an extra feature to add an extra table to decode Japanese DVB tables via iconv. This is meant to be used when the iconv itself doesn't come with the ARIB-STD-B24 and EN300-468-TAB00 tables.
gconv is an auto feature, so it will be auto-enabled in case the dependencies are satisfied. However, the gconv feature can be forced to enabled by running the following command during configuration step:
meson configure -Dgconv=enabled build/
The v4l-utils doesn't quite follow the release versioning defined at semver.org.
Instead, since version 1.0, it uses MAJOR.MINOR.PATCH
. Where:
-
MINOR
- an odd number means a development version. When the development is closed, we release an even numbered version and start a newer odd version; -
MAJOR
- It is incremented whenMINOR
number starts to be too big. The last change occurred from 0.9.x to 1.0. -
All numbers start with 0.
All versions have their own tags, except for the current development version (with uses the master branch at the git tree).
The PATCH
meaning actually depends if the version is stable or development.
-
For even
MAJOR.MINOR
versions (1.0, 1.2, 1.4, 1.6, ...):PATCH
is incremented when just bug fixes are added; -
For odd
MAJOR.MINOR
versions (1.1, 1.3, 1.5, 1.7, ...):PATCH
is incremented for release candidate versions.
There should not have any API/ABI changes when PATCH
is incremented.
When MAJOR
and/or MINOR
are incremented, the API/ABI for the libraries might
change, although we do all the efforts for not doing it, except when inevitable.
The TODO
files should specify the events that will generate API/ABI breaks.
There are currently three media libraries defined at lib/
directory, meant to
be used internally and by other applications.
This library is meant to be used by applications that need to talk with V4L2 devices (webcams, analog TV, stream grabbers).
It can be found on the following directories:
lib/libv4l1/
lib/libv4l2/
lib/libv4l-mplane/
lib/libv4lconvert/
See README.libv4l
for more information on libv4l.
The libv4l is released under the GNU Lesser General Public License.
This library is meant to be used by digital TV applications that need to talk with media hardware.
Full documentation is provided via Doxygen. Building documentation is enabled
by the auto feature: doxygen-doc
. If enabled, it will be built within the
project.
It is possible to generate documentation in html, man pages and pdf formats.
The documentation is also available via web, at: http://linuxtv.org/docs/libdvbv5/.
It can be found on the following directory lib/libdvbv5/
.
The libdvbv5 is released under GPL version 2.
This library provides support for RDS radio applications.
It can be found on the following directory lib/libv4l2rds/
.
The libv4l is released under the GNU Lesser General Public License.
The utilities are stored under utils/
directory.
The (for now for v4l-utils private use only) libv4l2util library is released under the GNU Lesser General Public License, all other code is released under the GNU General Public License.
v4l-utils includes the following utilities:
Decodes tm6000 proprietary format streams.
Installed under <prefix>/bin
.
Dump, Load or Modify ir receiver input tables. The ir tables for remotes which
are known by the kernel (and loaded by default depending on dvb card type) can
be found under utils/keytable/keycodes
.
v4l-keytable does not get installed during the install step.
A swiss-knife tool to handle raw IR and to set lirc options.
QT v4l2 control panel application.
Installed under <prefix>/bin
.
Poll i2c RDS receiver [Philips saa6588].
rds-saa6588 does not get installed during the install step.
Tool to test v4l2 API compliance of drivers.
Installed under <prefix>/bin
.
Tool to control v4l2 controls from the cmdline.
Installed under <prefix>/bin
.
Tool to directly get and set registers of v4l2 devices, this requires a
kernel >= 2.6.29 with the ADV_DEBUG
option enabled. This tool can only be
used by root and is meant for development purposes only!
Installed under <prefix>/sbin
.
FIXME add description.
Installed under <prefix>/bin
.
Tool to trace, record and replay userspace applications that implement the v4l2 memory-to-memory stateless video decoder interface.
Installed by make install
under <prefix>/bin
.
Xceive XC2028/3028 tuner module firmware manipulation tool.
xc3028-firmware does not get installed during the install step.
There are a number of files on this package that depends on the Linux Kernel.
In order to make easier to keep it in sync, there's a target on this package to do the synchronism.
For the sync to work, you need to run it on with 64 bits userspace and be sure that glibc has the development package for 32 bits.
For Fedora, this is provided via this package: glibc-devel.i686
There are some steps required:
-
At the Kernel git tree:
We need to sanitize the headers to be installed. To do that, you should run:
make headers_install INSTALL_HDR_PATH=usr/
This will create the dir
usr/
inside the Kernel tree. -
Be sure that you have installed both glibc development packages for 32 and 64 bits, as otherwise the next step will fail.
-
At v4l-utils tree:
./sync-with-kernel.sh location/of/the/kernel/tree
Alternatively, steps 1 to 3 can be replaced with:
KERNEL_DIR=location/of/the/kernel/tree && (cd $KERNEL_DIR && make headers_install INSTALL_HDR_PATH=usr/) && ./sync-with-kernel.sh $KERNEL_DIR
-
Remove the
usr/
from the Kernel tree.