vgrabbj purpose is to read data from a v4l-device and put it in a file,
formatted as jpeg, png, or pnm. Except for the ftp-options described
below everything can also handled on the commandline.
Here the configuration statements are described.
Syntax is <keyword> <value>. Comments start with a ';' or '#'. Those
lines are ignored by vgrabbj. Case of the keywords and named options
doesn't matter except for the timestamp option as well as any filename.
The configuration file is parsed line by line. If any keyword appears
twice or more often, the last one is the one used.
On startup, the pre-defined configuration file /etc/vgrabbj.conf is
read. Then, commandline parameters are evaluated one by one, the last is
the most significant, if one option is provide twice or more often.
Same applies for the commandline parameter -c <config-file>.
Daemonize & loop with seconds intervals (min. 1).
Daemonize & loop microseconds intervals (min. 1). Same as -l
except you can control it more precisely.
Defines if vgrabbj's brightness adjustment is used. This option works only
if the device supports data fetch via read and RGB24 videopalette. See
ForcePalette on how-to set RGB24. Some device do not support RGB24,
hence, Brightness is ignored.
Sets the quality of a jpeg output to quality (1-100, default: 75).
Sets the imagesize of input device, where imagesize is one of:
Sets the width of the image to width. Needs -H.
The v4l-device has to support the image width you set with
Sets the height of the image to height. Needs -w.
The v4l-device has to support the image height you set with
Sets the output to format (either jpeg, png, or
pnm, default: jpeg). Alternative, you may provide jpg for
Output is written to filename (default: /dev/stdout)
Additional output is written to path/filename (default: not set),
whereas the path-filename can include any strftime component. The path-
filename must not be on a different filesystem as the output defined above.
Additionally, you need to take care of the number of files stored. There is
no upper ceiling for archiving.
Sets the input device to device (default: /dev/video)
Defines if vgrabbj opens the device only while image data is grabbed
(Off) or keeps it opened while it is running (On).
Setting it to Off is helpful if you need access to the device besides
vgrabbj. This use is discouraged though, due to possible problems with memory
fragmentation. Default is On.
Defines if the image size (see -i, -H, and -w) of the
device is set by vgrabbj. Necessary for certain v4l-devices which do not
support to be set to a particular image size (e.g. IBM-usb-cam, QuickCam).
For these devices you have to specify the size at module load time.
Default is On.
Switches colormap from BGR to RGB (or vice versa) if set to On. Default
is Off. Use if you have odd colors.
Swaps left and right of the image like a mirror. Default: Off.
Swaps top and bottom of the image like a mirror. Default: Off.
Turns off the use of mmap'ed (better) memory allocation for grabbing frames.
Some (very rare) cams cannot use mmap'ed memory and have to use read. If you
want to switch easily, use this switch. If you don't know what I'm talking
about, leafe it like it is: Default is Off.
Sets the loglevel of vgrabbj. Valid for value are 0, 2, 3, 4, 6, 7
(default: 4). 0 means no messages at all, 7 is debug. Don't use 7 if
you are running vgrabbj in daemon mode, it'll surely fill your syslog.
Be aware, that loglevel 7 will also post you ftp-password (if defined)
in the logfile!
Sets the use of the temporary outputfile. Default is On. Ignored in case
the default output (/dev/stdout) is used. If set to Off, the data
is written directly to the file defined by OutputFile.
If filename is different from /dev/stdout (given via -f
parameter or OutputFile, vgrabbj defaults to use a temporary file called
filename.tmp to write the image. This file is then renamed to
filename to shorten the time period corrupt data may be read from
Force the usage of the specified palette. If palette is not
supported by either vgrabbj or the v4l-device, fallback to a palette
supported by both is provided. If no common denominator is available, vgrabbj
exits. Supported palettes are marked with * below. Possible values are (copy
value images are grabbed and immediately discarded. Only the
last image is written to the output. This might be helpful if your v4l-device
needs to take a couple of images to auto-adjust to the current light.
The following options are useful if you want to keep a certain amount
of images in an archive. Currently, the archive is only supported if kept
on the same filesystem as the images taken.
The archive-filename-pattern is evaluated as a timestring, hence
the same applies as to TimeStamp (see below, default: /tmp/arch/cam-%Y-%d-%m-%H-%M-%S.jpg)
Defines how many images have to be taken before a copy is made for the
archive. E.g. if defined 1, each image is put in the archive; if defined 5
every fifth image is put in the archive.
Sets the maximum number of images to be put in the archive.
The following options are available only if vgrabbj was compiled with
the freetype library available. The timestamp will only be enabled if
all values evaluated (inlcuding defaults) lead to a valid configuration
and UseTimestamp is set to On.
This is the essential setting to enable timestamps
if defined in the config file. Without this being set
to On, it just won't work (although, if there are options
set to have an invalid configuration, it won't work either).
This is different to the handling on the commandline.
The TrueType font to be used for the timestamp
Set the fontsize to size for timestamp (3-100, default: 12).
Defines the timestamp. format-str can be plain text or any
strftime format. Any '""' at the beginning or the end will be eliminated
for compatibility reasons, i.e. they are not necessary (default: "%a, %e.
%B %Y - %T" - see strftime(3) for details).
Alignment of the timestamp in the image. Possible
ul = upper left, ur = upper right,
ll = lower left, lr = lower right,
uc = upper center, lc = lower center
(default: upper right). You can use either the short or the long version.
Defines the blend between font background and image (1-100, default: 60).
value pixels will be used as border around the timestamp string (1-255,
There are no options for ftp-upload on the command line. This is due to the need
to provide a password which would be visible via the ps(1) command.
Ftp-Connection will only be opened if set to On. Be aware that this
might bring up a dial-up connection. See also KeepAlive. (default: Off)
Host to which a ftp-connection will be established everytime an image has
been written (see also: Daemon, DaemonSeconds, KeepAlive,
The path consists of the full path on the remote host defined by
RemoteHost (default: /).
The filename consists of the full path and filename on the remote host
defined by RemoteHost (default: foo.bar.com).
The name of the user to log on the remote ftp-server (default: foo).
The password of the user to log on the remote ftp-server (default: bar). Be
aware, that the password is kept unencrypted in memory, it might be read by
If set to On, the connection will be kept. This will cause a dial-up
line to be up all the time, which in turn may cost a lot of money! If set
to Off, the connection will be established after an image was written
to the OutputFile. After transmission, the ftp-connection will be ended.
This may also result in phone charges, for which Author takes no responsibility. See License.
If set to On, passive ftp will be used. This can help connecting to
ftp servers from the inside of a NAT-ed network.
Not implemented, yet.
With the following options you may alter the settings of your hardware (the cam), if
supported by the cam. Be aware, this might break your hardware, as there are no checks
if the values supplied are valid, allowed, or supported!
At my own machine running vgrabbj, the %F in a Archive-Filename causes memory corruption.
This is not validated by any other machine. No further bugs are known at this time.