- configuration file for vgrabbj
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>.
- DaemonSeconds seconds
- Daemonize & loop with seconds intervals (min.
- Daemon microseconds
- Daemonize & loop microseconds intervals (min.
1). Same as -l except you can control it more precisely.
- AutoBrightness On|Off
- 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.
- ImageQuality quality
- Sets the quality of a jpeg output to quality (1-100,
- ImageSize imagesize
- Sets the imagesize of input device, where imagesize
is one of:
sqcif= 128x96, qsif = 160x120,
qcif = 176x144, sif = 320x240,
cif = 352x288, vga = 640x480,
svga = 800x600, xga = 1024x768,
sxga = 1280x1024, uxga = 1600x1200,
- (default: cif)
- ImageWidth width
- Sets the width of the image to width. Needs
-H. The v4l-device has to support the image width you set with this
- ImageHeight height
- Sets the height of the image to height. Needs
-w. The v4l-device has to support the image height you set with
- OutputFormat format
- Sets the output to format (either jpeg,
png, or pnm, default: jpeg). Alternative, you may provide
jpg for jpeg.
- OutputFile <filename>
- Output is written to filename (default:
- Archive <path/filename>
- 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
- VideoDevice <device>
- Sets the input device to device (default:
- OpenOnce On|Off
- 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.
- SetImageSize On|Off
- 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.
- SwitchColor On|Off
- Switches colormap from BGR to RGB (or vice versa) if set to
On. Default is Off. Use if you have odd colors.
- SwapRL On|Off
- Swaps left and right of the image like a mirror. Default:
Off. is Off.
- SwapTB On|Off
- Swaps top and bottom of the image like a mirror. Default:
Off. is Off.
- NoUseMmap On|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
- DebugLevel value
- 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!
- UseTmpOut On|Off
- 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
- Exec commands
- Ask vgrabbj to launch an external program. May be used to
pass the picture through ImageMagick or others filters. The first '%s'
instance in the command line will be replaced with filename. If
UseTmpOut is On, commands will be run before the file
- ForcePalette palette
- 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 from videodev.h):
1 VIDEO_PALETTE_GREY Linear greyscale
2 VIDEO_PALETTE_HI240 High 240 cube (BT848)
3 VIDEO_PALETTE_RGB565 565 16 bit RGB
4 *VIDEO_PALETTE_RGB24 24bit RGB
5 *VIDEO_PALETTE_RGB32 32bit RGB
6 VIDEO_PALETTE_RGB555 555 15bit RGB
7 *VIDEO_PALETTE_YUV422 YUV422 capture
10 VIDEO_PALETTE_YUV411 YUV411 capture
11 VIDEO_PALETTE_RAW RAW capture (BT848)
12 VIDEO_PALETTE_YUV422P YUV 4:2:2 Planar
13 VIDEO_PALETTE_YUV411P YUV 4:1:1 Planar
14*VIDEO_PALETTE_YUV420P YUV 4:2:0 Planar
15 VIDEO_PALETTE_YUV410P YUV 4:1:0 Planar
- (no default, depends on v4l-device).
- DiscardFrames value
- 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
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.
- Archive <archive-filename-pattern>
- The archive-filename-pattern is evaluated as a
timestring, hence the same applies as to TimeStamp (see below,
- ArchiveEach <value>
- 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.
- ArchiveMax <value>
- Sets the maximum number of images to be put in the
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 (including defaults) lead to a valid configuration and UseTimestamp
is set to On.
- UseTimestamp On|Off
- 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
- FontFile filename
- The TrueType font to be used for the timestamp (default
- FontSize size
- Set the fontsize to size for timestamp (3-100,
- TimeStamp format-str
- 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
- Position value
- 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
- Blend value
- Defines the blend between font background and image (1-100,
- BorderSize value
- value pixels will be used as border around the
timestamp string (1-255, default: 2).
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
- EnableFtp On|Off
- 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)
- RemoteHost hostname
- Host to which a ftp-connection will be established
everytime an image has been written (see also: Daemon,
DaemonSeconds, KeepAlive, default: camimage.jpg).
- RemoteDir path
- The path consists of the full path on the remote
host defined by RemoteHost (default: /).
- RemoteImageName filename
- The filename consists of the full path and filename
on the remote host defined by RemoteHost (default:
- Username username
- The name of the user to log on the remote ftp-server
- Password password
- 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 others.
- KeepAlive On|Off
- 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.
- Passive On|Off
- If set to On, passive ftp will be used. This can
help connecting to ftp servers from the inside of a NAT-ed network.
- TryHarder On|Off
- 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!
- -W <value>
- Whiteness definition.
- -r <value>
- Color definition.
- -x <value>
- Contrast definition.
- -b <value>
- Brightness definition.
- -u <value>
- Hue definition.
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.
This manual page was originally written by Michael Janssen
<email@example.com>, for the Debian GNU/Linux system and enhanced by
Jens Gecius <firstname.lastname@example.org>.