directvnc - a vnc client for the linux framebuffer device
directvnc server:display [options]
DirectVNC is a client implementing the remote framebuffer
protocol (rfb) which is used by VNC servers. If a VNC server is running on a
machine you can connect to it using this client and have the contents of its
display shown on your screen. Keyboard and mouse events are sent to the
server, so you can basically control a VNC server remotely. There are
servers (and other clients) freely available for all operating systems.
What makes DirectVNC different from other unix vnc clients is that
it uses the linux framebuffer device through the DirectFB library which
enables it to run on anything that has a framebuffer without the need for a
running X server. This includes embedded devices. DirectFB even uses
acceleration features of certain graphics cards. Thus a lot of configuration
can be done by creating the library specific configuration file
/etc/directfbrc or the program-specific configuration file
/etc/directfbrc.directvnc. See directfbrc(5) or find out all about DirectFB
here:
www.directfb.org
DirectVNC basically provides a very thin VNC client for unix
framebuffer systems.
Hitting <ctrl-q> exits the viewer.
- -h, --help
- display help output and exit
- -v, --version
- output version information and exit
- -p, --password
- password string to be passed to the server for authentication. Use this
with care!
- -b, --bpp
- the bits per pixel to be used by the client. Currently only 16 and 24 bpp
are available.
- -e --encodings
- DirectVNC supports several different compression methods to encode screen
updates; this option specifies a set of them to use in order of
preference. Encodings are specified separated with spaces, and must thus
be enclosed in quotes if more than one is specified. Available encodings,
in default order for a remote connection, are "copyrect tight hextile
zlib corre rre raw". For a local connection (to the same machine),
the default order to try is "raw copyrect tight hextile zlib corre
rre". Raw encoding is always assumed as a last option if no other
encoding can be used for some reason.
- -f --pollfrequency
- time in ms to wait between polls for screen updates when no events are to
be processed. This reduces cpu and network load. Default is 50 ms.
- -s, --shared
(default)
- Don't disconnect already connected clients.
- -n, --noshared
- Disconnect already connected clients.
- -n,
--nolocalcursor
- Disable local cursor tracking By default, and if the server is capable of
the SoftCursor encoding, mouse movements do not generate framebuffer
updates and the cursor state is kept locally. This removes mouse pointer
lag and lets the connection appear faster.
- -c --compresslevel
level
- Use specified compression level (0..9) for "tight" and
"zlib" encodings (only usable with servers capable of those
encodings). Level 1 uses minimum of CPU time and achieves weak compression
ratios, while level 9 offers best compression but is slow in terms of CPU
time consumption on the server side. Use high levels with very slow
network connections, and low levels when working over high-speed LANs.
It's not recommended to use compression level 0, reasonable choices start
from the level 1.
- -q --quality level
- Use the specified image quality level (0..9) for "tight"
encoding (only usable with servers capable of those encodings). Specifying
this option allows "tight" encoder to use lossy JPEG
compression. Quality level 0 denotes bad image quality but very impressive
compression ratios, while level 9 offers very good image quality at lower
compression ratios. Note that "tight" encoder uses JPEG to
encode only those screen areas that look suitable for lossy compression,
so quality level 0 does not always mean unacceptable image quality.
- -m --modmap PATH
- Path to the modmap (subset of X-style) file to load. With this option, it
is possible to set an alternative keyboard layout, with ability to support
non-latin characters such as Cyrillic. A plain text file, containing a
subset of xmodmap(1) syntax (only keycode expressions are recognized with
up to four KEYSYMNAMEs) can be converted into the format that directvnc
understands, and can be loaded upon directvnc startup with this option.
See directvnc-kbmapping(7).
At the moment, it is still necessary to use the --bpp command line
option to set color depth. When negotiating with the remote VNC server side,
color depth supplied by the server will be used. It is therefore necessary
to make sure (at least in the present) that screen color depth (default, or
set in the DirectFB configuration file), color depth supplied at the command
line, and remote VNC server color depth all match.
Till Adam, Dimitry Golubovsky, Malte S. Stretz, Loris Boillet and
others, based on AT&T and tightvnc VNC implementations.