Limrendir

What is it ?

Limrendir allows to view and save a video stream from a Genicam compatible camera using the Aravis library. It is a mashup between Aravis Viewer, which allows for user-friendly interactions with a camera including control and stream visualisation, and gevCapture, which allows for user-unfriendly recording of said stream.

How to install

First you have to install some dependencies to be able to install Aravis

sudo apt install libxml2-dev libglib2.0-dev cmake libusb-1.0-0-dev gobject-introspection \
                 libgtk-3-dev gtk-doc-tools  xsltproc libgstreamer1.0-dev \
                 libgstreamer-plugins-base1.0-dev \
                 libgirepository1.0-dev gettext

Also, because Aravis relies on it you have to install meson (if the version given by apt is too old, try using pip).

Then install the Aravis library (version >= 0.8).

Then download this project and in the main directory type

cmake .
make
./limrendir

Use option --help to know about the available options.

Note: If your version of cmake is too old, you can use pip to update it. If it doesn't work, try lowering the required version in the CMakeLists.txt file (but then I can't guarantee everything will work properly).

Troubleshooting missing frames

During recording there can be dropped frames, i.e. frames that were not saved for one reason or another and that are missing in the video. These are especially frequent when having a high data rate (around and above 100 MB/s), a slow computer and/or several programs running in parallel. Limrendir should indicate that a frame was dropped by displaying "(X)" in a warning message. If you are experiencing dropped frames, you may try the following:

Check the camera-computer connection

• Ensure that the camera is properly connected to your computer with an appropriate cable (for example, a category 6 Ethernet cable).
• Verify that the connection MTU is high enough. Go to network manager, select the network connection, check that MTU >= 8192 (preferrably 9000).

Upgrade the permissions given to limrendir

• Run limrendir as administrator (using sudo), which will allow to make the Aravis thread relatime.
• Use packet sockets: sudo setcap cap_net_raw+ep limrendir
• Nice the program: sudo nice -5 ./limrendir

Use higher timeouts

• If the dropped frames comes from timeouts being reached (usually indicated by the ARV_BUFFER_STATUS_TIMEOUT buffer state), try using higher packet timeout and frame retention time: launch limrendir with arguments -m 1000 -p 1000

Limit other usages of CPU resources

• If your computer is a 2000's toaster with less than 2 GB of RAM, try buying another one
• Limitate usage of CPU-heavy and RAM-guzzling applications such as Chrome

See also the advices here.

About the code

Limrendir is written in C and based on Aravis (0.8), gstreamer (1.0) and GTK+ (3.0).

A consequent part of the code is directly burrowed or adapted from Aravis Viewer. My additions consist mainly of

• Smoother control of the acquisition and field of view parameters with key bindings routines inspired by gevCapture and
• Recording capabilities, with different formats supported (at term).

I am not a professional software developer so the code quality might not be perfect. But hey, it works !

Also there is a GObject error when launching the software. I don't know why. It doesn't seem to inhibit anything so I didn't search too hard. Any patch welcome :)

To-Do list

Add a confirmation notification / mini dialog box when attempting to saved in an existing .gcv folder

? Add zebra patterns

Licence

GNU something.

Why the strange-sounding name ?

Limrendir is a sindarin (middle-earth elvish) name meaning "the one who swiftly remembers what he looks at". That seemed appropriate for a camera recording software ! Many thanks to Elaran for coining the term.