CameraManager and Integration with Cheese

[Matthew Brush <mbrush codebrainz ca>]

Hi,

I've started writing something I'm going to call probably GCam or 
CameraManager.  The intention of the code is to behave more or less like 
NetworkManager/nm-applet except with capture devices.

The first part is a lightweight daemon (gcamd) that uses libudev to 
monitor for new video4linux devices, checks that they have at least one 
"camera" input and sends a signal out on dbus with the device node, as 
unique an ID as possible, and the event (add, remove, etc).  My plans 
are to expand the daemon to be able to store camera/device configuration 
(v4l2 controls, etc) in an sqlite3 database.  Ideally, what it should do 
is, when the camera (or any v4l2 capture device) is detected/plugged-in, 
it's "unique" ID is looked up in the config database and the controls 
values are applied to the device.  I guess the daemon will need to 
accept an "update" method over dbus or something to tell it to (re)store 
the settings in the database.  I'll probably get this last stuff working 
over next weekend.

The second part is a GtkStatusIcon-based app (also supports 
app-indicator, to some extent), that sits in the panel.  When it gets 
the signals from the dbus daemon, it uses libnotify to popup a bubble to 
tell the user that the system detected a "camera" being 
connected/disconnected.  When you click on the status icon, it drops 
down a menu of v4l2 capture devices, and in their submenus it shows the 
"camera" inputs on the device, with a OK icon if v4l2 doesn't give any 
bad status flags, and a X icon when there's a bad status flag (no power, 
no signal, etc).  When you hover your mouse over the camera menu item, 
it sends a tooltip-notify signal to a custom tooltip window which 
renders a video into GdkPixbuf/window.  I took a screenshot[1] to better 
show what it looks like.  Currently I'm using my libfg2[2] library for 
getting the video but I'm considering switching to GStreamer if it's 
fast enough (the tooltip preview window has to popup pretty darn fast).

The next step is to determine what happens when the user clicks the 
camera's menu item. I've had several ideas, including:

1) Writing a simple GStreamer/GTK+ app that just shows the live feed, 
nothing more.
2) Writing a nice (and comprehensive) GTK+ control application with 
preview that allows tons of configuration for the device (calling a dbus 
method on the above mentioned daemon to store the changed settings).
3) Opening Cheese with the selected device activated (my favourite 
option) and patching it to call the dbus method to store the settings 
when changed in Cheese.  I haven't checked if Cheese is using v4l2 
controls or GStreamer elements (or both) to control camera settings.

I was hoping to solicit feedback and/or help from anyone interested in 
any and all of the above.  So I have a few questions:

  - Does this seem like something that should/could become part of Cheese?

  - Should my panel 'applet' just shell out to cheese or should there 
be tighter integration?  Maybe option 1) or 2) is better?

  - Are there any ideas to improve the daemon/gtk app?

  - I haven't found anything online, but am I duplicating efforts here, 
is there something like this already (or in planning)?

  - Is anyone interested in helping out with this?

I should have code pushed to my GitHub[3] account by the end of this 
coming weekend, I haven't done so yet because I'm re-writing the daemon 
to remove GLib/GDBus due to the (relatively) massive overhead it imposed 
on my lightweight system daemon.

P.S. Sorry for the long message.

[1] http://imageshack.us/photo/my-images/195/gcamscreenshot.png/
[2] https://github.com/codebrainz/libfg2
[3] https://github.com/codebrainz

Cheers,
Matthew Brush