live video stacking/integration/slow shutter?

[Nicolas Dufresne]

Le 2015-01-31 13:41, Paul Groessel a écrit :
> Hi there
> I would like to ask you if it is possible to do image stacking with 
> gstreamer on an v4l source.
> There are a lot of cameras out there that can do image stacking 
> internal also called "integration".
> Many astronomical cameras can do internal integration up to 30 seconds.
> This cameras do an image addition like it is done in astronomy. The 
> stacking increases low light scenes
> and reduces some noise. Lets say I have an ordinary webcam
> that sends 30fps to v4l. Is it possible to somehow stack those 30 
> images to have a "slow shutter",
> brightness enhanced 1 fps video? There's a video on yt that shows what 
> I mean:
> https://www.youtube.com/watch?v=DcITFgbWNtU
> Is this somehow possible or is someone aware of any linux dsp software 
> that can do that in realtime?
Assuming you have:
- A working webcam
- A working library that can post process N frames into 1

You can write an element that will receive 30pfs and produce less. This 
is not ready made, but with some coding skill it is possible. The 
post-processing library need to be fast enough to be real-time of course.
> My goal is to use an ordinary webcam, modify the stream to have an 
> 10fps stacked video out that will be
> redirected to v4l2loopback. The v4l2loopback then can be used in 
> kstars as guiding camera source.
v4l2loopback isn't very stable and require root permission to setup. 
KStar is Open Source, it will be much more natural if you integrated 
your GStreamer pipeline as a backend or directly integrate your work 
into KStars. Regardless the direction, my recommendation would be to 
improve KStars instead of looking for complicated workaround like 
v4l2-loopback driver.

Nicolas