Re: Getting a hook from shell mode to do motion detection?

I've been thinking about this.  I plan to write in C, and between
system() and popen() and pipe() and etc there's probably a way to do
it.  From a console you type shell and give commands, then you can
type more commands.  But I'm not sure how a program would do that: as
a file descriptor or a pipe (or a socket) (dbus?)?  Gphoto as a
process stays running, you just need a programmatic way to communicate
with it.  The looping and branching wouldn't happen in Gphoto's shell,
that would be more like a low level server or driver.  I could of
course modify my copy of the source but I'd rather not do that.  I was
about to experiment a bit until I found my oldschool loadjpeg function
evidently doesn't work under Linux, I need to make a Turbo Jpeg
equivalent.  Or maybe I still need some dev file or header.  Wacky, it
doesn't know jpeg_CreateDecompress or what a size_t is?  I wrote it
under OpenBSD a couple years ago, it's been reasonably portable until
now.  Loading a straight uncompressed RGB binary would be optimum but
I need to decompress jpegs.  Don't know yet if I can send to stdout.

I ran across motion last night but didn't bother to install it.  I
think it's strictly V4L so it's low quality just because the cameras
are.  I've got a 640x480 USB webcam that does V4L but I'd rather not
use it.  My motion detection scheme comes partly from a D-Link IP cam,
that also only does 640x480.  I'll probably be running this on a
Raspberry Pi, and I've got a few of those cameras, but I'd rather not
use them.

The standard Gphoto --capture-preview or the shell equivalent gets me
a 320x240 jpeg which, if I decompress and compare in C, not something
awful like Python, should be fast enough.  I'd rather not use 2
cameras.  I'm from the Nikon camp, new to Canons for this project.
For $20 used I got a 7 MP camera that not only works with Gphoto but
also shoots RAW, most low-end Nikons won't do either.  I'm not
sticking my D5200 DSLR in a birdfeeder.

Shell mode is good for this because there's only 1 start-up time, the
delay between pictures can be much lower than if you call Gphoto in a
loop to start from scratch each time.  1 frame per second might be
adequate but I'm aiming at 10.  CPU time on a Pi 3 comes cheap since
it runs on a watt or two.  So I don't need to compare 320x240 images
but if I can do it efficiently I can live with it.

On 12/30/17, Tomas Alonso <[email protected]> wrote:
> El Viernes, 29 de diciembre de 2017 17:39:08 Alan Corey escribió:
>> I want to set up a wildlife camera, so I've read a few articles about
>> it.  I've been practicing with an old Canon PowerShot S70 and it seems
>> suitable.  What I'd like to try to do is use the preview images for
>> motion detection.  I need to mask out some areas to avoid false
>> activations from clouds passing over, that sort of stuff, and probably
>> some averaging to account for the sun rising and setting.
>>
>> For speed it seems advisable to work in Gphoto2's shell mode but I'm
>> trying to figure out a way to provide input from an external program.
>> I want to do capture-preview in a loop: get a preview, run my compare
>> program, get another preview.  If the compare sees something go into
>> another loop grabbing big images for some amount of time, then back to
>> previews.
>>
>> I did help in shell mode but I don't see anything listed that looks
>> like it would work, like being able to detect the presence of some
>> file I could use a a semaphore.  There aren't any branch (or loop)
>> instructions either.
>>
>>   Alan
>
> Hello Alan,
>
> For other needs related to security I'm also interested in doing something
> equivalent. I thought my first try would be
>
> http://www.chriswpage.com/2009/05/setup-an-advanced-webcam-security-system-with-ubuntu-8-04-and-motion/
>
> using the motion program under Linux. It allows to launch scripts when
> motion
> is detected, but you need a webcam for motion detection and a camera for
> good
> quality shots. That's (and the fact I own a Canon 40D) why I'm not sure at
> all
> about the webcam approach.
>
> I have high programming skills and experience with gphoto so to implement
> this
> myself will not be a problem. If you can't find a solution for your case
> just
> send me the exact gphoto commands you use for your camera to enter shell
> mode,
> take a preview, and take also a big image in auto mode or whatever you use
> (including the file names generated in your computer after executing those
> commands).
>
> Can't promise to do it for a given date but likely it will take few weeks.
>
> Regards,
> Tomas.
>
>
> ------------------------------------------------------------------------------
> Check out the vibrant tech community on one of the world's most
> engaging tech sites, Slashdot.org! http://sdm.link/slashdot
> _______________________________________________
> Gphoto-user mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/gphoto-user
>


-- 
-------------
No, I won't  call it "climate change", do you have a "reality problem"? - AB1JX
Impeach  Impeach  Impeach  Impeach  Impeach  Impeach  Impeach  Impeach

------------------------------------------------------------------------------
Check out the vibrant tech community on one of the world's most
engaging tech sites, Slashdot.org! http://sdm.link/slashdot
_______________________________________________
Gphoto-user mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/gphoto-user