Taking Pictures with a Webcam?

GoogleGroups
#1

I'm building a simple application that will use my webcam to take a
picture every 2 minutes and save it as a JPEG (or PNG) to the SD card.
I thought this would be simple, but the hardest part is finding a
program to take a picture with the webcam AND will work on the Beagle
Board.

I've tried Motion, but it does way more than I need (i.e. motion
detection) and seems to be buggy; perhaps it's too processor intensive
or something. For some reason it will take the first picture and then
all others will just be a copy of the first. Then the USB hub is
automatically reconnected a couple of times. Very strange.

Is there any good tool that I can use from the command line that will
simply take a picture and save it as a JPEG or PNG?

Could I use OpenCV for this? If so, are there any good examples?

Thanks!
Jeremy

#2

mplayer is both able to read from a webcam and to save to a series of
PNGs; I'm not sure what options are better to save an image every 2
minutes (as opposed to one for each frame) but googling gave e.g.
these results

http://www.infohit.net/blog/post/taking-snapshots-from-a-webcam-under-linux.html

http://mydebian.blogdns.org/?p=120

#3

vidcat
See http://www.elinux.org/BeagleBoard/James#vidcat

FM

#4

I’m building a simple application that will use my webcam to take a
picture every 2 minutes and save it as a JPEG (or PNG) to the SD card.
I thought this would be simple, but the hardest part is finding a
program to take a picture with the webcam AND will work on the Beagle
Board.

I’ve tried Motion, but it does way more than I need (i.e. motion
detection) and seems to be buggy; perhaps it’s too processor intensive
or something. For some reason it will take the first picture and then
all others will just be a copy of the first. Then the USB hub is
automatically reconnected a couple of times. Very strange.

Is there any good tool that I can use from the command line that will
simply take a picture and save it as a JPEG or PNG?

Hi Jeremy:
Reading BeagleBoard forum on the possibility to take photos with the plate every 2 minutes, found some application?.
We are working in a hot air balloon and we would like the BeagleBoard in the journey doing this task.
From already thank you very much
Carlos

#5

ffmpeg can do this, it shouldn't be difficult to build for beagleboard.

e.g. for 1 frame every 50 seconds:

ffmpeg -f v4l2 -i /dev/video0 -r 0.02 cam-%05d.png

s/png/jpg/ for jpeg, And obviously you can save it in piles of video formats as well. Depending on your camera, i suspect jpeg or mjpeg (mov) format would be the lightest load for decent quality.

This was with 1.0 - some older version on my machine didn't like fps < 1.

You can also just grab 1 frame, and put the rest in a script:

ffmpeg -f v4l2 -i /dev/video0 -vframes 1 capture.jpeg

  Michael

#6

I think it would be possible to use gstreamer to do that too.