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Video4Linux in YARP
(thanks to Jonas Ruesch for help with this)
Supported via FFMPEG library
video4linux is currently supported in YARP via ffmpeg.
Run "ccmake ." to turn on compilation with ffmpeg (making sure you have the library present first).
Then make. You should now have this device available:
Device <ffmpeg_grabber> documented by the C++ class FfmpegGrabber Wrapped for the network by <grabber>
You can start a server for your camera with something like:
yarpdev --name /rightEye --framerate 20 --device ffmpeg_grabber --v4l --v4ldevice /dev/video0 --channel 1 --standard ntsc --width 640 --height 480 --time_base_den 29 --time_base_num 1
Many of the parameters can be omitted.
It is a bit neater to use a .ini file:
yarpdev --file mycam.ini
where mycam.ini is something like:
device ffmpeg_grabber name /rightEye v4l v4ldevice /dev/video0 width 640 height 480
A note from Jonas:
I checked the newest cvs version with the configurable v4l ffmpeg_grabber on a camera attached to a tv-card. It works as expected. There seems to be one issue left which I think was there already before; when starting a v4l device driver (ServerFrameGrabber) the first time, yarpview stays blind. The 'solution' is then to start xawtv change to s-video, see the camera picture appear, shut down xawtv and restart ServerFrameGrabber. Some initalization which does xawtv and we don't?
A note from Paul
Don't know what this might be. Finally got to try out a webcam and it works fine. Maybe kernel or v4l version dependant?
A note from Jonas
The issue seems to be dependent on the tv-card used. Some require the 'xawtv initialization' and some don't.