Re: [libdc] Fwd: question

[David M. <dcm@MIT.EDU>]

On Sun, 2009-05-31 at 02:19 +0000, Michael Williamson wrote:

> OK, on the openSuSE computer,
> I got the new libdc1394 version, I unplugged the AVT Marlin F131B,
> and plugged in the IMI-17FT camera, and it worked at first:
> 

Okay, good progress.  A couple things:

- It seems the camera gets into a bad state after a capture operation is
not cleaned up properly.  While that is squarely the camera firmware's
fault, you might try running
dc1394_video_set_transmission(camera, DC1394_OFF)
at the start of your program to see if that helps unwedging it.

- On legacy ieee1394 kernel drivers (opensuse), you need to call
dc1394_capture_stop() in order to free channel and bandwidth allocations
from the bus.  If you ctrl-c without doing this, they will not get
cleaned up, and eventually the bus will run out of bandwidth.  Run the
dc1394_reset_bus() function, or the command-line program
examples/dc1394_reset_bus to forcibly free these resources after an
uncleanly aborted program.  Note that on juju (fedora), the kernel will
do this cleanup automatically.

- You can use the dc1394_camera_reset() function to ask the camera to
reset itself.  However, there is no guarantee this will do anything
meaningful -- it is up to the camera's firmware.  Unfortunately, there
is no way to force a power-cycle without physically unplugging the
camera.

- You might also find the resetting the bus (as above) may cause the
camera to do some amount of internal reset.


-David