Forums > Jitter

(usb) cam control autofocus autoexposure (osx)

March 29, 2012 | 12:07 pm

there is this issue with a wide range of usb webcams, that you cannot turn off settings like autofocus, autoexposure etc. in osx.
i found a very nice unix-command work that deals with that, offering full control for cams: uvc-controller:
http://www.dm9.se/?p=693
however, if max (jit.qt.grab) connects to the camera, the communication for uvc-controller with the cam is blocked.
my first guess was, that this is a quicktime issue, but when i test it with QuickTime Player all works fine. meaning i can turn off autoexposure eg. of my cam (a logitech c910) when having QuickTime Player receiving the video-stream.

so my question to jitter experts is, if there is an explanation for this behaviour and maybe any sort of workaround.

thanks klaus


April 3, 2012 | 10:45 pm

i found a solution for my problem:
when jit.qt.grab is connected to the cam, i just switch to the builtin iSight without closing the connection.
in this state i can modify all settings on the external camera, and it keeps it, when i switch back, again without closing.

uvc-ctrl (see link above) comes without GUI, so i made one as max patch.
the max patch needs to be in the same folder like uvc-ctrl and can be found here:
http://ppooll.klingt.org/index.php/downloads
(some 3rd party objects are needed: shell, ll_number) but there is also a standalone.

cheers
klaus


April 17, 2012 | 11:19 am

Wauw Klaus, great, I was looking for this. Having manual control over a webcam is such a must have in most installation situations!

From testing I see it works well. I tested the Logitech C910 and Logitech Vision Pro.

Both their autofocus can be turned off, which is excellent, and also the exposure can be fixed! This all works while both camera’s are connected and I use one instance of your uvc-ctrl GUI patch.
It’s like you say: in jit.qt.grab you switch between the camera’s without closing/disconnecting.

Excellent!

I was looking for this a long time. I came across this xcode project/ app:

http://www.phoboslab.org/log/2009/07/uvc-camera-control-for-mac-os-x

Which works but is less complete (no camera selector, no autofocus settings), but I guess it can be added.
Combined with the syphon project (http://syphon.v002.info/) the set camera image could be send to Max or any mac app via GL.
But my xcode skills are not good to make it happen, so I am looking for somebody who could do it…

But cheers for this!

Maarten



dtr
April 17, 2012 | 11:58 am

great! this auto behavior is a big pain in *ss indeed…



mmd
October 3, 2012 | 11:52 am

Hi guys! Since I’m interested in using a logitech c910 its great to see this kinds of workaround for the autoexposure!

Ideally I would like a hd video to go through jitter and sent out to a video projector, with low latency when possible.

Since you guys probably about now have experience with using the c910… I am wondering the following:

The reason I would like to use a c910 is because I want to use a higher resolution more than the 640 * 480 i am currently getting for my project from the PS3Eye.

- How likely is it possible to ‘grab’ a resolution of about 1024*500 (or something like 720p) on a decent framerate (25-30 fps) ?
- And in general, how is the latency on this camera?

My system is a MBP 2.2ghz i7, 16g ram, high end videocard.

Thanks!


Viewing 5 posts - 1 through 5 (of 5 total)