Hi Raúl, sorry for the late reply, and thanks for the very detailled description of your problem.
On Wednesday 19 March 2008, Raúl Sánchez Siles wrote: > Hello: > > Basically same story but with some more appreciations. > > Raúl Sánchez Siles wrote: > >>> Raúl Sánchez Siles wrote: > >>>> Hello All: > >>>> > >>>> On skype I had the same problem and is this: I can start my video > >>>> and the > >>>> other end will see it, but after a randon time ranging from little > >>>> seconds to little minutes, the image I sent (and that I'm able to see) > >>>> goes to black unconditionally. > >>>> > >>>> After this, same as before the video was working at this point, but > >>>> stops > >>>> working after some time. Along the video conference skype seems to try > >>>> to reinitialize webcam, it starts working again, but then it goes to > >>>> black again. > >> > >> [...] > > > > Now I got to reproduce the problem. I think it's related to > > environmental > > light somehow. I had some trouble to reproduce problem in the mornings > > because I had a lot of natural light, but it was at evening that I was > > trying to use the camera. So to test it out I turned on a lighter lamp. > > This way it was harder to get the problem, and I only got it when I > > covered the camera focus totally, after that, just a black image like the > > one I used to see remained there. The only difference was a small whitish > > point. > > > > After this I think there's some problem in the light/bright regulation > > mechanish. I think next step is starting to look at the code and see > > where some of this regulation happen, any pointer would be appreciated. > > Now I'm more certain that this is a trouble in the light regulation > mechanism, but I don't know how to get more information from the driver. I > don't know even where the light regulation happens. Is it on driver, on > hardware or in the userspace application by chance (doubtfully this last)? The driver doesn't perform any image processing. What you call light regulation is mostly auto-exposure (and maybe to a lesser extent auto white balance). Your camera doesn't report any exposure-related control in its USB descriptors, so it's not clear if the camera doesn't do any exposure control or if it doesn't allow exposure parameters to be changed. I'd vote for the second option. Userspace applications can also implement all kind of image enhancement algorithms. That's up to the application, and there's no easy way to know what skype does due to its closed-source nature. > My most reliable method to reproduce up to know is being on a very soft > light environment, for example: night with a dim indirect light(12W low > consumption lamp). In this situation you will see the image, but not very > well defined using a regular videoconferencing resolution and frame rate. > Now cover the camera focus completely using your hand, the image will > become totally black and, if the light is not clear enough it will remain > in that state unless you reinitialise the video streaming or use a light > enough light so the brightness regulates automatically to a useful value. That seems to be a bug either in the camera hardware/firmware or in the application. I'd try using the camera with luvcview. If you can reproduce the problem the hardware will be to blame. Otherwise skype will be at fault. > Thanks for your patience, and I still appreciate help and/or pointers. Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
