On Mon, 2002-12-02 at 09:48, Duncan Haldane wrote: > If you have a USB webcam please let me know what happens if you > disconnect its usb cable while it is streaming images to a v4l viewer > (e.g. xawtv) > > I'm trying to understand what the "normal" behaviour of a USB > v4l1 webcam should be (and what it actually is) > when the usb cable is just yanked out and > the /dev/video<n> it is connected to disappears. The *normal* behavior would be that the /dev/videoN does NOT disappear. Instead, the driver should return a reasonable error code to each and every request, until the application figures out that something is wrong and closes the file handle. > I'm working on maintaining the cpia driver, and this causes a nasty hang of > the v4l application (xawtv, gqcam...) when one tries to close > the app, the app (and the kernel driver) are left in a frozen "busy" state that > can only be cleared by a reboot.... > > The same thing happens when I yank the usb cable of a running ov511 > cam, so its not just a cpia issue.... > (I only have cpia and ov511 cams to test with). > > Do *any* usb v4l1 webcams + apps behave nicely when the cable > is yanked? (I would like to hear about > actual behavior, not just theoretical!) All cameras based on usbvideo should be safe. Dmitri
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