Hi Florian, On Tuesday 14 September 2010 12:14:04 Florian Echtler wrote: > > > The webcam sends a frame at high speed and then waits a (relatively) > > > long time before sending the next frame. > > > > > >> *A possible solution* ? > > >> > > >> Instead, could the UVC driver 'simulate' a reduced framerate by > > >> instead using the "STILL_IMAGE_FRAME" mode of the webcam and grab for > > >> itself a set number of images per second? Or even only when polled by > > >> a read from the user application? > > > > > > Still image capture isn't supported yet. The reason is that most > > > webcams just ask the driver to take the next picture in the video > > > stream to emulate still image capture. Very few cameras support > > > out-of-band still image capture, and I don't own any that support > > > that. > > > > That's quite a shame... And very wasteful of bandwidth. > > A few days ago, I posted a very rough patch for preliminary still image > support. According to the descriptors you attached, your camera actually > supports still image capture method 2, which is the "true" one.
Just for the sake of completeness, methods 2 and 3 are the "true" ones. Method 0 is "no still image capture supported", and method 1 just asks the host to capture the next image in the active video stream. > Right now, with this patch, it is necessary to start and stop the stream > before and after each picture; I assume ffmpeg should do this if you ask > it to capture exactly 1 frame. > > So if you are feeling curious, you could give my patch a try; I'd be > quite interested in some experience reports. I'll review the patch :-) -- Regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
