Hi, On Wednesday 31 March 2010 12:37:36 Gallon Fr wrote: > 2010/3/30 Paulo Assis <pj.as...@gmail.com> > > >> > usb 1-1: new full speed USB device using s3c2410-ohci and address 5 > > > > I think this explains why you only have MJPG on the ARM board. > > YUYV requires a higher bandwidth, so it's only available in usb2. > > > > But MJPG should also be available with usb2 and from what I understand > > you only have YUYV ? > > If this is true then its a bit strange. > > > > Best regards, > > Paulo > > I've confirmed that I can ONLY use "YUYV" format on PC, "MJPG" will end up > with an error.
It's weird, but not unusual. There's no technical reason not to provide MJPEG on high-speed USB (USB 2.0). There could be a marketing reason though: MJPEG being compressed, it will produce lower quality images than YUYV (although with the bad sensors found on most webcams that doesn't really matter). The vendor might not want customers seeing lower quality images when "higher" quality is available. > Then I test another cam embedded in my laptop (04f2:b13e from Chicony).I > don't want to mix up the two cam,so just call the "PC Cam" and the "Laptop > Cam". > ---------------------------------------------------------- > result of Laptop Cam (just make sense as you say) > It says: > Index:0 Format:YUV 4:2:2 (YUYV) > Index:1 Format:MJPEG > ---------------------------------------------------------- > result of PC Cam on PC > It says: > Index:0 Format:YUV 4:2:2 (YUYV) > ---------------------------------------------------------- > result of PC Cam on laptop > It says: > Index:0 Format:YUV 4:2:2 (YUYV) > ---------------------------------------------------------- > result of PC Cam on ARM > It says: > Index=0 Format:MJPEG > ---------------------------------------------------------- > Do this mean the PC cam don't work well with the UVC driver?It seem I can > only choose one format, no matter on USB1.1 or USB2.0. It just means that it only exposes a single format (YUYV) on USB 2.0 for whatever reason the vendor came up with during development. The camera otherwise works. -- Regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
