On Tuesday 12 December 2006 10:14 am, Zhang Daniel wrote: > Hi, > I am trying to run two cameras in YUV 640x480 30 fps in Linux. The first > one is running correctly. But the second one always fails with "NO SPACE" > error.
The measure relevant to USB is not "YUV @size [but no bitwidth] @fps", but is instead the size and frequency of the isochronous transfer. A "cat /proc/bus/usb/devices" while running one camera should show which altsetting is active, and isochronous endpoint config it uses. > I was told this is bandwidth issue. But why they can work run under Windows > XP. > > I am curious if there is something different bandwidth allocation mechanism > between Windows and Linux. Or there is one silver bullets (some patch > somewhere?). First place to look is the driver you're using. Driver bugs have been known to happen... However, there is a USB 2.0 spec inconsistency in this area. From memory, the issue is that two high bandwidth ISO transfers (24 KB/msec) exceed the amount of bandwidth reserved for periodic transfers (80%) ... yet one spot in the spec says that two such transfers ought to work. - Dave ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
