On Wed, 18 Oct 2006, Rumjantsev Egor wrote: > Sorry if i explained badly for understanding. My English isn't good enough.
Your English is pretty good. > When i started video stream from camera data transfers frame per frame. > Each frame has a frame marker. It transfers in the first word of each > frame. When i told that video data is lost i meant that after few > seconds i found the frame marker not in the first word of the frame but > with some offset. It means that some data from current frame were lost. Or extra data were inserted. > But all urb returned with right value of data that i wanted to read. I think you mean that the URBs returned the right _amount_ of data? > The situation that i described appears when i call 1-2 times per second > usb_control_msg to ask camera about it internal state. If i don't call > this function all works fine and the frame marker is placed in right > position. > So i don't understand where is mistake is taken place. If we see from > point of view of urb - all urb returned right value of size and we > shouldn't raise any claims. The most interesting thing for me how the > data can disappear completely but i use the bulk mode so this mode > promise guarantee of delivery all data. That's right. The only reason the data could disappear is because the camera didn't send it. > >> I receive data with 4 urb in queue. I tried to change the size of urb > >> (4096...61440 bytes) but it didn't help - the data is lost > >> So i'd like to know why this happened. I understand that usb_control_msg > >> isn't finished until its callback function not called or timeout is not > >> finished but i though that data receive process not freeze in that moment. > >> I use Mandriva 2006; Kernel version 2.6.13.5 > >> > > > > Maybe the camera doesn't like to handle control messages while it is > > transferring video data. > > > > > There is driver for Windows where all works normally and control > messages also sending in the moment of transferring data without loosing > of data. Maybe the Windows driver is careful to transfer the control messages only when the bulk data stream is between frames. Maybe the camera doesn't like to handle control messages while it's in the middle of sending a frame. Have you tried doing this with Linux 2.6.18? Alan Stern ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
