Hi Laurent, > The SCR value increases with each incoming isochronous packet, so it's not > constant across a video frame.
You are right, but this is the only field having device SOF counter value. It is needed to establish correspondence between device internal clock (STC) and device SOF counter. It is not needed every video frame, in fact, single value should be sufficient assuming we know details about STC and SOF counter period/overflow/reload. Value of PTS is probably not a good alternative for synchronizing two devices, because it would be really surprising to see their internal clocks synchronized. All above concerns only experimental driver, it doesn't have to be a part of final driver. I went through section 5.12 twice and I don't see anything helpful there, in fact it is discouraging. UVC stipulates that compliant devices use Isochronous Asynchronous mode, which means that device internal clock (STC) is free running and doesn't synchronize with USB bus. It is perfectly reasonable, since most users don't care about camera pixel clock being synchronized with USB clock. They care about frame rate being stable and possibly synchronized with audio. It seems that what I described in previous paragraph is the only way to synchronize the device and USB clocks. Cheers, Paul ____________________________________________________________________________________ TV dinner still cooling? Check out "Tonight's Picks" on Yahoo! TV. http://tv.yahoo.com/ _______________________________________________ Linux-uvc-devel mailing list Linux-uvc-devel@lists.berlios.de https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
