Hi Laurent, hi all 1) In fact I would be interested in a MJPEG camera with more than 1600x1200 resolution. Even if a bit more expensive than usual consumer cameras. The problem I guess is that econding in jpeg requires processing power which is not availble on the low end hardware.
2) Regarding the flip there are a few things to notice a) I implemented mine in the video window just before display (display using SDL) b) I am using a software buffer which is directly given to the driver. The horiz flip is done without copy - in place (in place 4 bytes on each swap operation for yuv422 - byte by byte) which yields something around 800x600x2 bytes swapped. c) I am not using hardware buffers (video memory) as that one is slow reading. Given this when streaming at 800x600 (aprox 10-15 grames/sec never measured it exactly) I get 95% idle processor time and around 93%-94% (with flip activated) on a pentium IV celeron at 2.4Ghz ( a low end machine). The figures don't change when streaming at 1600x1200 as I get half only the frames count/sec anyway which is just about the sama data quantity. Adrian -----Original Message----- From: Laurent Pinchart [mailto:[email protected]] Sent: Thursday, December 18, 2008 1:30 PM To: [email protected] Cc: Adrian Sergiu DARABANT Subject: Re: [Linux-uvc-devel] USB1 support Hi Adrian, On Thursday 18 December 2008, Adrian Sergiu DARABANT wrote: > Also for high resolutions I found that many cameras have higher resolution > in YUV than in MJPEG - 2Mpix you get 1600x1200 in UV and less in MJPEG for > those that support the MJPEG format. Yes that's right. Probably because MJPEG encoders used in webcams can't handle high resolutions. Best regards, Laurent Pinchart _______________________________________________ Linux-uvc-devel mailing list [email protected] https://lists.berlios.de/mailman/listinfo/linux-uvc-devel
