At 09:35 PM 8/9/2002 -0700, you wrote: >It does not, indeed. It had been decided that a v4l driver should only >produce the stream in one format, preferrably closest to the native device >format (palette). A driver must not convert palettes - this is difficult >to do in kernel space, awkward to do without FPU, makes the driver much >more complicated and crash-prone, and pollutes the kernel space with >similar-but-different pieces of conversion code (in each driver).
I'm not sure I agree that this is necessarily awkward without FPU. Every webcam I've seen scans images through a Bayer (or similar) pattern matrix of RGB filters sitting in front of a CMOS image sensor. The hardware on the camera does the Bayer RGB->YUV/Planar/etc conversion. Chances are the embedded microcontroller is using integer arithmetic since the silicon cost of an integer unit is much less than a floating point unit. Reversing the process with integer arithmetic to get RGB back shouldn't be the impossible proposition many here seem to think it is. >The ibmcam driver produces BGR24 - this is almost the native format in >many IBM/Xirlink cameras. > >It is gnomemeeting's responsibility to take one of standard formats and >make use of it. xawtv, for example, does exactly that. I know from experience making my own driver work with everything that with several applications (such as gnomemeeting), if they call VIDIOCSPICT with a palette type you do not support and you do not return -EINVAL (saying, NO you can't have that palette) they will NOT work. A cursory glance at the drivers/usb/usbvideo.c seems to indicate that apps doing this speculative palette request will not work with any minidriver unless the first palette requested happens to be the native one of the hardware. >If gnomemeeting can be configured for BGR24, then it should work. Couple >of years ago I wrote a patch for voxilla (openH.323 client) to accept >BGR24, and the patch is still somewhere on http://www.linux-usb.org. My 3comhc driver can decode to BGR24 (it defaults to RGB24), and it works with gnomemeeting. _______________________________________________ Video4linux-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/video4linux-list
