Hi Jiri, Jiri Slaby a ?crit : > On 09/28/2007 02:13 PM, Bertrik Sikken wrote: > >> Hi all, >> >> A couple of years ago I worked on getting some webcams working >> with Linux. To be honest, I was unpleasantly surprised. >> There seems to be a lack of direction on how webcams >> are even supposed to be supported. >> >> The problem is that many USB webcams send raw 'bayer' sensor >> data in a compressed form to the PC in order to get reasonable >> frames-per-second over a full-speed (12 Mb/s) USB connection >> AFAIK, the linux kernel developers decided that is was no longer >> allowed to do decompression and bayer format conversion in the kernel. >> > > Exactly. > > >> Some ideas: >> * create a user-space library for webcams that reads the compressed >> data from a v4l(2) device file, decompresses and unbayers it, >> then exposes it through a standard API to applications. >> > > This idea is already in progress: v4l library. [Needed also for stk11xx (only in > -mm due to not having yet another bayer->rgb conversion in the kernel) and > usbvision (in v4l yet).] > > Thierry Merle <thierry.merle at free.fr>: > http://thierry.merle.free.fr/v4l2_extension/general.html > > regards, > Thanks for pointing it. The spec has moved on linuxtv: http://www.linuxtv.org/v4lwiki/index.php/V4L2UserspaceLibrary The code skeleton is not yet finished but advancing slowly. If you do not understand something in the spec, please tell me. It is perfectible I am sure. The basic idea to have a basic driver that would provide compressed video frames, and a virtual driver (the v4l extended driver) that would uncompress these videoframes with the help of a userspace daemon. I am currently writing the userspace daemon interface, this corresponds to the step 'Control the hardware' in the spec. Cheers, Thierry
