On 22 Feb, this message from Reinoud echoed through cyberspace: > > This may not be the right place to ask, but I have a feeling that the > right expertise may well be in this group... > > The V4L(2) streaming capture to mmap-ed buffers works *great*, > excellent performance and very little CPU overhead. However, I'm > having less luck at the other side: transferring from system memory > to the video card. I can't get X to do DMA transfers; instead, the X > server completely clogs up the CPU doing transfers at video rates. > (Note that I can't use V4L hardware preview, the images have to be > processed). > > At the advice of an XFree guru (of all people), I tried the nvidia > closed-source drivers, as they should have good 2D acceleration. No > luck, no DMA. You may want to have a look at DRI (somewhere on sourceforge, IIRC); they have implemented DMA for some ATI chips (either Rage128 or Radeon). In that case it's the graphics chip fetching data from main memory, not the CPU pushing it. Cheers Michel ------------------------------------------------------------------------- Michel Lanners | " Read Philosophy. Study Art. 23, Rue Paul Henkes | Ask Questions. Make Mistakes. L-1710 Luxembourg | email mlan@xxxxxx | http://www.cpu.lu/~mlan | Learn Always. "
