¼ÛÈ£»ó wrote: > > > "Gleicon S. Moraes" wrote: > > > > > Hi all. > > > Ben Bridgwater sent to me some source code for capture, overlay, etc, > > > etc. > > > > > > To read the README for this tarball: > > > http://planeta.terra.com.br/informatica/gleicon/video4linux/README > > > > > > To get the source code: > > > http://planeta.terra.com.br/informatica/gleicon/video4linux/v4ldemos.tar.gz > > > > Yes, it works well for me. > I'm using bttv driver and tested vidrgb. ( NTSC ) > > Speed is about( :-< ) 15~20 fps. absolutely not exact. > If using overlay for display( not mmap and mcapture etc. ), it could be better I think. Yes, overlay will give you a better frame rate on slower hardware. I wasn't interested in that myself because I'm more interested in image recognition type stuff. If you consider a full 640x480x32bpp 30fpb capture, thats over 36MB/sec(!) being moved from the capture card to app. memory (hopefully acrosss the PCI bus, not ISA or USB!), being copied by the app, to MITSHM X memory, then from X to the video memory. If you don't have MITSHM then that's another copy. Now bear in mind that the PCI bus only does 132MB max, and you're goiing to get contention well below that. The poor north bridge is getting hit pretty hard too on those memory transfers. This is all not even sonsidering the CPU doing all those transfers, color space conversions etc, plus the X server sucking up a few cycles.. I'm using a PCI based graphics card, and I expect that an upgrade to a system with AGP would help a lot by moving the display writes off the PCI bus where they're contending with the capture transfers. Bottom line is that you need to have a pretty high performance well tuned system to get max. capture rates. Anyway - glad it's working for you. Ben
