"Robert D." wrote: > I'm trying to get video capture from all 4 inputs of a bttv > card simultanously ( multiplexed). I've been doing this under > FreeBSD/OpenBSD following way: > > switch_input(0) > capture_frame(0) > ... > ... > ... > switch_input(3) > capture_frame(3) > > This works ok, although the 25fps dives to 2-3fps with all 4 inputs > capturing. I've got pthreaded mmaped capture going under Linux and I'm > wondering how I should go about this input switching problem? > Is there a better way to archive this under Linux? I'm gonna test this > method tonight: > This is a hardware problem. not a software one the bttv chip have one reader for pictures and thats it. The bttv does have 4 inputs for reading but these input are multiplexed in front of the reader. Sory, but if you wont to capture all 4 chanels you need 4 cards. Anders Gnistrup > > [background capture thread] > VIDEOCSYNC( buffer# ) //wait for imaged to be captured > memcpy from mmaped region to my_buffer[input#] > VIDIOCSTUNER( next input# ) > VIDEOCCAPTURE //async grab frame into next buffer > > Is there any voodoo-magic/c that I can do to get linux to sync to the > inputs faster? > > Would using VIDEO_CAPTURE_ODD or VIDEO_CAPTURE_EVEN and recording > < 300 lines speed this up. I've tried it under FreeBSD with out any > extra speed. > > I've noticed some refereces to 50/60fps capture in the Brooktree specs and > in the FreeBSD/OpenBSD drivers. Would I need to use some special cameras > with external sync signals to get this magical speed? > > What extra capabilites does v4l2 for Bt878? Apart from the great API > cleanup I can't really tell. > > _______________________________________________ > Video4linux-list mailing list > Video4linux-list@xxxxxxxxxx > https://listman.redhat.com/mailman/listinfo/video4linux-list
